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Commit b13ea45a authored by Jamie Gennis's avatar Jamie Gennis
Browse files

cutils: add a way to disable tracing for a process 

This change adds the atrace_set_tracing_enabled call to libcutils.  The call
can be used to disable all tracing (of the atrace variety) for the current
process.  This is to be used to disable tracing in the Zygote process, as there
is no way for Zygote to be notified of changes to the enabled trace tags.

Change-Id: I0b691cc0dcfc65b16e3d17e1db2866a4deb253a7
parent c796ed97

include/cutils/trace.h

+7 −1
Original line number Diff line number Diff line
@@ -106,12 +106,18 @@ void atrace_update_tags(); 
 */

void atrace_set_debuggable(bool debuggable);



/**

 * Set whether tracing is enabled for the current process.  This is used to

 * prevent tracing within the Zygote process.

 */

void atrace_set_tracing_enabled(bool enabled);



/**

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

 * Nonzero indicates setup has completed.

 * Note: This does NOT indicate whether or not setup was successful.

 */

extern int32_t atrace_is_ready;

extern volatile int32_t atrace_is_ready;



/**

 * Set of ATRACE_TAG flags to trace for, initialized to ATRACE_TAG_NOT_READY.

libcutils/trace.c

+29 −11
Original line number Diff line number Diff line
@@ -30,10 +30,11 @@ 
#define LOG_TAG "cutils-trace"

#include <cutils/log.h>



int32_t                atrace_is_ready      = 0;

volatile int32_t        atrace_is_ready      = 0;

int                     atrace_marker_fd     = -1;

uint64_t                atrace_enabled_tags  = ATRACE_TAG_NOT_READY;

static bool             atrace_is_debuggable = false;

static volatile int32_t atrace_is_enabled    = 1;

static pthread_once_t   atrace_once_control  = PTHREAD_ONCE_INIT;

static pthread_mutex_t  atrace_tags_mutex    = PTHREAD_MUTEX_INITIALIZER;
@@ -46,9 +47,18 @@ void atrace_set_debuggable(bool debuggable) 
    atrace_update_tags();

}



// Set whether tracing is enabled in this process.  This is used to prevent

// the Zygote process from tracing.

void atrace_set_tracing_enabled(bool enabled)

{

    android_atomic_release_store(enabled ? 1 : 0, &atrace_is_enabled);

    atrace_update_tags();

}



// Check whether the given command line matches one of the comma-separated

// values listed in the app_cmdlines property.

static bool atrace_is_cmdline_match(const char* cmdline) {

static bool atrace_is_cmdline_match(const char* cmdline)

{

    char value[PROPERTY_VALUE_MAX];

    char* start = value;
@@ -140,10 +150,18 @@ void atrace_update_tags() 
{

    uint64_t tags;

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

        if (android_atomic_acquire_load(&atrace_is_enabled)) {

            tags = atrace_get_property();

            pthread_mutex_lock(&atrace_tags_mutex);

            atrace_enabled_tags = tags;

            pthread_mutex_unlock(&atrace_tags_mutex);

        } else {

            // Tracing is disabled for this process, so we simply don't

            // initialize the tags.

            pthread_mutex_lock(&atrace_tags_mutex);

            atrace_enabled_tags = ATRACE_TAG_NOT_READY;

            pthread_mutex_unlock(&atrace_tags_mutex);

        }

    }

}