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/*
* Copyright 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
// This file contains Macros for creating proxies for webrtc MediaStream and
// PeerConnection classes.
// TODO(deadbeef): Move this to pc/; this is part of the implementation.
//
// Example usage:
//
// class TestInterface : public rtc::RefCountInterface {
// public:
// std::string FooA() = 0;
// std::string FooB(bool arg1) const = 0;
// std::string FooC(bool arg1) = 0;
// };
//
// Note that return types can not be a const reference.
//
// class Test : public TestInterface {
// ... implementation of the interface.
// };
//
// BEGIN_PROXY_MAP(Test)
// PROXY_SIGNALING_THREAD_DESTRUCTOR()
// PROXY_METHOD0(std::string, FooA)
// PROXY_CONSTMETHOD1(std::string, FooB, arg1)
// PROXY_WORKER_METHOD1(std::string, FooC, arg1)
// END_PROXY_MAP()
//
// Where the destructor and first two methods are invoked on the signaling
// thread, and the third is invoked on the worker thread.
//
// The proxy can be created using
//
// TestProxy::Create(Thread* signaling_thread, Thread* worker_thread,
// TestInterface*).
//
// The variant defined with BEGIN_SIGNALING_PROXY_MAP is unaware of
// the worker thread, and invokes all methods on the signaling thread.
//
// The variant defined with BEGIN_OWNED_PROXY_MAP does not use
// refcounting, and instead just takes ownership of the object being proxied.
#ifndef API_PROXY_H_
#define API_PROXY_H_
#include <memory>
#include <string>
#include <tuple>
#include <type_traits>
#include <utility>
#include "api/scoped_refptr.h"
#include "rtc_base/event.h"
#include "rtc_base/message_handler.h"
#include "rtc_base/ref_counted_object.h"
#include "rtc_base/system/rtc_export.h"
#include "rtc_base/thread.h"
namespace rtc {
class Location;
}
namespace webrtc {
template <typename R>
class ReturnType {
public:
template <typename C, typename M, typename... Args>
void Invoke(C* c, M m, Args&&... args) {
r_ = (c->*m)(std::forward<Args>(args)...);
}
R moved_result() { return std::move(r_); }
private:
R r_;
};
template <>
class ReturnType<void> {
public:
template <typename C, typename M, typename... Args>
void Invoke(C* c, M m, Args&&... args) {
(c->*m)(std::forward<Args>(args)...);
}
void moved_result() {}
};
namespace internal {
class RTC_EXPORT SynchronousMethodCall : public rtc::MessageData,
public rtc::MessageHandler {
public:
explicit SynchronousMethodCall(rtc::MessageHandler* proxy);
~SynchronousMethodCall() override;
void Invoke(const rtc::Location& posted_from, rtc::Thread* t);
private:
void OnMessage(rtc::Message*) override;
rtc::Event e_;
rtc::MessageHandler* proxy_;
};
} // namespace internal
template <typename C, typename R, typename... Args>
class MethodCall : public rtc::Message, public rtc::MessageHandler {
public:
typedef R (C::*Method)(Args...);
MethodCall(C* c, Method m, Args&&... args)
: c_(c),
m_(m),
args_(std::forward_as_tuple(std::forward<Args>(args)...)) {}
R Marshal(const rtc::Location& posted_from, rtc::Thread* t) {
internal::SynchronousMethodCall(this).Invoke(posted_from, t);
return r_.moved_result();
}
private:
void OnMessage(rtc::Message*) { Invoke(std::index_sequence_for<Args...>()); }
template <size_t... Is>
void Invoke(std::index_sequence<Is...>) {
r_.Invoke(c_, m_, std::move(std::get<Is>(args_))...);
}
C* c_;
Method m_;
ReturnType<R> r_;
std::tuple<Args&&...> args_;
};
template <typename C, typename R, typename... Args>
class ConstMethodCall : public rtc::Message, public rtc::MessageHandler {
public:
typedef R (C::*Method)(Args...) const;
ConstMethodCall(const C* c, Method m, Args&&... args)
: c_(c),
m_(m),
args_(std::forward_as_tuple(std::forward<Args>(args)...)) {}
R Marshal(const rtc::Location& posted_from, rtc::Thread* t) {
internal::SynchronousMethodCall(this).Invoke(posted_from, t);
return r_.moved_result();
}
private:
void OnMessage(rtc::Message*) { Invoke(std::index_sequence_for<Args...>()); }
template <size_t... Is>
void Invoke(std::index_sequence<Is...>) {
r_.Invoke(c_, m_, std::move(std::get<Is>(args_))...);
}
const C* c_;
Method m_;
ReturnType<R> r_;
std::tuple<Args&&...> args_;
};
// Helper macros to reduce code duplication.
#define PROXY_MAP_BOILERPLATE(c) \
template <class INTERNAL_CLASS> \
class c##ProxyWithInternal; \
typedef c##ProxyWithInternal<c##Interface> c##Proxy; \
template <class INTERNAL_CLASS> \
class c##ProxyWithInternal : public c##Interface { \
protected: \
typedef c##Interface C; \
\
public: \
const INTERNAL_CLASS* internal() const { return c_; } \
INTERNAL_CLASS* internal() { return c_; }
// clang-format off
// clang-format would put the semicolon alone,
// leading to a presubmit error (cpplint.py)
#define END_PROXY_MAP() \
};
// clang-format on
#define SIGNALING_PROXY_MAP_BOILERPLATE(c) \
protected: \
c##ProxyWithInternal(rtc::Thread* signaling_thread, INTERNAL_CLASS* c) \
: signaling_thread_(signaling_thread), c_(c) {} \
\
private: \
mutable rtc::Thread* signaling_thread_;
#define WORKER_PROXY_MAP_BOILERPLATE(c) \
protected: \
c##ProxyWithInternal(rtc::Thread* signaling_thread, \
rtc::Thread* worker_thread, INTERNAL_CLASS* c) \
: signaling_thread_(signaling_thread), \
worker_thread_(worker_thread), \
c_(c) {} \
\
private: \
mutable rtc::Thread* signaling_thread_; \
mutable rtc::Thread* worker_thread_;
// Note that the destructor is protected so that the proxy can only be
// destroyed via RefCountInterface.
#define REFCOUNTED_PROXY_MAP_BOILERPLATE(c) \
protected: \
~c##ProxyWithInternal() { \
MethodCall<c##ProxyWithInternal, void> call( \
this, &c##ProxyWithInternal::DestroyInternal); \
call.Marshal(RTC_FROM_HERE, destructor_thread()); \
} \
\
private: \
void DestroyInternal() { c_ = nullptr; } \
rtc::scoped_refptr<INTERNAL_CLASS> c_;
// Note: This doesn't use a unique_ptr, because it intends to handle a corner
// case where an object's deletion triggers a callback that calls back into
// this proxy object. If relying on a unique_ptr to delete the object, its
// inner pointer would be set to null before this reentrant callback would have
// a chance to run, resulting in a segfault.
#define OWNED_PROXY_MAP_BOILERPLATE(c) \
public: \
~c##ProxyWithInternal() { \
MethodCall<c##ProxyWithInternal, void> call( \
this, &c##ProxyWithInternal::DestroyInternal); \
call.Marshal(RTC_FROM_HERE, destructor_thread()); \
} \
\
private: \
void DestroyInternal() { delete c_; } \
INTERNAL_CLASS* c_;
#define BEGIN_SIGNALING_PROXY_MAP(c) \
PROXY_MAP_BOILERPLATE(c) \
SIGNALING_PROXY_MAP_BOILERPLATE(c) \
REFCOUNTED_PROXY_MAP_BOILERPLATE(c) \
public: \
static rtc::scoped_refptr<c##ProxyWithInternal> Create( \
rtc::Thread* signaling_thread, INTERNAL_CLASS* c) { \
return new rtc::RefCountedObject<c##ProxyWithInternal>(signaling_thread, \
c); \
}
#define BEGIN_PROXY_MAP(c) \
PROXY_MAP_BOILERPLATE(c) \
WORKER_PROXY_MAP_BOILERPLATE(c) \
REFCOUNTED_PROXY_MAP_BOILERPLATE(c) \
public: \
static rtc::scoped_refptr<c##ProxyWithInternal> Create( \
rtc::Thread* signaling_thread, rtc::Thread* worker_thread, \
INTERNAL_CLASS* c) { \
return new rtc::RefCountedObject<c##ProxyWithInternal>(signaling_thread, \
worker_thread, c); \
}
#define BEGIN_OWNED_PROXY_MAP(c) \
PROXY_MAP_BOILERPLATE(c) \
WORKER_PROXY_MAP_BOILERPLATE(c) \
OWNED_PROXY_MAP_BOILERPLATE(c) \
public: \
static std::unique_ptr<c##Interface> Create( \
rtc::Thread* signaling_thread, rtc::Thread* worker_thread, \
std::unique_ptr<INTERNAL_CLASS> c) { \
return std::unique_ptr<c##Interface>(new c##ProxyWithInternal( \
signaling_thread, worker_thread, c.release())); \
}
#define PROXY_SIGNALING_THREAD_DESTRUCTOR() \
private: \
rtc::Thread* destructor_thread() const { return signaling_thread_; } \
\
public: // NOLINTNEXTLINE
#define PROXY_WORKER_THREAD_DESTRUCTOR() \
private: \
rtc::Thread* destructor_thread() const { return worker_thread_; } \
\
public: // NOLINTNEXTLINE
#define PROXY_METHOD0(r, method) \
r method() override { \
MethodCall<C, r> call(c_, &C::method); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
#define PROXY_CONSTMETHOD0(r, method) \
r method() const override { \
ConstMethodCall<C, r> call(c_, &C::method); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
#define PROXY_METHOD1(r, method, t1) \
r method(t1 a1) override { \
MethodCall<C, r, t1> call(c_, &C::method, std::move(a1)); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
#define PROXY_CONSTMETHOD1(r, method, t1) \
r method(t1 a1) const override { \
ConstMethodCall<C, r, t1> call(c_, &C::method, std::move(a1)); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
#define PROXY_METHOD2(r, method, t1, t2) \
r method(t1 a1, t2 a2) override { \
MethodCall<C, r, t1, t2> call(c_, &C::method, std::move(a1), \
std::move(a2)); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
#define PROXY_METHOD3(r, method, t1, t2, t3) \
r method(t1 a1, t2 a2, t3 a3) override { \
MethodCall<C, r, t1, t2, t3> call(c_, &C::method, std::move(a1), \
std::move(a2), std::move(a3)); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
#define PROXY_METHOD4(r, method, t1, t2, t3, t4) \
r method(t1 a1, t2 a2, t3 a3, t4 a4) override { \
MethodCall<C, r, t1, t2, t3, t4> call(c_, &C::method, std::move(a1), \
std::move(a2), std::move(a3), \
std::move(a4)); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
#define PROXY_METHOD5(r, method, t1, t2, t3, t4, t5) \
r method(t1 a1, t2 a2, t3 a3, t4 a4, t5 a5) override { \
MethodCall<C, r, t1, t2, t3, t4, t5> call(c_, &C::method, std::move(a1), \
std::move(a2), std::move(a3), \
std::move(a4), std::move(a5)); \
return call.Marshal(RTC_FROM_HERE, signaling_thread_); \
}
// Define methods which should be invoked on the worker thread.
#define PROXY_WORKER_METHOD0(r, method) \
r method() override { \
MethodCall<C, r> call(c_, &C::method); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
#define PROXY_WORKER_CONSTMETHOD0(r, method) \
r method() const override { \
ConstMethodCall<C, r> call(c_, &C::method); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
#define PROXY_WORKER_METHOD1(r, method, t1) \
r method(t1 a1) override { \
MethodCall<C, r, t1> call(c_, &C::method, std::move(a1)); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
#define PROXY_WORKER_CONSTMETHOD1(r, method, t1) \
r method(t1 a1) const override { \
ConstMethodCall<C, r, t1> call(c_, &C::method, std::move(a1)); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
#define PROXY_WORKER_METHOD2(r, method, t1, t2) \
r method(t1 a1, t2 a2) override { \
MethodCall<C, r, t1, t2> call(c_, &C::method, std::move(a1), \
std::move(a2)); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
#define PROXY_WORKER_CONSTMETHOD2(r, method, t1, t2) \
r method(t1 a1, t2 a2) const override { \
ConstMethodCall<C, r, t1, t2> call(c_, &C::method, std::move(a1), \
std::move(a2)); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
#define PROXY_WORKER_METHOD3(r, method, t1, t2, t3) \
r method(t1 a1, t2 a2, t3 a3) override { \
MethodCall<C, r, t1, t2, t3> call(c_, &C::method, std::move(a1), \
std::move(a2), std::move(a3)); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
#define PROXY_WORKER_CONSTMETHOD3(r, method, t1, t2) \
r method(t1 a1, t2 a2, t3 a3) const override { \
ConstMethodCall<C, r, t1, t2, t3> call(c_, &C::method, std::move(a1), \
std::move(a2), std::move(a3)); \
return call.Marshal(RTC_FROM_HERE, worker_thread_); \
}
// For use when returning purely const state (set during construction).
// Use with caution. This method should only be used when the return value will
// always be the same.
#define BYPASS_PROXY_CONSTMETHOD0(r, method) \
r method() const override { \
static_assert(!std::is_pointer<r>::value, "Type is a pointer"); \
static_assert(!std::is_reference<r>::value, "Type is a reference"); \
return c_->method(); \
}
} // namespace webrtc
#endif // API_PROXY_H_