Autofill phone number enhancements and integration of Phone Number Util Library: part 1

third_party/libphonenumber/cpp/src/base/synchronization/lock.h

+// 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_H_
+#define BASE_SYNCHRONIZATION_LOCK_H_
+#pragma once
+
+#include "base/synchronization/lock_impl.h"
+#include "base/threading/platform_thread.h"
+
+namespace base {
+
+// A convenient wrapper for an OS specific critical section.  The only real
+// intelligence in this class is in debug mode for the support for the
+// AssertAcquired() method.
+class Lock {
+ public:
+#if defined(NDEBUG)             // Optimized wrapper implementation
+  Lock() : lock_() {}
+  ~Lock() {}
+  void Acquire() { lock_.Lock(); }
+  void Release() { lock_.Unlock(); }
+
+  // If the lock is not held, take it and return true. If the lock is already
+  // held by another thread, immediately return false. This must not be called
+  // by a thread already holding the lock (what happens is undefined and an
+  // assertion may fail).
+  bool Try() { return lock_.Try(); }
+
+  // Null implementation if not debug.
+  void AssertAcquired() const {}
+#else
+  Lock();
+  ~Lock() {}
+
+  // NOTE: Although windows critical sections support recursive locks, we do not
+  // allow this, and we will commonly fire a DCHECK() if a thread attempts to
+  // acquire the lock a second time (while already holding it).
+  void Acquire() {
+    lock_.Lock();
+    CheckUnheldAndMark();
+  }
+  void Release() {
+    CheckHeldAndUnmark();
+    lock_.Unlock();
+  }
+
+  bool Try() {
+    bool rv = lock_.Try();
+    if (rv) {
+      CheckUnheldAndMark();
+    }
+    return rv;
+  }
+
+  void AssertAcquired() const;
+#endif                          // NDEBUG
+
+#if defined(OS_POSIX)
+  // The posix implementation of ConditionVariable needs to be able
+  // to see our lock and tweak our debugging counters, as it releases
+  // and acquires locks inside of pthread_cond_{timed,}wait.
+  // Windows doesn't need to do this as it calls the Lock::* methods.
+  friend class ConditionVariable;
+#endif
+
+ private:
+#if !defined(NDEBUG)
+  // Members and routines taking care of locks assertions.
+  // Note that this checks for recursive locks and allows them
+  // if the variable is set.  This is allowed by the underlying implementation
+  // on windows but not on Posix, so we're doing unneeded checks on Posix.
+  // It's worth it to share the code.
+  void CheckHeldAndUnmark();
+  void CheckUnheldAndMark();
+
+  // All private data is implicitly protected by lock_.
+  // Be VERY careful to only access members under that lock.
+
+  // Determines validity of owning_thread_id_.  Needed as we don't have
+  // a null owning_thread_id_ value.
+  bool owned_by_thread_;
+  base::PlatformThreadId owning_thread_id_;
+#endif  // NDEBUG
+
+  // Platform specific underlying lock implementation.
+  internal::LockImpl lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(Lock);
+};
+
+// A helper class that acquires the given Lock while the AutoLock is in scope.
+class AutoLock {
+ public:
+  explicit AutoLock(Lock& lock) : lock_(lock) {
+    lock_.Acquire();
+  }
+
+  ~AutoLock() {
+    lock_.AssertAcquired();
+    lock_.Release();
+  }
+
+ private:
+  Lock& lock_;
+  DISALLOW_COPY_AND_ASSIGN(AutoLock);
+};
+
+// AutoUnlock is a helper that will Release() the |lock| argument in the
+// constructor, and re-Acquire() it in the destructor.
+class AutoUnlock {
+ public:
+  explicit AutoUnlock(Lock& lock) : lock_(lock) {
+    // We require our caller to have the lock.
+    lock_.AssertAcquired();
+    lock_.Release();
+  }
+
+  ~AutoUnlock() {
+    lock_.Acquire();
+  }
+
+ private:
+  Lock& lock_;
+  DISALLOW_COPY_AND_ASSIGN(AutoUnlock);
+};
+
+}  // namespace base
+
+#endif  // BASE_SYNCHRONIZATION_LOCK_H_