xpcom/threads/ReentrantMonitor.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_ReentrantMonitor_h
   8 #define mozilla_ReentrantMonitor_h
   9
  10 #include "prmon.h"
  11
  12 #if defined(MOZILLA_INTERNAL_API) && !defined(DEBUG)
  13 #  include "GeckoProfiler.h"
  14 #endif  // defined( MOZILLA_INTERNAL_API) && !defined(DEBUG)
  15
  16 #include "mozilla/BlockingResourceBase.h"
  17 #include "nsISupports.h"
  18
  19 //
  20 // Provides:
  21 //
  22 //  - ReentrantMonitor, a Java-like monitor
  23 //  - ReentrantMonitorAutoEnter, an RAII class for ensuring that
  24 //    ReentrantMonitors are properly entered and exited
  25 //
  26 // Using ReentrantMonitorAutoEnter is MUCH preferred to making bare calls to
  27 // ReentrantMonitor.Enter and Exit.
  28 //
  29 namespace mozilla {
  30
  31 /**
  32  * ReentrantMonitor
  33  * Java-like monitor.
  34  * When possible, use ReentrantMonitorAutoEnter to hold this monitor within a
  35  * scope, instead of calling Enter/Exit directly.
  36  **/
  37 class ReentrantMonitor : BlockingResourceBase {
  38  public:
  39   /**
  40    * ReentrantMonitor
  41    * @param aName A name which can reference this monitor
  42    */
  43   explicit ReentrantMonitor(const char* aName)
  44       : BlockingResourceBase(aName, eReentrantMonitor)
  45 #ifdef DEBUG
  46         ,
  47         mEntryCount(0)
  48 #endif
  49   {
  50     MOZ_COUNT_CTOR(ReentrantMonitor);
  51     mReentrantMonitor = PR_NewMonitor();
  52     if (!mReentrantMonitor) {
  53       MOZ_CRASH("Can't allocate mozilla::ReentrantMonitor");
  54     }
  55   }
  56
  57   /**
  58    * ~ReentrantMonitor
  59    **/
  60   ~ReentrantMonitor() {
  61     NS_ASSERTION(mReentrantMonitor,
  62                  "improperly constructed ReentrantMonitor or double free");
  63     PR_DestroyMonitor(mReentrantMonitor);
  64     mReentrantMonitor = 0;
  65     MOZ_COUNT_DTOR(ReentrantMonitor);
  66   }
  67
  68 #ifndef DEBUG
  69   /**
  70    * Enter
  71    * @see prmon.h
  72    **/
  73   void Enter() { PR_EnterMonitor(mReentrantMonitor); }
  74
  75   /**
  76    * Exit
  77    * @see prmon.h
  78    **/
  79   void Exit() { PR_ExitMonitor(mReentrantMonitor); }
  80
  81   /**
  82    * Wait
  83    * @see prmon.h
  84    **/
  85   nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT) {
  86 #  ifdef MOZILLA_INTERNAL_API
  87     AUTO_PROFILER_THREAD_SLEEP;
  88 #  endif  // MOZILLA_INTERNAL_API
  89     return PR_Wait(mReentrantMonitor, aInterval) == PR_SUCCESS
  90                ? NS_OK
  91                : NS_ERROR_FAILURE;
  92   }
  93
  94 #else  // ifndef DEBUG
  95   void Enter();
  96   void Exit();
  97   nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT);
  98
  99 #endif  // ifndef DEBUG
 100
 101   /**
 102    * Notify
 103    * @see prmon.h
 104    **/
 105   nsresult Notify() {
 106     return PR_Notify(mReentrantMonitor) == PR_SUCCESS ? NS_OK
 107                                                       : NS_ERROR_FAILURE;
 108   }
 109
 110   /**
 111    * NotifyAll
 112    * @see prmon.h
 113    **/
 114   nsresult NotifyAll() {
 115     return PR_NotifyAll(mReentrantMonitor) == PR_SUCCESS ? NS_OK
 116                                                          : NS_ERROR_FAILURE;
 117   }
 118
 119 #ifdef DEBUG
 120   /**
 121    * AssertCurrentThreadIn
 122    * @see prmon.h
 123    **/
 124   void AssertCurrentThreadIn() {
 125     PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mReentrantMonitor);
 126   }
 127
 128   /**
 129    * AssertNotCurrentThreadIn
 130    * @see prmon.h
 131    **/
 132   void AssertNotCurrentThreadIn() {
 133     // FIXME bug 476536
 134   }
 135
 136 #else
 137   void AssertCurrentThreadIn() {}
 138   void AssertNotCurrentThreadIn() {}
 139
 140 #endif  // ifdef DEBUG
 141
 142  private:
 143   ReentrantMonitor();
 144   ReentrantMonitor(const ReentrantMonitor&);
 145   ReentrantMonitor& operator=(const ReentrantMonitor&);
 146
 147   PRMonitor* mReentrantMonitor;
 148 #ifdef DEBUG
 149   int32_t mEntryCount;
 150 #endif
 151 };
 152
 153 /**
 154  * ReentrantMonitorAutoEnter
 155  * Enters the ReentrantMonitor when it enters scope, and exits it when
 156  * it leaves scope.
 157  *
 158  * MUCH PREFERRED to bare calls to ReentrantMonitor.Enter and Exit.
 159  */
 160 class MOZ_STACK_CLASS ReentrantMonitorAutoEnter {
 161  public:
 162   /**
 163    * Constructor
 164    * The constructor aquires the given lock.  The destructor
 165    * releases the lock.
 166    *
 167    * @param aReentrantMonitor A valid mozilla::ReentrantMonitor*.
 168    **/
 169   explicit ReentrantMonitorAutoEnter(
 170       mozilla::ReentrantMonitor& aReentrantMonitor)
 171       : mReentrantMonitor(&aReentrantMonitor) {
 172     NS_ASSERTION(mReentrantMonitor, "null monitor");
 173     mReentrantMonitor->Enter();
 174   }
 175
 176   ~ReentrantMonitorAutoEnter(void) { mReentrantMonitor->Exit(); }
 177
 178   nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT) {
 179     return mReentrantMonitor->Wait(aInterval);
 180   }
 181
 182   nsresult Notify() { return mReentrantMonitor->Notify(); }
 183   nsresult NotifyAll() { return mReentrantMonitor->NotifyAll(); }
 184
 185  private:
 186   ReentrantMonitorAutoEnter();
 187   ReentrantMonitorAutoEnter(const ReentrantMonitorAutoEnter&);
 188   ReentrantMonitorAutoEnter& operator=(const ReentrantMonitorAutoEnter&);
 189   static void* operator new(size_t) noexcept(true);
 190
 191   friend class ReentrantMonitorAutoExit;
 192
 193   mozilla::ReentrantMonitor* mReentrantMonitor;
 194 };
 195
 196 /**
 197  * ReentrantMonitorAutoExit
 198  * Exit the ReentrantMonitor when it enters scope, and enters it when it leaves
 199  * scope.
 200  *
 201  * MUCH PREFERRED to bare calls to ReentrantMonitor.Exit and Enter.
 202  */
 203 class MOZ_STACK_CLASS ReentrantMonitorAutoExit {
 204  public:
 205   /**
 206    * Constructor
 207    * The constructor releases the given lock.  The destructor
 208    * acquires the lock. The lock must be held before constructing
 209    * this object!
 210    *
 211    * @param aReentrantMonitor A valid mozilla::ReentrantMonitor*. It
 212    *                 must be already locked.
 213    **/
 214   explicit ReentrantMonitorAutoExit(ReentrantMonitor& aReentrantMonitor)
 215       : mReentrantMonitor(&aReentrantMonitor) {
 216     NS_ASSERTION(mReentrantMonitor, "null monitor");
 217     mReentrantMonitor->AssertCurrentThreadIn();
 218     mReentrantMonitor->Exit();
 219   }
 220
 221   explicit ReentrantMonitorAutoExit(
 222       ReentrantMonitorAutoEnter& aReentrantMonitorAutoEnter)
 223       : mReentrantMonitor(aReentrantMonitorAutoEnter.mReentrantMonitor) {
 224     NS_ASSERTION(mReentrantMonitor, "null monitor");
 225     mReentrantMonitor->AssertCurrentThreadIn();
 226     mReentrantMonitor->Exit();
 227   }
 228
 229   ~ReentrantMonitorAutoExit(void) { mReentrantMonitor->Enter(); }
 230
 231  private:
 232   ReentrantMonitorAutoExit();
 233   ReentrantMonitorAutoExit(const ReentrantMonitorAutoExit&);
 234   ReentrantMonitorAutoExit& operator=(const ReentrantMonitorAutoExit&);
 235   static void* operator new(size_t) noexcept(true);
 236
 237   ReentrantMonitor* mReentrantMonitor;
 238 };
 239
 240 }  // namespace mozilla
 241
 242 #endif  // ifndef mozilla_ReentrantMonitor_h