xpcom/build/IOInterposerPrivate.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 xpcom_build_IOInterposerPrivate_h
   8 #define xpcom_build_IOInterposerPrivate_h
   9
  10 /* This header file contains declarations for helper classes that are
  11    to be used exclusively by IOInterposer and its observers. This header
  12    file is not to be used by anything else and MUST NOT be exported! */
  13
  14 #include <prcvar.h>
  15 #include <prlock.h>
  16
  17 namespace mozilla {
  18 namespace IOInterposer {
  19
  20 /**
  21  * The following classes are simple wrappers for PRLock and PRCondVar.
  22  * IOInterposer and friends use these instead of Mozilla::Mutex et al because
  23  * of the fact that IOInterposer is permitted to run until the process
  24  * terminates; we can't use anything that plugs into leak checkers or deadlock
  25  * detectors because IOInterposer will outlive those and generate false
  26  * positives.
  27  */
  28
  29 class Monitor {
  30  public:
  31   Monitor() : mLock(PR_NewLock()), mCondVar(PR_NewCondVar(mLock)) {}
  32
  33   ~Monitor() {
  34     PR_DestroyCondVar(mCondVar);
  35     mCondVar = nullptr;
  36     PR_DestroyLock(mLock);
  37     mLock = nullptr;
  38   }
  39
  40   void Lock() { PR_Lock(mLock); }
  41
  42   void Unlock() { PR_Unlock(mLock); }
  43
  44   bool Wait(PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT) {
  45     return PR_WaitCondVar(mCondVar, aTimeout) == PR_SUCCESS;
  46   }
  47
  48   bool Notify() { return PR_NotifyCondVar(mCondVar) == PR_SUCCESS; }
  49
  50  private:
  51   PRLock* mLock;
  52   PRCondVar* mCondVar;
  53 };
  54
  55 class MonitorAutoLock {
  56  public:
  57   explicit MonitorAutoLock(Monitor& aMonitor) : mMonitor(aMonitor) {
  58     mMonitor.Lock();
  59   }
  60
  61   ~MonitorAutoLock() { mMonitor.Unlock(); }
  62
  63   bool Wait(PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT) {
  64     return mMonitor.Wait(aTimeout);
  65   }
  66
  67   bool Notify() { return mMonitor.Notify(); }
  68
  69  private:
  70   Monitor& mMonitor;
  71 };
  72
  73 class MonitorAutoUnlock {
  74  public:
  75   explicit MonitorAutoUnlock(Monitor& aMonitor) : mMonitor(aMonitor) {
  76     mMonitor.Unlock();
  77   }
  78
  79   ~MonitorAutoUnlock() { mMonitor.Lock(); }
  80
  81  private:
  82   Monitor& mMonitor;
  83 };
  84
  85 class Mutex {
  86  public:
  87   Mutex() : mPRLock(PR_NewLock()) {}
  88
  89   ~Mutex() {
  90     PR_DestroyLock(mPRLock);
  91     mPRLock = nullptr;
  92   }
  93
  94   void Lock() { PR_Lock(mPRLock); }
  95
  96   void Unlock() { PR_Unlock(mPRLock); }
  97
  98  private:
  99   PRLock* mPRLock;
 100 };
 101
 102 class AutoLock {
 103  public:
 104   explicit AutoLock(Mutex& aLock) : mLock(aLock) { mLock.Lock(); }
 105
 106   ~AutoLock() { mLock.Unlock(); }
 107
 108  private:
 109   Mutex& mLock;
 110 };
 111
 112 }  // namespace IOInterposer
 113 }  // namespace mozilla
 114
 115 #endif  // xpcom_build_IOInterposerPrivate_h