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9a67cab0ae
--HG-- extra : rebase_source : bae5a25a76f4bb2f8ea4154923cfecbc4c39f128
190 lines
6.2 KiB
C++
190 lines
6.2 KiB
C++
/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* The Mozilla Foundation.
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* Portions created by the Initial Developer are Copyright (C) 2011
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Ted Mielczarek <ted.mielczarek@gmail.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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* Event loop instrumentation. This code attempts to measure the
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* latency of the UI-thread event loop by firing native events at it from
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* a background thread, and measuring how long it takes for them
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* to be serviced. The measurement interval (kMeasureInterval, below)
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* is also used as the upper bound of acceptable response time.
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* When an event takes longer than that interval to be serviced,
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* a sample will be written to the log.
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*
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* Usage:
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*
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* Set MOZ_INSTRUMENT_EVENT_LOOP=1 in the environment to enable
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* this instrumentation. Currently only the UI process is instrumented.
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*
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* Set MOZ_INSTRUMENT_EVENT_LOOP_OUTPUT in the environment to a
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* file path to contain the log output, the default is to log to stdout.
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*
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* All logged output lines start with MOZ_EVENT_TRACE. All timestamps
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* output are milliseconds since the epoch (PRTime / 1000).
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*
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* On startup, a line of the form:
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* MOZ_EVENT_TRACE start <timestamp>
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* will be output.
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*
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* On shutdown, a line of the form:
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* MOZ_EVENT_TRACE stop <timestamp>
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* will be output.
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*
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* When an event servicing time exceeds the threshold, a line of the form:
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* MOZ_EVENT_TRACE sample <timestamp> <duration>
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* will be output, where <duration> is the number of milliseconds that
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* it took for the event to be serviced.
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*/
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#include "EventTracer.h"
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#include <stdio.h>
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#include "mozilla/TimeStamp.h"
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#include "mozilla/WidgetTraceEvent.h"
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#include <prenv.h>
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#include <prinrval.h>
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#include <prthread.h>
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#include <prtime.h>
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using mozilla::TimeDuration;
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using mozilla::TimeStamp;
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using mozilla::FireAndWaitForTracerEvent;
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namespace {
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PRThread* sTracerThread = NULL;
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bool sExit = false;
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/*
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* The tracer thread fires events at the native event loop roughly
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* every kMeasureInterval. It will sleep to attempt not to send them
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* more quickly, but if the response time is longer than kMeasureInterval
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* it will not send another event until the previous response is received.
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*
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* The output defaults to stdout, but can be redirected to a file by
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* settting the environment variable MOZ_INSTRUMENT_EVENT_LOOP_OUTPUT
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* to the name of a file to use.
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*/
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void TracerThread(void *arg)
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{
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// This should be set to the maximum latency we'd like to allow
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// for responsiveness.
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const PRIntervalTime kMeasureInterval = PR_MillisecondsToInterval(50);
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FILE* log = NULL;
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char* envfile = PR_GetEnv("MOZ_INSTRUMENT_EVENT_LOOP_OUTPUT");
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if (envfile) {
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log = fopen(envfile, "w");
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}
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if (log == NULL)
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log = stdout;
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fprintf(log, "MOZ_EVENT_TRACE start %llu\n", PR_Now() / PR_USEC_PER_MSEC);
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while (!sExit) {
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TimeStamp start(TimeStamp::Now());
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PRIntervalTime next_sleep = kMeasureInterval;
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//TODO: only wait up to a maximum of kMeasureInterval, return
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// early if that threshold is exceeded and dump a stack trace
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// or do something else useful.
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if (FireAndWaitForTracerEvent()) {
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TimeDuration duration = TimeStamp::Now() - start;
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// Only report samples that exceed our measurement interval.
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if (duration.ToMilliseconds() > kMeasureInterval) {
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fprintf(log, "MOZ_EVENT_TRACE sample %llu %d\n",
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PR_Now() / PR_USEC_PER_MSEC,
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int(duration.ToSecondsSigDigits() * 1000));
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}
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if (next_sleep > duration.ToMilliseconds()) {
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next_sleep -= int(duration.ToMilliseconds());
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}
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else {
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// Don't sleep at all if this event took longer than the measure
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// interval to deliver.
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next_sleep = 0;
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}
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}
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if (next_sleep != 0 && !sExit) {
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PR_Sleep(next_sleep);
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}
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}
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fprintf(log, "MOZ_EVENT_TRACE stop %llu\n", PR_Now() / PR_USEC_PER_MSEC);
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if (log != stdout)
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fclose(log);
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}
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} // namespace
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namespace mozilla {
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bool InitEventTracing()
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{
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// Initialize the widget backend.
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if (!InitWidgetTracing())
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return false;
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// Create a thread that will fire events back at the
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// main thread to measure responsiveness.
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NS_ABORT_IF_FALSE(!sTracerThread, "Event tracing already initialized!");
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sTracerThread = PR_CreateThread(PR_USER_THREAD,
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TracerThread,
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NULL,
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PR_PRIORITY_NORMAL,
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PR_GLOBAL_THREAD,
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PR_JOINABLE_THREAD,
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0);
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return sTracerThread != NULL;
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}
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void ShutdownEventTracing()
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{
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sExit = true;
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if (sTracerThread)
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PR_JoinThread(sTracerThread);
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sTracerThread = NULL;
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// Allow the widget backend to clean up.
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CleanUpWidgetTracing();
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}
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} // namespace mozilla
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