mirror of
https://github.com/mozilla/gecko-dev.git
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361 lines
9.7 KiB
C++
361 lines
9.7 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/HangMonitor.h"
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#include "mozilla/Monitor.h"
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#include "mozilla/Preferences.h"
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#include "mozilla/Telemetry.h"
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#include "mozilla/ProcessedStack.h"
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#include "nsXULAppAPI.h"
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#include "nsThreadUtils.h"
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#include "nsStackWalk.h"
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#ifdef MOZ_CRASHREPORTER
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#include "nsExceptionHandler.h"
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#endif
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#ifdef XP_WIN
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#include <windows.h>
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#endif
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#if defined(MOZ_ENABLE_PROFILER_SPS) && defined(MOZ_PROFILING) && defined(XP_WIN)
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#define REPORT_CHROME_HANGS
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#endif
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namespace mozilla { namespace HangMonitor {
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/**
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* A flag which may be set from within a debugger to disable the hang
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* monitor.
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*/
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volatile bool gDebugDisableHangMonitor = false;
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const char kHangMonitorPrefName[] = "hangmonitor.timeout";
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#ifdef MOZ_TELEMETRY_ON_BY_DEFAULT
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const char kTelemetryPrefName[] = "toolkit.telemetry.enabledPreRelease";
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#else
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const char kTelemetryPrefName[] = "toolkit.telemetry.enabled";
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#endif
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// Monitor protects gShutdown and gTimeout, but not gTimestamp which rely on
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// being atomically set by the processor; synchronization doesn't really matter
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// in this use case.
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Monitor* gMonitor;
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// The timeout preference, in seconds.
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int32_t gTimeout;
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PRThread* gThread;
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// Set when shutdown begins to signal the thread to exit immediately.
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bool gShutdown;
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// The timestamp of the last event notification, or PR_INTERVAL_NO_WAIT if
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// we're currently not processing events.
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volatile PRIntervalTime gTimestamp = PR_INTERVAL_NO_WAIT;
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#ifdef REPORT_CHROME_HANGS
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// Main thread ID used in reporting chrome hangs under Windows
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static HANDLE winMainThreadHandle = NULL;
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// Default timeout for reporting chrome hangs to Telemetry (5 seconds)
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static const int32_t DEFAULT_CHROME_HANG_INTERVAL = 5;
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// Maximum number of PCs to gather from the stack
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static const int32_t MAX_CALL_STACK_PCS = 400;
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#endif
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// PrefChangedFunc
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int
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PrefChanged(const char*, void*)
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{
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int32_t newval = Preferences::GetInt(kHangMonitorPrefName);
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#ifdef REPORT_CHROME_HANGS
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// Monitor chrome hangs on the profiling branch if Telemetry enabled
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if (newval == 0) {
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bool telemetryEnabled = Preferences::GetBool(kTelemetryPrefName);
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if (telemetryEnabled) {
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newval = DEFAULT_CHROME_HANG_INTERVAL;
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}
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}
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#endif
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MonitorAutoLock lock(*gMonitor);
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if (newval != gTimeout) {
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gTimeout = newval;
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lock.Notify();
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}
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return 0;
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}
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void
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Crash()
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{
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if (gDebugDisableHangMonitor) {
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return;
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}
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#ifdef XP_WIN
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if (::IsDebuggerPresent()) {
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return;
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}
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#endif
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#ifdef MOZ_CRASHREPORTER
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CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("Hang"),
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NS_LITERAL_CSTRING("1"));
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#endif
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NS_RUNTIMEABORT("HangMonitor triggered");
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}
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#ifdef REPORT_CHROME_HANGS
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static void
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ChromeStackWalker(void *aPC, void *aSP, void *aClosure)
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{
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MOZ_ASSERT(aClosure);
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std::vector<uintptr_t> *stack =
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static_cast<std::vector<uintptr_t>*>(aClosure);
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if (stack->size() == MAX_CALL_STACK_PCS)
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return;
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MOZ_ASSERT(stack->size() < MAX_CALL_STACK_PCS);
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stack->push_back(reinterpret_cast<uintptr_t>(aPC));
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}
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static void
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GetChromeHangReport(Telemetry::ProcessedStack &aStack)
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{
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MOZ_ASSERT(winMainThreadHandle);
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// The thread we're about to suspend might have the alloc lock
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// so allocate ahead of time
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std::vector<uintptr_t> rawStack;
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rawStack.reserve(MAX_CALL_STACK_PCS);
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DWORD ret = ::SuspendThread(winMainThreadHandle);
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if (ret == -1)
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return;
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NS_StackWalk(ChromeStackWalker, /* skipFrames */ 0, /* maxFrames */ 0,
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reinterpret_cast<void*>(&rawStack),
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reinterpret_cast<uintptr_t>(winMainThreadHandle), nullptr);
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ret = ::ResumeThread(winMainThreadHandle);
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if (ret == -1)
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return;
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aStack = Telemetry::GetStackAndModules(rawStack);
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}
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#endif
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void
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ThreadMain(void*)
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{
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PR_SetCurrentThreadName("Hang Monitor");
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MonitorAutoLock lock(*gMonitor);
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// In order to avoid issues with the hang monitor incorrectly triggering
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// during a general system stop such as sleeping, the monitor thread must
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// run twice to trigger hang protection.
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PRIntervalTime lastTimestamp = 0;
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int waitCount = 0;
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#ifdef REPORT_CHROME_HANGS
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Telemetry::ProcessedStack stack;
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#endif
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while (true) {
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if (gShutdown) {
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return; // Exit the thread
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}
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// avoid rereading the volatile value in this loop
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PRIntervalTime timestamp = gTimestamp;
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PRIntervalTime now = PR_IntervalNow();
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if (timestamp != PR_INTERVAL_NO_WAIT &&
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now < timestamp) {
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// 32-bit overflow, reset for another waiting period
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timestamp = 1; // lowest legal PRInterval value
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}
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if (timestamp != PR_INTERVAL_NO_WAIT &&
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timestamp == lastTimestamp &&
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gTimeout > 0) {
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++waitCount;
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if (waitCount >= 2) {
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#ifdef REPORT_CHROME_HANGS
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GetChromeHangReport(stack);
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#else
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int32_t delay =
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int32_t(PR_IntervalToSeconds(now - timestamp));
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if (delay >= gTimeout) {
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MonitorAutoUnlock unlock(*gMonitor);
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Crash();
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}
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#endif
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}
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}
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else {
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#ifdef REPORT_CHROME_HANGS
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if (waitCount >= 2) {
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uint32_t hangDuration = PR_IntervalToSeconds(now - lastTimestamp);
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Telemetry::RecordChromeHang(hangDuration, stack);
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stack.Clear();
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}
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#endif
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lastTimestamp = timestamp;
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waitCount = 0;
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}
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PRIntervalTime timeout;
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if (gTimeout <= 0) {
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timeout = PR_INTERVAL_NO_TIMEOUT;
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}
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else {
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timeout = PR_MillisecondsToInterval(gTimeout * 500);
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}
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lock.Wait(timeout);
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}
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}
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void
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Startup()
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{
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// The hang detector only runs in chrome processes. If you change this,
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// you must also deal with the threadsafety of AnnotateCrashReport in
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// non-chrome processes!
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if (GeckoProcessType_Default != XRE_GetProcessType())
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return;
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MOZ_ASSERT(!gMonitor, "Hang monitor already initialized");
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gMonitor = new Monitor("HangMonitor");
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Preferences::RegisterCallback(PrefChanged, kHangMonitorPrefName, NULL);
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PrefChanged(NULL, NULL);
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#ifdef REPORT_CHROME_HANGS
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Preferences::RegisterCallback(PrefChanged, kTelemetryPrefName, NULL);
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winMainThreadHandle =
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OpenThread(THREAD_ALL_ACCESS, FALSE, GetCurrentThreadId());
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if (!winMainThreadHandle)
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return;
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#endif
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// Don't actually start measuring hangs until we hit the main event loop.
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// This potentially misses a small class of really early startup hangs,
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// but avoids dealing with some xpcshell tests and other situations which
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// start XPCOM but don't ever start the event loop.
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Suspend();
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gThread = PR_CreateThread(PR_USER_THREAD,
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ThreadMain,
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NULL, PR_PRIORITY_LOW, PR_GLOBAL_THREAD,
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PR_JOINABLE_THREAD, 0);
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}
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void
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Shutdown()
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{
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if (GeckoProcessType_Default != XRE_GetProcessType())
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return;
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MOZ_ASSERT(gMonitor, "Hang monitor not started");
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{ // Scope the lock we're going to delete later
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MonitorAutoLock lock(*gMonitor);
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gShutdown = true;
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lock.Notify();
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}
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// thread creation could theoretically fail
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if (gThread) {
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PR_JoinThread(gThread);
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gThread = NULL;
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}
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delete gMonitor;
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gMonitor = NULL;
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}
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static bool
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IsUIMessageWaiting()
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{
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#ifndef XP_WIN
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return false;
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#else
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#define NS_WM_IMEFIRST WM_IME_SETCONTEXT
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#define NS_WM_IMELAST WM_IME_KEYUP
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BOOL haveUIMessageWaiting = FALSE;
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MSG msg;
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haveUIMessageWaiting |= ::PeekMessageW(&msg, NULL, WM_KEYFIRST,
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WM_IME_KEYLAST, PM_NOREMOVE);
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haveUIMessageWaiting |= ::PeekMessageW(&msg, NULL, NS_WM_IMEFIRST,
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NS_WM_IMELAST, PM_NOREMOVE);
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haveUIMessageWaiting |= ::PeekMessageW(&msg, NULL, WM_MOUSEFIRST,
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WM_MOUSELAST, PM_NOREMOVE);
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return haveUIMessageWaiting;
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#endif
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}
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void
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NotifyActivity(ActivityType activityType)
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{
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MOZ_ASSERT(NS_IsMainThread(),
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"HangMonitor::Notify called from off the main thread.");
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// Determine the activity type more specifically
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if (activityType == kGeneralActivity) {
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activityType = IsUIMessageWaiting() ? kActivityUIAVail :
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kActivityNoUIAVail;
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}
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// Calculate the cumulative amount of lag time since the last UI message
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static uint32_t cumulativeUILagMS = 0;
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switch(activityType) {
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case kActivityNoUIAVail:
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cumulativeUILagMS = 0;
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break;
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case kActivityUIAVail:
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case kUIActivity:
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if (gTimestamp != PR_INTERVAL_NO_WAIT) {
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cumulativeUILagMS += PR_IntervalToMilliseconds(PR_IntervalNow() -
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gTimestamp);
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}
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break;
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default:
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break;
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}
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// This is not a locked activity because PRTimeStamp is a 32-bit quantity
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// which can be read/written atomically, and we don't want to pay locking
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// penalties here.
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gTimestamp = PR_IntervalNow();
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// If we have UI activity we should reset the timer and report it if it is
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// significant enough.
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if (activityType == kUIActivity) {
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// The minimum amount of lag time that we should report for telemetry data.
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// Mozilla's UI responsiveness goal is 50ms
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static const uint32_t kUIResponsivenessThresholdMS = 50;
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if (cumulativeUILagMS > kUIResponsivenessThresholdMS) {
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mozilla::Telemetry::Accumulate(mozilla::Telemetry::EVENTLOOP_UI_LAG_EXP_MS,
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cumulativeUILagMS);
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}
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cumulativeUILagMS = 0;
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}
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}
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void
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Suspend()
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{
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MOZ_ASSERT(NS_IsMainThread(),
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"HangMonitor::Suspend called from off the main thread.");
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// Because gTimestamp changes this resets the wait count.
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gTimestamp = PR_INTERVAL_NO_WAIT;
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}
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} } // namespace mozilla::HangMonitor
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