Commit 6699ed71 authored by Tzvetomir Stoyanov's avatar Tzvetomir Stoyanov Committed by Arnaldo Carvalho de Melo
Browse files

tools lib traceevent: Implement a new API, tep_list_events_copy() 



Existing API tep_list_events() is not thread safe, it uses the internal
array sort_events to keep cache of the sorted events and reuses it. This
patch implements a new API, tep_list_events_copy(), which allocates new
sorted array each time it is called. It could be used when a sorted
events functionality is needed in thread safe use cases. It is up to the
caller to free the array.

Signed-off-by: default avatarTzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/linux-trace-devel/20181218133013.31094-1-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190401164343.117437443@goodmis.org


Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent fed33e90

tools/lib/traceevent/event-parse.c

+87 −22
Original line number Diff line number Diff line
@@ -5651,32 +5651,26 @@ static int events_system_cmp(const void *a, const void *b) 
	return events_id_cmp(a, b);

}



struct tep_event **tep_list_events(struct tep_handle *pevent, enum tep_event_sort_type sort_type)

static struct tep_event **list_events_copy(struct tep_handle *tep)

{

	struct tep_event **events;

	int (*sort)(const void *a, const void *b);



	events = pevent->sort_events;



	if (events && pevent->last_type == sort_type)

		return events;

	if (!tep)

		return NULL;



	if (!events) {

		events = malloc(sizeof(*events) * (pevent->nr_events + 1));

	events = malloc(sizeof(*events) * (tep->nr_events + 1));

	if (!events)

		return NULL;



		memcpy(events, pevent->events, sizeof(*events) * pevent->nr_events);

		events[pevent->nr_events] = NULL;



		pevent->sort_events = events;



		/* the internal events are sorted by id */

		if (sort_type == TEP_EVENT_SORT_ID) {

			pevent->last_type = sort_type;

	memcpy(events, tep->events, sizeof(*events) * tep->nr_events);

	events[tep->nr_events] = NULL;

	return events;

}

	}



static void list_events_sort(struct tep_event **events, int nr_events,

			     enum tep_event_sort_type sort_type)

{

	int (*sort)(const void *a, const void *b);



	switch (sort_type) {

	case TEP_EVENT_SORT_ID:
@@ -5689,11 +5683,82 @@ struct tep_event **tep_list_events(struct tep_handle *pevent, enum tep_event_sor 
		sort = events_system_cmp;

		break;

	default:

		sort = NULL;

	}



	if (sort)

		qsort(events, nr_events, sizeof(*events), sort);

}



/**

 * tep_list_events - Get events, sorted by given criteria.

 * @tep: a handle to the tep context

 * @sort_type: desired sort order of the events in the array

 *

 * Returns an array of pointers to all events, sorted by the given

 * @sort_type criteria. The last element of the array is NULL. The returned

 * memory must not be freed, it is managed by the library.

 * The function is not thread safe.

 */

struct tep_event **tep_list_events(struct tep_handle *tep,

				   enum tep_event_sort_type sort_type)

{

	struct tep_event **events;



	if (!tep)

		return NULL;



	events = tep->sort_events;

	if (events && tep->last_type == sort_type)

		return events;



	if (!events) {

		events = list_events_copy(tep);

		if (!events)

			return NULL;



		tep->sort_events = events;



		/* the internal events are sorted by id */

		if (sort_type == TEP_EVENT_SORT_ID) {

			tep->last_type = sort_type;

			return events;

		}

	}



	list_events_sort(events, tep->nr_events, sort_type);

	tep->last_type = sort_type;



	return events;

}





/**

 * tep_list_events_copy - Thread safe version of tep_list_events()

 * @tep: a handle to the tep context

 * @sort_type: desired sort order of the events in the array

 *

 * Returns an array of pointers to all events, sorted by the given

 * @sort_type criteria. The last element of the array is NULL. The returned

 * array is newly allocated inside the function and must be freed by the caller

 */

struct tep_event **tep_list_events_copy(struct tep_handle *tep,

					enum tep_event_sort_type sort_type)

{

	struct tep_event **events;



	if (!tep)

		return NULL;



	events = list_events_copy(tep);

	if (!events)

		return NULL;



	/* the internal events are sorted by id */

	if (sort_type == TEP_EVENT_SORT_ID)

		return events;



	qsort(events, pevent->nr_events, sizeof(*events), sort);

	pevent->last_type = sort_type;

	list_events_sort(events, tep->nr_events, sort_type);



	return events;

}

tools/lib/traceevent/event-parse.h

+4 −1
Original line number Diff line number Diff line
@@ -544,7 +544,10 @@ void tep_event_info(struct trace_seq *s, struct tep_event *event, 
int tep_strerror(struct tep_handle *pevent, enum tep_errno errnum,

		 char *buf, size_t buflen);



struct tep_event **tep_list_events(struct tep_handle *pevent, enum tep_event_sort_type);

struct tep_event **tep_list_events(struct tep_handle *tep,

				   enum tep_event_sort_type);

struct tep_event **tep_list_events_copy(struct tep_handle *tep,

					enum tep_event_sort_type);

struct tep_format_field **tep_event_common_fields(struct tep_event *event);

struct tep_format_field **tep_event_fields(struct tep_event *event);

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