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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef PPAPI_UTILITY_THREADING_LOCK_H_
#define PPAPI_UTILITY_THREADING_LOCK_H_
#ifdef WIN32
#include <windows.h>
// MemoryBarrier is a Win32 macro that clashes with MemoryBarrier in
// base/atomicops.h.
#undef MemoryBarrier
#else
#include <pthread.h>
#endif
namespace pp {
/// A simple wrapper around a platform-specific lock. See also AutoLock.
class Lock {
public:
/// Creates a lock in the "not held" state.
Lock();
/// Destroys the lock.
~Lock();
/// Acquires the lock, blocking if it's already held by a different thread.
/// The lock must not already be held on the current thread (i.e. recursive
/// locks are not supported).
///
/// Most callers should consider using an AutoLock instead to automatically
/// acquire and release the lock.
void Acquire();
/// Releases the lock. This must be paired with a call to Acquire().
void Release();
private:
#if defined(WIN32)
typedef CRITICAL_SECTION OSLockType;
#else
typedef pthread_mutex_t OSLockType;
#endif
OSLockType os_lock_;
// Copy and assign not supported.
Lock(const Lock&);
Lock& operator=(const Lock&);
};
/// A helper class that scopes holding a lock.
///
/// @code
/// class MyClass {
/// public:
/// void DoSomething() {
/// pp::AutoLock lock(lock_);
/// ...do something with the lock held...
/// }
///
/// private:
/// pp::Lock lock_;
/// };
/// @endcode
class AutoLock {
public:
explicit AutoLock(Lock& lock) : lock_(lock) {
lock_.Acquire();
}
~AutoLock() {
lock_.Release();
}
private:
Lock& lock_;
// Copy and assign not supported.
AutoLock(const AutoLock&);
AutoLock& operator=(const AutoLock&);
};
} // namespace pp
#endif // PPAPI_UTILITY_THREADING_LOCK_H_
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