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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef CHROME_COMMON_IPC_CHANNEL_CAPABILITY_H_
#define CHROME_COMMON_IPC_CHANNEL_CAPABILITY_H_
#include "mozilla/ThreadSafety.h"
#include "mozilla/Mutex.h"
#include "mozilla/EventTargetCapability.h"
#include "nsISerialEventTarget.h"
namespace IPC {
// A thread-safety capability used in IPC channel implementations. Combines an
// EventTargetCapability and a Mutex to allow using each independently, as well
// as combined together.
//
// The ChannelCapability grants shared access if on the IOThread or if the send
// mutex is held, and only allows exclusive access if both on the IO thread and
// holding the send mutex. This is similar to a `MutexSingleWriter`, but more
// flexible due to providing access to each sub-capability.
class MOZ_CAPABILITY("channel cap") ChannelCapability {
public:
using Mutex = mozilla::Mutex;
using Thread = mozilla::EventTargetCapability<nsISerialEventTarget>;
ChannelCapability(const char* mutex_name, nsISerialEventTarget* io_thread)
: send_mutex_(mutex_name), io_thread_(io_thread) {}
const Thread& IOThread() const MOZ_RETURN_CAPABILITY(io_thread_) {
return io_thread_;
}
Mutex& SendMutex() MOZ_RETURN_CAPABILITY(send_mutex_) { return send_mutex_; }
// Note that we're on the IO thread, and thus have shared access to values
// guarded by the channel capability for the thread-safety analysis.
void NoteOnIOThread() const MOZ_REQUIRES(io_thread_)
MOZ_ASSERT_SHARED_CAPABILITY(this) {}
// Note that we're holding the send mutex, and thus have shared access to
// values guarded by the channel capability for the thread-safety analysis.
void NoteSendMutex() const MOZ_REQUIRES(send_mutex_)
MOZ_ASSERT_SHARED_CAPABILITY(this) {}
// Note that we're holding the send mutex while on the IO thread, and thus
// have exclusive access to values guarded by the channel capability for the
// thread-safety analysis.
void NoteExclusiveAccess() const MOZ_REQUIRES(io_thread_, send_mutex_)
MOZ_ASSERT_CAPABILITY(this) {}
private:
mozilla::Mutex send_mutex_;
mozilla::EventTargetCapability<nsISerialEventTarget> io_thread_;
};
} // namespace IPC
#endif // CHROME_COMMON_IPC_CHANNEL_CAPABILITY_H_
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