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// Copyright 2015 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 IPC_IPC_MESSAGE_TEMPLATES_H_
#define IPC_IPC_MESSAGE_TEMPLATES_H_
#include <stdint.h>
#include <tuple>
#include <type_traits>
#include <utility>
#include "base/logging.h"
#include "base/trace_event/trace_event.h"
#include "base/tuple.h"
#include "build/build_config.h"
#include "ipc/ipc_message.h"
#include "ipc/ipc_message_utils.h"
namespace IPC {
template <typename Tuple, size_t... Ns>
auto TupleForwardImpl(Tuple&& tuple, std::index_sequence<Ns...>) -> decltype(
std::forward_as_tuple(std::get<Ns>(std::forward<Tuple>(tuple))...)) {
return std::forward_as_tuple(std::get<Ns>(std::forward<Tuple>(tuple))...);
}
// Transforms std::tuple contents to the forwarding form.
// Example:
// std::tuple<int, int&, const int&, int&&>&&
// -> std::tuple<int&&, int&, const int&, int&&>.
// const std::tuple<int, const int&, int&&>&
// -> std::tuple<const int&, int&, const int&, int&>.
//
// TupleForward(std::make_tuple(a, b, c)) is equivalent to
// std::forward_as_tuple(a, b, c).
template <typename Tuple>
auto TupleForward(Tuple&& tuple) -> decltype(TupleForwardImpl(
std::forward<Tuple>(tuple),
std::make_index_sequence<std::tuple_size<std::decay_t<Tuple>>::value>())) {
return TupleForwardImpl(
std::forward<Tuple>(tuple),
std::make_index_sequence<std::tuple_size<std::decay_t<Tuple>>::value>());
}
// This function is for all the async IPCs that don't pass an extra parameter
// using IPC_BEGIN_MESSAGE_MAP_WITH_PARAM.
template <typename ObjT, typename Method, typename P, typename Tuple>
void DispatchToMethod(ObjT* obj, Method method, P*, Tuple&& tuple) {
base::DispatchToMethod(obj, method, std::forward<Tuple>(tuple));
}
template <typename ObjT,
typename Method,
typename P,
typename Tuple,
size_t... Ns>
void DispatchToMethodImpl(ObjT* obj,
Method method,
P* parameter,
Tuple&& tuple,
std::index_sequence<Ns...>) {
(obj->*method)(parameter, std::get<Ns>(std::forward<Tuple>(tuple))...);
}
// The following function is for async IPCs which have a dispatcher with an
// extra parameter specified using IPC_BEGIN_MESSAGE_MAP_WITH_PARAM.
template <typename ObjT, typename P, typename... Args, typename Tuple>
std::enable_if_t<sizeof...(Args) == std::tuple_size<std::decay_t<Tuple>>::value>
DispatchToMethod(ObjT* obj,
void (ObjT::*method)(P*, Args...),
P* parameter,
Tuple&& tuple) {
constexpr size_t size = std::tuple_size<std::decay_t<Tuple>>::value;
DispatchToMethodImpl(obj, method, parameter, std::forward<Tuple>(tuple),
std::make_index_sequence<size>());
}
enum class MessageKind {
CONTROL,
ROUTED,
};
// Routing is a helper struct so MessageT's private common constructor has a
// different type signature than the public "int32_t routing_id" one.
struct Routing {
explicit Routing(int32_t id) : id(id) {}
int32_t id;
};
// We want to restrict MessageT's constructors so that a routing_id is always
// provided for ROUTED messages and never provided for CONTROL messages, so
// use the SFINAE technique from N4387's "Implementation Hint" section.
#if defined(COMPILER_MSVC)
// MSVC 2013 doesn't support default arguments for template member functions
// of templated classes, so there we have to rely on the DCHECKs instead.
// TODO(mdempsky): Reevaluate once MSVC 2015.
#define IPC_MESSAGET_SFINAE(x)
#else
#define IPC_MESSAGET_SFINAE(x) \
template <bool X = (x), typename std::enable_if<X, bool>::type = false>
#endif
// MessageT is the common template used for all user-defined message types.
// It's intended to be used via the macros defined in ipc_message_macros.h.
template <typename Meta,
typename InTuple = typename Meta::InTuple,
typename OutTuple = typename Meta::OutTuple>
class MessageT;
// Asynchronous message partial specialization.
template <typename Meta, typename... Ins>
class MessageT<Meta, std::tuple<Ins...>, void> : public Message {
public:
using Param = std::tuple<Ins...>;
enum { ID = Meta::ID };
// TODO(mdempsky): Remove. Uses of MyMessage::Schema::Param can be replaced
// with just MyMessage::Param.
using Schema = MessageT;
IPC_MESSAGET_SFINAE(Meta::kKind == MessageKind::CONTROL)
MessageT(const Ins&... ins) : MessageT(Routing(MSG_ROUTING_CONTROL), ins...) {
DCHECK(Meta::kKind == MessageKind::CONTROL) << Meta::kName;
}
IPC_MESSAGET_SFINAE(Meta::kKind == MessageKind::ROUTED)
MessageT(int32_t routing_id, const Ins&... ins)
: MessageT(Routing(routing_id), ins...) {
DCHECK(Meta::kKind == MessageKind::ROUTED) << Meta::kName;
}
static bool Read(const Message* msg, Param* p);
static void Log(std::string* name, const Message* msg, std::string* l);
template <class T, class S, class P, class Method>
static bool Dispatch(const Message* msg,
T* obj,
S* sender,
P* parameter,
Method func) {
TRACE_EVENT0("ipc", Meta::kName);
Param p;
if (Read(msg, &p)) {
DispatchToMethod(obj, func, parameter, std::move(p));
return true;
}
return false;
}
private:
MessageT(Routing routing, const Ins&... ins);
};
// Synchronous message partial specialization.
template <typename Meta, typename... Ins, typename... Outs>
class MessageT<Meta, std::tuple<Ins...>, std::tuple<Outs...>>
: public SyncMessage {
public:
using SendParam = std::tuple<Ins...>;
using ReplyParam = std::tuple<Outs...>;
enum { ID = Meta::ID };
// TODO(mdempsky): Remove. Uses of MyMessage::Schema::{Send,Reply}Param can
// be replaced with just MyMessage::{Send,Reply}Param.
using Schema = MessageT;
IPC_MESSAGET_SFINAE(Meta::kKind == MessageKind::CONTROL)
MessageT(const Ins&... ins, Outs*... outs)
: MessageT(Routing(MSG_ROUTING_CONTROL), ins..., outs...) {
DCHECK(Meta::kKind == MessageKind::CONTROL) << Meta::kName;
}
IPC_MESSAGET_SFINAE(Meta::kKind == MessageKind::ROUTED)
MessageT(int32_t routing_id, const Ins&... ins, Outs*... outs)
: MessageT(Routing(routing_id), ins..., outs...) {
DCHECK(Meta::kKind == MessageKind::ROUTED) << Meta::kName;
}
static bool ReadSendParam(const Message* msg, SendParam* p);
static bool ReadReplyParam(const Message* msg, ReplyParam* p);
static void WriteReplyParams(Message* reply, const Outs&... outs);
static void Log(std::string* name, const Message* msg, std::string* l);
template <class T, class S, class P, class Method>
static bool Dispatch(const Message* msg,
T* obj,
S* sender,
P* /* parameter */,
Method func) {
TRACE_EVENT0("ipc", Meta::kName);
SendParam send_params;
bool ok = ReadSendParam(msg, &send_params);
Message* reply = SyncMessage::GenerateReply(msg);
if (!ok) {
NOTREACHED() << "Error deserializing message " << msg->type();
reply->set_reply_error();
sender->Send(reply);
return false;
}
ReplyParam reply_params;
base::DispatchToMethod(obj, func, std::move(send_params), &reply_params);
WriteParam(reply, reply_params);
LogReplyParamsToMessage(reply_params, msg);
sender->Send(reply);
return true;
}
template <class T, class P, class Method>
static bool DispatchDelayReply(const Message* msg,
T* obj,
P* /* parameter */,
Method func) {
TRACE_EVENT0("ipc", Meta::kName);
SendParam send_params;
bool ok = ReadSendParam(msg, &send_params);
Message* reply = SyncMessage::GenerateReply(msg);
if (!ok) {
NOTREACHED() << "Error deserializing message " << msg->type();
reply->set_reply_error();
obj->Send(reply);
return false;
}
std::tuple<Message&> t = std::tie(*reply);
ConnectMessageAndReply(msg, reply);
base::DispatchToMethod(obj, func, std::move(send_params), &t);
return true;
}
template <class T, class P, class Method>
static bool DispatchWithParamDelayReply(const Message* msg,
T* obj,
P* parameter,
Method func) {
TRACE_EVENT0("ipc", Meta::kName);
SendParam send_params;
bool ok = ReadSendParam(msg, &send_params);
Message* reply = SyncMessage::GenerateReply(msg);
if (!ok) {
NOTREACHED() << "Error deserializing message " << msg->type();
reply->set_reply_error();
obj->Send(reply);
return false;
}
std::tuple<Message&> t = std::tie(*reply);
ConnectMessageAndReply(msg, reply);
std::tuple<P*> parameter_tuple(parameter);
base::DispatchToMethod(
obj, func,
std::tuple_cat(std::move(parameter_tuple), TupleForward(send_params)),
&t);
return true;
}
private:
MessageT(Routing routing, const Ins&... ins, Outs*... outs);
};
} // namespace IPC
#if defined(IPC_MESSAGE_IMPL)
#include "ipc/ipc_message_templates_impl.h"
#endif
#endif // IPC_IPC_MESSAGE_TEMPLATES_H_