thread/Name: set thread names

For debugging.

Makefile.am

@@ -290,6 +290,7 @@ libutil_a_SOURCES = \
 
 libthread_a_SOURCES = \
 	src/thread/Util.hxx \
+	src/thread/Name.hxx \
 	src/thread/Mutex.hxx \
 	src/thread/PosixMutex.hxx \
 	src/thread/CriticalSection.hxx \

configure.ac

@@ -181,6 +181,13 @@ AC_SEARCH_LIBS([exp], [m],,
 AC_CHECK_HEADERS(locale.h)
 AC_CHECK_HEADERS(valgrind/memcheck.h)
 
+AC_CHECK_LIB([pthread], [pthread_setname_np],
+	[have_pthread_setname_np=yes],
+	[have_pthread_setname_np=no])
+if test x$have_pthread_setname_np = xyes; then
+	AC_DEFINE(HAVE_PTHREAD_SETNAME_NP, 1, [Is pthread_setname_np() available?])
+fi
+
 dnl ---------------------------------------------------------------------------
 dnl Event loop selection
 dnl ---------------------------------------------------------------------------

src/DecoderThread.cxx

@@ -34,6 +34,7 @@
 #include "util/UriUtil.hxx"
 #include "util/Error.hxx"
 #include "util/Domain.hxx"
+#include "thread/Name.hxx"
 #include "tag/ApeReplayGain.hxx"
 #include "Log.hxx"
 
@@ -127,8 +128,12 @@ decoder_stream_decode(const DecoderPlugin &plugin,
 
 	decoder.dc.Unlock();
 
+	FormatThreadName("decoder:%s", plugin.name);
+
 	plugin.StreamDecode(decoder, input_stream);
 
+	SetThreadName("decoder");
+
 	decoder.dc.Lock();
 
 	assert(decoder.dc.state == DecoderState::START ||
@@ -155,8 +160,12 @@ decoder_file_decode(const DecoderPlugin &plugin,
 
 	decoder.dc.Unlock();
 
+	FormatThreadName("decoder:%s", plugin.name);
+
 	plugin.FileDecode(decoder, path);
 
+	SetThreadName("decoder");
+
 	decoder.dc.Lock();
 
 	assert(decoder.dc.state == DecoderState::START ||
@@ -421,6 +430,8 @@ decoder_task(void *arg)
 {
 	DecoderControl &dc = *(DecoderControl *)arg;
 
+	SetThreadName("decoder");
+
 	dc.Lock();
 
 	do {

src/IOThread.cxx

@@ -22,6 +22,7 @@
 #include "thread/Mutex.hxx"
 #include "thread/Cond.hxx"
 #include "thread/Thread.hxx"
+#include "thread/Name.hxx"
 #include "event/Loop.hxx"
 #include "system/FatalError.hxx"
 #include "util/Error.hxx"
@@ -48,6 +49,8 @@ io_thread_run(void)
 static void
 io_thread_func(gcc_unused void *arg)
 {
+	SetThreadName("io");
+
 	/* lock+unlock to synchronize with io_thread_start(), to be
 	   sure that io.thread is set */
 	io.mutex.lock();

src/OutputThread.cxx

@@ -31,6 +31,7 @@
 #include "MusicPipe.hxx"
 #include "MusicChunk.hxx"
 #include "thread/Util.hxx"
+#include "thread/Name.hxx"
 #include "system/FatalError.hxx"
 #include "util/Error.hxx"
 #include "Log.hxx"
@@ -579,6 +580,8 @@ audio_output_task(void *arg)
 {
 	struct audio_output *ao = (struct audio_output *)arg;
 
+	FormatThreadName("output:%s", ao->name);
+
 	SetThreadRealtime();
 
 	ao->mutex.lock();

src/PlayerThread.cxx

@@ -33,6 +33,7 @@
 #include "Idle.hxx"
 #include "GlobalEvents.hxx"
 #include "util/Domain.hxx"
+#include "thread/Name.hxx"
 #include "Log.hxx"
 
 #include <string.h>
@@ -1106,6 +1107,8 @@ player_task(void *arg)
 {
 	PlayerControl &pc = *(PlayerControl *)arg;
 
+	SetThreadName("player");
+
 	DecoderControl dc(pc.mutex, pc.cond);
 	decoder_thread_start(dc);
 

src/thread/Name.hxx

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_THREAD_NAME_HXX
+#define MPD_THREAD_NAME_HXX
+
+#ifdef HAVE_PTHREAD_SETNAME_NP
+#include <pthread.h>
+#include <stdio.h>
+#endif
+
+static inline void
+SetThreadName(const char *name)
+{
+#ifdef HAVE_PTHREAD_SETNAME_NP
+	pthread_setname_np(pthread_self(), name);
+#else
+	(void)name;
+#endif
+}
+
+template<typename... Args>
+static inline void
+FormatThreadName(const char *fmt, gcc_unused Args&&... args)
+{
+#ifdef HAVE_PTHREAD_SETNAME_NP
+	char buffer[16];
+	snprintf(buffer, sizeof(buffer), fmt, args...);
+	SetThreadName(buffer);
+#else
+	(void)fmt;
+#endif
+}
+
+#endif