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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/cast/message_port/blink_message_port_adapter.h"
#include <string_view>
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "components/cast/message_port/cast/message_port_cast.h"
#include "components/cast/message_port/platform_message_port.h"
namespace cast_api_bindings {
namespace {
// MessagePortAdapters are used to adapt between two different implementations
// of cast_api_bindings::MessagePort.
//
// PostMessageWithTransferables flow including adaptation:
//+---+ +-------+ +---------+ +---------+ +-------+ +---+
//| A | | PortA | | AdptrA | | AdptrB | | PortB | | B |
//+---+ +-------+ +---------+ +---------+ +-------+ +---+
// | Post | | | | |
// |---------->| | | | |
// | | OnMsg | | | |
// | |------------>| | | |
// | | | Adapt Ports | | |
// | | |-----------| | | |
// | | |<----------| | | |
// | | | Post | | |
// | | |----------------->| | |
// | | | | OnMsg | |
// | | | |----------->| |
// | | | | | OnMsg |
// | | | | |-------->|
//
// Error flow including deletion, for example when OnMessage fails
// | | | | | false |
// | | | | |<--------|
// | | | | OnErr | |
// | | | |<-----------| |
// | | | delete | | |
// | | |<-----------------| | |
// | | delete | | | |
// | |<------------| | | |
// | OnErr | | | | |
// |<----------| | | | |
// | | | | delete | |
// | | | |------| | |
// | | | |<-----| | |
class MessagePortAdapter : public MessagePort::Receiver {
public:
using CreatePairRepeatingCallback =
base::RepeatingCallback<void(std::unique_ptr<MessagePort>*,
std::unique_ptr<MessagePort>*)>;
// PortType is used to track whether the held port represents a client or a
// server port. Clients must respect client and server semantics because some
// platforms have asymmetric port implementations.
enum class PortType {
CLIENT = 1,
SERVER = 2,
};
// Two MessagePortAdapters are used to adapt between their respective
// |port|s. Some implementations are directional, so |port_type| is used
// determine how the |create_pair| function should be invoked when
// adapting transferred ports. The adapter pair manages its own lifetime
// and is destroyed on error.
MessagePortAdapter(std::unique_ptr<MessagePort> port,
PortType port_type,
CreatePairRepeatingCallback create_pair_cb)
: port_(std::move(port)),
port_type_(port_type),
create_pair_cb_(create_pair_cb) {
DCHECK(port_);
port_->SetReceiver(this);
}
~MessagePortAdapter() override = default;
MessagePortAdapter(const MessagePortAdapter&) = delete;
MessagePortAdapter(MessagePortAdapter&&) = delete;
// Pairs the port with a |peer|. Their lifetimes will be the same.
void SetPeer(MessagePortAdapter* peer) {
DCHECK(peer);
peer_ = peer;
}
// Invokes |create_pair_|, which should create a new pair of ports with the
// same type as |port_|.
void CreatePair(std::unique_ptr<MessagePort>* client,
std::unique_ptr<MessagePort>* server) {
create_pair_cb_.Run(client, server);
}
private:
// MessagePort::Receiver implementation:
void OnPipeError() override {
DCHECK(peer_);
// Ports are closed on error; when an error occurs, destroy the adapters.
delete peer_;
delete this;
}
bool OnMessage(std::string_view message,
std::vector<std::unique_ptr<MessagePort>> ports) override {
DCHECK(peer_);
std::vector<std::unique_ptr<MessagePort>> transferables;
// Because we are adapting port types, an adapter to the peer's type is
// needed for each transferred port.
for (auto& port : ports) {
// The incoming |port| is the same kind of port as |this|.
MessagePortAdapter* incoming =
new MessagePortAdapter(std::move(port), port_type_, create_pair_cb_);
// The outgoing port is the same kind of port as |peer_|.
std::unique_ptr<MessagePort> client;
std::unique_ptr<MessagePort> server;
peer_->CreatePair(&client, &server);
// If |incoming| is a client port adapter, it will be talking to a
// |server| of the port type of the |peer_|, and vice versa.
MessagePortAdapter* outgoing = new MessagePortAdapter(
incoming->port_type_ == PortType::CLIENT ? std::move(server)
: std::move(client),
peer_->port_type_, peer_->create_pair_cb_);
// Connect the adapters together.
incoming->SetPeer(outgoing);
outgoing->SetPeer(incoming);
// If |incoming| is a client port adapter, the |client| port of the
// |peer_| type will be transferred, and vice versa.
// |server| of the port type of the |peer_|, and vice versa.
transferables.push_back(port_type_ == PortType::CLIENT
? std::move(client)
: std::move(server));
}
return peer_->port_->PostMessageWithTransferables(message,
std::move(transferables));
}
std::unique_ptr<MessagePort> port_;
raw_ptr<MessagePortAdapter, DanglingUntriaged> peer_ = nullptr;
const PortType port_type_;
const CreatePairRepeatingCallback create_pair_cb_;
};
} // namespace
// static
std::unique_ptr<MessagePort>
BlinkMessagePortAdapter::ToClientPlatformMessagePort(
blink::WebMessagePort&& client) {
MessagePortAdapter* blink =
new MessagePortAdapter(MessagePortCast::Create(std::move(client)),
MessagePortAdapter::PortType::CLIENT,
base::BindRepeating(&MessagePortCast::CreatePair));
std::unique_ptr<MessagePort> adapted_client;
std::unique_ptr<MessagePort> server;
CreatePlatformMessagePortPair(&adapted_client, &server);
MessagePortAdapter* platform = new MessagePortAdapter(
std::move(server), MessagePortAdapter::PortType::SERVER,
base::BindRepeating(&CreatePlatformMessagePortPair));
blink->SetPeer(platform);
platform->SetPeer(blink);
return adapted_client;
}
// static
blink::WebMessagePort BlinkMessagePortAdapter::FromServerPlatformMessagePort(
std::unique_ptr<MessagePort> server) {
MessagePortAdapter* platform = new MessagePortAdapter(
std::move(server), MessagePortAdapter::PortType::SERVER,
base::BindRepeating(&CreatePlatformMessagePortPair));
std::unique_ptr<MessagePort> client;
std::unique_ptr<MessagePort> adapted_server;
MessagePortCast::CreatePair(&client, &adapted_server);
MessagePortAdapter* blink = new MessagePortAdapter(
std::move(client), MessagePortAdapter::PortType::CLIENT,
base::BindRepeating(&MessagePortCast::CreatePair));
blink->SetPeer(platform);
platform->SetPeer(blink);
return MessagePortCast::FromMessagePort(adapted_server.get())->TakePort();
}
} // namespace cast_api_bindings
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