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cutils: trace: add atrace_update_tags()

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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
This commit is contained in:
Alex Ray 2012-11-20 01:39:09 -08:00
parent 0a34643160
commit e7bb7bca4f
2 changed files with 19 additions and 0 deletions
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6
include/cutils/trace.h
View file

@ -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.

13
libcutils/trace.c
View file

@ -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);