Create a QUIC wrapper around a mutex and a mutex lock.

net/quic/platform/api/quic_mutex.h

Index: net/quic/platform/api/quic_mutex.h
diff --git a/net/quic/platform/api/quic_mutex.h b/net/quic/platform/api/quic_mutex.h
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+// Copyright (c) 2016 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 NET_QUIC_PLATFORM_API_QUIC_MUTEX_H_
+#define NET_QUIC_PLATFORM_API_QUIC_MUTEX_H_
+
+#include "net/quic/platform/impl/quic_mutex_impl.h"
+
+namespace net {
+
+// A class representing a non-reentrant mutex in QUIC.
+class QUIC_EXPORT_PRIVATE LOCKABLE QuicMutex {
+ public:
+  QuicMutex() = default;
+
+  // Block until this Mutex is free, then acquire it exclusively.
+  void WriterLock() EXCLUSIVE_LOCK_FUNCTION();
+
+  // Release this Mutex. Caller must hold it exclusively.
+  void WriterUnlock() UNLOCK_FUNCTION();
+
+  // Block until this Mutex is free or shared, then acquire a share of it.
+  void ReaderLock() SHARED_LOCK_FUNCTION();
+
+  // Release this Mutex. Caller could hold it in shared mode.
+  void ReaderUnlock() UNLOCK_FUNCTION();
+
+  // Returns immediately if current thread holds the Mutex in at least shared
+  // mode.  Otherwise, may report an error (typically by crashing with a
+  // diagnostic), or may return immediately.
+  void AssertReaderHeld() const ASSERT_SHARED_LOCK();
+
+ private:
+  QuicLockImpl impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(QuicMutex);
+};
+
+// A helper class that acquires the given QuicMutex shared lock while the
+// QuicReaderMutexLock is in scope.
+class QUIC_EXPORT_PRIVATE SCOPED_LOCKABLE QuicReaderMutexLock {
+ public:
+  explicit QuicReaderMutexLock(QuicMutex* lock) SHARED_LOCK_FUNCTION(lock);
+
+  ~QuicReaderMutexLock() UNLOCK_FUNCTION();
+
+ private:
+  QuicMutex* const lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(QuicReaderMutexLock);
+};
+
+// A helper class that acquires the given QuicMutex exclusive lock while the
+// QuicWriterMutexLock is in scope.
+class QUIC_EXPORT_PRIVATE SCOPED_LOCKABLE QuicWriterMutexLock {
+ public:
+  explicit QuicWriterMutexLock(QuicMutex* lock) EXCLUSIVE_LOCK_FUNCTION(lock);
+
+  ~QuicWriterMutexLock() UNLOCK_FUNCTION();
+
+ private:
+  QuicMutex* const lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(QuicWriterMutexLock);
+};
+
+}  // namespace net
+
+#endif  // NET_QUIC_PLATFORM_API_QUIC_MUTEX_H_