[lttng-dev] [RFC PATCH 2/2] Add -ust to the name of UST threads of the application

[Sebastien Boisvert]

> 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 at gmail.com <https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev>>
> ---
>  liblttng-ust/Makefile.am      |  1 +
>  liblttng-ust/compat.h         | 35 +++++++++++++++++++++++++++++++++++
>  liblttng-ust/lttng-ust-comm.c |  2 ++
>  3 files changed, 38 insertions(+)
> 
> diff --git a/liblttng-ust/Makefile.am b/liblttng-ust/Makefile.am
> index 876e9b5..8d78d63 100644
> --- a/liblttng-ust/Makefile.am
> +++ b/liblttng-ust/Makefile.am
> @@ -13,6 +13,7 @@ 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..161b957 100644
> --- a/liblttng-ust/compat.h
> +++ b/liblttng-ust/compat.h
> @@ -24,6 +24,7 @@
>   */
>  #ifdef __linux__
>  
> +#include <pthread.h>
>  #include <sys/prctl.h>
>  
>  #define LTTNG_UST_PROCNAME_LEN 17
> @@ -34,6 +35,23 @@ void lttng_ust_getprocname(char *name)
>  	(void) prctl(PR_GET_NAME, (unsigned long) name, 0, 0, 0);
>  }
>  
> +static inline
> +void lttng_ust_setustprocname()
> +{
> +	char name[LTTNG_UST_PROCNAME_LEN];
> +	int limit = LTTNG_UST_PROCNAME_LEN - 4;
> +
> +	lttng_ust_getprocname(name);
> +
> +	if (strlen(name) >= limit) {
> +		name[limit] = 0;
> +	}
> +
> +	sprintf(name, "%s%s", name, "-ust");
> +
> +	pthread_setname_np(pthread_self(), name);
> +}
> +
>  #elif defined(__FreeBSD__)
>  #include <stdlib.h>
>  #include <string.h>
> @@ -59,6 +77,23 @@ void lttng_ust_getprocname(char *name)
>  		strncpy(name, bsd_name, LTTNG_UST_PROCNAME_LEN - 1);
>  }
>  
> +static inline
> +void lttng_ust_setustprocname()
> +{
> +	char name[LTTNG_UST_PROCNAME_LEN];
> +	int limit = LTTNG_UST_PROCNAME_LEN - 4;
> +
> +	lttng_ust_getprocname(name);
> +
> +	if (strlen(name) >= limit) {
> +		name[limit] = 0;
> +	}
> +
> +	sprintf(name, "%s%s", name, "-ust");
> +
> +	pthread_set_name_np(pthread_self(), name);
> +}
> +
>  #endif
>  
>  #include <errno.h>
> diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
> index e00a22c..a85cb21 100644
> --- a/liblttng-ust/lttng-ust-comm.c
> +++ b/liblttng-ust/lttng-ust-comm.c
> @@ -1295,6 +1295,8 @@ void *ust_listener_thread(void *arg)
>  	int sock, ret, prev_connect_failed = 0, has_waited = 0;
>  	long timeout;
>  
> +	lttng_ust_setustprocname();
> +
>  	/* Restart trying to connect to the session daemon */
>  restart:
>  	if (prev_connect_failed) {
> -- 
> 2.1.4
> 

Hi Raphaël,

Since the only difference between the Linux hunk and the FreeBSD hunk is *one* line, you
should simplify this patch.

Z1$ diff -u linux-hunk freebsd-hunk 
--- linux-hunk	2016-06-02 09:02:14.790865459 -0400
+++ freebsd-hunk	2016-06-02 09:02:38.863865110 -0400
@@ -12,6 +12,6 @@
 +
 +	sprintf(name, "%s%s", name, "-ust");
 +
-+	pthread_setname_np(pthread_self(), name);
++	pthread_set_name_np(pthread_self(), name);
 +}
 +
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