/toolkit/xre/EventTracer.cpp
http://github.com/zpao/v8monkey · C++ · 234 lines · 99 code · 29 blank · 106 comment · 34 complexity · d9f260b1f21b88168f9ef564dd04b7ca MD5 · raw file
- /* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is mozilla.org code.
- *
- * The Initial Developer of the Original Code is
- * The Mozilla Foundation.
- * Portions created by the Initial Developer are Copyright (C) 2011
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- * Ted Mielczarek <ted.mielczarek@gmail.com>
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
- /*
- * Event loop instrumentation. This code attempts to measure the
- * latency of the UI-thread event loop by firing native events at it from
- * a background thread, and measuring how long it takes for them
- * to be serviced. The measurement interval (kMeasureInterval, below)
- * is also used as the upper bound of acceptable response time.
- * When an event takes longer than that interval to be serviced,
- * a sample will be written to the log.
- *
- * Usage:
- *
- * Set MOZ_INSTRUMENT_EVENT_LOOP=1 in the environment to enable
- * this instrumentation. Currently only the UI process is instrumented.
- *
- * Set MOZ_INSTRUMENT_EVENT_LOOP_OUTPUT in the environment to a
- * file path to contain the log output, the default is to log to stdout.
- *
- * Set MOZ_INSTRUMENT_EVENT_LOOP_THRESHOLD in the environment to an
- * integer number of milliseconds to change the threshold for reporting.
- * The default is 20 milliseconds. Unresponsive periods shorter than this
- * threshold will not be reported.
- *
- * Set MOZ_INSTRUMENT_EVENT_LOOP_INTERVAL in the environment to an
- * integer number of milliseconds to change the maximum sampling frequency.
- * This variable controls how often events will be sent to the main
- * thread's event loop to sample responsiveness. The sampler will not
- * send events twice within LOOP_INTERVAL milliseconds.
- * The default is 10 milliseconds.
- *
- * All logged output lines start with MOZ_EVENT_TRACE. All timestamps
- * output are milliseconds since the epoch (PRTime / 1000).
- *
- * On startup, a line of the form:
- * MOZ_EVENT_TRACE start <timestamp>
- * will be output.
- *
- * On shutdown, a line of the form:
- * MOZ_EVENT_TRACE stop <timestamp>
- * will be output.
- *
- * When an event servicing time exceeds the threshold, a line of the form:
- * MOZ_EVENT_TRACE sample <timestamp> <duration>
- * will be output, where <duration> is the number of milliseconds that
- * it took for the event to be serviced.
- */
- #include "sampler.h"
- #include "EventTracer.h"
- #include <stdio.h>
- #include "mozilla/TimeStamp.h"
- #include "mozilla/WidgetTraceEvent.h"
- #include <limits.h>
- #include <prenv.h>
- #include <prinrval.h>
- #include <prthread.h>
- #include <prtime.h>
- using mozilla::TimeDuration;
- using mozilla::TimeStamp;
- using mozilla::FireAndWaitForTracerEvent;
- namespace {
- PRThread* sTracerThread = NULL;
- bool sExit = false;
- /*
- * The tracer thread fires events at the native event loop roughly
- * every kMeasureInterval. It will sleep to attempt not to send them
- * more quickly, but if the response time is longer than kMeasureInterval
- * it will not send another event until the previous response is received.
- *
- * The output defaults to stdout, but can be redirected to a file by
- * settting the environment variable MOZ_INSTRUMENT_EVENT_LOOP_OUTPUT
- * to the name of a file to use.
- */
- void TracerThread(void *arg)
- {
- // These are the defaults. They can be overridden by environment vars.
- // This should be set to the maximum latency we'd like to allow
- // for responsiveness.
- PRIntervalTime threshold = PR_MillisecondsToInterval(20);
- // This is the sampling interval.
- PRIntervalTime interval = PR_MillisecondsToInterval(10);
- sExit = false;
- FILE* log = NULL;
- char* envfile = PR_GetEnv("MOZ_INSTRUMENT_EVENT_LOOP_OUTPUT");
- if (envfile) {
- log = fopen(envfile, "w");
- }
- if (log == NULL)
- log = stdout;
- char* thresholdenv = PR_GetEnv("MOZ_INSTRUMENT_EVENT_LOOP_THRESHOLD");
- if (thresholdenv && *thresholdenv) {
- int val = atoi(thresholdenv);
- if (val != 0 && val != INT_MAX && val != INT_MIN) {
- threshold = PR_MillisecondsToInterval(val);
- }
- }
- char* intervalenv = PR_GetEnv("MOZ_INSTRUMENT_EVENT_LOOP_INTERVAL");
- if (intervalenv && *intervalenv) {
- int val = atoi(intervalenv);
- if (val != 0 && val != INT_MAX && val != INT_MIN) {
- interval = PR_MillisecondsToInterval(val);
- }
- }
- fprintf(log, "MOZ_EVENT_TRACE start %llu\n", PR_Now() / PR_USEC_PER_MSEC);
- while (!sExit) {
- TimeStamp start(TimeStamp::Now());
- SAMPLER_RESPONSIVENESS(start);
- PRIntervalTime next_sleep = interval;
- //TODO: only wait up to a maximum of interval; return
- // early if that threshold is exceeded and dump a stack trace
- // or do something else useful.
- if (FireAndWaitForTracerEvent()) {
- TimeDuration duration = TimeStamp::Now() - start;
- // Only report samples that exceed our measurement threshold.
- if (duration.ToMilliseconds() > threshold) {
- fprintf(log, "MOZ_EVENT_TRACE sample %llu %d\n",
- PR_Now() / PR_USEC_PER_MSEC,
- int(duration.ToSecondsSigDigits() * 1000));
- }
- if (next_sleep > duration.ToMilliseconds()) {
- next_sleep -= int(duration.ToMilliseconds());
- }
- else {
- // Don't sleep at all if this event took longer than the measure
- // interval to deliver.
- next_sleep = 0;
- }
- }
- if (next_sleep != 0 && !sExit) {
- PR_Sleep(next_sleep);
- }
- }
- fprintf(log, "MOZ_EVENT_TRACE stop %llu\n", PR_Now() / PR_USEC_PER_MSEC);
- if (log != stdout)
- fclose(log);
- }
- } // namespace
- namespace mozilla {
- bool InitEventTracing()
- {
- if (sTracerThread)
- return true;
- // Initialize the widget backend.
- if (!InitWidgetTracing())
- return false;
- // Create a thread that will fire events back at the
- // main thread to measure responsiveness.
- NS_ABORT_IF_FALSE(!sTracerThread, "Event tracing already initialized!");
- sTracerThread = PR_CreateThread(PR_USER_THREAD,
- TracerThread,
- NULL,
- PR_PRIORITY_NORMAL,
- PR_GLOBAL_THREAD,
- PR_JOINABLE_THREAD,
- 0);
- return sTracerThread != NULL;
- }
- void ShutdownEventTracing()
- {
- if (!sTracerThread)
- return;
- sExit = true;
- // Ensure that the tracer thread doesn't hang.
- SignalTracerThread();
- if (sTracerThread)
- PR_JoinThread(sTracerThread);
- sTracerThread = NULL;
- // Allow the widget backend to clean up.
- CleanUpWidgetTracing();
- }
- } // namespace mozilla