fixes #960 NNG threads inherit application thread name

This also exposes an nng_thread_set_name() function for
applications to use.  All NNG thread names start with "nng:".
Note that support is highly dependent on the operating system.

24 files changed, 179 insertions, 24 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0aecbd8e..77233435 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -317,6 +317,8 @@ else ()
     nng_check_lib(rt clock_gettime NNG_HAVE_CLOCK_GETTIME)
     nng_check_lib(pthread sem_wait NNG_HAVE_SEMAPHORE_PTHREAD)
     nng_check_lib(pthread pthread_atfork NNG_HAVE_PTHREAD_ATFORK_PTHREAD)
+    nng_check_lib(pthread pthread_set_name_np NNG_HAVE_PTHREAD_SET_NAME_NP)
+    nng_check_lib(pthread pthread_setname_np NNG_HAVE_PTHREAD_SETNAME_NP)
     nng_check_lib(nsl gethostbyname NNG_HAVE_LIBNSL)
     nng_check_lib(socket socket NNG_HAVE_LIBSOCKET)
 
diff --git a/docs/man/CMakeLists.txt b/docs/man/CMakeLists.txt
index d17a1cfe..0f175195 100644
--- a/docs/man/CMakeLists.txt
+++ b/docs/man/CMakeLists.txt
@@ -303,6 +303,7 @@ if (NNG_ENABLE_DOC)
             nng_random
             nng_thread_create
             nng_thread_destroy
+            nng_thread_set_name
             )
 
     set(NNG_MAN3STR
diff --git a/docs/man/libnng.3.adoc b/docs/man/libnng.3.adoc
index 6107da99..ab1a6b11 100644
--- a/docs/man/libnng.3.adoc
+++ b/docs/man/libnng.3.adoc
@@ -291,6 +291,7 @@ as a convenience to aid in creating portable applications.
 |xref:nng_random.3supp.adoc[nng_random()]|get random number
 |xref:nng_thread_create.3supp.adoc[nng_thread_create()]|create thread
 |xref:nng_thread_destroy.3supp.adoc[nng_thread_destroy()]|reap thread
+|xref:nng_thread_set_name.3supp.adoc[nng_thread_set_name()]|set thread name
 |===
 
 === Byte Streams
diff --git a/docs/man/nng_thread_set_name.3supp.adoc b/docs/man/nng_thread_set_name.3supp.adoc
new file mode 100644
index 00000000..385d2727
--- /dev/null
+++ b/docs/man/nng_thread_set_name.3supp.adoc
@@ -0,0 +1,48 @@
+= nng_thread_set_name(3supp)
+//
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+//
+// 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_thread_set_name - set thread name
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+#include <nng/supplemental/util/platform.h>
+
+void nng_set_thread_name(nng_thread *thread, const char *name);
+----
+
+== DESCRIPTION
+
+The `nng_thread_set_name()` function attempts to set the name for the _thread_ to _name_.
+
+If _thread_ is `NULL`, then the name is set for the current thread.
+
+Support for this, and how names are exposed, varies between platform implementations.
+This function is intended to facilitate debugging applications that may have many threads.
+
+TIP: Internal threads created by _NNG_ will have names beginning with `nng:`.
+
+== RETURN VALUES
+
+None.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_thread_create.3supp.adoc[nng_thread_create(3supp)],
+xref:nng.7.adoc[nng(7)]
diff --git a/include/nng/supplemental/util/platform.h b/include/nng/supplemental/util/platform.h
index 87e0305f..feca858a 100644
--- a/include/nng/supplemental/util/platform.h
+++ b/include/nng/supplemental/util/platform.h
@@ -49,6 +49,11 @@ typedef struct nng_thread nng_thread;
 // I/O APIs provided by nng.  The thread runs until completion.
 NNG_DECL int nng_thread_create(nng_thread **, void (*)(void *), void *);
 
+// Set the thread name.  Support for this is platform specific and varies.
+// It is intended to provide information for use when debugging applications,
+// and not for programmatic use beyond that.
+NNG_DECL void nng_thread_set_name(nng_thread *, const char *);
+
 // Destroy a thread (waiting for it to complete.)  When this function
 // returns all resources for the thread are cleaned up.
 NNG_DECL void nng_thread_destroy(nng_thread *);
diff --git a/src/core/aio.c b/src/core/aio.c
index ea2203f2..97bb9153 100644
--- a/src/core/aio.c
+++ b/src/core/aio.c
@@ -488,6 +488,8 @@ nni_aio_expire_loop(void *unused)
 
 	NNI_ARG_UNUSED(unused);
 
+        nni_thr_set_name(NULL, "nng:aio:expire");
+
 	for (;;) {
 		nni_aio_cancelfn fn;
 		nni_time         now;
diff --git a/src/core/platform.h b/src/core/platform.h
index c6f4ef30..6eff2f7d 100644
--- a/src/core/platform.h
+++ b/src/core/platform.h
@@ -157,6 +157,10 @@ extern void nni_plat_thr_fini(nni_plat_thr *);
 // prevention in callbacks, for example.)
 extern bool nni_plat_thr_is_self(nni_plat_thr *);
 
+// nni_plat_thr_set_name is used to set the thread name, which
+// should be a short ASCII string.  It may or may not be supported --
+// this is intended to facilitate debugging.
+extern void nni_plat_thr_set_name(nni_plat_thr *, const char *);
 //
 // Atomics support.  This will evolve over time.
 //
diff --git a/src/core/reap.c b/src/core/reap.c
index bfad6c32..ddd2a06e 100644
--- a/src/core/reap.c
+++ b/src/core/reap.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2017 Garrett D'Amore <garrett@damore.org>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2017 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -27,7 +27,9 @@ reap_worker(void *notused)
 {
 	NNI_ARG_UNUSED(notused);
 
-	nni_mtx_lock(&reap_mtx);
+        nni_thr_set_name(NULL, "nng:reap");
+
+        nni_mtx_lock(&reap_mtx);
 	for (;;) {
 		nni_reap_item *item;
 		while ((item = nni_list_first(&reap_list)) != NULL) {
diff --git a/src/core/taskq.c b/src/core/taskq.c
index fbd93ebe..9ccd5845 100644
--- a/src/core/taskq.c
+++ b/src/core/taskq.c
@@ -34,7 +34,9 @@ nni_taskq_thread(void *self)
 	nni_taskq *    tq  = thr->tqt_tq;
 	nni_task *     task;
 
-	nni_mtx_lock(&tq->tq_mtx);
+        nni_thr_set_name(NULL, "nng:task");
+
+        nni_mtx_lock(&tq->tq_mtx);
 	for (;;) {
 		if ((task = nni_list_first(&tq->tq_tasks)) != NULL) {
 
diff --git a/src/core/thread.c b/src/core/thread.c
index adc35542..986ff331 100644
--- a/src/core/thread.c
+++ b/src/core/thread.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2017 Garrett D'Amore <garrett@damore.org>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 //
 // This software is supplied under the terms of the MIT License, a
 // copy of which should be located in the distribution where this
@@ -182,3 +182,9 @@ nni_thr_is_self(nni_thr *thr)
 	}
 	return (nni_plat_thr_is_self(&thr->thr));
 }
+
+void
+nni_thr_set_name(nni_thr *thr, const char *name)
+{
+	nni_plat_thr_set_name(&thr->thr, name);
+}
\ No newline at end of file
diff --git a/src/core/thread.h b/src/core/thread.h
index c3d5531e..154b4616 100644
--- a/src/core/thread.h
+++ b/src/core/thread.h
@@ -1,5 +1,5 @@
 //
-// Copyright 2017 Garrett D'Amore <garrett@damore.org>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2017 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -85,4 +85,7 @@ extern void nni_thr_wait(nni_thr *thr);
 // nni_thr_is_self returns true if the caller is the named thread.
 extern bool nni_thr_is_self(nni_thr *thr);
 
+// nni_thr_set_name is used to set a short name for the thread.
+extern void nni_thr_set_name(nni_thr *thr, const char *);
+
 #endif // CORE_THREAD_H
diff --git a/src/core/timer.c b/src/core/timer.c
index ad47ae33..36024817 100644
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 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
@@ -136,6 +136,8 @@ nni_timer_loop(void *arg)
 	nni_time        now;
 	nni_timer_node *node;
 
+        nni_thr_set_name(NULL, "nng:timer");
+
 	for (;;) {
 		nni_mtx_lock(&timer->t_mx);
 		timer->t_active = NULL;
diff --git a/src/platform/posix/posix_pollq_epoll.c b/src/platform/posix/posix_pollq_epoll.c
index d7a2c70f..bbfa9f6e 100644
--- a/src/platform/posix/posix_pollq_epoll.c
+++ b/src/platform/posix/posix_pollq_epoll.c
@@ -377,6 +377,7 @@ nni_posix_pollq_create(nni_posix_pollq *pq)
 		nni_mtx_fini(&pq->mtx);
 		return (rv);
 	}
+	nni_thr_set_name(&pq->thr, "nng:poll:epoll");
 	nni_thr_run(&pq->thr);
 	return (0);
 }
diff --git a/src/platform/posix/posix_pollq_kqueue.c b/src/platform/posix/posix_pollq_kqueue.c
index 7d827d7d..dda81be4 100644
--- a/src/platform/posix/posix_pollq_kqueue.c
+++ b/src/platform/posix/posix_pollq_kqueue.c
@@ -229,6 +229,8 @@ nni_posix_poll_thr(void *arg)
 {
 	nni_posix_pollq *pq = arg;
 
+	nni_thr_set_name(NULL, "nng:poll:kqueue");
+
 	for (;;) {
 		int              n;
 		struct kevent    evs[NNI_MAX_KQUEUE_EVENTS];
@@ -335,7 +337,6 @@ nni_posix_pollq_create(nni_posix_pollq *pq)
 int
 nni_posix_pollq_sysinit(void)
 {
-
 	return (nni_posix_pollq_create(&nni_posix_global_pollq));
 }
 
diff --git a/src/platform/posix/posix_pollq_poll.c b/src/platform/posix/posix_pollq_poll.c
index 12c5e541..f6f81703 100644
--- a/src/platform/posix/posix_pollq_poll.c
+++ b/src/platform/posix/posix_pollq_poll.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2019 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 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
@@ -329,6 +329,7 @@ nni_posix_pollq_create(nni_posix_pollq *pq)
 		nni_plat_pipe_close(pq->wakewfd, pq->wakerfd);
 		return (rv);
 	}
+	nni_thr_set_name(&pq->thr, "nng:poll:poll");
 	nni_mtx_init(&pq->mtx);
 	nni_thr_run(&pq->thr);
 	return (0);
diff --git a/src/platform/posix/posix_pollq_port.c b/src/platform/posix/posix_pollq_port.c
index bf628e47..7ce96f68 100644
--- a/src/platform/posix/posix_pollq_port.c
+++ b/src/platform/posix/posix_pollq_port.c
@@ -228,6 +228,7 @@ nni_posix_pollq_create(nni_posix_pollq *pq)
 		nni_posix_pollq_destroy(pq);
 		return (rv);
 	}
+	nni_thr_set_name(&pq->thr, "nng:poll:port");
 
 	nni_thr_run(&pq->thr);
 	return (0);
diff --git a/src/platform/posix/posix_resolv_gai.c b/src/platform/posix/posix_resolv_gai.c
index 88313045..1799935e 100644
--- a/src/platform/posix/posix_resolv_gai.c
+++ b/src/platform/posix/posix_resolv_gai.c
@@ -318,7 +318,9 @@ resolv_worker(void *unused)
 
 	NNI_ARG_UNUSED(unused);
 
-	nni_mtx_lock(&resolv_mtx);
+        nni_thr_set_name(NULL, "nng:resolver");
+
+        nni_mtx_lock(&resolv_mtx);
 	for (;;) {
 		nni_aio *    aio;
 		resolv_item *item;
diff --git a/src/platform/posix/posix_thread.c b/src/platform/posix/posix_thread.c
index b8fa814e..0178455f 100644
--- a/src/platform/posix/posix_thread.c
+++ b/src/platform/posix/posix_thread.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 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
@@ -254,6 +254,31 @@ nni_plat_thr_is_self(nni_plat_thr *thr)
 }
 
 void
+nni_plat_thr_set_name(nni_plat_thr *thr, const char *name)
+{
+#if defined(NNG_HAVE_PTHREAD_SET_NAME_NP)
+	if (thr == NULL) {
+		pthread_set_name_np(pthread_self(), name);
+	} else {
+        	pthread_set_name_np(thr->tid, name);
+	}
+#elif defined(NNG_HAVE_PTHREAD_SETNAME_NP)
+#if defined(__APPLE__)
+	// Darwin is weird, it can only set the name of pthread_self.
+	if ((thr == NULL) || (pthread_self() == thr->tid)) {
+        	pthread_setname_np(name);
+	}
+#else
+	if (thr == NULL) {
+                pthread_setname_np(pthread_self(), name);
+	} else {
+                pthread_setname_np(thr->tid, name);
+	}
+#endif
+#endif
+}
+
+void
 nni_atfork_child(void)
 {
 	nni_plat_forked = 1;
diff --git a/src/platform/windows/win_io.c b/src/platform/windows/win_io.c
index 81214498..489dc01a 100644
--- a/src/platform/windows/win_io.c
+++ b/src/platform/windows/win_io.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 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
@@ -114,6 +114,7 @@ nni_win_io_sysinit(void)
 		if (rv != 0) {
 			goto fail;
 		}
+		nni_thr_set_name(&win_io_thrs[i], "nng:iocp");
 	}
 	for (i = 0; i < win_io_nthr; i++) {
 		nni_thr_run(&win_io_thrs[i]);
diff --git a/src/platform/windows/win_ipcdial.c b/src/platform/windows/win_ipcdial.c
index 5deebc01..65d1b544 100644
--- a/src/platform/windows/win_ipcdial.c
+++ b/src/platform/windows/win_ipcdial.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2019 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 // Copyright 2019 Devolutions <info@devolutions.net>
 //
@@ -269,7 +269,7 @@ nni_win_ipc_sysinit(void)
 	if (rv != 0) {
 		return (rv);
 	}
-
+        nni_thr_set_name(&worker->thr, "nng:ipc:dial");
 	nni_thr_run(&worker->thr);
 
 	return (0);
diff --git a/src/platform/windows/win_resolv.c b/src/platform/windows/win_resolv.c
index d80b5ddf..d1cc058e 100644
--- a/src/platform/windows/win_resolv.c
+++ b/src/platform/windows/win_resolv.c
@@ -432,6 +432,7 @@ nni_win_resolv_sysinit(void)
 			nni_win_resolv_sysfini();
 			return (rv);
 		}
+		nni_thr_set_name(&resolv_thrs[i], "nng:resolver");
 	}
 	for (int i = 0; i < NNG_RESOLV_CONCURRENCY; i++) {
 		nni_thr_run(&resolv_thrs[i]);
diff --git a/src/platform/windows/win_thread.c b/src/platform/windows/win_thread.c
index 785376df..7cc87eb3 100644
--- a/src/platform/windows/win_thread.c
+++ b/src/platform/windows/win_thread.c
@@ -14,10 +14,14 @@
 
 #ifdef NNG_PLATFORM_WINDOWS
 
+typedef HRESULT(WINAPI *pfnSetThreadDescription)(HANDLE, PCWSTR);
+static HMODULE hKernel32;
+
+static pfnSetThreadDescription set_thread_desc;
+
 // mingw does not define InterlockedAddNoFence64, use the mingw equivalent
 #if defined(__MINGW32__) || defined(__MINGW64__)
-#define InterlockedAddNoFence(a, b) \
-	__atomic_add_fetch(a, b, __ATOMIC_RELAXED)
+#define InterlockedAddNoFence(a, b) __atomic_add_fetch(a, b, __ATOMIC_RELAXED)
 #define InterlockedAddNoFence64(a, b) \
 	__atomic_add_fetch(a, b, __ATOMIC_RELAXED)
 #define InterlockedIncrementAcquire64(a) \
@@ -219,11 +223,10 @@ bool
 nni_atomic_cas64(nni_atomic_u64 *v, uint64_t comp, uint64_t new)
 {
 	uint64_t old;
-	old = InterlockedCompareExchange64(&v->v, (LONG64)new, (LONG64)comp);
+	old = InterlockedCompareExchange64(&v->v, (LONG64) new, (LONG64) comp);
 	return (old == comp);
 }
 
-
 void
 nni_atomic_add(nni_atomic_int *v, int bump)
 {
@@ -278,11 +281,10 @@ bool
 nni_atomic_cas(nni_atomic_int *v, int comp, int new)
 {
 	int old;
-	old = InterlockedCompareExchange(&v->v, (LONG)new, (LONG)comp);
+	old = InterlockedCompareExchange(&v->v, (LONG) new, (LONG) comp);
 	return (old == comp);
 }
 
-
 static unsigned int __stdcall nni_plat_thr_main(void *arg)
 {
 	nni_plat_thr *thr = arg;
@@ -325,6 +327,30 @@ nni_plat_thr_is_self(nni_plat_thr *thr)
 	return (GetCurrentThreadId() == thr->id);
 }
 
+void
+nni_plat_thr_set_name(nni_plat_thr *thr, const char *name)
+{
+	if (set_thread_desc != NULL) {
+                wchar_t *wcs;
+                size_t len;
+		HANDLE h;
+
+		if (thr == NULL) {
+			h = GetCurrentThread();
+		} else {
+			h = thr->handle;
+		}
+
+                len = strlen(name) + 1;
+		if ((wcs = nni_alloc(len * 2)) == NULL) {
+			return;
+		}
+		(void) MultiByteToWideChar(CP_UTF8, 0, name, len, wcs, len);
+		set_thread_desc(h, wcs);
+		nni_free(wcs, len * 2);
+	}
+}
+
 static LONG plat_inited = 0;
 
 int
@@ -346,10 +372,18 @@ nni_plat_init(int (*helper)(void))
 		return (0); // fast path
 	}
 
-	AcquireSRWLockExclusive(&lock);
+
+        AcquireSRWLockExclusive(&lock);
 
 	if (!plat_inited) {
-		if (((rv = nni_win_io_sysinit()) != 0) ||
+                // Let's look up the function to set thread descriptions.
+                hKernel32 = LoadLibrary(TEXT("kernel32.dll"));
+                if (hKernel32 != NULL) {
+                        set_thread_desc = (pfnSetThreadDescription)
+                            GetProcAddress(hKernel32, "SetThreadDescription");
+                }
+
+                if (((rv = nni_win_io_sysinit()) != 0) ||
 		    ((rv = nni_win_ipc_sysinit()) != 0) ||
 		    ((rv = nni_win_tcp_sysinit()) != 0) ||
 		    ((rv = nni_win_udp_sysinit()) != 0) ||
@@ -376,6 +410,9 @@ nni_plat_fini(void)
 	nni_win_tcp_sysfini();
 	nni_win_io_sysfini();
 	WSACleanup();
+	if (hKernel32 != NULL) {
+		FreeLibrary(hKernel32);
+	}
 	plat_inited = 0;
 }
 
diff --git a/src/supplemental/util/platform.c b/src/supplemental/util/platform.c
index 468582bd..8898b680 100644
--- a/src/supplemental/util/platform.c
+++ b/src/supplemental/util/platform.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 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
@@ -52,12 +52,18 @@ nng_thread_create(nng_thread **thrp, void (*func)(void *), void *arg)
 	return (0);
 }
 
+void
+nng_thread_set_name(nng_thread *thr, const char *name)
+{
+	nni_thr_set_name((void *)thr, name);
+}
+
 // Destroy a thread (waiting for it to complete.)  When this function
 // returns all resources for the thread are cleaned up.
 void
-nng_thread_destroy(nng_thread *thrp)
+nng_thread_destroy(nng_thread *thr)
 {
-	nni_thr *t = (void *) thrp;
+	nni_thr *t = (void *) thr;
 	nni_thr_fini(t);
 	NNI_FREE_STRUCT(t);
 }
diff --git a/src/transport/zerotier/zerotier.c b/src/transport/zerotier/zerotier.c
index 64fdad87..e4cddb20 100644
--- a/src/transport/zerotier/zerotier.c
+++ b/src/transport/zerotier/zerotier.c
@@ -1458,6 +1458,7 @@ zt_node_create(zt_node **ztnp, const char *path)
 		zt_node_destroy(ztn);
 		return (rv);
 	}
+	nni_thr_set_name(&ztn->zn_bgthr, "nng:zt");
 
 	if (strlen(path) > 0) {
 		char *lkfile;