From ec41d849bbc460d4002ae19e3891b3bda513307e Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Thu, 23 Jan 2014 10:07:14 +0100
Subject: [PATCH] thread/Name: set thread names

For debugging.
---
 Makefile.am           |  1 +
 configure.ac          |  7 ++++++
 src/DecoderThread.cxx | 11 ++++++++++
 src/IOThread.cxx      |  3 +++
 src/OutputThread.cxx  |  3 +++
 src/PlayerThread.cxx  |  3 +++
 src/thread/Name.hxx   | 51 +++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 79 insertions(+)
 create mode 100644 src/thread/Name.hxx

diff --git a/Makefile.am b/Makefile.am
index cdeca8dc6..80ae9bdd8 100644
--- a/Makefile.am
+++ b/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 \
diff --git a/configure.ac b/configure.ac
index 52db236ba..13ff64ba7 100644
--- a/configure.ac
+++ b/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 ---------------------------------------------------------------------------
diff --git a/src/DecoderThread.cxx b/src/DecoderThread.cxx
index 8658c8883..5c0e31034 100644
--- a/src/DecoderThread.cxx
+++ b/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 {
diff --git a/src/IOThread.cxx b/src/IOThread.cxx
index 8877d3c2d..e21ede4f3 100644
--- a/src/IOThread.cxx
+++ b/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();
diff --git a/src/OutputThread.cxx b/src/OutputThread.cxx
index b56e7f1ca..f7e28b5f4 100644
--- a/src/OutputThread.cxx
+++ b/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();
diff --git a/src/PlayerThread.cxx b/src/PlayerThread.cxx
index 8512c6051..750a1732a 100644
--- a/src/PlayerThread.cxx
+++ b/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);
 
diff --git a/src/thread/Name.hxx b/src/thread/Name.hxx
new file mode 100644
index 000000000..a6faa0508
--- /dev/null
+++ b/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