[lttng-ust PATCH v3 1/1] Add -ust to the name of UST threads of the application

["Raphaël Beamonte" <raphael.beamonte@gmail.com>]

Add the required functions to change the thread name of the UST
threads and add the -ust string at its end. This will help to
identify LTTng-UST processes when analyzing the trace of a process.

Signed-off-by: Raphaël Beamonte <raphael.beamonte@gmail.com>
---
 configure.ac                  |  5 +++++
 liblttng-ust/Makefile.am      |  1 +
 liblttng-ust/compat.h         | 51 ++++++++++++++++++++++++++++++++++++++++++-
 liblttng-ust/lttng-ust-comm.c |  6 +++++
 4 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 5692553..de462ff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -135,6 +135,11 @@ AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBDL], [test "x$have_libdl" = "xyes"])
 AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBC_DL], [test "x$have_libc_dl" = "xyes"])
 
 AC_CHECK_LIB([pthread], [pthread_create])
+AC_CHECK_LIB([pthread], [pthread_setname_np],
+	AC_DEFINE([HAVE_PTHREAD_SETNAME_NP], [1], [Define to 1 if pthread_setname_np is available.]),
+	AC_CHECK_LIB([pthread], [pthread_set_name_np],
+		AC_DEFINE([HAVE_PTHREAD_SET_NAME_NP], [1], [Define to 1 if pthread_set_name_np is available.]),
+		AC_MSG_RESULT([pthread setname/set_name not found.])))
 
 # Check for dlfcn.h
 AC_CHECK_HEADER([dlfcn.h])
diff --git a/liblttng-ust/Makefile.am b/liblttng-ust/Makefile.am
index f1801cf..05929be 100644
--- a/liblttng-ust/Makefile.am
+++ b/liblttng-ust/Makefile.am
@@ -14,6 +14,7 @@ liblttng_ust_tracepoint_la_SOURCES = \
 	error.h
 liblttng_ust_tracepoint_la_LIBADD = \
 	-lurcu-bp \
+	-lpthread \
 	$(top_builddir)/snprintf/libustsnprintf.la
 liblttng_ust_tracepoint_la_LDFLAGS = -no-undefined -version-info $(LTTNG_UST_LIBRARY_VERSION)
 liblttng_ust_tracepoint_la_CFLAGS = -DUST_COMPONENT="liblttng_ust_tracepoint" -fno-strict-aliasing
diff --git a/liblttng-ust/compat.h b/liblttng-ust/compat.h
index 43b2223..68d4d50 100644
--- a/liblttng-ust/compat.h
+++ b/liblttng-ust/compat.h
@@ -3,6 +3,7 @@
 
 /*
  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2016 Raphaël Beamonte <raphael.beamonte@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -23,7 +24,6 @@
  * lttng_ust_getprocname.
  */
 #ifdef __linux__
-
 #include <sys/prctl.h>
 
 #define LTTNG_UST_PROCNAME_LEN 17
@@ -34,6 +34,13 @@ void lttng_ust_getprocname(char *name)
 	(void) prctl(PR_GET_NAME, (unsigned long) name, 0, 0, 0);
 }
 
+/*
+ * if pthread_setname_np is available.
+ */
+#ifdef HAVE_PTHREAD_SETNAME_NP
+#define PTHREAD_SETNAME_NP pthread_setname_np
+#endif
+
 #elif defined(__FreeBSD__)
 #include <stdlib.h>
 #include <string.h>
@@ -59,6 +66,48 @@ void lttng_ust_getprocname(char *name)
 		strncpy(name, bsd_name, LTTNG_UST_PROCNAME_LEN - 1);
 }
 
+/*
+ * if pthread_set_name_np is available.
+ */
+#ifdef HAVE_PTHREAD_SET_NAME_NP
+#define PTHREAD_SETNAME_NP pthread_set_name_np
+#endif
+
+#endif
+
+/*
+ * if a pthread setname/set_name function is available, declare
+ * the setustprocname() function that will add '-ust' to the end
+ * of the current process name, while truncating it if needed.
+ */
+#ifdef PTHREAD_SETNAME_NP
+#define LTTNG_UST_PROCNAME_SUFFIX "-ust"
+
+#include <pthread.h>
+
+static inline
+void lttng_ust_setustprocname(void)
+{
+	char name[LTTNG_UST_PROCNAME_LEN];
+	int limit = LTTNG_UST_PROCNAME_LEN - strlen(LTTNG_UST_PROCNAME_SUFFIX);
+	int len;
+
+	lttng_ust_getprocname(name);
+
+	len = strlen(name);
+	if (len > limit) {
+		len = limit;
+	}
+
+	sprintf(name + len, LTTNG_UST_PROCNAME_SUFFIX);
+
+	PTHREAD_SETNAME_NP(pthread_self(), name);
+}
+#else
+static inline
+void lttng_ust_setustprocname(void)
+{
+}
 #endif
 
 #include <errno.h>
diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index e00a22c..c32e8ae 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -1295,6 +1295,12 @@ void *ust_listener_thread(void *arg)
 	int sock, ret, prev_connect_failed = 0, has_waited = 0;
 	long timeout;
 
+	/*
+	 * If available, add '-ust' to the end of this thread's
+	 * process name
+	 */
+	lttng_ust_setustprocname();
+
 	/* Restart trying to connect to the session daemon */
 restart:
 	if (prev_connect_failed) {
-- 
2.8.1

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