[lttng-dev] [PATCH lttng-tools 8/8] Fix: add missing synchronization point for before app test case

[Mathieu Desnoyers]

Patch 8/8 will be replaced by a v2 (upcoming).

----- Original Message -----
> From: "Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>
> To: jgalar at efficios.com
> Cc: lttng-dev at lists.lttng.org
> Sent: Wednesday, November 19, 2014 11:45:59 PM
> Subject: Re: [lttng-dev] [PATCH lttng-tools 8/8] Fix: add missing synchronization point for before app test case
> 
> ----- Original Message -----
> > From: "Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>
> > To: jgalar at efficios.com
> > Cc: lttng-dev at lists.lttng.org, "Mathieu Desnoyers"
> > <mathieu.desnoyers at efficios.com>
> > Sent: Wednesday, November 19, 2014 10:40:32 PM
> > Subject: [PATCH lttng-tools 8/8] Fix: add missing synchronization point for
> > before app test case
> > 
> > Fixes a race where the application could generate all its events before
> > trace start.
> > 
> > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> > ---
> [...]
> > b/tests/utils/testapp/gen-ust-events/gen-ust-events.c
> > index 42fa082..60f1c6f 100644
> > --- a/tests/utils/testapp/gen-ust-events/gen-ust-events.c
> > +++ b/tests/utils/testapp/gen-ust-events/gen-ust-events.c
> > @@ -15,6 +15,7 @@
> >   * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
> >   */
> >  
> > +#define _GNU_SOURCE
> >  #include <assert.h>
> >  #include <arpa/inet.h>
> >  #include <fcntl.h>
> > @@ -27,15 +28,21 @@
> >  #include <sys/types.h>
> >  #include <unistd.h>
> >  #include <stdbool.h>
> > +#include <signal.h>
> > +#include <poll.h>
> > +#include <errno.h>
> >  
> >  #define TRACEPOINT_DEFINE
> >  #include "tp.h"
> >  
> >  void create_file(const char *path)
> >  {
> > +	static bool file_created = false;
> >  	int ret;
> >  
> > -	assert(path);
> > +	if (!path || file_created) {
> > +		return;
> > +	}
> >  
> >  	ret = creat(path, S_IRWXU);
> >  	if (ret < 0) {
> > @@ -44,6 +51,30 @@ void create_file(const char *path)
> >  	}
> >  
> >  	(void) close(ret);
> > +	file_created = true;
> > +}
> > +
> > +static
> > +void wait_on_file(const char *path)
> > +{
> > +	if (!path) {
> > +		return;
> > +	}
> > +	for (;;) {
> > +		int ret;
> > +		struct stat buf;
> > +
> > +		ret = stat(path, &buf);
> > +		if (ret == -1 && errno == ENOENT) {
> > +			(void) poll(NULL, 0, 10);	/* 10 ms delay */
> > +			continue;			/* retry */
> > +		}
> > +		if (ret) {
> > +			perror("stat");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +		break;	/* found */
> > +	}
> >  }
> >  
> >  int main(int argc, char **argv)
> > @@ -55,8 +86,8 @@ int main(int argc, char **argv)
> >  	float flt = 2222.0;
> >  	int nr_iter = 100;
> >  	useconds_t nr_usec = 0;
> > -	char *tmp_file_path = NULL;
> > -	bool file_created = false;
> > +	char *after_first_event_file_path = NULL;
> > +	char *before_last_event_file_path = NULL;
> >  
> >  	if (argc >= 2) {
> >  		/*
> > @@ -71,22 +102,30 @@ int main(int argc, char **argv)
> >  	}
> >  
> >  	if (argc >= 4) {
> > -		tmp_file_path = argv[3];
> > +		after_first_event_file_path = argv[3];
> > +	}
> > +
> > +	if (argc >= 5) {
> > +		before_last_event_file_path = argv[4];
> >  	}
> >  
> >  	for (i = 0; nr_iter < 0 || i < nr_iter; i++) {
> > +		if (nr_iter >= 0 && i == nr_iter) {
> 
> This should be if (nr_iter >= 0 && i == nr_iter - 1)
> 
> Thanks,
> 
> Mathieu
> 
> > +			/*
> > +			 * Wait on synchronization before writing last
> > +			 * event.
> > +			 */
> > +			wait_on_file(before_last_event_file_path);
> > +		}
> >  		netint = htonl(i);
> > -		tracepoint(tp, tptest, i, netint, values, text, strlen(text), dbl,
> > -				flt);
> > +		tracepoint(tp, tptest, i, netint, values, text,
> > +			strlen(text), dbl, flt);
> >  
> >  		/*
> > -		 * First loop we create the file if asked to indicate that at least one
> > -		 * tracepoint has been hit.
> > +		 * First loop we create the file if asked to indicate
> > +		 * that at least one tracepoint has been hit.
> >  		 */
> > -		if (!file_created && tmp_file_path) {
> > -			create_file(tmp_file_path);
> > -			file_created = true;
> > -		}
> > +		create_file(after_first_event_file_path);
> >  		usleep(nr_usec);
> >  	}
> >  
> > --
> > 2.1.1
> > 
> > 
> 
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
> 
> _______________________________________________
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> lttng-dev at lists.lttng.org
> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com