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// Copyright 2013 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 MOJO_SYSTEM_RAW_CHANNEL_H_
#define MOJO_SYSTEM_RAW_CHANNEL_H_
#include <vector>
#include "base/basictypes.h"
#include "mojo/system/constants.h"
#include "mojo/system/embedder/scoped_platform_handle.h"
#include "mojo/system/system_impl_export.h"
namespace base {
class MessageLoop;
}
namespace mojo {
namespace system {
class MessageInTransit;
// |RawChannel| is an interface to objects that wrap an OS "pipe". It presents
// the following interface to users:
// - Receives and dispatches messages on a thread (running a |MessageLoop|; it
// must be a |MessageLoopForIO| in the case of the POSIX libevent
// implementation).
// - Provides a thread-safe way of writing messages (|WriteMessage()|);
// writing/queueing messages will not block and is atomic from the point of
// view of the caller. If necessary, messages are queued (to be written on
// the aforementioned thread).
//
// OS-specific implementation subclasses are to be instantiated using the
// |Create()| static factory method.
//
// With the exception of |WriteMessage()|, this class is thread-unsafe (and in
// general its methods should only be used on the I/O thread).
class MOJO_SYSTEM_IMPL_EXPORT RawChannel {
public:
virtual ~RawChannel() {}
// The |Delegate| is only accessed on the same thread as the message loop
// (passed in on creation).
class MOJO_SYSTEM_IMPL_EXPORT Delegate {
public:
enum FatalError {
FATAL_ERROR_UNKNOWN = 0,
FATAL_ERROR_FAILED_READ,
FATAL_ERROR_FAILED_WRITE
};
// Called when a message is read. This may call |Shutdown()| on the
// |RawChannel|, but must not destroy it.
virtual void OnReadMessage(const MessageInTransit& message) = 0;
// Called when there's a fatal error, which leads to the channel no longer
// being viable.
// For each raw channel, at most one |FATAL_ERROR_FAILED_READ| and one
// |FATAL_ERROR_FAILED_WRITE| notification will be issued. (And it is
// possible to get both.)
// After |OnFatalError(FATAL_ERROR_FAILED_READ)| there won't be further
// |OnReadMessage()| calls.
virtual void OnFatalError(FatalError fatal_error) = 0;
protected:
virtual ~Delegate() {}
};
// Static factory method. |handle| should be a handle to a
// (platform-appropriate) bidirectional communication channel (e.g., a socket
// on POSIX, a named pipe on Windows). Does *not* take ownership of |delegate|
// and |message_loop|, which must remain alive while this object does.
static RawChannel* Create(embedder::ScopedPlatformHandle handle,
Delegate* delegate,
base::MessageLoop* message_loop);
// This must be called (on the I/O thread) before this object is used. Returns
// true on success. On failure, |Shutdown()| should *not* be called.
virtual bool Init() = 0;
// This must be called (on the I/O thread) before this object is destroyed.
virtual void Shutdown() = 0;
// This is thread-safe. It takes ownership of |message| (always, even on
// failure). Returns true on success.
virtual bool WriteMessage(MessageInTransit* message) = 0;
protected:
RawChannel(Delegate* delegate, base::MessageLoop* message_loop)
: delegate_(delegate), message_loop_(message_loop) {}
Delegate* delegate() { return delegate_; }
base::MessageLoop* message_loop() { return message_loop_; }
private:
Delegate* const delegate_;
base::MessageLoop* const message_loop_;
DISALLOW_COPY_AND_ASSIGN(RawChannel);
};
} // namespace system
} // namespace mojo
#endif // MOJO_SYSTEM_RAW_CHANNEL_H_
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