fixes #4 Statistics support

This introduces new public APIs for obtaining statistics,
and adds some generic stats for dialers, listeners, pipes, and
sockets.  Also added are stats for inproc and pairv1 protocol.

The other protocols and transports will have stats added
incrementally as time goes on.

A simple test program, and man pages are provided for this.
Start by looking at nng_stat(5).

Statistics does have some impact, and they can be disabled by
using the advanced NNG_ENABLE_STATS (setting it to OFF, it's
ON by default) if you need to build a minimized configuration.

38 files changed, 2325 insertions, 186 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ee05c64b..3042be38 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -120,6 +120,12 @@ if (NNG_ENABLE_HTTP)
 endif()
 mark_as_advanced(NNG_ENABLE_HTTP)
 
+option (NNG_ENABLE_STATS "Enable statistics" ON)
+if (NNG_ENABLE_STATS)
+    add_definitions(-DNNG_ENABLE_STATS)
+endif()
+mark_as_advanced(NNG_ENABLE_STATS)
+
 option (NNG_PROTO_BUS0 "Enable BUSv0 protocol." ON)
 if (NNG_PROTO_BUS0)
     add_definitions (-DNNG_HAVE_BUS0)
@@ -363,10 +369,10 @@ elseif (CMAKE_SYSTEM_NAME MATCHES "Windows")
 
 elseif (CMAKE_SYSTEM_NAME MATCHES "QNX")
     add_definitions (-DNNG_PLATFORM_POSIX)
-    add_definitions (-D__EXT_BSD)    
+    add_definitions (-D__EXT_BSD)
     add_definitions (-D_QNX_SOURCE)
     add_definitions (-DNNG_PLATFORM_QNX)
-    set(NNG_PLATFORM_POSIX ON)   
+    set(NNG_PLATFORM_POSIX ON)
 
 else ()
     message (AUTHOR_WARNING "WARNING: This platform may not be supported: ${CMAKE_SYSTEM_NAME}")
diff --git a/docs/man/CMakeLists.txt b/docs/man/CMakeLists.txt
index 21651ba5..e39f2da3 100644
--- a/docs/man/CMakeLists.txt
+++ b/docs/man/CMakeLists.txt
@@ -151,6 +151,17 @@ if (NNG_ENABLE_DOC)
 	nng_setopt
 	nng_sleep_aio
 	nng_socket_id
+	nng_stats_free
+	nng_stats_get
+	nng_stat_child
+	nng_stat_desc
+	nng_stat_name
+	nng_stat_next
+	nng_stat_string
+	nng_stat_timestamp
+	nng_stat_type
+	nng_stat_unit
+	nng_stat_value
 	nng_strdup
 	nng_strerror
 	nng_strfree
@@ -305,6 +316,7 @@ if (NNG_ENABLE_DOC)
 	nng_sockaddr_ipc
 	nng_sockaddr_zt
 	nng_socket
+	nng_stat
     )
 
     set(NNG_MAN7
diff --git a/docs/man/libnng.3.adoc b/docs/man/libnng.3.adoc
index 3e3037f9..299b73ef 100644
--- a/docs/man/libnng.3.adoc
+++ b/docs/man/libnng.3.adoc
@@ -222,6 +222,25 @@ concurrent applications.
 |<<nng_ctx_setopt.3#,nng_ctx_setopt()>>|set context option
 |===
 
+=== Statistics
+
+The following functions provide access to statistics which can be used
+to observe program behaviors and as an aid in troubleshooting.
+
+|===
+|<<nng_stat_child.3#,nng_stat_child()>>|get child statistic
+|<<nng_stat_desc.3#,nng_stat_name()>>|get statistic description
+|<<nng_stat_name.3#,nng_stat_name()>>|get statistic name
+|<<nng_stat_next.3#,nng_stat_next()>>|get next statistic
+|<<nng_stat_string.3#,nng_stat_string()>>|get statistic string value
+|<<nng_stat_timestamp.3#,nng_stat_timestamp()>>|get statistic timestamp
+|<<nng_stat_type.3#,nng_stat_type()>>|get statistic type
+|<<nng_stat_unit.3#,nng_stat_unit()>>|get statistic unit
+|<<nng_stat_value.3#,nng_stat_valueg()>>|get statistic value
+|<<nng_stats_free.3#,nng_stats_free()>>|free statistics
+|<<nng_stats_get.3#,nng_stats_get()>>|get statistics
+|===
+
 === URL Object
 
 Common functionality is supplied for parsing and handling
diff --git a/docs/man/nng_msg.5.adoc b/docs/man/nng_msg.5.adoc
index 45b04e03..69789560 100644
--- a/docs/man/nng_msg.5.adoc
+++ b/docs/man/nng_msg.5.adoc
@@ -44,15 +44,6 @@ automatic data conversion, and removing data from the beginning or end.
 These functions are designed to try to avoid copying message contents
 by making use of scratch areas at the beginning and end of the message.
 
-== RETURN VALUES
-
-This function returns 0 on success, and non-zero otherwise.
-
-== ERRORS
-
-[horizontal]
-`NNG_ENOMEM`:: Insufficient free memory exists to allocate a message.
-
 == SEE ALSO
 
 [.text-left]
diff --git a/docs/man/nng_stat.5.adoc b/docs/man/nng_stat.5.adoc
new file mode 100644
index 00000000..8c8a5746
--- /dev/null
+++ b/docs/man/nng_stat.5.adoc
@@ -0,0 +1,78 @@
+= nng_socket(5)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat - statistic
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+----
+
+== DESCRIPTION
+
+An `nng_stat`(((statistic))) represents a statistic.
+All statistics have names (`<<nng_stat_name.3#,nng_stat_name()>>`) and
+descriptions (`<<nng_stat_desc.3#,nng_stat_desc()>>`), and are
+typed (`<<nng_stat_type.3#,nng_stat_type()>>`).
+
+Most statistics are numeric,
+and thus carry a value (`<<nng_stat_value.3#,nng_stat_value()>>`)
+and frequently also a unit that the value measures (`<<nng_stat_unit.3#,nng_stat_unit()>>`).
+
+Some statistics however, are simply strings (`<<nng_stat_string.3#,nng_stat_string()>>`),
+and thus carry no numeric value.
+
+Statistics are organized as a tree, and any given statistic can have siblings
+(`<<nng_stat_next.3#,nng_stat_next()>>`).
+Note however that generally only `NNG_STAT_SCOPE` statistics, which are
+act as placeholders in the tree (and carry no value),
+will have children (`<<nng_stat_child.3#,nng_stat_child()>>`).
+
+A tree of statistics is collected using `<<nng_stats_get.3#,nng_stats_get()>>`,
+and can be freed when no longer needed with `<<nng_stats_free.3#,nng_stats_free()>>`.
+This collection process is generally performed in a way to minimize impact
+to running operations, but there is still some impact caused by collection
+of statistics.
+
+The time when a statistic`'s value is captured can be obtained using
+`<<nng_stat_timestamp.3#,nng_stat_timestap()>>`, which is useful for
+measuring rates of change in certain statistics.
+
+NOTE: The presence, names, and meanings of any given statistic are
+subject to change at any time. These statistics are provided as an aid
+for debugging, and should generally not be relied upon for programmatic
+behaviors.
+
+NOTE: Statistics may be disabled by build-time configuration options,
+in order to reduce program size and run-time overheads.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stats_free.3#,nng_stats_free(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat_child.3#,nng_stat_child(3)>>,
+<<nng_stat_desc.3#,nng_stat_desc(3)>>,
+<<nng_stat_name.3#,nng_stat_name(3)>>,
+<<nng_stat_next.3#,nng_stat_next(3)>>,
+<<nng_stat_string.3#,nng_stat_string(3)>>,
+<<nng_stat_timestamp.3#,nng_stat_timestamp(3)>>,
+<<nng_stat_type.3#,nng_stat_type(3)>>,
+<<nng_stat_unit.3#,nng_stat_unit(3)>>,
+<<nng_stat_value.3#,nng_stat_value(3)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_child.3.adoc b/docs/man/nng_stat_child.3.adoc
new file mode 100644
index 00000000..c77e7135
--- /dev/null
+++ b/docs/man/nng_stat_child.3.adoc
@@ -0,0 +1,51 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_child - get child statistic
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+nng_stat *nng_stat_child(nng_stat *parent);
+----
+
+== DESCRIPTION
+
+The `nng_stat_child()` function returns the first child statistic of the
+statistic _parent_.
+If no children are present, then `NULL` is returned.
+
+TIP: Only statistics with type (see `<<nng_stat_type.3#,nng_stat_type()>>`)
+of `NNG_STAT_SCOPE` will have children.
+
+== RETURN VALUES
+
+The first child statistic of _parent_, or NULL if _parent_ has no children.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stat_next.3#,nng_stat_next(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_desc.3.adoc b/docs/man/nng_stat_desc.3.adoc
new file mode 100644
index 00000000..3f184366
--- /dev/null
+++ b/docs/man/nng_stat_desc.3.adoc
@@ -0,0 +1,52 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_desc - get statistic description
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+const char *nng_stat_desc(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_desc()` function returns a brief, human-readable description
+for the statistic _stat_.
+
+TIP: This description can be used for a tool-tip in user interfaces
+displaying these statistic values.
+
+NOTE: At this time, only English descriptions are provided.
+
+== RETURN VALUES
+
+The description of statistic _stat_.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stat_name.3#,nng_stats_name(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_name.3.adoc b/docs/man/nng_stat_name.3.adoc
new file mode 100644
index 00000000..aaf854f5
--- /dev/null
+++ b/docs/man/nng_stat_name.3.adoc
@@ -0,0 +1,47 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_name - get statistic name
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+const char *nng_stat_name(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_name()` function returns the name for the statistic _stat_.
+
+NOTE: The global root statistic will have the empty string ("") as it`'s name.
+
+== RETURN VALUES
+
+The name of statistic _stat_.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_next.3.adoc b/docs/man/nng_stat_next.3.adoc
new file mode 100644
index 00000000..d2ae24a4
--- /dev/null
+++ b/docs/man/nng_stat_next.3.adoc
@@ -0,0 +1,48 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_next - get next statistic
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+nng_stat *nng_stat_next(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_next()` function returns the next sibling statistic of the
+statistic _stat_.
+If no more siblings are present, then `NULL` is returned.
+
+== RETURN VALUES
+
+The next sibling statistic of _stat_, or NULL if _stat_ is the last sibling.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stat_child.3#,nng_stat_child(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_string.3.adoc b/docs/man/nng_stat_string.3.adoc
new file mode 100644
index 00000000..9f44b5b7
--- /dev/null
+++ b/docs/man/nng_stat_string.3.adoc
@@ -0,0 +1,51 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_string - get statistic string value
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+const char *nng_stat_string(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_string()` function returns a string value for the statistic _stat_,
+which must be of type `NNG_STAT_STRING` (see `<<nng_stat_type.3#,nng_stat_type(3)>>`).
+
+If the statistic is not of type `NNG_STAT_STRING`, then `NULL` will be returned.
+
+== RETURN VALUES
+
+The string value associated with _stat_, or `NULL` if the statistic is not
+a string type.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat_type.3#,nng_stats_type(3)>>,
+<<nng_stat_value.3#,nng_stats_value(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_timestamp.3.adoc b/docs/man/nng_stat_timestamp.3.adoc
new file mode 100644
index 00000000..f23d8720
--- /dev/null
+++ b/docs/man/nng_stat_timestamp.3.adoc
@@ -0,0 +1,60 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_timestamp - get statistic timestamp
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+uint64_t nng_stat_timestamp(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_timestamp()` function returns the a timestamp, which is measured
+as a number of milliseconds since some arbitrary value in the past.
+
+Even within the same snapshot, statistics might have different timestamp
+values, as the timestamp represents the time when that particular statistic
+was captured.
+
+TIP: These values are intended to facilitate calculation of rates, by
+comparing values from one snapshot with a subsequent one.
+
+TIP: The values used here have the same offset as the
+`<<nng_clock.3supp#,nng_clock()>>` supplementation function.
+This can be useful when converting these values to local clock time.
+
+== RETURN VALUES
+
+The timestamp when _stat_ was captured, measured as a number of
+milliseconds since some time in the past.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat_value.3#,nng_stat_value(3)>>,
+<<nng_clock.3supp#,nng_clock(3supp)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_type.3.adoc b/docs/man/nng_stat_type.3.adoc
new file mode 100644
index 00000000..d1b1586d
--- /dev/null
+++ b/docs/man/nng_stat_type.3.adoc
@@ -0,0 +1,95 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_value - get statistic value
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+enum {
+        NNG_STAT_SCOPE,
+        NNG_STAT_LEVEL,
+        NNG_STAT_COUNTER,
+        NNG_STAT_STRING,
+        NNG_STAT_BOOLEAN,
+        NNG_STAT_ID
+};
+
+int nng_stat_type(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_type()` function returns the type of the statistic _stat_.
+
+The returned type will be one of the following values:
+
+((`NNG_STAT_SCOPE`))::
+This is a placeholder providing scope, and carries no value on it's own.
+Instead it is a parent node with child statistics (see
+`<<nng_stat_child.3#,nng_stat_child()>>`.)
+
+((`NNG_STAT_LEVEL`))::
+This is a numeric statistic, but it's value is a level, so rate calculations
+based on changes in this value should not be considered significant.
+
+((`NNG_STAT_COUNTER`))::
+This is a numeric statistic that represents an increasing count, typically
+of events, messages, or bytes.
+Frequently, it is interesting to consider changes in this statistic divided
+by time to obtain a rate.
+(For example, throughput might be calculated as changes in a byte counter
+divided by the interval over which the change occurred.)
+
+((`NNG_STAT_STRING`))::
+This is a string, and carries no numeric value.
+Instead the `<<nng_stat_string.3#,nng_stat_string(3)>>` function
+should be used to obtain the value.
+
+((`NNG_STAT_BOOLEAN`))::
+This is a boolean value.
+The `<<nng_stat_value.3#,nng_stat_value()>>` function will return zero
+to represent a `false` value, and one to represent a `true` value.
+
+((`NNG_STAT_ID`)):
+The statistic is a numeric ID.
+These are generally immutable values that represent an identity that might
+be used with another interface.
+
+TIP: For `NNG_STAT_COUNTER` and `NNG_STAT_LEVEL` statistics, the
+`<<nng_stat_unit.3#,nng_stat_unit()>>` function will provide more
+detail about the units measured by the static.
+
+== RETURN VALUES
+
+The statistic type for _stat_.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat_string.3#,nng_stat_string(3)>>,
+<<nng_stat_unit.3#,nng_stat_unit(3)>>,
+<<nng_stat_value.3#,nng_stat_value(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_unit.3.adoc b/docs/man/nng_stat_unit.3.adoc
new file mode 100644
index 00000000..cb9bb7cf
--- /dev/null
+++ b/docs/man/nng_stat_unit.3.adoc
@@ -0,0 +1,86 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_value - get statistic value
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+enum {
+        NNG_UNIT_NONE,
+        NNG_UNIT_BYTES,
+        NNG_UNIT_MESSAGES,
+        NNG_UNIT_MILLIS,
+        NNG_UNIT_EVENTS
+};
+
+int nng_stat_unit(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_unit()` function returns the unit of quantity measured
+by the statistic _stat_.
+
+The returned value will be one of the following values:
+
+((`NNG_UNIT_NONE`))::
+There are no particular units measured.
+In some cases there may be units, but the type of the unit will be obvious
+from the name (see `<<nng_stat_name.3#,nng_stat_name()>>`) of the statistic.
+
+((`NNG_UNIT_BYTES`))::
+The statistic is a count of bytes.
+
+((`NNG_UNIT_MESSAGES`))::
+The statistic is a count of messages.
+Typically, one message corresponds to a single `<<nng_msg.5#,nng_msg>>` structure.
+
+((`NNG_UNIT_MILLIS`))::
+The statistic is a count of milliseconds.
+
+((`NNG_STAT_EVENTS`))::
+The statistic is a count of some other type of event.
+
+For statistics that are neither `NNG_STAT_COUNTER` nor `NNG_STAT_LEVEL`
+type (see `<<nng_stat_type.3#,nng_stat_type()>>`), the unit will
+generally be `NNG_UNIT_NONE`.
+
+TIP: Normally rates can be calculated for `NNG_STAT_COUNTER` values for
+any of these units, but for `NNG_UNIT_MILLIS` rate calculations are generally
+meaningless.
+
+== RETURN VALUES
+
+The units measured by _stat_.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat_name.3#,nng_stat_name(3)>>,
+<<nng_stat_type.3#,nng_stat_type(3)>>,
+<<nng_stat_value.3#,nng_stat_value(3)>>,
+<<nng_msg.5#,nng_msg(5)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stat_value.3.adoc b/docs/man/nng_stat_value.3.adoc
new file mode 100644
index 00000000..2864ba30
--- /dev/null
+++ b/docs/man/nng_stat_value.3.adoc
@@ -0,0 +1,51 @@
+= nng_version(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stat_value - get statistic value
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+uint64_t nng_stat_string(nng_stat *stat);
+----
+
+== DESCRIPTION
+
+The `nng_stat_value()` function returns a numeric value for the statistic _stat_.
+If the statistic has a boolean value, then zero is returned for `false`, and
+one is returned for `true`.
+Otherwise, if the string is not of numeric type, then zero is returned.
+See `<<nng_stat_type.3#,nng_stat_type(3)>>` for a description of statistic types.
+
+== RETURN VALUES
+
+The numeric or boolean value associated with _stat_.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<libnng.3#,libnng(3)>>,
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat_type.3#,nng_stat_type(3)>>,
+<<nng_stat_unit.3#,nng_stat_unit(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stats_free.3.adoc b/docs/man/nng_stats_free.3.adoc
new file mode 100644
index 00000000..3b5c7457
--- /dev/null
+++ b/docs/man/nng_stats_free.3.adoc
@@ -0,0 +1,51 @@
+= nng_free(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stats_free - free statistics snapshot
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef nng_stat nng_stat;
+
+void nng_stats_free(nng_stat *);
+----
+
+== DESCRIPTION
+
+The `nng_stats_free()` function deallocates a statistics snapshot
+previously collected with
+`<<nng_stats_get.3#,nng_stats_get()>>`.
+After calling this, all values associated with the snapshot are
+invalidated.
+
+IMPORTANT: Only the top of the collected statistics tree can be
+freed using this function.
+
+== RETURN VALUES
+
+None.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+<<nng_stats_get.3#,nng_stats_get(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/docs/man/nng_stats_get.3.adoc b/docs/man/nng_stats_get.3.adoc
new file mode 100644
index 00000000..caf91dc3
--- /dev/null
+++ b/docs/man/nng_stats_get.3.adoc
@@ -0,0 +1,86 @@
+= nng_alloc(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_stats_get - get statistics snapshot
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+typedef struct nng_stat nng_stat;
+
+int nng_stats_get(nng_stat *statsp)
+----
+
+== DESCRIPTION
+
+The `nng_stat_get()` function attempts to obtain a snapshot of all the
+various diagnostic statistics that are present in the system.
+
+NOTE: The process of collecting statistics is designed to have minimal
+impact on the system, but there is still some impact.
+
+The statistics are organized as a tree, rooted with a parent
+statistic of type `NNG_STAT_SCOPE` that carries no value, and which
+has an empty name.
+This parent statistic is returned through the _statsp_ pointer.
+
+The `<<nng_stat_child.3#,nng_stat_child()>>` and
+`<<nng_stat_next.3#,nng_stat_next()>>` function can be used to
+iterate over the the tree.
+
+When no longer needed, the statistics can be freed with the
+`<<nng_stats_free.3#,nng_stats_free()>>` function, but that
+function must be called only with the root statistic that is returned
+through the _statsp_ pointer.
+
+NOTE: The values of individual statistics are guaranteed to be atomic,
+but due the way statistics are collected there can be discrepancies between them at certain times.
+For example, statistics counting bytes and messages received may not
+reflect the same number of messages, depending on when the snapshot is taken.
+This potential inconsistency arises as a result of optimizations to minimize
+the impact of statistics on actual operations.
+
+NOTE: The names, values, and semantics of statistics provided may change
+from release to release.
+These are provided for informational and debugging use only, and applications
+should not rely on the presence, names, or meanings of any individual statistics.
+
+== RETURN VALUES
+
+This function returns a pointer to the allocated memory on success,
+and `NULL` otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_ENOMEM`:: Insufficient free memory to collect statistics.
+`NNG_ENOTSUP`:: Statistics are not supported (compile time option).
+
+== SEE ALSO
+
+[.text-left]
+<<nng_stats_free.3#,nng_stats_free(3)>>,
+<<nng_stat_child.3#,nng_stat_child(3)>>,
+<<nng_stat_desc.3#,nng_stat_desc(3)>>,
+<<nng_stat_name.3#,nng_stat_name(3)>>,
+<<nng_stat_next.3#,nng_stat_next(3)>>,
+<<nng_stat_string.3#,nng_stat_string(3)>>,
+<<nng_stat_type.3#,nng_stat_type(3)>>,
+<<nng_stat_timestamp.3#,nng_stat_timestamp(3)>>,
+<<nng_stat_unit.3#,nng_stat_unit(3)>>,
+<<nng_stat_value.3#,nng_stat_value(3)>>,
+<<nng_stat.5#,nng_stat(5)>>,
+<<nng.7#,nng(7)>>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 14894db8..305922db 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -70,6 +70,8 @@ set (NNG_SOURCES
     core/reap.h
     core/socket.c
     core/socket.h
+    core/stats.c
+    core/stats.h
     core/strs.c
     core/strs.h
     core/taskq.c
diff --git a/src/core/dialer.c b/src/core/dialer.c
index 00ebb513..11faed7c 100644
--- a/src/core/dialer.c
+++ b/src/core/dialer.c
@@ -23,6 +23,8 @@ static void dialer_timer_cb(void *);
 static nni_idhash *dialers;
 static nni_mtx     dialers_lk;
 
+#define BUMPSTAT(x) nni_stat_inc_atomic(x, 1)
+
 int
 nni_dialer_sys_init(void)
 {
@@ -32,8 +34,7 @@ nni_dialer_sys_init(void)
 		return (rv);
 	}
 	nni_mtx_init(&dialers_lk);
-	nni_idhash_set_limits(
-	    dialers, 1, 0x7fffffff, nni_random() & 0x7fffffff);
+	nni_idhash_set_limits(dialers, 1, 0x7fffffff, 1);
 
 	return (0);
 }
@@ -70,6 +71,55 @@ nni_dialer_destroy(nni_dialer *d)
 	NNI_FREE_STRUCT(d);
 }
 
+static void
+dialer_stats_init(nni_dialer *d)
+{
+	nni_dialer_stats *st   = &d->d_stats;
+	nni_stat_item *   root = &st->s_root;
+
+	nni_stat_init_scope(root, st->s_scope, "dialer statistics");
+
+	nni_stat_init_id(&st->s_id, "id", "dialer id", d->d_id);
+	nni_stat_append(root, &st->s_id);
+
+	nni_stat_init_id(&st->s_sock, "socket", "socket for dialer",
+	    nni_sock_id(d->d_sock));
+	nni_stat_append(root, &st->s_sock);
+
+	nni_stat_init_string(
+	    &st->s_url, "url", "dialer url", d->d_url->u_rawurl);
+	nni_stat_append(root, &st->s_url);
+
+	nni_stat_init_atomic(&st->s_npipes, "npipes", "open pipes");
+	nni_stat_append(root, &st->s_npipes);
+
+	nni_stat_init_atomic(&st->s_connok, "connok", "connections made");
+	nni_stat_append(root, &st->s_connok);
+
+	nni_stat_init_atomic(
+	    &st->s_canceled, "canceled", "connections canceled");
+	nni_stat_append(root, &st->s_canceled);
+
+	nni_stat_init_atomic(&st->s_refused, "refused", "connections refused");
+	nni_stat_append(root, &st->s_refused);
+
+	nni_stat_init_atomic(
+	    &st->s_timedout, "timedout", "connections timed out");
+	nni_stat_append(root, &st->s_timedout);
+
+	nni_stat_init_atomic(
+	    &st->s_othererr, "othererr", "other connection errors");
+	nni_stat_append(root, &st->s_othererr);
+
+	nni_stat_init_atomic(
+	    &st->s_protorej, "protoreject", "pipes rejected by protocol");
+	nni_stat_append(root, &st->s_protorej);
+
+	nni_stat_init_atomic(
+	    &st->s_apprej, "appreject", "pipes rejected by application");
+	nni_stat_append(root, &st->s_apprej);
+}
+
 int
 nni_dialer_create(nni_dialer **dp, nni_sock *s, const char *urlstr)
 {
@@ -110,6 +160,7 @@ nni_dialer_create(nni_dialer **dp, nni_sock *s, const char *urlstr)
 
 	nni_mtx_init(&d->d_mtx);
 
+	dialer_stats_init(d);
 	if (((rv = nni_aio_init(&d->d_con_aio, dialer_connect_cb, d)) != 0) ||
 	    ((rv = nni_aio_init(&d->d_tmo_aio, dialer_timer_cb, d)) != 0) ||
 	    ((rv = d->d_ops.d_init(&d->d_data, url, d)) != 0) ||
@@ -119,6 +170,10 @@ nni_dialer_create(nni_dialer **dp, nni_sock *s, const char *urlstr)
 		return (rv);
 	}
 
+	snprintf(d->d_stats.s_scope, sizeof(d->d_stats.s_scope), "dialer%u",
+	    d->d_id);
+	nni_stat_set_value(&d->d_stats.s_id, d->d_id);
+	nni_stat_append(NULL, &d->d_stats.s_root);
 	*dp = d;
 	return (0);
 }
@@ -167,6 +222,7 @@ nni_dialer_rele(nni_dialer *d)
 	nni_mtx_lock(&dialers_lk);
 	d->d_refcnt--;
 	if ((d->d_refcnt == 0) && (d->d_closed)) {
+		nni_stat_remove(&d->d_stats.s_root);
 		nni_reap(&d->d_reap, (nni_cb) nni_dialer_reap, d);
 	}
 	nni_mtx_unlock(&dialers_lk);
@@ -242,12 +298,33 @@ dialer_connect_cb(void *arg)
 
 	switch ((rv = nni_aio_result(aio))) {
 	case 0:
+		BUMPSTAT(&d->d_stats.s_connok);
 		nni_dialer_add_pipe(d, nni_aio_get_output(aio, 0));
 		break;
 	case NNG_ECLOSED:   // No further action.
 	case NNG_ECANCELED: // No further action.
+		BUMPSTAT(&d->d_stats.s_canceled);
 		break;
+	case NNG_ECONNREFUSED:
+		BUMPSTAT(&d->d_stats.s_refused);
+		if (uaio == NULL) {
+			nni_dialer_timer_start(d);
+		} else {
+			nni_atomic_flag_reset(&d->d_started);
+		}
+		break;
+
+	case NNG_ETIMEDOUT:
+		BUMPSTAT(&d->d_stats.s_timedout);
+		if (uaio == NULL) {
+			nni_dialer_timer_start(d);
+		} else {
+			nni_atomic_flag_reset(&d->d_started);
+		}
+		break;
+
 	default:
+		BUMPSTAT(&d->d_stats.s_othererr);
 		if (uaio == NULL) {
 			nni_dialer_timer_start(d);
 		} else {
@@ -389,3 +466,9 @@ nni_dialer_getopt(
 
 	return (nni_sock_getopt(d->d_sock, name, valp, szp, t));
 }
+
+void
+nni_dialer_add_stat(nni_dialer *d, nni_stat_item *stat)
+{
+	nni_stat_append(&d->d_stats.s_root, stat);
+}
diff --git a/src/core/dialer.h b/src/core/dialer.h
index 361c6d5e..da2cc992 100644
--- a/src/core/dialer.h
+++ b/src/core/dialer.h
@@ -26,5 +26,6 @@ extern int nni_dialer_setopt(
     nni_dialer *, const char *, const void *, size_t, nni_opt_type);
 extern int nni_dialer_getopt(
     nni_dialer *, const char *, void *, size_t *, nni_opt_type);
+extern void nni_dialer_add_stat(nni_dialer *, nni_stat_item *);
 
 #endif // CORE_DIALER_H
diff --git a/src/core/init.c b/src/core/init.c
index c66e54d2..60736fb7 100644
--- a/src/core/init.c
+++ b/src/core/init.c
@@ -27,7 +27,8 @@ nni_init_helper(void)
 	NNI_LIST_INIT(&nni_init_list, nni_initializer, i_node);
 	nni_inited = true;
 
-	if (((rv = nni_taskq_sys_init()) != 0) ||
+	if (((rv = nni_stat_sys_init()) != 0) ||
+	    ((rv = nni_taskq_sys_init()) != 0) ||
 	    ((rv = nni_reap_sys_init()) != 0) ||
 	    ((rv = nni_timer_sys_init()) != 0) ||
 	    ((rv = nni_aio_sys_init()) != 0) ||
@@ -81,6 +82,7 @@ nni_fini(void)
 	nni_timer_sys_fini();
 	nni_taskq_sys_fini();
 	nni_reap_sys_fini(); // must be before timer and aio (expire)
+	nni_stat_sys_fini();
 
 	nni_mtx_fini(&nni_init_mtx);
 	nni_plat_fini();
diff --git a/src/core/listener.c b/src/core/listener.c
index 1fe6faab..135478de 100644
--- a/src/core/listener.c
+++ b/src/core/listener.c
@@ -24,6 +24,8 @@ static void listener_timer_cb(void *);
 static nni_idhash *listeners;
 static nni_mtx     listeners_lk;
 
+#define BUMPSTAT(x) nni_stat_inc_atomic(x, 1)
+
 int
 nni_listener_sys_init(void)
 {
@@ -33,8 +35,7 @@ nni_listener_sys_init(void)
 		return (rv);
 	}
 	nni_mtx_init(&listeners_lk);
-	nni_idhash_set_limits(
-	    listeners, 1, 0x7fffffff, nni_random() & 0x7fffffff);
+	nni_idhash_set_limits(listeners, 1, 0x7fffffff, 1);
 
 	return (0);
 }
@@ -70,6 +71,55 @@ nni_listener_destroy(nni_listener *l)
 	NNI_FREE_STRUCT(l);
 }
 
+static void
+listener_stats_init(nni_listener *l)
+{
+	nni_listener_stats *st   = &l->l_stats;
+	nni_stat_item *     root = &st->s_root;
+
+	nni_stat_init_scope(root, st->s_scope, "listener statistics");
+
+	// NB: This will be updated later.
+	nni_stat_init_id(&st->s_id, "id", "listener id", l->l_id);
+	nni_stat_append(root, &st->s_id);
+
+	nni_stat_init_id(&st->s_sock, "socket", "socket for listener",
+	    nni_sock_id(l->l_sock));
+	nni_stat_append(root, &st->s_sock);
+
+	nni_stat_init_string(
+	    &st->s_url, "url", "listener url", l->l_url->u_rawurl);
+	nni_stat_append(root, &st->s_url);
+
+	nni_stat_init_atomic(&st->s_npipes, "npipes", "open pipes");
+	nni_stat_append(root, &st->s_npipes);
+
+	nni_stat_init_atomic(&st->s_accept, "accept", "connections accepted");
+	nni_stat_append(root, &st->s_accept);
+
+	nni_stat_init_atomic(
+	    &st->s_aborted, "aborted", "accepts aborted remotely");
+	nni_stat_append(root, &st->s_aborted);
+
+	nni_stat_init_atomic(&st->s_timedout, "timedout", "accepts timed out");
+	nni_stat_append(root, &st->s_timedout);
+
+	nni_stat_init_atomic(&st->s_canceled, "canceled", "accepts canceled");
+	nni_stat_append(root, &st->s_canceled);
+
+	nni_stat_init_atomic(
+	    &st->s_othererr, "othererr", "other accept errors");
+	nni_stat_append(root, &st->s_othererr);
+
+	nni_stat_init_atomic(
+	    &st->s_protorej, "protoreject", "pipes rejected by protocol");
+	nni_stat_append(root, &st->s_protorej);
+
+	nni_stat_init_atomic(
+	    &st->s_apprej, "appreject", "pipes rejected by application");
+	nni_stat_append(root, &st->s_apprej);
+}
+
 int
 nni_listener_create(nni_listener **lp, nni_sock *s, const char *urlstr)
 {
@@ -107,6 +157,7 @@ nni_listener_create(nni_listener **lp, nni_sock *s, const char *urlstr)
 
 	NNI_LIST_NODE_INIT(&l->l_node);
 	NNI_LIST_INIT(&l->l_pipes, nni_pipe, p_ep_node);
+	listener_stats_init(l);
 
 	if (((rv = nni_aio_init(&l->l_acc_aio, listener_accept_cb, l)) != 0) ||
 	    ((rv = nni_aio_init(&l->l_tmo_aio, listener_timer_cb, l)) != 0) ||
@@ -117,6 +168,12 @@ nni_listener_create(nni_listener **lp, nni_sock *s, const char *urlstr)
 		return (rv);
 	}
 
+	// Update a few stat bits, and register them.
+	snprintf(l->l_stats.s_scope, sizeof(l->l_stats.s_scope), "listener%u",
+	    l->l_id);
+	nni_stat_set_value(&l->l_stats.s_id, l->l_id);
+	nni_stat_append(NULL, &l->l_stats.s_root);
+
 	*lp = l;
 	return (0);
 }
@@ -165,6 +222,7 @@ nni_listener_rele(nni_listener *l)
 	nni_mtx_lock(&listeners_lk);
 	l->l_refcnt--;
 	if ((l->l_refcnt == 0) && (l->l_closed)) {
+		nni_stat_remove(&l->l_stats.s_root);
 		nni_reap(&l->l_reap, (nni_cb) nni_listener_reap, l);
 	}
 	nni_mtx_unlock(&listeners_lk);
@@ -233,18 +291,30 @@ listener_accept_cb(void *arg)
 
 	switch (nni_aio_result(aio)) {
 	case 0:
+		BUMPSTAT(&l->l_stats.s_accept);
 		nni_listener_add_pipe(l, nni_aio_get_output(aio, 0));
 		listener_accept_start(l);
 		break;
 	case NNG_ECONNABORTED: // remote condition, no cooldown
 	case NNG_ECONNRESET:   // remote condition, no cooldown
-	case NNG_EPEERAUTH:    // peer validation failure
+		BUMPSTAT(&l->l_stats.s_aborted);
+		listener_accept_start(l);
+		break;
+	case NNG_ETIMEDOUT:
+		// No need to sleep since we timed out already.
+		BUMPSTAT(&l->l_stats.s_timedout);
+		listener_accept_start(l);
+		break;
+	case NNG_EPEERAUTH: // peer validation failure
+		BUMPSTAT(&l->l_stats.s_othererr);
 		listener_accept_start(l);
 		break;
 	case NNG_ECLOSED:   // no further action
 	case NNG_ECANCELED: // no further action
+		BUMPSTAT(&l->l_stats.s_canceled);
 		break;
 	default:
+		BUMPSTAT(&l->l_stats.s_othererr);
 		// We don't really know why we failed, but we backoff
 		// here. This is because errors here are probably due
 		// to system failures (resource exhaustion) and we hope
@@ -339,3 +409,9 @@ nni_listener_getopt(
 
 	return (nni_sock_getopt(l->l_sock, name, valp, szp, t));
 }
+
+void
+nni_listener_add_stat(nni_listener *l, nni_stat_item *stat)
+{
+	nni_stat_append(&l->l_stats.s_root, stat);
+}
diff --git a/src/core/listener.h b/src/core/listener.h
index 67a782bd..828102a2 100644
--- a/src/core/listener.h
+++ b/src/core/listener.h
@@ -26,5 +26,6 @@ extern int nni_listener_setopt(
     nni_listener *, const char *, const void *, size_t, nni_opt_type);
 extern int nni_listener_getopt(
     nni_listener *, const char *, void *, size_t *, nni_opt_type);
+extern void nni_listener_add_stat(nni_listener *, nni_stat_item *);
 
 #endif // CORE_LISTENER_H
diff --git a/src/core/msgqueue.c b/src/core/msgqueue.c
index 62a3893b..4b59aead 100644
--- a/src/core/msgqueue.c
+++ b/src/core/msgqueue.c
@@ -37,6 +37,15 @@ struct nni_msgq {
 	// Filters.
 	nni_msgq_filter mq_filter_fn;
 	void *          mq_filter_arg;
+
+	// Statistics.
+	nni_atomic_u64 mq_get_msgs;
+	nni_atomic_u64 mq_put_msgs;
+	nni_atomic_u64 mq_get_bytes;
+	nni_atomic_u64 mq_put_bytes;
+	nni_atomic_u64 mq_get_errs;
+	nni_atomic_u64 mq_put_errs;
+	nni_atomic_u64 mq_discards;
 };
 
 static void nni_msgq_run_notify(nni_msgq *);
@@ -76,6 +85,14 @@ nni_msgq_init(nni_msgq **mqp, unsigned cap)
 	mq->mq_geterr   = 0;
 	*mqp            = mq;
 
+	nni_atomic_init64(&mq->mq_get_bytes);
+	nni_atomic_init64(&mq->mq_put_bytes);
+	nni_atomic_init64(&mq->mq_get_msgs);
+	nni_atomic_init64(&mq->mq_put_msgs);
+	nni_atomic_init64(&mq->mq_get_errs);
+	nni_atomic_init64(&mq->mq_put_errs);
+	nni_atomic_init64(&mq->mq_discards);
+
 	return (0);
 }
 
@@ -185,6 +202,7 @@ nni_msgq_flush(nni_msgq *mq)
 			mq->mq_get = 0;
 		}
 		mq->mq_len--;
+		nni_atomic_inc64(&mq->mq_discards, 1);
 		nni_msg_free(msg);
 	}
 	nni_msgq_run_notify(mq);
@@ -215,13 +233,20 @@ nni_msgq_run_putq(nni_msgq *mq)
 
 			nni_aio_set_msg(waio, NULL);
 			nni_aio_list_remove(waio);
+			nni_atomic_inc64(&mq->mq_put_bytes, len);
+			nni_atomic_inc64(&mq->mq_put_msgs, 1);
 
 			if (mq->mq_filter_fn != NULL) {
 				msg = mq->mq_filter_fn(mq->mq_filter_arg, msg);
 			}
 			if (msg != NULL) {
+				len = nni_msg_len(msg);
+				nni_atomic_inc64(&mq->mq_get_bytes, len);
+				nni_atomic_inc64(&mq->mq_get_msgs, 1);
 				nni_aio_list_remove(raio);
 				nni_aio_finish_msg(raio, msg);
+			} else {
+				nni_atomic_inc64(&mq->mq_discards, 1);
 			}
 
 			nni_aio_finish(waio, 0, len);
@@ -230,6 +255,8 @@ nni_msgq_run_putq(nni_msgq *mq)
 
 		// Otherwise if we have room in the buffer, just queue it.
 		if (mq->mq_len < mq->mq_cap) {
+			nni_atomic_inc64(&mq->mq_put_bytes, len);
+			nni_atomic_inc64(&mq->mq_put_msgs, 1);
 			nni_list_remove(&mq->mq_aio_putq, waio);
 			mq->mq_msgs[mq->mq_put++] = msg;
 			if (mq->mq_put == mq->mq_alloc) {
@@ -265,8 +292,13 @@ nni_msgq_run_getq(nni_msgq *mq)
 				msg = mq->mq_filter_fn(mq->mq_filter_arg, msg);
 			}
 			if (msg != NULL) {
+				size_t len = nni_msg_len(msg);
+				nni_atomic_inc64(&mq->mq_get_bytes, len);
+				nni_atomic_inc64(&mq->mq_get_msgs, 1);
 				nni_aio_list_remove(raio);
 				nni_aio_finish_msg(raio, msg);
+			} else {
+				nni_atomic_inc64(&mq->mq_discards, 1);
 			}
 			continue;
 		}
@@ -278,18 +310,26 @@ nni_msgq_run_getq(nni_msgq *mq)
 			msg = nni_aio_get_msg(waio);
 			len = nni_msg_len(msg);
 
+			nni_atomic_inc64(&mq->mq_put_bytes, len);
+			nni_atomic_inc64(&mq->mq_put_msgs, 1);
+
 			nni_aio_set_msg(waio, NULL);
 			nni_aio_list_remove(waio);
+			nni_aio_finish(waio, 0, len);
 
 			if (mq->mq_filter_fn != NULL) {
 				msg = mq->mq_filter_fn(mq->mq_filter_arg, msg);
 			}
 			if (msg != NULL) {
+				len = nni_msg_len(msg);
 				nni_aio_list_remove(raio);
 				nni_aio_finish_msg(raio, msg);
+				nni_atomic_inc64(&mq->mq_get_bytes, len);
+				nni_atomic_inc64(&mq->mq_get_msgs, 1);
+			} else {
+				nni_atomic_inc64(&mq->mq_discards, 1);
 			}
 
-			nni_aio_finish(waio, 0, len);
 			continue;
 		}
 
@@ -338,6 +378,7 @@ nni_msgq_aio_put(nni_msgq *mq, nni_aio *aio)
 	}
 	nni_mtx_lock(&mq->mq_lock);
 	if (mq->mq_puterr) {
+		nni_atomic_inc64(&mq->mq_put_errs, 1);
 		nni_aio_finish_error(aio, mq->mq_puterr);
 		nni_mtx_unlock(&mq->mq_lock);
 		return;
@@ -348,6 +389,7 @@ nni_msgq_aio_put(nni_msgq *mq, nni_aio *aio)
 	rv = nni_aio_schedule(aio, nni_msgq_cancel, mq);
 	if ((rv != 0) && (mq->mq_len >= mq->mq_cap) &&
 	    (nni_list_empty(&mq->mq_aio_getq))) {
+		nni_atomic_inc64(&mq->mq_put_errs, 1);
 		nni_mtx_unlock(&mq->mq_lock);
 		nni_aio_finish_error(aio, rv);
 		return;
@@ -370,6 +412,7 @@ nni_msgq_aio_get(nni_msgq *mq, nni_aio *aio)
 	nni_mtx_lock(&mq->mq_lock);
 	if (mq->mq_geterr) {
 		nni_mtx_unlock(&mq->mq_lock);
+		nni_atomic_inc64(&mq->mq_get_errs, 1);
 		nni_aio_finish_error(aio, mq->mq_geterr);
 		return;
 	}
@@ -377,6 +420,7 @@ nni_msgq_aio_get(nni_msgq *mq, nni_aio *aio)
 	if ((rv != 0) && (mq->mq_len == 0) &&
 	    (nni_list_empty(&mq->mq_aio_putq))) {
 		nni_mtx_unlock(&mq->mq_lock);
+		nni_atomic_inc64(&mq->mq_get_errs, 1);
 		nni_aio_finish_error(aio, rv);
 		return;
 	}
@@ -392,6 +436,7 @@ int
 nni_msgq_tryput(nni_msgq *mq, nni_msg *msg)
 {
 	nni_aio *raio;
+	size_t   len;
 
 	nni_mtx_lock(&mq->mq_lock);
 	if (mq->mq_closed) {
@@ -399,15 +444,22 @@ nni_msgq_tryput(nni_msgq *mq, nni_msg *msg)
 		return (NNG_ECLOSED);
 	}
 
+	len = nni_msg_len(msg);
+
 	// The presence of any blocked reader indicates that
 	// the queue is empty, otherwise it would have just taken
 	// data from the queue.
 	if ((raio = nni_list_first(&mq->mq_aio_getq)) != NULL) {
+		nni_atomic_inc64(&mq->mq_put_bytes, len);
+		nni_atomic_inc64(&mq->mq_put_msgs, 1);
 
 		if (mq->mq_filter_fn != NULL) {
 			msg = mq->mq_filter_fn(mq->mq_filter_arg, msg);
 		}
 		if (msg != NULL) {
+			len = nni_msg_len(msg);
+			nni_atomic_inc64(&mq->mq_get_bytes, len);
+			nni_atomic_inc64(&mq->mq_get_msgs, 1);
 			nni_list_remove(&mq->mq_aio_getq, raio);
 			nni_aio_finish_msg(raio, msg);
 			nni_msgq_run_notify(mq);
@@ -418,6 +470,9 @@ nni_msgq_tryput(nni_msgq *mq, nni_msg *msg)
 
 	// Otherwise if we have room in the buffer, just queue it.
 	if (mq->mq_len < mq->mq_cap) {
+		nni_atomic_inc64(&mq->mq_put_bytes, len);
+		nni_atomic_inc64(&mq->mq_put_msgs, 1);
+
 		mq->mq_msgs[mq->mq_put++] = msg;
 		if (mq->mq_put == mq->mq_alloc) {
 			mq->mq_put = 0;
@@ -514,6 +569,7 @@ nni_msgq_resize(nni_msgq *mq, int cap)
 			mq->mq_get = 0;
 		}
 		mq->mq_len--;
+		nni_atomic_inc64(&mq->mq_discards, 1);
 		nni_msg_free(msg);
 	}
 	if (newq == NULL) {
@@ -586,3 +642,45 @@ nni_msgq_get_sendable(nni_msgq *mq, nni_pollable **sp)
 	*sp = mq->mq_sendable;
 	return (0);
 }
+
+uint64_t
+nni_msgq_stat_get_bytes(nni_msgq *mq)
+{
+	return (nni_atomic_get64(&mq->mq_get_bytes));
+}
+
+uint64_t
+nni_msgq_stat_put_bytes(nni_msgq *mq)
+{
+	return (nni_atomic_get64(&mq->mq_put_bytes));
+}
+
+uint64_t
+nni_msgq_stat_get_msgs(nni_msgq *mq)
+{
+	return (nni_atomic_get64(&mq->mq_get_msgs));
+}
+
+uint64_t
+nni_msgq_stat_put_msgs(nni_msgq *mq)
+{
+	return (nni_atomic_get64(&mq->mq_put_msgs));
+}
+
+uint64_t
+nni_msgq_stat_get_errs(nni_msgq *mq)
+{
+	return (nni_atomic_get64(&mq->mq_get_errs));
+}
+
+uint64_t
+nni_msgq_stat_put_errs(nni_msgq *mq)
+{
+	return (nni_atomic_get64(&mq->mq_put_errs));
+}
+
+uint64_t
+nni_msgq_stat_discards(nni_msgq *mq)
+{
+	return (nni_atomic_get64(&mq->mq_discards));
+}
diff --git a/src/core/msgqueue.h b/src/core/msgqueue.h
index 7dc5800d..bd9b3682 100644
--- a/src/core/msgqueue.h
+++ b/src/core/msgqueue.h
@@ -99,4 +99,13 @@ extern int nni_msgq_len(nni_msgq *mq);
 extern int nni_msgq_get_recvable(nni_msgq *mq, nni_pollable **);
 extern int nni_msgq_get_sendable(nni_msgq *mq, nni_pollable **);
 
+// message queues keep statistics
+extern uint64_t nni_msgq_stat_get_bytes(nni_msgq *);
+extern uint64_t nni_msgq_stat_put_bytes(nni_msgq *);
+extern uint64_t nni_msgq_stat_get_msgs(nni_msgq *);
+extern uint64_t nni_msgq_stat_put_msgs(nni_msgq *);
+extern uint64_t nni_msgq_stat_get_errs(nni_msgq *);
+extern uint64_t nni_msgq_stat_put_errs(nni_msgq *);
+extern uint64_t nni_msgq_stat_discards(nni_msgq *);
+
 #endif // CORE_MSQUEUE_H
diff --git a/src/core/nng_impl.h b/src/core/nng_impl.h
index 9af12720..f28ddf8c 100644
--- a/src/core/nng_impl.h
+++ b/src/core/nng_impl.h
@@ -41,6 +41,7 @@
 #include "core/protocol.h"
 #include "core/random.h"
 #include "core/reap.h"
+#include "core/stats.h"
 #include "core/strs.h"
 #include "core/taskq.h"
 #include "core/thread.h"
diff --git a/src/core/pipe.c b/src/core/pipe.c
index bdbc76e0..d623e158 100644
--- a/src/core/pipe.c
+++ b/src/core/pipe.c
@@ -11,6 +11,7 @@
 #include "core/nng_impl.h"
 #include "sockimpl.h"
 
+#include <stdio.h>
 #include <string.h>
 
 // This file contains functions relating to pipes.
@@ -82,6 +83,7 @@ pipe_destroy(nni_pipe *p)
 		p->p_tran_ops.p_stop(p->p_tran_data);
 	}
 
+	nni_stat_remove(&p->p_stats.s_root);
 	nni_pipe_remove(p);
 
 	if (p->p_proto_data != NULL) {
@@ -177,6 +179,28 @@ nni_pipe_peer(nni_pipe *p)
 	return (p->p_tran_ops.p_peer(p->p_tran_data));
 }
 
+void
+nni_pipe_stats_init(nni_pipe *p)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_pipe_stats *st = &p->p_stats;
+
+	if (p->p_listener != NULL) {
+		st->s_ep_id.si_name  = "listener";
+		st->s_ep_id.si_desc  = "listener for pipe";
+		st->s_ep_id.si_value = nni_listener_id(p->p_listener);
+	} else {
+		st->s_ep_id.si_name  = "dialer";
+		st->s_ep_id.si_desc  = "dialer for pipe";
+		st->s_ep_id.si_value = nni_dialer_id(p->p_dialer);
+	}
+
+	nni_stat_append(NULL, &st->s_root);
+#else
+	NNI_ARG_UNUSED(p);
+#endif
+}
+
 int
 nni_pipe_create(nni_pipe **pp, nni_sock *sock, nni_tran *tran, void *tdata)
 {
@@ -184,7 +208,6 @@ nni_pipe_create(nni_pipe **pp, nni_sock *sock, nni_tran *tran, void *tdata)
 	int                 rv;
 	void *              sdata = nni_sock_proto_data(sock);
 	nni_proto_pipe_ops *pops  = nni_sock_proto_pipe_ops(sock);
-	uint64_t            id;
 
 	if ((p = NNI_ALLOC_STRUCT(p)) == NULL) {
 		// In this case we just toss the pipe...
@@ -210,12 +233,27 @@ nni_pipe_create(nni_pipe **pp, nni_sock *sock, nni_tran *tran, void *tdata)
 	nni_cv_init(&p->p_cv, &nni_pipe_lk);
 
 	nni_mtx_lock(&nni_pipe_lk);
-	if ((rv = nni_idhash_alloc(nni_pipes, &id, p)) == 0) {
-		p->p_id     = (uint32_t) id;
+	if ((rv = nni_idhash_alloc32(nni_pipes, &p->p_id, p)) == 0) {
 		p->p_refcnt = 1;
 	}
 	nni_mtx_unlock(&nni_pipe_lk);
 
+	nni_pipe_stats *st = &p->p_stats;
+	snprintf(st->s_scope, sizeof(st->s_scope), "pipe%u", p->p_id);
+
+	nni_stat_init_scope(&st->s_root, st->s_scope, "pipe statistics");
+
+	nni_stat_init_id(&st->s_id, "id", "pipe id", p->p_id);
+	nni_stat_append(&st->s_root, &st->s_id);
+
+	// name and description fleshed out later.
+	nni_stat_init_id(&st->s_ep_id, "", "", 0);
+	nni_stat_append(&st->s_root, &st->s_ep_id);
+
+	nni_stat_init_id(&st->s_sock_id, "socket", "socket for pipe",
+	    nni_sock_id(p->p_sock));
+	nni_stat_append(&st->s_root, &st->s_sock_id);
+
 	if ((rv != 0) || ((rv = tran->tran_pipe->p_init(tdata, p)) != 0) ||
 	    ((rv = pops->pipe_init(&p->p_proto_data, p, sdata)) != 0)) {
 		nni_pipe_close(p);
@@ -274,3 +312,9 @@ nni_pipe_dialer_id(nni_pipe *p)
 {
 	return (p->p_dialer ? nni_dialer_id(p->p_dialer) : 0);
 }
+
+void
+nni_pipe_add_stat(nni_pipe *p, nni_stat_item *item)
+{
+	nni_stat_append(&p->p_stats.s_root, item);
+}
diff --git a/src/core/pipe.h b/src/core/pipe.h
index 1e2f2b5d..5a83059f 100644
--- a/src/core/pipe.h
+++ b/src/core/pipe.h
@@ -62,4 +62,7 @@ extern uint32_t nni_pipe_dialer_id(nni_pipe *);
 // nni_pipe_rele releases the hold on the pipe placed by nni_pipe_find.
 extern void nni_pipe_rele(nni_pipe *);
 
+// nni_pipe_add_stat adds a statistic to the pipe
+extern void nni_pipe_add_stat(nni_pipe *p, nni_stat_item *);
+
 #endif // CORE_PIPE_H
diff --git a/src/core/socket.c b/src/core/socket.c
index b2f331fb..63696b36 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -53,6 +53,22 @@ typedef struct nni_sock_pipe_cb {
 	void *      cb_arg;
 } nni_sock_pipe_cb;
 
+typedef struct sock_stats {
+	nni_stat_item s_root;       // socket scope
+	nni_stat_item s_id;         // socket id
+	nni_stat_item s_name;       // socket name
+	nni_stat_item s_protocol;   // socket protocol
+	nni_stat_item s_ndialers;   // number of dialers
+	nni_stat_item s_nlisteners; // number of listeners
+	nni_stat_item s_npipes;     // number of pipes
+	nni_stat_item s_rxbytes;    // number of bytes received
+	nni_stat_item s_txbytes;    // number of bytes received
+	nni_stat_item s_rxmsgs;     // number of msgs received
+	nni_stat_item s_txmsgs;     // number of msgs sent
+	nni_stat_item s_protorej;   // pipes rejected by protocol
+	nni_stat_item s_apprej;     // pipes rejected by application
+} sock_stats;
+
 struct nni_socket {
 	nni_list_node s_node;
 	nni_mtx       s_mx;
@@ -82,6 +98,7 @@ struct nni_socket {
 	size_t       s_rcvmaxsz;  // max receive size
 	nni_list     s_options;   // opts not handled by sock/proto
 	char         s_name[64];  // socket name (legacy compat)
+	char         s_scope[24]; // socket scope ("socket%u", 32 bits max)
 
 	nni_list s_listeners; // active listeners
 	nni_list s_dialers;   // active dialers
@@ -94,6 +111,8 @@ struct nni_socket {
 
 	nni_mtx          s_pipe_cbs_mtx;
 	nni_sock_pipe_cb s_pipe_cbs[NNG_PIPE_EV_NUM];
+
+	sock_stats s_stats;
 };
 
 static void nni_ctx_destroy(nni_ctx *);
@@ -400,6 +419,81 @@ nni_sock_rele(nni_sock *s)
 }
 
 static void
+sock_stats_fini(nni_sock *s)
+{
+#ifdef NNG_ENABLE_STATS
+	sock_stats *st = &s->s_stats;
+	nni_stat_remove(&st->s_root);
+#else
+	NNI_ARG_UNUSED(s);
+#endif
+}
+
+static void
+sock_stats_init(nni_sock *s)
+{
+#ifdef NNG_ENABLE_STATS
+	sock_stats *   st   = &s->s_stats;
+	nni_stat_item *root = &s->s_stats.s_root;
+
+	// To make collection cheap and atomic for the socket,
+	// we just use a single lock for the entire chain.
+
+	nni_stat_init_scope(root, s->s_scope, "socket statistics");
+
+	nni_stat_init_id(&st->s_id, "id", "socket id", s->s_id);
+	nni_stat_append(root, &st->s_id);
+
+	nni_stat_init_string(&st->s_name, "name", "socket name", s->s_name);
+	nni_stat_set_lock(&st->s_name, &s->s_mx);
+	nni_stat_append(root, &st->s_name);
+
+	nni_stat_init_string(&st->s_protocol, "protocol", "socket protocol",
+	    nni_sock_proto_name(s));
+	nni_stat_append(root, &st->s_protocol);
+
+	nni_stat_init_atomic(&st->s_ndialers, "ndialers", "open dialers");
+	nni_stat_set_type(&st->s_ndialers, NNG_STAT_LEVEL);
+	nni_stat_append(root, &st->s_ndialers);
+
+	nni_stat_init_atomic(
+	    &st->s_nlisteners, "nlisteners", "open listeners");
+	nni_stat_set_type(&st->s_nlisteners, NNG_STAT_LEVEL);
+	nni_stat_append(root, &st->s_nlisteners);
+
+	nni_stat_init_atomic(&st->s_npipes, "npipes", "open pipes");
+	nni_stat_set_type(&st->s_npipes, NNG_STAT_LEVEL);
+	nni_stat_append(root, &st->s_npipes);
+
+	nni_stat_init_atomic(&st->s_rxbytes, "rxbytes", "bytes received");
+	nni_stat_set_unit(&st->s_rxbytes, NNG_UNIT_BYTES);
+	nni_stat_append(root, &st->s_rxbytes);
+
+	nni_stat_init_atomic(&st->s_txbytes, "txbytes", "bytes sent");
+	nni_stat_set_unit(&st->s_txbytes, NNG_UNIT_BYTES);
+	nni_stat_append(root, &st->s_txbytes);
+
+	nni_stat_init_atomic(&st->s_rxmsgs, "rxmsgs", "messages received");
+	nni_stat_set_unit(&st->s_rxmsgs, NNG_UNIT_MESSAGES);
+	nni_stat_append(root, &st->s_rxmsgs);
+
+	nni_stat_init_atomic(&st->s_txmsgs, "txmsgs", "messages sent");
+	nni_stat_set_unit(&st->s_txmsgs, NNG_UNIT_MESSAGES);
+	nni_stat_append(root, &st->s_txmsgs);
+
+	nni_stat_init_atomic(
+	    &st->s_protorej, "protoreject", "pipes rejected by protocol");
+	nni_stat_append(root, &st->s_protorej);
+
+	nni_stat_init_atomic(
+	    &st->s_apprej, "appreject", "pipes rejected by application");
+	nni_stat_append(root, &st->s_apprej);
+#else
+	NNI_ARG_UNUSED(s);
+#endif
+}
+
+static void
 sock_destroy(nni_sock *s)
 {
 	nni_sockopt *sopt;
@@ -418,6 +512,7 @@ sock_destroy(nni_sock *s)
 	nni_mtx_lock(&s->s_mx);
 	nni_mtx_unlock(&s->s_mx);
 
+	sock_stats_fini(s);
 	nni_msgq_fini(s->s_urq);
 	nni_msgq_fini(s->s_uwq);
 	nni_cv_fini(&s->s_close_cv);
@@ -469,6 +564,7 @@ nni_sock_create(nni_sock **sp, const nni_proto *proto)
 	nni_mtx_init(&s->s_pipe_cbs_mtx);
 	nni_cv_init(&s->s_cv, &s->s_mx);
 	nni_cv_init(&s->s_close_cv, &sock_lk);
+	sock_stats_init(s);
 
 	if (((rv = nni_msgq_init(&s->s_uwq, 0)) != 0) ||
 	    ((rv = nni_msgq_init(&s->s_urq, 1)) != 0) ||
@@ -567,7 +663,14 @@ nni_sock_open(nni_sock **sockp, const nni_proto *proto)
 	// Set the sockname.
 	(void) snprintf(s->s_name, sizeof(s->s_name), "%u", s->s_id);
 
-	return (rv);
+	// Set up basic stat values.
+	(void) snprintf(s->s_scope, sizeof(s->s_scope), "socket%u", s->s_id);
+	nni_stat_set_value(&s->s_stats.s_id, s->s_id);
+
+	// Add our stats chain.
+	nni_stat_append(NULL, &s->s_stats.s_root);
+
+	return (0);
 }
 
 // nni_sock_shutdown shuts down the socket; after this point no
@@ -699,6 +802,8 @@ nni_sock_close(nni_sock *s)
 	// is idempotent.
 	nni_sock_shutdown(s);
 
+	nni_stat_remove(&s->s_stats.s_root);
+
 	nni_mtx_lock(&sock_lk);
 	if (s->s_closed) {
 		// Some other thread called close.  All we need to do
@@ -830,6 +935,9 @@ nni_sock_add_listener(nni_sock *s, nni_listener *l)
 	}
 
 	nni_list_append(&s->s_listeners, l);
+
+	nni_stat_inc_atomic(&s->s_stats.s_nlisteners, 1);
+
 	nni_mtx_unlock(&s->s_mx);
 	return (0);
 }
@@ -856,34 +964,11 @@ nni_sock_add_dialer(nni_sock *s, nni_dialer *d)
 	}
 
 	nni_list_append(&s->s_dialers, d);
-	nni_mtx_unlock(&s->s_mx);
-	return (0);
-}
 
-void
-nni_sock_remove_listener(nni_sock *s, nni_listener *l)
-{
-	nni_mtx_lock(&s->s_mx);
-	if (nni_list_active(&s->s_listeners, l)) {
-		nni_list_remove(&s->s_listeners, l);
-		if ((s->s_closing) && (nni_list_empty(&s->s_listeners))) {
-			nni_cv_wake(&s->s_cv);
-		}
-	}
-	nni_mtx_unlock(&s->s_mx);
-}
+	nni_stat_inc_atomic(&s->s_stats.s_ndialers, 1);
 
-void
-nni_sock_remove_dialer(nni_sock *s, nni_dialer *d)
-{
-	nni_mtx_lock(&s->s_mx);
-	if (nni_list_active(&s->s_dialers, d)) {
-		nni_list_remove(&s->s_dialers, d);
-		if ((s->s_closing) && (nni_list_empty(&s->s_dialers))) {
-			nni_cv_wake(&s->s_cv);
-		}
-	}
 	nni_mtx_unlock(&s->s_mx);
+	return (0);
 }
 
 int
@@ -1398,13 +1483,25 @@ nni_dialer_add_pipe(nni_dialer *d, void *tpipe)
 	d->d_pipe     = p;
 	d->d_currtime = d->d_inirtime;
 	nni_mtx_unlock(&s->s_mx);
+	nni_stat_inc_atomic(&s->s_stats.s_npipes, 1);
+	nni_stat_inc_atomic(&d->d_stats.s_npipes, 1);
+
+	nni_pipe_stats_init(p);
 
 	nni_pipe_run_cb(p, NNG_PIPE_EV_ADD_PRE);
 
 	nni_mtx_lock(&s->s_mx);
-	if ((p->p_closed) ||
-	    (p->p_proto_ops.pipe_start(p->p_proto_data) != 0)) {
+	if (p->p_closed) {
 		nni_mtx_unlock(&s->s_mx);
+		nni_stat_inc_atomic(&d->d_stats.s_apprej, 1);
+		nni_stat_inc_atomic(&s->s_stats.s_apprej, 1);
+		nni_pipe_rele(p);
+		return;
+	}
+	if (p->p_proto_ops.pipe_start(p->p_proto_data) != 0) {
+		nni_mtx_unlock(&s->s_mx);
+		nni_stat_inc_atomic(&d->d_stats.s_protorej, 1);
+		nni_stat_inc_atomic(&s->s_stats.s_protorej, 1);
 		nni_pipe_close(p);
 		nni_pipe_rele(p);
 		return;
@@ -1493,17 +1590,30 @@ nni_listener_add_pipe(nni_listener *l, void *tpipe)
 		nni_mtx_unlock(&s->s_mx);
 		return;
 	}
+
 	p->p_listener = l;
 	nni_list_append(&l->l_pipes, p);
 	nni_list_append(&s->s_pipes, p);
 	nni_mtx_unlock(&s->s_mx);
+	nni_stat_inc_atomic(&l->l_stats.s_npipes, 1);
+	nni_stat_inc_atomic(&s->s_stats.s_npipes, 1);
+
+	nni_pipe_stats_init(p);
 
 	nni_pipe_run_cb(p, NNG_PIPE_EV_ADD_PRE);
 
 	nni_mtx_lock(&s->s_mx);
-	if ((p->p_closed) ||
-	    (p->p_proto_ops.pipe_start(p->p_proto_data) != 0)) {
+	if (p->p_closed) {
 		nni_mtx_unlock(&s->s_mx);
+		nni_stat_inc_atomic(&l->l_stats.s_apprej, 1);
+		nni_stat_inc_atomic(&s->s_stats.s_apprej, 1);
+		nni_pipe_rele(p);
+		return;
+	}
+	if (p->p_proto_ops.pipe_start(p->p_proto_data) != 0) {
+		nni_mtx_unlock(&s->s_mx);
+		nni_stat_inc_atomic(&l->l_stats.s_protorej, 1);
+		nni_stat_inc_atomic(&s->s_stats.s_protorej, 1);
 		nni_pipe_close(p);
 		nni_pipe_rele(p);
 		return;
@@ -1616,6 +1726,15 @@ nni_pipe_remove(nni_pipe *p)
 	nni_dialer *d = p->p_dialer;
 
 	nni_mtx_lock(&s->s_mx);
+	if (nni_list_node_active(&p->p_sock_node)) {
+		nni_stat_dec_atomic(&s->s_stats.s_npipes, 1);
+	}
+	if (p->p_listener != NULL) {
+		nni_stat_dec_atomic(&p->p_listener->l_stats.s_npipes, 1);
+	}
+	if (p->p_dialer != NULL) {
+		nni_stat_dec_atomic(&p->p_dialer->d_stats.s_npipes, 1);
+	}
 	nni_list_node_remove(&p->p_sock_node);
 	nni_list_node_remove(&p->p_ep_node);
 	p->p_listener = NULL;
@@ -1629,3 +1748,38 @@ nni_pipe_remove(nni_pipe *p)
 	}
 	nni_mtx_unlock(&s->s_mx);
 }
+
+void
+nni_sock_add_stat(nni_sock *s, nni_stat_item *stat)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_stat_append(&s->s_stats.s_root, stat);
+#else
+	NNI_ARG_UNUSED(s);
+	NNI_ARG_UNUSED(stat);
+#endif
+}
+
+void
+nni_sock_bump_tx(nni_sock *s, uint64_t sz)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_stat_inc_atomic(&s->s_stats.s_txmsgs, 1);
+	nni_stat_inc_atomic(&s->s_stats.s_txbytes, sz);
+#else
+	NNI_ARG_UNUSED(s);
+	NNI_ARG_UNUSED(sz);
+#endif
+}
+
+void
+nni_sock_bump_rx(nni_sock *s, uint64_t sz)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_stat_inc_atomic(&s->s_stats.s_rxmsgs, 1);
+	nni_stat_inc_atomic(&s->s_stats.s_rxbytes, sz);
+#else
+	NNI_ARG_UNUSED(s);
+	NNI_ARG_UNUSED(sz);
+#endif
+}
diff --git a/src/core/socket.h b/src/core/socket.h
index 4b9c4642..5486918e 100644
--- a/src/core/socket.h
+++ b/src/core/socket.h
@@ -25,6 +25,7 @@ extern uint16_t    nni_sock_peer_id(nni_sock *);
 extern const char *nni_sock_proto_name(nni_sock *);
 extern const char *nni_sock_peer_name(nni_sock *);
 extern void *      nni_sock_proto_data(nni_sock *);
+extern void        nni_sock_add_stat(nni_sock *, nni_stat_item *);
 
 extern struct nni_proto_pipe_ops *nni_sock_proto_pipe_ops(nni_sock *);
 
@@ -107,4 +108,12 @@ extern int nni_ctx_getopt(
 extern int nni_ctx_setopt(
     nni_ctx *, const char *, const void *, size_t, nni_opt_type);
 
+// nni_sock_bump_rx is called by a protocol when a message is received by
+// a consuming app.  It bumps the rxmsgs by one and rxbytes by the size.
+extern void nni_sock_bump_rx(nni_sock *s, uint64_t sz);
+
+// nni_sock_bump_rx is called by a protocol when a message is sent by
+// a consuming app.  It bumps the txmsgs by one and txbytes by the size.
+extern void nni_sock_bump_tx(nni_sock *s, uint64_t sz);
+
 #endif // CORE_SOCKET_H
diff --git a/src/core/sockimpl.h b/src/core/sockimpl.h
index be454d8a..ae1fd92e 100644
--- a/src/core/sockimpl.h
+++ b/src/core/sockimpl.h
@@ -15,6 +15,22 @@
 // and pipes.  This must not be exposed to other subsystems -- these internals
 // are subject to change at any time.
 
+typedef struct nni_dialer_stats {
+	nni_stat_item s_root;
+	nni_stat_item s_id;
+	nni_stat_item s_sock;
+	nni_stat_item s_url;
+	nni_stat_item s_npipes;
+	nni_stat_item s_connok;
+	nni_stat_item s_refused;
+	nni_stat_item s_canceled;
+	nni_stat_item s_timedout;
+	nni_stat_item s_othererr;
+	nni_stat_item s_protorej;
+	nni_stat_item s_apprej;
+	char          s_scope[24]; // scope name for stats
+} nni_dialer_stats;
+
 struct nni_dialer {
 	nni_tran_dialer_ops d_ops;  // transport ops
 	nni_tran *          d_tran; // transport pointer
@@ -38,8 +54,25 @@ struct nni_dialer {
 	nni_duration        d_inirtime; // initial time for reconnect
 	nni_time            d_conntime; // time of last good connect
 	nni_reap_item       d_reap;
+	nni_dialer_stats    d_stats;
 };
 
+typedef struct nni_listener_stats {
+	nni_stat_item s_root;
+	nni_stat_item s_id;
+	nni_stat_item s_sock;
+	nni_stat_item s_url;
+	nni_stat_item s_npipes;
+	nni_stat_item s_accept;
+	nni_stat_item s_aborted; // aborted remotely
+	nni_stat_item s_timedout;
+	nni_stat_item s_canceled;
+	nni_stat_item s_othererr;
+	nni_stat_item s_protorej;
+	nni_stat_item s_apprej;
+	char          s_scope[24]; // scope name for stats
+} nni_listener_stats;
+
 struct nni_listener {
 	nni_tran_listener_ops l_ops;  // transport ops
 	nni_tran *            l_tran; // transport pointer
@@ -56,8 +89,17 @@ struct nni_listener {
 	nni_aio *             l_acc_aio;
 	nni_aio *             l_tmo_aio;
 	nni_reap_item         l_reap;
+	nni_listener_stats    l_stats;
 };
 
+typedef struct nni_pipe_stats {
+	nni_stat_item s_root;
+	nni_stat_item s_id;
+	nni_stat_item s_ep_id;
+	nni_stat_item s_sock_id;
+	char          s_scope[16]; // scope name for stats ("pipe" is short)
+} nni_pipe_stats;
+
 struct nni_pipe {
 	uint32_t           p_id;
 	nni_tran_pipe_ops  p_tran_ops;
@@ -76,13 +118,11 @@ struct nni_pipe {
 	nni_mtx            p_mtx;
 	nni_cv             p_cv;
 	nni_reap_item      p_reap;
+	nni_pipe_stats     p_stats;
 };
 
-extern int  nni_sock_add_dialer(nni_sock *, nni_dialer *);
-extern void nni_sock_remove_dialer(nni_sock *, nni_dialer *);
-
-extern int  nni_sock_add_listener(nni_sock *, nni_listener *);
-extern void nni_sock_remove_listener(nni_sock *, nni_listener *);
+extern int nni_sock_add_dialer(nni_sock *, nni_dialer *);
+extern int nni_sock_add_listener(nni_sock *, nni_listener *);
 
 extern void nni_dialer_add_pipe(nni_dialer *, void *);
 extern void nni_dialer_shutdown(nni_dialer *);
@@ -101,5 +141,6 @@ extern void nni_pipe_remove(nni_pipe *);
 extern void nni_pipe_run_cb(nni_pipe *, nng_pipe_ev);
 extern int  nni_pipe_create(nni_pipe **, nni_sock *, nni_tran *, void *);
 extern void nni_pipe_start(nni_pipe *);
+extern void nni_pipe_stats_init(nni_pipe *);
 
 #endif // CORE_SOCKIMPL_H
diff --git a/src/core/stats.c b/src/core/stats.c
new file mode 100644
index 00000000..0363a932
--- /dev/null
+++ b/src/core/stats.c
@@ -0,0 +1,525 @@
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+#include <stdio.h>
+#include <string.h>
+
+#include "core/nng_impl.h"
+
+typedef struct nng_stat nni_stat;
+
+struct nng_stat {
+	char *         s_name;
+	const char *   s_desc;
+	const char *   s_string;
+	uint64_t       s_value;
+	nni_time       s_time;
+	nni_stat_type  s_type;
+	nni_stat_unit  s_unit;
+	nni_stat_item *s_item; // Used during snapshot collection
+	nni_list       s_children;
+	nni_stat *     s_parent;
+	nni_list_node  s_node;
+};
+
+#ifdef NNG_ENABLE_STATS
+static nni_stat_item stats_root;
+static nni_mtx       stats_lock;
+static nni_mtx *     stats_held = NULL;
+#endif
+
+void
+nni_stat_append(nni_stat_item *parent, nni_stat_item *child)
+{
+#ifdef NNG_ENABLE_STATS
+	if (parent == NULL) {
+		parent = &stats_root;
+	}
+	nni_mtx_lock(&stats_lock);
+	// Make sure that the lists for both children and parents
+	// are correctly initialized.
+	if (parent->si_children.ll_head.ln_next == NULL) {
+		NNI_LIST_INIT(&parent->si_children, nni_stat_item, si_node);
+	}
+	if (child->si_children.ll_head.ln_next == NULL) {
+		NNI_LIST_INIT(&child->si_children, nni_stat_item, si_node);
+	}
+	nni_list_append(&parent->si_children, child);
+	child->si_parent = parent;
+	nni_mtx_unlock(&stats_lock);
+#else
+	NNI_ARG_UNUSED(parent);
+	NNI_ARG_UNUSED(child);
+#endif
+}
+
+void
+nni_stat_remove(nni_stat_item *child)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_stat_item *parent;
+	nni_mtx_lock(&stats_lock);
+	if ((parent = child->si_parent) != NULL) {
+		nni_list_remove(&parent->si_children, child);
+		child->si_parent = NULL;
+	}
+	nni_mtx_unlock(&stats_lock);
+#else
+	NNI_ARG_UNUSED(child);
+#endif
+}
+
+#ifdef NNG_ENABLE_STATS
+void
+nni_stat_init(nni_stat_item *stat, const char *name, const char *desc)
+{
+	NNI_LIST_INIT(&stat->si_children, nni_stat_item, si_node);
+	stat->si_parent  = NULL;
+	stat->si_name    = name;
+	stat->si_desc    = desc;
+	stat->si_lock    = NULL;
+	stat->si_update  = NULL;
+	stat->si_private = NULL;
+	stat->si_string  = NULL;
+	stat->si_value   = 0;
+	stat->si_type    = NNG_STAT_COUNTER;
+	stat->si_unit    = NNG_UNIT_NONE;
+}
+
+void
+nni_stat_init_scope(nni_stat_item *stat, const char *name, const char *desc)
+{
+	nni_stat_init(stat, name, desc);
+	stat->si_type = NNG_STAT_SCOPE;
+	stat->si_unit = NNG_UNIT_NONE;
+}
+
+void
+nni_stat_init_string(
+    nni_stat_item *stat, const char *name, const char *desc, const char *str)
+{
+	nni_stat_init(stat, name, desc);
+	stat->si_string = str;
+	stat->si_type   = NNG_STAT_STRING;
+	stat->si_unit   = NNG_UNIT_NONE;
+}
+
+void
+nni_stat_init_id(
+    nni_stat_item *stat, const char *name, const char *desc, uint64_t id)
+{
+	nni_stat_init(stat, name, desc);
+	stat->si_value = id;
+	stat->si_type  = NNG_STAT_ID;
+	stat->si_unit  = NNG_UNIT_NONE;
+}
+
+void
+nni_stat_init_bool(
+    nni_stat_item *stat, const char *name, const char *desc, bool v)
+{
+	nni_stat_init(stat, name, desc);
+	stat->si_value = v ? 1 : 0;
+	stat->si_type  = NNG_STAT_BOOLEAN;
+	stat->si_unit  = NNG_UNIT_NONE;
+}
+
+static void
+stat_atomic_update(nni_stat_item *stat, void *notused)
+{
+	NNI_ARG_UNUSED(notused);
+	stat->si_value = nni_atomic_get64(&stat->si_atomic);
+}
+
+void
+nni_stat_init_atomic(nni_stat_item *stat, const char *name, const char *desc)
+{
+
+	nni_stat_init(stat, name, desc);
+	stat->si_value   = 0;
+	stat->si_private = NULL;
+	stat->si_update  = stat_atomic_update;
+	nni_atomic_init64(&stat->si_atomic);
+}
+
+void
+nni_stat_inc_atomic(nni_stat_item *stat, uint64_t inc)
+{
+	nni_atomic_inc64(&stat->si_atomic, inc);
+}
+
+void
+nni_stat_dec_atomic(nni_stat_item *stat, uint64_t inc)
+{
+	nni_atomic_dec64(&stat->si_atomic, inc);
+}
+#endif
+
+void
+nni_stat_set_value(nni_stat_item *stat, uint64_t v)
+{
+#ifdef NNG_ENABLE_STATS
+	stat->si_value = v;
+#else
+	NNI_ARG_UNUSED(stat);
+	NNI_ARG_UNUSED(v);
+#endif
+}
+
+void
+nni_stat_set_string(nni_stat_item *stat, const char *str)
+{
+#ifdef NNG_ENABLE_STATS
+	stat->si_string = str;
+#else
+	NNI_ARG_UNUSED(stat);
+	NNI_ARG_UNUSED(str);
+#endif
+}
+
+void
+nni_stat_set_lock(nni_stat_item *stat, nni_mtx *mtx)
+{
+#ifdef NNG_ENABLE_STATS
+	stat->si_lock = mtx;
+#else
+	NNI_ARG_UNUSED(stat);
+	NNI_ARG_UNUSED(mtx);
+#endif
+}
+
+void
+nni_stat_set_update(nni_stat_item *stat, nni_stat_update f, void *a)
+{
+#ifdef NNG_ENABLE_STATS
+	stat->si_update  = f;
+	stat->si_private = a;
+#else
+	NNI_ARG_UNUSED(stat);
+	NNI_ARG_UNUSED(f);
+	NNI_ARG_UNUSED(a);
+#endif
+}
+
+#ifdef NNG_ENABLE_STATS
+void
+nni_stat_set_type(nni_stat_item *stat, int type)
+{
+	stat->si_type = type;
+}
+
+void
+nni_stat_set_unit(nni_stat_item *stat, int unit)
+{
+	stat->si_unit = unit;
+}
+#endif
+
+void
+nng_stats_free(nni_stat *st)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_stat *child;
+
+	while ((child = nni_list_first(&st->s_children)) != NULL) {
+		nni_list_remove(&st->s_children, child);
+		nng_stats_free(child);
+	}
+	nni_strfree(st->s_name);
+	NNI_FREE_STRUCT(st);
+#else
+	NNI_ARG_UNUSED(st);
+#endif
+}
+
+#ifdef NNG_ENABLE_STATS
+static int
+stat_make_tree(nni_stat_item *item, nni_stat **sp)
+{
+	nni_stat *     stat;
+	nni_stat_item *child;
+
+	if ((stat = NNI_ALLOC_STRUCT(stat)) == NULL) {
+		return (NNG_ENOMEM);
+	}
+	if ((stat->s_name = nni_strdup(item->si_name)) == NULL) {
+		NNI_FREE_STRUCT(stat);
+		return (NNG_ENOMEM);
+	}
+	NNI_LIST_INIT(&stat->s_children, nni_stat, s_node);
+	stat->s_item   = item;
+	stat->s_type   = item->si_type;
+	stat->s_unit   = item->si_unit;
+	stat->s_desc   = item->si_desc;
+	stat->s_parent = NULL;
+
+	NNI_LIST_FOREACH (&item->si_children, child) {
+		nni_stat *cs;
+		int       rv;
+		if ((rv = stat_make_tree(child, &cs)) != 0) {
+			nng_stats_free(stat);
+			return (rv);
+		}
+		nni_list_append(&stat->s_children, cs);
+		cs->s_parent = stat;
+	}
+	*sp = stat;
+	return (0);
+}
+
+static void
+stat_update(nni_stat *stat)
+{
+	nni_stat_item *item = stat->s_item;
+
+	if (item->si_lock != stats_held) {
+		if (stats_held != NULL) {
+			nni_mtx_unlock(stats_held);
+			stats_held = NULL;
+		}
+		if (item->si_lock != NULL) {
+			nni_mtx_lock(item->si_lock);
+			stats_held = item->si_lock;
+		}
+	}
+	if (item->si_update != NULL) {
+		item->si_update(item, item->si_private);
+	}
+	stat->s_value  = item->si_value;
+	stat->s_string = item->si_string;
+	stat->s_time   = nni_clock();
+}
+
+static void
+stat_update_tree(nni_stat *stat)
+{
+	nni_stat *child;
+	stat_update(stat);
+	NNI_LIST_FOREACH (&stat->s_children, child) {
+		stat_update_tree(child);
+	}
+}
+
+int
+nni_stat_snapshot(nni_stat **statp, nni_stat_item *item)
+{
+	int       rv;
+	nni_stat *stat;
+
+	if (item == NULL) {
+		item = &stats_root;
+	}
+	nni_mtx_lock(&stats_lock);
+	if ((rv = stat_make_tree(item, &stat)) != 0) {
+		nni_mtx_unlock(&stats_lock);
+		return (rv);
+	}
+	stat_update_tree(stat);
+	if (stats_held != NULL) {
+		nni_mtx_unlock(stats_held);
+		stats_held = NULL;
+	}
+	nni_mtx_unlock(&stats_lock);
+	*statp = stat;
+	return (0);
+}
+#endif
+
+int
+nng_stats_get(nng_stat **statp)
+{
+#ifdef NNG_ENABLE_STATS
+	return (nni_stat_snapshot(statp, &stats_root));
+#else
+	NNI_ARG_UNUSED(statp);
+	return (NNG_ENOTSUP);
+#endif
+}
+
+nng_stat *
+nng_stat_parent(nng_stat *stat)
+{
+	return (stat->s_parent);
+}
+
+nng_stat *
+nng_stat_next(nng_stat *stat)
+{
+	if (stat->s_parent == NULL) {
+		return (NULL); // Root node, no siblings.
+	}
+	return (nni_list_next(&stat->s_parent->s_children, stat));
+}
+
+nng_stat *
+nng_stat_child(nng_stat *stat)
+{
+	return (nni_list_first(&stat->s_children));
+}
+
+const char *
+nng_stat_name(nni_stat *stat)
+{
+	return (stat->s_name);
+}
+
+uint64_t
+nng_stat_value(nni_stat *stat)
+{
+	return (stat->s_value);
+}
+
+const char *
+nng_stat_string(nng_stat *stat)
+{
+	return (stat->s_string);
+}
+
+uint64_t
+nng_stat_timestamp(nng_stat *stat)
+{
+	return ((uint64_t) stat->s_time);
+}
+
+int
+nng_stat_type(nng_stat *stat)
+{
+	return (stat->s_type);
+}
+
+int
+nng_stat_unit(nng_stat *stat)
+{
+	return (stat->s_unit);
+}
+
+const char *
+nng_stat_desc(nng_stat *stat)
+{
+	return (stat->s_desc);
+}
+
+int
+nni_stat_sys_init(void)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_mtx_init(&stats_lock);
+	NNI_LIST_INIT(&stats_root.si_children, nni_stat_item, si_node);
+	stats_root.si_name = "";
+	stats_root.si_desc = "all statistsics";
+#endif
+
+	return (0);
+}
+
+void
+nni_stat_sys_fini(void)
+{
+#ifdef NNG_ENABLE_STATS
+	nni_mtx_fini(&stats_lock);
+#endif
+}
+
+#ifdef NNG_ENABLE_STATS
+void
+stat_sprint_scope(nni_stat *stat, char **scope, int *lenp)
+{
+	if (stat->s_parent != NULL) {
+		stat_sprint_scope(stat->s_parent, scope, lenp);
+	}
+	if (strlen(stat->s_name) > 0) {
+		snprintf(*scope, *lenp, "%s.", stat->s_name);
+	} else {
+		(*scope)[0] = '\0';
+	}
+	*lenp -= strlen(*scope);
+	*scope += strlen(*scope);
+}
+#endif
+
+void
+nng_stats_dump(nng_stat *stat)
+{
+#ifdef NNG_ENABLE_STATS
+	static char        buf[128]; // to minimize recursion, not thread safe
+	static char        line[128];
+	int                len;
+	char *             scope;
+	char *             indent = "        ";
+	unsigned long long val;
+	nni_stat *         child;
+
+	switch (nng_stat_type(stat)) {
+	case NNG_STAT_SCOPE:
+		scope = buf;
+		len   = sizeof(buf);
+		stat_sprint_scope(stat, &scope, &len);
+		len = strlen(buf);
+		if (len > 0) {
+			if (buf[len - 1] == '.') {
+				buf[--len] = '\0';
+			}
+		}
+		if (len > 0) {
+			snprintf(line, sizeof(line), "\n%s:", buf);
+		}
+		break;
+	case NNG_STAT_STRING:
+		snprintf(line, sizeof(line), "%s%-32s\"%s\"", indent,
+		    nng_stat_name(stat), nng_stat_string(stat));
+		break;
+	case NNG_STAT_BOOLEAN:
+		val = nng_stat_value(stat);
+		snprintf(line, sizeof(line), "%s%-32s%s", indent,
+		    nng_stat_name(stat), val != 0 ? "true" : "false");
+		break;
+	case NNG_STAT_LEVEL:
+	case NNG_STAT_COUNTER:
+		val = nng_stat_value(stat);
+		switch (nng_stat_unit(stat)) {
+		case NNG_UNIT_BYTES:
+			snprintf(line, sizeof(line), "%s%-32s%llu bytes",
+			    indent, nng_stat_name(stat), val);
+			break;
+		case NNG_UNIT_MESSAGES:
+			snprintf(line, sizeof(line), "%s%-32s%llu msgs",
+			    indent, nng_stat_name(stat), val);
+			break;
+		case NNG_UNIT_MILLIS:
+			snprintf(line, sizeof(line), "%s%-32s%llu msec",
+			    indent, nng_stat_name(stat), val);
+			break;
+		case NNG_UNIT_NONE:
+		case NNG_UNIT_EVENTS:
+		default:
+			snprintf(line, sizeof(line), "%s%-32s%llu", indent,
+			    nng_stat_name(stat), val);
+			break;
+		}
+		break;
+	case NNG_STAT_ID:
+		val = nng_stat_value(stat);
+		snprintf(line, (sizeof line), "%s%-32s%llu", indent,
+		    nng_stat_name(stat), val);
+		break;
+	default:
+		snprintf(line, (sizeof line), "%s%-32s<?>", indent,
+		    nng_stat_name(stat));
+		break;
+	}
+	nni_plat_println(line);
+
+	NNI_LIST_FOREACH (&stat->s_children, child) {
+		nng_stats_dump(child);
+	}
+#else
+	NNI_ARG_UNUSED(stat);
+#endif
+}
diff --git a/src/core/stats.h b/src/core/stats.h
new file mode 100644
index 00000000..8cfe14de
--- /dev/null
+++ b/src/core/stats.h
@@ -0,0 +1,108 @@
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+#ifndef CORE_STATS_H
+#define CORE_STATS_H
+
+#include "core/defs.h"
+
+// Statistics support.  This is inspired in part by the Solaris
+// kstats framework, but we've simplified and tuned it for our use.
+//
+// Collection of the stats will be done in two steps.  First we
+// will walk the list of stats, with the chain held, allocating
+// a user local copy of the stat and pointers.
+//
+// In phase 2, we run the update, and copy the values. We conditionally
+// acquire the lock on the stat first though.
+
+typedef struct nni_stat_item nni_stat_item;
+
+typedef void (*nni_stat_update)(nni_stat_item *, void *);
+typedef enum nng_stat_type_enum nni_stat_type;
+typedef enum nng_unit_enum      nni_stat_unit;
+
+// nni_stat_item is used by providers
+struct nni_stat_item {
+#ifdef NNG_ENABLE_STATS
+	nni_list_node   si_node;     // list node, framework use only
+	nni_stat_item * si_parent;   // link back to parent, framework use only
+	nni_list        si_children; // children, framework use only
+	const char *    si_name;     // name of statistic
+	const char *    si_desc;     // description of statistic (English)
+	nni_mtx *       si_lock;     // lock for accessing, can be NULL
+	void *          si_private;  // provider private pointer
+	nni_stat_type   si_type;     // type of stat, e.g. NNG_STAT_LEVEL
+	nni_stat_unit   si_unit;     // units, e.g. NNG_UNIT_MILLIS
+	nni_stat_update si_update;   // update function (can be NULL)
+	const char *    si_string;   // string value (NULL for numerics)
+	uint64_t        si_value;    // numeric value
+	nni_atomic_u64  si_atomic;   // atomic value
+#endif
+};
+
+void nni_stat_append(nni_stat_item *, nni_stat_item *);
+void nni_stat_remove(nni_stat_item *);
+
+void nni_stat_set_value(nni_stat_item *, uint64_t);
+void nni_stat_set_string(nni_stat_item *, const char *);
+void nni_stat_set_lock(nni_stat_item *, nni_mtx *);
+void nni_stat_set_update(nni_stat_item *, nni_stat_update, void *);
+
+#ifdef NNG_ENABLE_STATS
+void nni_stat_init(nni_stat_item *, const char *, const char *);
+void nni_stat_init_scope(nni_stat_item *, const char *, const char *);
+void nni_stat_init_string(
+    nni_stat_item *, const char *, const char *, const char *);
+void nni_stat_init_id(nni_stat_item *, const char *, const char *, uint64_t);
+void nni_stat_init_bool(nni_stat_item *, const char *, const char *, bool);
+void nni_stat_init_atomic(nni_stat_item *, const char *, const char *);
+void nni_stat_inc_atomic(nni_stat_item *, uint64_t);
+void nni_stat_dec_atomic(nni_stat_item *, uint64_t);
+void nni_stat_set_type(nni_stat_item *, int);
+void nni_stat_set_unit(nni_stat_item *, int);
+#else
+// We override initialization so that we can avoid compiling static strings
+// into the binary.  Presumably if stats are disabled, we are trying to save
+// space for constrained environments.  We do evaluate an unused arg to
+// prevent the compiler from bitching about unused values.
+#define nni_stat_init(a, b, c) ((void) (a))
+#define nni_stat_init_scope(a, b, c) ((void) (a))
+#define nni_stat_init_atomic(a, b, c) ((void) (a))
+#define nni_stat_init_id(a, b, c, d) ((void) (a))
+#define nni_stat_init_bool(a, b, c, d) ((void) (a))
+#define nni_stat_init_string(a, b, c, d) ((void) (a))
+#define nni_stat_set_unit(a, b) ((void) (a))
+#define nni_stat_set_type(a, b) ((void) (a))
+#define nni_stat_inc_atomic(stat, inc)
+#define nni_stat_dec_atomic(stat, inc)
+#endif
+
+#if 0
+#define nni_stat_append(a, b)
+#define nni_stat_remove(a)
+#define nni_stat_init(a, b, c)
+#define nni_stat_init_scope(a, b, c)
+#define nni_stat_init_string(a, b, c, d)
+#define nni_stat_init_id(a, b, c, d)
+#define nni_stat_init_bool(a, b, c, d)
+#define nni_stat_dec_atomic(a, b)
+#define nni_stat_set_value(a, b)
+#define nni_stat_set_string(a, b)
+#define nni_stat_set_lock(a, b)
+#define nni_stat_set_update(a, b, c)
+#define nni_stat_set_type(a, b)
+#define nni_stat_set_unit(a, b)
+#endif
+
+int  nni_stat_sys_init(void);
+void nni_stat_sys_fini(void);
+
+#endif // CORE_STATS_H
diff --git a/src/nng.c b/src/nng.c
index 64968cae..f98727ce 100644
--- a/src/nng.c
+++ b/src/nng.c
@@ -1594,74 +1594,6 @@ nng_aio_begin(nng_aio *aio)
 	return (true);
 }
 
-#if 0
-int
-nng_snapshot_create(nng_socket sock, nng_snapshot **snapp)
-{
-	// Stats TBD.
-	NNI_ARG_UNUSED(sock)
-	NNI_ARG_UNUSED(snapp)
-	return (NNG_ENOTSUP);
-}
-
-void
-nng_snapshot_free(nng_snapshot *snap)
-{
-	NNI_ARG_UNUSED(snap)
-	// Stats TBD.
-}
-
-int
-nng_snapshot_update(nng_snapshot *snap)
-{
-	NNI_ARG_UNUSED(snap)
-	// Stats TBD.
-	return (NNG_ENOTSUP);
-}
-
-int
-nng_snapshot_next(nng_snapshot *snap, nng_stat **statp)
-{
-	NNI_ARG_UNUSED(snap)
-	NNI_ARG_UNUSED(statp)
-	// Stats TBD.
-	*statp = NULL;
-	return (NNG_ENOTSUP);
-}
-
-const char *
-nng_stat_name(nng_stat *stat)
-{
-	NNI_ARG_UNUSED(stat)
-	// Stats TBD.
-	return (NULL);
-}
-
-int
-nng_stat_type(nng_stat *stat)
-{
-	NNI_ARG_UNUSED(stat)
-	// Stats TBD.
-	return (0);
-}
-
-int
-nng_stat_unit(nng_stat *stat)
-{
-	NNI_ARG_UNUSED(stat)
-    // Stats TBD.
-    return (0);
-}
-
-int64_t
-nng_stat_value(nng_stat *stat)
-{
-	NNI_ARG_UNUSED(stat)
-	// Stats TBD.
-	return (0);
-}
-#endif
-
 int
 nng_url_parse(nng_url **result, const char *ustr)
 {
diff --git a/src/nng.h b/src/nng.h
index 863ce363..0af21fc7 100644
--- a/src/nng.h
+++ b/src/nng.h
@@ -90,11 +90,10 @@ typedef struct nng_socket_s {
 	uint32_t id;
 } nng_socket;
 
-typedef int32_t             nng_duration; // in milliseconds
-typedef struct nng_msg      nng_msg;
-typedef struct nng_snapshot nng_snapshot;
-typedef struct nng_stat     nng_stat;
-typedef struct nng_aio      nng_aio;
+typedef int32_t         nng_duration; // in milliseconds
+typedef struct nng_msg  nng_msg;
+typedef struct nng_stat nng_stat;
+typedef struct nng_aio  nng_aio;
 
 // Initializers.
 // clang-format off
@@ -762,36 +761,37 @@ enum nng_flag_enum {
 // but the individual statistic names, values, and meanings are all
 // subject to change.
 
-// nng_snapshot_create creates a statistics snapshot. The snapshot
-// object must be deallocated expressly by the user, and may persist beyond
-// the lifetime of any socket object used to update it. Note that the
-// values of the statistics are initially unset.
-// NNG_DECL int nng_snapshot_create(nng_socket, nng_snapshot **);
-
-// nng_snapshot_free frees a snapshot object. All statistic objects
-// contained therein are destroyed as well.
-// NNG_DECL void nng_snapshot_free(nng_snapshot *);
-
-// nng_snapshot_update updates a snapshot of all the statistics
-// relevant to a particular socket. All prior values are overwritten.
-// NNG_DECL int nng_snapshot_update(nng_snapshot *);
-
-// nng_snapshot_next is used to iterate over the individual statistic
-// objects inside the snapshot. Note that the statistic object, and the
-// meta-data for the object (name, type, units) is fixed, and does not
-// change for the entire life of the snapshot.  Only the value
-// is subject to change, and then only when a snapshot is updated.
-//
-// Iteration begins by providing NULL in the value referenced. Successive
-// calls will update this value, returning NULL when no more statistics
-// are available in the snapshot.
-// NNG_DECL int nng_snapshot_next(nng_snapshot *, nng_stat **);
+// nng_stats_get takes a snapshot of the entire set of statistics.
+// While the operation can be somewhat expensive (allocations), it
+// is done in a way that minimizes impact to running operations.
+// Note that the statistics are provided as tree, with parents
+// used for grouping, and with child statistics underneath.  The
+// top stat returned will be of type NNG_STAT_SCOPE with name "".
+// Applications may choose to consider this root scope as "root", if
+// the empty string is not suitable.
+NNG_DECL int nng_stats_get(nng_stat **);
+
+// nng_stats_free frees a previous list of snapshots.  This should only
+// be called on the parent statistic that obtained via nng_stats_get.
+NNG_DECL void nng_stats_free(nng_stat *);
+
+// nng_stats_dump is a debugging function that dumps the entire set of
+// statistics to stdout.
+NNG_DECL void nng_stats_dump(nng_stat *);
+
+// nng_stat_next finds the next sibling for the current stat.  If there
+// are no more siblings, it returns NULL.
+NNG_DECL nng_stat *nng_stat_next(nng_stat *);
+
+// nng_stat_child finds the first child of the current stat.  If no children
+// exist, then NULL is returned.
+NNG_DECL nng_stat *nng_stat_child(nng_stat *);
 
 // nng_stat_name is used to determine the name of the statistic.
 // This is a human readable name.  Statistic names, as well as the presence
 // or absence or semantic of any particular statistic are not part of any
 // stable API, and may be changed without notice in future updates.
-// NNG_DECL const char *nng_stat_name(nng_stat *);
+NNG_DECL const char *nng_stat_name(nng_stat *);
 
 // nng_stat_type is used to determine the type of the statistic.
 // At present, only NNG_STAT_TYPE_LEVEL and and NNG_STAT_TYPE_COUNTER
@@ -799,32 +799,48 @@ enum nng_flag_enum {
 // value over time are likely more interesting than the actual level.  Level
 // values reflect some absolute state however, and should be presented to the
 // user as is.
-// NNG_DECL int nng_stat_type(nng_stat *);
+NNG_DECL int nng_stat_type(nng_stat *);
 
 enum nng_stat_type_enum {
-	NNG_STAT_LEVEL   = 0, // Numeric "absolute" value, diffs meaningless
-	NNG_STAT_COUNTER = 1  // Incrementing value (diffs are meaningful)
+	NNG_STAT_SCOPE   = 0, // Stat is for scoping, and carries no value
+	NNG_STAT_LEVEL   = 1, // Numeric "absolute" value, diffs meaningless
+	NNG_STAT_COUNTER = 2, // Incrementing value (diffs are meaningful)
+	NNG_STAT_STRING  = 3, // Value is a string
+	NNG_STAT_BOOLEAN = 4, // Value is a boolean
+	NNG_STAT_ID      = 5, // Value is a numeric ID
 };
 
 // nng_stat_unit provides information about the unit for the statistic,
 // such as NNG_UNIT_BYTES or NNG_UNIT_BYTES.  If no specific unit is
-// applicable, such as a relative priority, then NN_UNIT_NONE is
-// returned.
-// NNG_DECL int nng_stat_unit(nng_stat *);
+// applicable, such as a relative priority, then NN_UNIT_NONE is returned.
+NNG_DECL int nng_stat_unit(nng_stat *);
 
 enum nng_unit_enum {
-	NNG_UNIT_NONE     = 0,
-	NNG_UNIT_BYTES    = 1,
-	NNG_UNIT_MESSAGES = 2,
-	NNG_UNIT_BOOLEAN  = 3,
-	NNG_UNIT_MILLIS   = 4,
-	NNG_UNIT_EVENTS   = 5
+	NNG_UNIT_NONE     = 0, // No special units
+	NNG_UNIT_BYTES    = 1, // Bytes, e.g. bytes sent, etc.
+	NNG_UNIT_MESSAGES = 2, // Messages, one per message
+	NNG_UNIT_MILLIS   = 3, // Milliseconds
+	NNG_UNIT_EVENTS   = 4  // Some other type of event
 };
 
 // nng_stat_value returns returns the actual value of the statistic.
 // Statistic values reflect their value at the time that the corresponding
 // snapshot was updated, and are undefined until an update is performed.
-// NNG_DECL int64_t nng_stat_value(nng_stat *);
+NNG_DECL uint64_t nng_stat_value(nng_stat *);
+
+// nng_stat_string returns the string associated with a string statistic,
+// or NULL if the statistic is not part of the string.  The value returned
+// is valid until the associated statistic is freed.
+NNG_DECL const char *nng_stat_string(nng_stat *);
+
+// nng_stat_desc returns a human readable description of the statistic.
+// This may be useful for display in diagnostic interfaces, etc.
+NNG_DECL const char *nng_stat_desc(nng_stat *);
+
+// nng_stat_timestamp returns a timestamp (milliseconds) when the statistic
+// was captured.  The base offset is the same as used by nng_clock().
+// We don't use nng_time though, because that's in the supplemental header.
+NNG_DECL uint64_t nng_stat_timestamp(nng_stat *);
 
 // Device functionality.  This connects two sockets together in a device,
 // which means that messages from one side are forwarded to the other.
diff --git a/src/protocol/pair1/pair.c b/src/protocol/pair1/pair.c
index dc250943..3033b196 100644
--- a/src/protocol/pair1/pair.c
+++ b/src/protocol/pair1/pair.c
@@ -23,6 +23,8 @@
 #define NNI_PROTO_PAIR_V1 NNI_PROTO(1, 1)
 #endif
 
+#define BUMPSTAT(x) nni_stat_inc_atomic(x, 1)
+
 typedef struct pair1_pipe pair1_pipe;
 typedef struct pair1_sock pair1_sock;
 
@@ -35,16 +37,21 @@ static void pair1_pipe_fini(void *);
 
 // pair1_sock is our per-socket protocol private structure.
 struct pair1_sock {
-	nni_msgq *  uwq;
-	nni_msgq *  urq;
-	bool        raw;
-	int         ttl;
-	nni_mtx     mtx;
-	nni_idhash *pipes;
-	nni_list    plist;
-	bool        started;
-	bool        poly;
-	nni_aio *   aio_getq;
+	nni_msgq *    uwq;
+	nni_msgq *    urq;
+	nni_sock *    nsock;
+	bool          raw;
+	int           ttl;
+	nni_mtx       mtx;
+	nni_idhash *  pipes;
+	nni_list      plist;
+	bool          started;
+	bool          poly;
+	nni_aio *     aio_getq;
+	nni_stat_item stat_poly;
+	nni_stat_item stat_raw;
+	nni_stat_item stat_rejmismatch;
+	nni_stat_item stat_rejinuse;
 };
 
 // pair1_pipe is our per-pipe protocol private structure.
@@ -94,12 +101,29 @@ pair1_sock_init_impl(void **sp, nni_sock *nsock, bool raw)
 		return (rv);
 	}
 
-	s->raw  = raw;
-	s->poly = false;
-	s->uwq  = nni_sock_sendq(nsock);
-	s->urq  = nni_sock_recvq(nsock);
-	s->ttl  = 8;
-	*sp     = s;
+	nni_stat_init_bool(
+	    &s->stat_poly, "polyamorous", "polyamorous mode?", false);
+	nni_stat_set_lock(&s->stat_poly, &s->mtx);
+	nni_sock_add_stat(nsock, &s->stat_poly);
+
+	nni_stat_init_bool(&s->stat_raw, "raw", "raw mode?", raw);
+	nni_sock_add_stat(nsock, &s->stat_raw);
+
+	nni_stat_init_atomic(&s->stat_rejmismatch, "mismatch",
+	    "pipes rejected (protocol mismatch)");
+	nni_sock_add_stat(nsock, &s->stat_rejmismatch);
+
+	nni_stat_init_atomic(&s->stat_rejinuse, "already",
+	    "pipes rejected (already connected)");
+	nni_sock_add_stat(nsock, &s->stat_rejinuse);
+
+	s->nsock = nsock;
+	s->raw   = raw;
+	s->poly  = false;
+	s->uwq   = nni_sock_sendq(nsock);
+	s->urq   = nni_sock_recvq(nsock);
+	s->ttl   = 8;
+	*sp      = s;
 
 	return (0);
 }
@@ -173,13 +197,15 @@ pair1_pipe_start(void *arg)
 	uint32_t    id;
 	int         rv;
 
+	nni_mtx_lock(&s->mtx);
 	if (nni_pipe_peer(p->npipe) != NNI_PROTO_PAIR_V1) {
+		nni_mtx_unlock(&s->mtx);
+		BUMPSTAT(&s->stat_rejmismatch);
 		// Peer protocol mismatch.
 		return (NNG_EPROTO);
 	}
 
 	id = nni_pipe_id(p->npipe);
-	nni_mtx_lock(&s->mtx);
 	if ((rv = nni_idhash_insert(s->pipes, id, p)) != 0) {
 		nni_mtx_unlock(&s->mtx);
 		return (rv);
@@ -188,6 +214,7 @@ pair1_pipe_start(void *arg)
 		if (!nni_list_empty(&s->plist)) {
 			nni_idhash_remove(s->pipes, id);
 			nni_mtx_unlock(&s->mtx);
+			BUMPSTAT(&s->stat_rejinuse);
 			return (NNG_EBUSY);
 		}
 	} else {
@@ -242,6 +269,7 @@ pair1_pipe_recv_cb(void *arg)
 	uint32_t    hdr;
 	nni_pipe *  npipe = p->npipe;
 	int         rv;
+	size_t      len;
 
 	if (nni_aio_result(p->aio_recv) != 0) {
 		nni_pipe_close(p->npipe);
@@ -266,10 +294,12 @@ pair1_pipe_recv_cb(void *arg)
 		nni_pipe_close(npipe);
 		return;
 	}
+	len = nni_msg_len(msg);
 
 	// If we bounced too many times, discard the message, but
 	// keep getting more.
 	if (hdr > (unsigned) s->ttl) {
+		// STAT: bump TTLdrop
 		nni_msg_free(msg);
 		nni_pipe_recv(npipe, p->aio_recv);
 		return;
@@ -277,6 +307,7 @@ pair1_pipe_recv_cb(void *arg)
 
 	// Store the hop count in the header.
 	if ((rv = nni_msg_header_append_u32(msg, hdr)) != 0) {
+		// STAT: bump allocfail
 		nni_msg_free(msg);
 		nni_pipe_recv(npipe, p->aio_recv);
 		return;
@@ -284,6 +315,7 @@ pair1_pipe_recv_cb(void *arg)
 
 	// Send the message up.
 	nni_aio_set_msg(p->aio_putq, msg);
+	nni_sock_bump_rx(s->nsock, len);
 	nni_msgq_aio_put(s->urq, p->aio_putq);
 }
 
@@ -452,6 +484,7 @@ pair1_sock_set_poly(void *arg, const void *buf, size_t sz, nni_opt_type t)
 	int         rv;
 	nni_mtx_lock(&s->mtx);
 	rv = s->started ? NNG_ESTATE : nni_copyin_bool(&s->poly, buf, sz, t);
+	nni_stat_set_value(&s->stat_poly, s->poly);
 	nni_mtx_unlock(&s->mtx);
 	return (rv);
 }
@@ -468,6 +501,7 @@ pair1_sock_send(void *arg, nni_aio *aio)
 {
 	pair1_sock *s = arg;
 
+	nni_sock_bump_tx(s->nsock, nni_msg_len(nni_aio_get_msg(aio)));
 	nni_msgq_aio_put(s->uwq, aio);
 }
 
diff --git a/src/transport/inproc/inproc.c b/src/transport/inproc/inproc.c
index ab6486bd..6199e949 100644
--- a/src/transport/inproc/inproc.c
+++ b/src/transport/inproc/inproc.c
@@ -37,6 +37,16 @@ struct nni_inproc_pipe {
 	uint16_t         peer;
 	uint16_t         proto;
 	size_t           rcvmax;
+	nni_stat_item    st_rxbytes;
+	nni_stat_item    st_txbytes;
+	nni_stat_item    st_rxmsgs;
+	nni_stat_item    st_txmsgs;
+	nni_stat_item    st_rxdiscards;
+	nni_stat_item    st_txdiscards;
+	nni_stat_item    st_rxerrs;
+	nni_stat_item    st_txerrs;
+	nni_stat_item    st_rxoversize;
+	nni_stat_item    st_rcvmaxsz;
 };
 
 // nni_inproc_pair represents a pair of pipes.  Because we control both
@@ -60,6 +70,7 @@ struct nni_inproc_ep {
 	nni_mtx       mtx;
 	nni_dialer *  ndialer;
 	nni_listener *nlistener;
+	nni_stat_item st_rcvmaxsz;
 };
 
 // nni_inproc is our global state - this contains the list of active endpoints
@@ -123,11 +134,120 @@ nni_inproc_pipe_alloc(nni_inproc_pipe **pipep, nni_inproc_ep *ep)
 	return (0);
 }
 
+#ifdef NNG_ENABLE_STATS
+static void
+inproc_get_rxbytes(nni_stat_item *st, void *arg)
+{
+	nni_msgq *mq = arg;
+	nni_stat_set_value(st, nni_msgq_stat_get_bytes(mq));
+}
+
+static void
+inproc_get_rxmsgs(nni_stat_item *st, void *arg)
+{
+	nni_msgq *mq = arg;
+	nni_stat_set_value(st, nni_msgq_stat_get_msgs(mq));
+}
+
+static void
+inproc_get_txbytes(nni_stat_item *st, void *arg)
+{
+	nni_msgq *mq = arg;
+	nni_stat_set_value(st, nni_msgq_stat_put_bytes(mq));
+}
+
+static void
+inproc_get_txmsgs(nni_stat_item *st, void *arg)
+{
+	nni_msgq *mq = arg;
+	nni_stat_set_value(st, nni_msgq_stat_put_msgs(mq));
+}
+
+static void
+inproc_get_discards(nni_stat_item *st, void *arg)
+{
+	nni_msgq *mq = arg;
+	nni_stat_set_value(st, nni_msgq_stat_discards(mq));
+}
+
+static void
+inproc_get_txerrs(nni_stat_item *st, void *arg)
+{
+	nni_msgq *mq = arg;
+	nni_stat_set_value(st, nni_msgq_stat_put_errs(mq));
+}
+
+static void
+inproc_get_rxerrs(nni_stat_item *st, void *arg)
+{
+	nni_msgq *mq = arg;
+	nni_stat_set_value(st, nni_msgq_stat_get_errs(mq));
+}
+#else
+#undef nni_stat_set_update
+#define nni_stat_set_update(p, x, f)
+#endif
+
 static int
 nni_inproc_pipe_init(void *arg, nni_pipe *p)
 {
 	nni_inproc_pipe *pipe = arg;
 	pipe->npipe           = p;
+
+	nni_stat_init(&pipe->st_rxbytes, "rxbytes", "bytes received (raw)");
+	nni_stat_set_update(&pipe->st_rxbytes, inproc_get_rxbytes, pipe->rq);
+	nni_stat_set_unit(&pipe->st_rxbytes, NNG_UNIT_BYTES);
+	nni_pipe_add_stat(p, &pipe->st_rxbytes);
+
+	nni_stat_init(&pipe->st_txbytes, "txbytes", "bytes sent (raw)");
+	nni_stat_set_update(&pipe->st_txbytes, inproc_get_txbytes, pipe->wq);
+	nni_stat_set_unit(&pipe->st_txbytes, NNG_UNIT_BYTES);
+	nni_pipe_add_stat(p, &pipe->st_txbytes);
+
+	nni_stat_init(&pipe->st_rxmsgs, "rxmsgs", "msgs received");
+	nni_stat_set_update(&pipe->st_rxmsgs, inproc_get_rxmsgs, pipe->rq);
+	nni_stat_set_unit(&pipe->st_rxmsgs, NNG_UNIT_MESSAGES);
+	nni_pipe_add_stat(p, &pipe->st_rxmsgs);
+
+	nni_stat_init(&pipe->st_txmsgs, "txmsgs", "msgs sent");
+	nni_stat_set_update(&pipe->st_txmsgs, inproc_get_txmsgs, pipe->wq);
+	nni_stat_set_unit(&pipe->st_txmsgs, NNG_UNIT_MESSAGES);
+	nni_pipe_add_stat(p, &pipe->st_txmsgs);
+
+	nni_stat_init(
+	    &pipe->st_rxdiscards, "rxdiscards", "receives discarded");
+	nni_stat_set_update(
+	    &pipe->st_rxdiscards, inproc_get_discards, pipe->rq);
+	nni_stat_set_unit(&pipe->st_rxdiscards, NNG_UNIT_MESSAGES);
+	nni_pipe_add_stat(p, &pipe->st_rxdiscards);
+
+	nni_stat_init(&pipe->st_txdiscards, "txdiscards", "sends discarded");
+	nni_stat_set_update(
+	    &pipe->st_txdiscards, inproc_get_discards, pipe->wq);
+	nni_stat_set_unit(&pipe->st_txdiscards, NNG_UNIT_MESSAGES);
+	nni_pipe_add_stat(p, &pipe->st_txdiscards);
+
+	nni_stat_init(&pipe->st_rxerrs, "rxerrs", "receive errors");
+	nni_stat_set_update(&pipe->st_rxerrs, inproc_get_rxerrs, pipe->rq);
+	nni_stat_set_unit(&pipe->st_rxerrs, NNG_UNIT_MESSAGES);
+	nni_pipe_add_stat(p, &pipe->st_rxerrs);
+
+	nni_stat_init(&pipe->st_txerrs, "txerrs", "send errors");
+	nni_stat_set_update(&pipe->st_txerrs, inproc_get_txerrs, pipe->wq);
+	nni_stat_set_unit(&pipe->st_txerrs, NNG_UNIT_MESSAGES);
+	nni_pipe_add_stat(p, &pipe->st_txerrs);
+
+	nni_stat_init_atomic(&pipe->st_rxoversize, "rxoversize",
+	    "oversize msgs received (dropped)");
+	nni_stat_set_unit(&pipe->st_rxoversize, NNG_UNIT_MESSAGES);
+	nni_pipe_add_stat(p, &pipe->st_rxoversize);
+
+	nni_stat_init(&pipe->st_rcvmaxsz, "rcvmaxsz", "maximum receive size");
+	nni_stat_set_type(&pipe->st_rcvmaxsz, NNG_UNIT_BYTES);
+	nni_stat_set_unit(&pipe->st_rcvmaxsz, NNG_UNIT_BYTES);
+	nni_stat_set_value(&pipe->st_rcvmaxsz, pipe->rcvmax);
+	nni_pipe_add_stat(p, &pipe->st_rcvmaxsz);
+
 	return (0);
 }
 
@@ -225,7 +345,15 @@ nni_inproc_dialer_init(void **epp, nni_url *url, nni_dialer *ndialer)
 	nni_aio_list_init(&ep->aios);
 
 	ep->addr = url->u_rawurl; // we match on the full URL.
-	*epp     = ep;
+
+	nni_stat_init(&ep->st_rcvmaxsz, "rcvmaxsz", "maximum receive size");
+	nni_stat_set_type(&ep->st_rcvmaxsz, NNG_STAT_LEVEL);
+	nni_stat_set_unit(&ep->st_rcvmaxsz, NNG_UNIT_BYTES);
+	nni_stat_set_lock(&ep->st_rcvmaxsz, &ep->mtx);
+
+	nni_dialer_add_stat(ndialer, &ep->st_rcvmaxsz);
+
+	*epp = ep;
 	return (0);
 }
 
@@ -248,7 +376,14 @@ nni_inproc_listener_init(void **epp, nni_url *url, nni_listener *nlistener)
 	nni_aio_list_init(&ep->aios);
 
 	ep->addr = url->u_rawurl; // we match on the full URL.
-	*epp     = ep;
+
+	nni_stat_init(&ep->st_rcvmaxsz, "rcvmaxsz", "maximum receive size");
+	nni_stat_set_type(&ep->st_rcvmaxsz, NNG_STAT_LEVEL);
+	nni_stat_set_unit(&ep->st_rcvmaxsz, NNG_UNIT_BYTES);
+	nni_stat_set_lock(&ep->st_rcvmaxsz, &ep->mtx);
+	nni_listener_add_stat(nlistener, &ep->st_rcvmaxsz);
+
+	*epp = ep;
 	return (0);
 }
 
@@ -284,6 +419,7 @@ inproc_filter(void *arg, nni_msg *msg)
 {
 	nni_inproc_pipe *p = arg;
 	if (p->rcvmax && (nni_msg_len(msg) > p->rcvmax)) {
+		nni_stat_inc_atomic(&p->st_rxoversize, 1);
 		nni_msg_free(msg);
 		return (NULL);
 	}
@@ -509,6 +645,7 @@ inproc_ep_set_recvmaxsz(void *arg, const void *v, size_t sz, nni_opt_type t)
 	if ((rv = nni_copyin_size(&val, v, sz, 0, NNI_MAXSZ, t)) == 0) {
 		nni_mtx_lock(&ep->mtx);
 		ep->rcvmax = val;
+		nni_stat_set_value(&ep->st_rcvmaxsz, val);
 		nni_mtx_unlock(&ep->mtx);
 	}
 	return (rv);
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 4139c046..4c3625b6 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -157,6 +157,7 @@ add_nng_test1(resolv 10 NNG_STATIC_LIB)
 add_nng_test(scalability 20 ON)
 add_nng_test2(sha1 5 NNG_STATIC_LIB NNG_SUPP_SHA1)
 add_nng_test(sock 5)
+add_nng_test1(stats 5 NNG_ENABLE_STATS)
 add_nng_test1(synch 5 NNG_STATIC_LIB)
 add_nng_test2(tls 60 NNG_STATIC_LIB NNG_TRANSPORT_TLS)
 add_nng_test1(tcp 180 NNG_TRANSPORT_TCP)
diff --git a/tests/stats.c b/tests/stats.c
new file mode 100644
index 00000000..b8ca8da8
--- /dev/null
+++ b/tests/stats.c
@@ -0,0 +1,78 @@
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+#include "convey.h"
+#include "nng.h"
+#include "trantest.h"
+
+#include "protocol/pubsub0/sub.h"
+
+#include "protocol/pair1/pair.h"
+
+#include "supplemental/util/platform.h"
+
+#include "stubs.h"
+
+#include <string.h>
+
+#define SECONDS(x) ((x) *1000)
+
+TestMain("Stats Test", {
+	atexit(nng_fini);
+
+	Convey("We are able to open a PAIR socket", {
+		nng_socket s1;
+
+		So(nng_pair_open(&s1) == 0);
+
+		Reset({ nng_close(s1); });
+
+		Convey("We can send and receive messages", {
+			nng_socket   s2;
+			int          len;
+			size_t       sz;
+			nng_duration to = SECONDS(3);
+			char *       buf;
+			char *       a = "inproc://stats";
+			nng_stat *   stats;
+
+			So(nng_pair_open(&s2) == 0);
+			Reset({ nng_close(s2); });
+
+			So(nng_setopt_int(s1, NNG_OPT_RECVBUF, 1) == 0);
+			So(nng_getopt_int(s1, NNG_OPT_RECVBUF, &len) == 0);
+			So(len == 1);
+
+			So(nng_setopt_int(s1, NNG_OPT_SENDBUF, 1) == 0);
+			So(nng_setopt_int(s2, NNG_OPT_SENDBUF, 1) == 0);
+
+			So(nng_setopt_ms(s1, NNG_OPT_SENDTIMEO, to) == 0);
+			So(nng_setopt_ms(s1, NNG_OPT_RECVTIMEO, to) == 0);
+			So(nng_setopt_ms(s2, NNG_OPT_SENDTIMEO, to) == 0);
+			So(nng_setopt_ms(s2, NNG_OPT_RECVTIMEO, to) == 0);
+
+			So(nng_listen(s1, a, NULL, 0) == 0);
+			So(nng_dial(s2, a, NULL, 0) == 0);
+
+			So(nng_send(s1, "abc", 4, 0) == 0);
+			So(nng_recv(s2, &buf, &sz, NNG_FLAG_ALLOC) == 0);
+			So(buf != NULL);
+			So(sz == 4);
+			So(memcmp(buf, "abc", 4) == 0);
+			nng_free(buf, sz);
+
+			Convey("We can collect stats", {
+				So(nng_stats_get(&stats) == 0);
+				nng_stats_dump(stats);
+				nng_stats_free(stats);
+			});
+		});
+	});
+})