From 5f7289e1f8e1427c9214c8e3e96ad56b1f868d53 Mon Sep 17 00:00:00 2001
From: Garrett D'Amore <garrett@damore.org>
Date: Wed, 4 Apr 2018 13:36:54 -0700
Subject: fixes #334 Separate context for state machines from sockets

This provides context support for REQ and REP sockets.
More discussion around this is in the issue itself.

Optionally we would like to extend this to the surveyor pattern.

Note that we specifically do not support pollable descriptors
for non-default contexts, and the results of using file descriptors
for polling (NNG_OPT_SENDFD and NNG_OPT_RECVFD) is undefined.

In the future, it might be nice to figure out how to factor in
optional use of a message queue for users who want more buffering,
but we think there is little need for this with cooked mode.
---
 docs/man/nng_ctx_getopt.3.adoc | 128 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 docs/man/nng_ctx_getopt.3.adoc

(limited to 'docs/man/nng_ctx_getopt.3.adoc')

diff --git a/docs/man/nng_ctx_getopt.3.adoc b/docs/man/nng_ctx_getopt.3.adoc
new file mode 100644
index 00000000..b20ea3b4
--- /dev/null
+++ b/docs/man/nng_ctx_getopt.3.adoc
@@ -0,0 +1,128 @@
+= nng_ctx_getopt(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_ctx_getopt - get context option
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_ctx_getopt(nng_ctx ctx, const char *opt, void *val, size_t *valszp);
+
+int nng_ctx_getopt_bool(nng_ctx ctx, const char *opt, bool *bvalp);
+
+int nng_ctx_getopt_int(nng_ctx ctx, const char *opt, int *ivalp);
+
+int nng_ctx_getopt_ms(nng_ctx ctx, const char *opt, nng_duration *durp);
+
+int nng_ctx_getopt_size(nng_ctx ctx, const char *opt, size_t *zp);
+
+int nng_ctx_getopt_string(nng_ctx ctx, const char *opt, char **strp);
+
+int nng_ctx_getopt_uint64(nng_ctx ctx, const char *opt, uint64_t *u64p);
+----
+
+== DESCRIPTION
+
+(((options, context)))
+The `nng_ctx_getopt()` functions are used to retrieve option values for
+the <<nng_ctx.5#,context>> _ctx_.
+The actual options that may be retrieved in this way vary.
+A number of them are documented in <<nng_options.5#,nng_options(5)>>.
+
+NOTE: Context options are protocol specific.
+The details will be documented with the protocol.
+
+=== Forms
+
+In all of these forms, the option _opt_ is retrieved from the context _ctx_.
+The forms vary based on the type of the option they take.
+
+The details of the type, size, and semantics of the option will depend
+on the actual option, and will be documented with the option itself.
+
+TIP: Generally, it will be easier to use one of the typed forms instead.
+
+==== `nng_ctx_getopt()`
+This function is untyped and can be used to retrieve the value of any option.
+The caller must store a pointer to a buffer to receive the value in _val_,
+and the size of the buffer shall be stored at the location referenced by
+_valszp_.
+
+When the function returns, the actual size of the data copied (or that
+would have been copied if sufficient space were present) is stored at
+the location referened by _valszp_.
+If the caller's buffer is not large enough to hold the entire object,
+then the copy is truncated.
+Therefore the caller should check for truncation by verifyng that the
+returned size in _valszp_ does not exceed the original buffer size.
+
+It is acceptable to pass `NULL` for _val_ if the value in _valszp_ is zero.
+This can be used to determine the size of the buffer needed to receive
+the object.
+
+==== `nng_ctx_getopt_bool()`
+This function is for options which take a boolean (`bool`).
+The value will be stored at _ivalp_.
+
+==== `nng_ctx_getopt_int()`
+This function is for options which take an integer (`int`).
+The value will be stored at _ivalp_.
+
+==== `nng_ctx_getopt_ms()`
+This function is used to retrieve time <<nng_duration.5#,durations>>
+(such as timeouts), stored in _durp_ as a number of milliseconds.
+(The special value ((`NNG_DUR_INFINITE`)) means an infinite amount of time, and
+the special value ((`NNG_DUR_DEFAULT`)) means a context-specific default.)
+
+==== `nng_ctx_getopt_size()`
+This function is used to retrieve a size into the pointer _zp_,
+typically for buffer sizes, message maximum sizes, and similar options.
+
+==== `nng_ctx_getopt_string()`
+This function is used to retrieve a string into _strp_.
+This string is created from the source using <<nng_strdup.3#,`nng_strdup()`>>
+and consequently must be freed by the caller using
+<<nng_strfree.3#,`nng_strfree()`>> when it is no longer needed.
+
+==== `nng_ctx_getopt_uint64()`
+This function is used to retrieve a 64-bit unsigned value into the value
+referenced by _u64p_.
+This is typically used for options related to identifiers, network
+numbers, and similar.
+
+== RETURN VALUES
+
+These functions return 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+`NNG_EBADTYPE`:: Incorrect type for option.
+`NNG_ECLOSED`:: Parameter _s_ does not refer to an open socket.
+`NNG_EINVAL`:: Size of destination _val_ too small for object.
+`NNG_ENOMEM`:: Insufficient memory exists.
+`NNG_ENOTSUP`:: The option _opt_ is not supported.
+`NNG_EWRITEONLY`:: The option _opt_ is write-only.
+
+== SEE ALSO
+
+<<nng_ctx_setopt.3#,nng_ctx_setopt(3)>>,
+<<nng_strdup.3#,nng_strdup(3)>>,
+<<nng_strerror.3#,nng_strerror(3)>>,
+<<nng_strfree.3#,nng_strfree(3)>>,
+<<nng_duration.5#,nng_duration(5)>>,
+<<nng_ctx.5#,nng_ctx(5)>>,
+<<nng_options.5#,nng_options(5)>>,
+<<nng.7#,nng(7)>>
-- 
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