Commit 6a1b0f3a authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Stefan Hajnoczi
Browse files

trace: add trace event iterator APIs 



Currently methods which want to iterate over trace events,
do so using the trace_event_count() and trace_event_id()
methods. This leaks the concept of a single ID enum to
the callers. There is an alternative trace_event_pattern()
method which can be used in an iteration context, but its
design is stateless, so is not easy to expand it in the
future.

This defines a formal iterator API will provide a future-
proof way of iterating over events.

The iterator is also able to apply a pattern match filter
to events, further removing the need for the pattern

Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: default avatarLluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Message-id: 1475588159-30598-4-git-send-email-berrange@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 170f75ad

trace/control.c

+21 −0
Original line number Diff line number Diff line
@@ -125,6 +125,27 @@ TraceEvent *trace_event_pattern(const char *pat, TraceEvent *ev) 
    return NULL;

}



void trace_event_iter_init(TraceEventIter *iter, const char *pattern)

{

    iter->event = 0;

    iter->pattern = pattern;

}



TraceEvent *trace_event_iter_next(TraceEventIter *iter)

{

    while (iter->event < TRACE_EVENT_COUNT) {

        TraceEvent *ev = &(trace_events[iter->event]);

        iter->event++;

        if (!iter->pattern ||

            pattern_glob(iter->pattern,

                         trace_event_get_name(ev))) {

            return ev;

        }

    }



    return NULL;

}



void trace_list_events(void)

{

    int i;

trace/control.h

+27 −0
Original line number Diff line number Diff line
@@ -13,6 +13,10 @@ 
#include "qemu-common.h"

#include "trace/generated-events.h"



typedef struct TraceEventIter {

    size_t event;

    const char *pattern;

} TraceEventIter;



/**

 * TraceEventID:
@@ -25,6 +29,29 @@ 
 */

enum TraceEventID;





/**

 * trace_event_iter_init:

 * @iter: the event iterator struct

 * @pattern: optional pattern to filter events on name

 *

 * Initialize the event iterator struct @iter,

 * optionally using @pattern to filter out events

 * with non-matching names.

 */

void trace_event_iter_init(TraceEventIter *iter, const char *pattern);



/**

 * trace_event_iter_next:

 * @iter: the event iterator struct

 *

 * Get the next event, if any. When this returns NULL,

 * the iterator should no longer be used.

 *

 * Returns: the next event, or NULL if no more events exist

 */

TraceEvent *trace_event_iter_next(TraceEventIter *iter);



/**

 * trace_event_id:

 * @id: Event identifier.