michael@0: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_LOCK_IMPL_H_
michael@0: #define BASE_LOCK_IMPL_H_
michael@0: 
michael@0: #include "build/build_config.h"
michael@0: 
michael@0: #if defined(OS_WIN)
michael@0: #include <windows.h>
michael@0: #elif defined(OS_POSIX)
michael@0: #include <pthread.h>
michael@0: #endif
michael@0: 
michael@0: #include "base/basictypes.h"
michael@0: #include "base/platform_thread.h"
michael@0: 
michael@0: // This class implements the underlying platform-specific spin-lock mechanism
michael@0: // used for the Lock class.  Most users should not use LockImpl directly, but
michael@0: // should instead use Lock.
michael@0: class LockImpl {
michael@0:  public:
michael@0: #if defined(OS_WIN)
michael@0:   typedef CRITICAL_SECTION OSLockType;
michael@0: #elif defined(OS_POSIX)
michael@0:   typedef pthread_mutex_t OSLockType;
michael@0: #endif
michael@0: 
michael@0:   LockImpl();
michael@0:   ~LockImpl();
michael@0: 
michael@0:   // If the lock is not held, take it and return true.  If the lock is already
michael@0:   // held by something else, immediately return false.
michael@0:   bool Try();
michael@0: 
michael@0:   // Take the lock, blocking until it is available if necessary.
michael@0:   void Lock();
michael@0: 
michael@0:   // Release the lock.  This must only be called by the lock's holder: after
michael@0:   // a successful call to Try, or a call to Lock.
michael@0:   void Unlock();
michael@0: 
michael@0:   // Debug-only method that will DCHECK() if the lock is not acquired by the
michael@0:   // current thread.  In non-debug builds, no check is performed.
michael@0:   // Because linux and mac condition variables modify the underlyning lock
michael@0:   // through the os_lock() method, runtime assertions can not be done on those
michael@0:   // builds.
michael@0: #if defined(NDEBUG) || !defined(OS_WIN)
michael@0:   void AssertAcquired() const {}
michael@0: #else
michael@0:   void AssertAcquired() const;
michael@0: #endif
michael@0: 
michael@0:   // Return the native underlying lock.  Not supported for Windows builds.
michael@0:   // TODO(awalker): refactor lock and condition variables so that this is
michael@0:   // unnecessary.
michael@0: #if !defined(OS_WIN)
michael@0:   OSLockType* os_lock() { return &os_lock_; }
michael@0: #endif
michael@0: 
michael@0:  private:
michael@0:   OSLockType os_lock_;
michael@0: 
michael@0: #if !defined(NDEBUG) && defined(OS_WIN)
michael@0:   // All private data is implicitly protected by lock_.
michael@0:   // Be VERY careful to only access members under that lock.
michael@0:   PlatformThreadId owning_thread_id_;
michael@0:   int32_t recursion_count_shadow_;
michael@0:   bool recursion_used_;      // Allow debugging to continued after a DCHECK().
michael@0: #endif  // NDEBUG
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(LockImpl);
michael@0: };
michael@0: 
michael@0: 
michael@0: #endif  // BASE_LOCK_IMPL_H_