Repo created

TMessagesProj/jni/voip/webrtc/base/synchronization/lock_impl.h

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+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_SYNCHRONIZATION_LOCK_IMPL_H_
+#define BASE_SYNCHRONIZATION_LOCK_IMPL_H_
+
+#include "base/base_export.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/thread_annotations.h"
+#include "build/build_config.h"
+
+#if defined(OS_WIN)
+#include "base/win/windows_types.h"
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
+#include <errno.h>
+#include <pthread.h>
+#endif
+
+namespace base {
+namespace internal {
+
+// This class implements the underlying platform-specific spin-lock mechanism
+// used for the Lock class.  Most users should not use LockImpl directly, but
+// should instead use Lock.
+class BASE_EXPORT LockImpl {
+ public:
+#if defined(OS_WIN)
+  using NativeHandle = CHROME_SRWLOCK;
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
+  using NativeHandle = pthread_mutex_t;
+#endif
+
+  LockImpl();
+  ~LockImpl();
+
+  // If the lock is not held, take it and return true.  If the lock is already
+  // held by something else, immediately return false.
+  bool Try();
+
+  // Take the lock, blocking until it is available if necessary.
+  void Lock();
+
+  // Release the lock.  This must only be called by the lock's holder: after
+  // a successful call to Try, or a call to Lock.
+  inline void Unlock();
+
+  // Return the native underlying lock.
+  // TODO(awalker): refactor lock and condition variables so that this is
+  // unnecessary.
+  NativeHandle* native_handle() { return &native_handle_; }
+
+#if defined(OS_POSIX) || defined(OS_FUCHSIA)
+  // Whether this lock will attempt to use priority inheritance.
+  static bool PriorityInheritanceAvailable();
+#endif
+
+ private:
+  NativeHandle native_handle_;
+
+  DISALLOW_COPY_AND_ASSIGN(LockImpl);
+};
+
+#if defined(OS_WIN)
+void LockImpl::Unlock() {
+  ::ReleaseSRWLockExclusive(reinterpret_cast<PSRWLOCK>(&native_handle_));
+}
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
+void LockImpl::Unlock() {
+  int rv = pthread_mutex_unlock(&native_handle_);
+  DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+}
+#endif
+
+// This is an implementation used for AutoLock templated on the lock type.
+template <class LockType>
+class SCOPED_LOCKABLE BasicAutoLock {
+ public:
+  struct AlreadyAcquired {};
+
+  explicit BasicAutoLock(LockType& lock) EXCLUSIVE_LOCK_FUNCTION(lock)
+      : lock_(lock) {
+    lock_.Acquire();
+  }
+
+  BasicAutoLock(LockType& lock, const AlreadyAcquired&)
+      EXCLUSIVE_LOCKS_REQUIRED(lock)
+      : lock_(lock) {
+    lock_.AssertAcquired();
+  }
+
+  ~BasicAutoLock() UNLOCK_FUNCTION() {
+    lock_.AssertAcquired();
+    lock_.Release();
+  }
+
+ private:
+  LockType& lock_;
+  DISALLOW_COPY_AND_ASSIGN(BasicAutoLock);
+};
+
+// This is an implementation used for AutoUnlock templated on the lock type.
+template <class LockType>
+class BasicAutoUnlock {
+ public:
+  explicit BasicAutoUnlock(LockType& lock) : lock_(lock) {
+    // We require our caller to have the lock.
+    lock_.AssertAcquired();
+    lock_.Release();
+  }
+
+  ~BasicAutoUnlock() { lock_.Acquire(); }
+
+ private:
+  LockType& lock_;
+  DISALLOW_COPY_AND_ASSIGN(BasicAutoUnlock);
+};
+
+// This is an implementation used for AutoLockMaybe templated on the lock type.
+template <class LockType>
+class SCOPED_LOCKABLE BasicAutoLockMaybe {
+ public:
+  explicit BasicAutoLockMaybe(LockType* lock) EXCLUSIVE_LOCK_FUNCTION(lock)
+      : lock_(lock) {
+    if (lock_)
+      lock_->Acquire();
+  }
+
+  ~BasicAutoLockMaybe() UNLOCK_FUNCTION() {
+    if (lock_) {
+      lock_->AssertAcquired();
+      lock_->Release();
+    }
+  }
+
+ private:
+  LockType* const lock_;
+  DISALLOW_COPY_AND_ASSIGN(BasicAutoLockMaybe);
+};
+
+// This is an implementation used for ReleasableAutoLock templated on the lock
+// type.
+template <class LockType>
+class SCOPED_LOCKABLE BasicReleasableAutoLock {
+ public:
+  explicit BasicReleasableAutoLock(LockType* lock) EXCLUSIVE_LOCK_FUNCTION(lock)
+      : lock_(lock) {
+    DCHECK(lock_);
+    lock_->Acquire();
+  }
+
+  ~BasicReleasableAutoLock() UNLOCK_FUNCTION() {
+    if (lock_) {
+      lock_->AssertAcquired();
+      lock_->Release();
+    }
+  }
+
+  void Release() UNLOCK_FUNCTION() {
+    DCHECK(lock_);
+    lock_->AssertAcquired();
+    lock_->Release();
+    lock_ = nullptr;
+  }
+
+ private:
+  LockType* lock_;
+  DISALLOW_COPY_AND_ASSIGN(BasicReleasableAutoLock);
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_SYNCHRONIZATION_LOCK_IMPL_H_