chromium/mojo/public/cpp/bindings/pending_remote.h

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MOJO_PUBLIC_CPP_BINDINGS_PENDING_REMOTE_H_
#define MOJO_PUBLIC_CPP_BINDINGS_PENDING_REMOTE_H_

#include <cstdint>
#include <type_traits>
#include <utility>

#include "base/check.h"
#include "base/compiler_specific.h"
#include "build/build_config.h"
#include "mojo/public/c/system/types.h"
#include "mojo/public/cpp/bindings/disconnect_reason.h"
#include "mojo/public/cpp/bindings/interface_id.h"
#include "mojo/public/cpp/bindings/lib/pending_remote_state.h"
#include "mojo/public/cpp/bindings/message.h"
#include "mojo/public/cpp/bindings/pipe_control_message_proxy.h"
#include "mojo/public/cpp/bindings/runtime_features.h"
#include "mojo/public/cpp/system/message_pipe.h"

namespace mojo {

template <typename T>
class PendingReceiver;

template <typename T>
struct PendingRemoteConverter;

// A valid PendingRemote is entangled with exactly one Receiver or
// PendingReceiver, and can be consumed to bind a Remote in order to begin
// issuing method calls to that receiver. See Remote documentation for more
// details.
//
// PendingRemote instances may be freely moved to another thread/sequence, or
// even transferred to another process via a Mojo interface call (see
// pending_remote<T> syntax in mojom IDL).
//
// NOTE: This object is essentially semantic sugar wrapping a raw message pipe
// handle that is expected to send Interface messages of a specified version
// (typically 0) to a Receiver. As such, consumers who know what they're doing
// (i.e. who are confident about what lies on the other side of a pipe) may
// freely convert between a PendingRemote and a 2-tuple of
// [raw message pipe handle, expected interface version number].
template <typename Interface>
class PendingRemote { … };

class COMPONENT_EXPORT(MOJO_CPP_BINDINGS) NullRemote { … };

// Fuses a PendingReceiver<T> endpoint with a PendingRemote<T> endpoint. The
// endpoints must belong to two different message pipes, and this effectively
// fuses two pipes into a single pipe. Returns |true| on success or |false| on
// failure.
template <typename Interface>
bool FusePipes(PendingReceiver<Interface> receiver,
               PendingRemote<Interface> remote) { … }

}  // namespace mojo

#include "mojo/public/cpp/bindings/pending_receiver.h"

namespace mojo {

template <typename Interface>
PendingReceiver<Interface>
PendingRemote<Interface>::InitWithNewPipeAndPassReceiver() { … }

}  // namespace mojo

#endif  // MOJO_PUBLIC_CPP_BINDINGS_PENDING_REMOTE_H_