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Commit e7bb7bca authored by Alex Ray's avatar Alex Ray
Browse files

cutils: trace: add atrace_update_tags() 

Adds a function to read the current trace system property value, and
sets the trace tags to it, do be used as a sysprop change callback.

Change-Id: Ia6336652173aa5b07188898736c2c795a69fe79a
parent 0a346431

include/cutils/trace.h

+6 −0
Original line number Diff line number Diff line
@@ -85,6 +85,12 @@ __BEGIN_DECLS 
 */

void atrace_setup();



/**

 * If tracing is ready, set atrace_enabled_tags to the system property

 * debug.atrace.tags.enableflags. Can be used as a sysprop change callback.

 */

void atrace_update_tags();



/**

 * Flag indicating whether setup has been completed, initialized to 0.

 * Nonzero indicates setup has completed.

libcutils/trace.c

+13 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ int32_t atrace_is_ready = 0; 
int                   atrace_marker_fd    = -1;

uint64_t              atrace_enabled_tags = ATRACE_TAG_NOT_READY;

static pthread_once_t atrace_once_control = PTHREAD_ONCE_INIT;

static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER;



// Read the sysprop and return the value tags should be set to

static uint64_t atrace_get_property()
@@ -54,6 +55,18 @@ static uint64_t atrace_get_property() 
    return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK;

}



// Update tags if tracing is ready. Useful as a sysprop change callback.

void atrace_update_tags()

{

    uint64_t tags;

    if (CC_UNLIKELY(android_atomic_acquire_load(&atrace_is_ready))) {

        tags = atrace_get_property();

        pthread_mutex_lock(&atrace_tags_mutex);

        atrace_enabled_tags = tags;

        pthread_mutex_unlock(&atrace_tags_mutex);

    }

}



static void atrace_init_once()

{

    atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY);