xpcom/threads/CPUUsageWatcher.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_CPUUsageWatcher_h
   8 #define mozilla_CPUUsageWatcher_h
   9
  10 #include <stdint.h>
  11
  12 #include "mozilla/HangAnnotations.h"
  13 #include "mozilla/Result.h"
  14
  15 // We only support OSX and Windows, because on Linux we're forced to read
  16 // from /proc/stat in order to get global CPU values. We would prefer to not
  17 // eat that cost for this.
  18 #if defined(NIGHTLY_BUILD) && (defined(XP_WIN) || defined(XP_MACOSX))
  19 #  define CPU_USAGE_WATCHER_ACTIVE
  20 #endif
  21
  22 namespace mozilla {
  23
  24 // Start error values at 1 to allow using the UnusedZero Result
  25 // optimization.
  26 enum CPUUsageWatcherError : uint8_t {
  27   ClockGetTimeError = 1,
  28   GetNumberOfProcessorsError,
  29   GetProcessTimesError,
  30   GetSystemTimesError,
  31   HostStatisticsError,
  32   ProcStatError,
  33 };
  34
  35 namespace detail {
  36
  37 template <>
  38 struct UnusedZero<CPUUsageWatcherError> : UnusedZeroEnum<CPUUsageWatcherError> {
  39 };
  40
  41 }  // namespace detail
  42
  43 class CPUUsageHangAnnotator : public BackgroundHangAnnotator {
  44  public:
  45 };
  46
  47 class CPUUsageWatcher : public BackgroundHangAnnotator {
  48  public:
  49 #ifdef CPU_USAGE_WATCHER_ACTIVE
  50   CPUUsageWatcher()
  51       : mInitialized(false),
  52         mExternalUsageThreshold(0),
  53         mExternalUsageRatio(0),
  54         mProcessUsageTime(0),
  55         mProcessUpdateTime(0),
  56         mGlobalUsageTime(0),
  57         mGlobalUpdateTime(0),
  58         mNumCPUs(0) {}
  59 #endif
  60
  61   Result<Ok, CPUUsageWatcherError> Init();
  62
  63   void Uninit();
  64
  65   // Updates necessary values to allow AnnotateHang to function. This must be
  66   // called on some semi-regular basis, as it will calculate the mean CPU
  67   // usage values between now and the last time it was called.
  68   Result<Ok, CPUUsageWatcherError> CollectCPUUsage();
  69
  70   void AnnotateHang(BackgroundHangAnnotations& aAnnotations) final;
  71
  72  private:
  73 #ifdef CPU_USAGE_WATCHER_ACTIVE
  74   bool mInitialized;
  75   // The threshold above which we will mark a hang as occurring under high
  76   // external CPU usage conditions
  77   float mExternalUsageThreshold;
  78   // The CPU usage (0-1) external to our process, averaged between the two
  79   // most recent monitor thread runs
  80   float mExternalUsageRatio;
  81   // The total cumulative CPU usage time by our process as of the last
  82   // CollectCPUUsage or Startup
  83   uint64_t mProcessUsageTime;
  84   // A time value in the same units as mProcessUsageTime used to
  85   // determine the ratio of CPU usage time to idle time
  86   uint64_t mProcessUpdateTime;
  87   // The total cumulative CPU usage time by all processes as of the last
  88   // CollectCPUUsage or Startup
  89   uint64_t mGlobalUsageTime;
  90   // A time value in the same units as mGlobalUsageTime used to
  91   // determine the ratio of CPU usage time to idle time
  92   uint64_t mGlobalUpdateTime;
  93   // The number of virtual cores on our machine
  94   uint64_t mNumCPUs;
  95 #endif
  96 };
  97
  98 }  // namespace mozilla
  99
 100 #endif  // mozilla_CPUUsageWatcher_h