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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: Tzvetomir 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: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
hifive-unleashed-5.2
Tzvetomir Stoyanov 2019-04-01 12:43:08 -04:00 committed by Arnaldo Carvalho de Melo
parent fed33e905c
commit 6699ed712a
2 changed files with 95 additions and 27 deletions
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117
tools/lib/traceevent/event-parse.c
View File

@ -5651,33 +5651,27 @@ 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;
if (!tep)
return NULL;
events = malloc(sizeof(*events) * (tep->nr_events + 1));
if (!events)
return NULL;
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);
events = pevent->sort_events;
if (events && pevent->last_type == sort_type)
return events;
if (!events) {
events = malloc(sizeof(*events) * (pevent->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;
return events;
}
}
switch (sort_type) {
case TEP_EVENT_SORT_ID:
sort = events_id_cmp;
@ -5689,11 +5683,82 @@ struct tep_event **tep_list_events(struct tep_handle *pevent, enum tep_event_sor
sort = events_system_cmp;
break;
default:
return events;
sort = NULL;
}
qsort(events, pevent->nr_events, sizeof(*events), sort);
pevent->last_type = sort_type;
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;
list_events_sort(events, tep->nr_events, sort_type);
return events;
}

5
tools/lib/traceevent/event-parse.h
View File

@ -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);