base/synchronization/lock_impl.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_SYNCHRONIZATION_LOCK_IMPL_H_
   6 #define BASE_SYNCHRONIZATION_LOCK_IMPL_H_
   7
   8 #include "build/build_config.h"
   9
  10 #if defined(OS_WIN)
  11 #include <windows.h>
  12 #elif defined(OS_POSIX)
  13 #include <pthread.h>
  14 #endif
  15
  16 #include "base/base_export.h"
  17 #include "base/basictypes.h"
  18
  19 namespace base {
  20 namespace internal {
  21
  22 // This class implements the underlying platform-specific spin-lock mechanism
  23 // used for the Lock class.  Most users should not use LockImpl directly, but
  24 // should instead use Lock.
  25 class BASE_EXPORT LockImpl {
  26  public:
  27 #if defined(OS_WIN)
  28   typedef CRITICAL_SECTION NativeHandle;
  29 #elif defined(OS_POSIX)
  30   typedef pthread_mutex_t NativeHandle;
  31 #endif
  32
  33   LockImpl();
  34   ~LockImpl();
  35
  36   // If the lock is not held, take it and return true.  If the lock is already
  37   // held by something else, immediately return false.
  38   bool Try();
  39
  40   // Take the lock, blocking until it is available if necessary.
  41   void Lock();
  42
  43   // Release the lock.  This must only be called by the lock's holder: after
  44   // a successful call to Try, or a call to Lock.
  45   void Unlock();
  46
  47   // Return the native underlying lock.
  48   // TODO(awalker): refactor lock and condition variables so that this is
  49   // unnecessary.
  50   NativeHandle* native_handle() { return &native_handle_; }
  51
  52  private:
  53   NativeHandle native_handle_;
  54
  55   DISALLOW_COPY_AND_ASSIGN(LockImpl);
  56 };
  57
  58 }  // namespace internal
  59 }  // namespace base
  60
  61 #endif  // BASE_SYNCHRONIZATION_LOCK_IMPL_H_