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 #include "mozilla/ThreadSafety.h"
  18
  19 namespace mozilla {
  20 namespace IOInterposer {
  21
  22 /**
  23  * The following classes are simple wrappers for PRLock and PRCondVar.
  24  * IOInterposer and friends use these instead of Mozilla::Mutex et al because
  25  * of the fact that IOInterposer is permitted to run until the process
  26  * terminates; we can't use anything that plugs into leak checkers or deadlock
  27  * detectors because IOInterposer will outlive those and generate false
  28  * positives.
  29  */
  30
  31 class MOZ_CAPABILITY("monitor") Monitor {
  32  public:
  33   Monitor() : mLock(PR_NewLock()), mCondVar(PR_NewCondVar(mLock)) {}
  34
  35   ~Monitor() {
  36     PR_DestroyCondVar(mCondVar);
  37     mCondVar = nullptr;
  38     PR_DestroyLock(mLock);
  39     mLock = nullptr;
  40   }
  41
  42   void Lock() MOZ_CAPABILITY_ACQUIRE() { PR_Lock(mLock); }
  43
  44   void Unlock() MOZ_CAPABILITY_RELEASE() { PR_Unlock(mLock); }
  45
  46   bool Wait(PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT)
  47       MOZ_REQUIRES(this) {
  48     return PR_WaitCondVar(mCondVar, aTimeout) == PR_SUCCESS;
  49   }
  50
  51   bool Notify() { return PR_NotifyCondVar(mCondVar) == PR_SUCCESS; }
  52
  53  private:
  54   PRLock* mLock;
  55   PRCondVar* mCondVar;
  56 };
  57
  58 class MOZ_SCOPED_CAPABILITY MonitorAutoLock {
  59  public:
  60   explicit MonitorAutoLock(Monitor& aMonitor) MOZ_CAPABILITY_ACQUIRE(aMonitor)
  61       : mMonitor(aMonitor) {
  62     mMonitor.Lock();
  63   }
  64
  65   ~MonitorAutoLock() MOZ_CAPABILITY_RELEASE() { mMonitor.Unlock(); }
  66
  67  private:
  68   Monitor& mMonitor;
  69 };
  70
  71 class MOZ_SCOPED_CAPABILITY MonitorAutoUnlock {
  72  public:
  73   explicit MonitorAutoUnlock(Monitor& aMonitor)
  74       MOZ_SCOPED_UNLOCK_RELEASE(aMonitor)
  75       : mMonitor(aMonitor) {
  76     mMonitor.Unlock();
  77   }
  78
  79   ~MonitorAutoUnlock() MOZ_SCOPED_UNLOCK_REACQUIRE() { mMonitor.Lock(); }
  80
  81  private:
  82   Monitor& mMonitor;
  83 };
  84
  85 class MOZ_CAPABILITY("mutex") Mutex {
  86  public:
  87   Mutex() : mPRLock(PR_NewLock()) {}
  88
  89   ~Mutex() {
  90     PR_DestroyLock(mPRLock);
  91     mPRLock = nullptr;
  92   }
  93
  94   void Lock() MOZ_CAPABILITY_ACQUIRE() { PR_Lock(mPRLock); }
  95
  96   void Unlock() MOZ_CAPABILITY_RELEASE() { PR_Unlock(mPRLock); }
  97
  98  private:
  99   PRLock* mPRLock;
 100 };
 101
 102 class MOZ_SCOPED_CAPABILITY AutoLock {
 103  public:
 104   explicit AutoLock(Mutex& aLock) MOZ_CAPABILITY_ACQUIRE(aLock) : mLock(aLock) {
 105     mLock.Lock();
 106   }
 107
 108   ~AutoLock() MOZ_CAPABILITY_RELEASE() { mLock.Unlock(); }
 109
 110  private:
 111   Mutex& mLock;
 112 };
 113
 114 }  // namespace IOInterposer
 115 }  // namespace mozilla
 116
 117 #endif  // xpcom_build_IOInterposerPrivate_h