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/*
* Copyright 2016 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.
*/
#ifndef WEBRTC_API_RTCSTATS_H_
#define WEBRTC_API_RTCSTATS_H_
#include <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "webrtc/base/checks.h"
namespace webrtc {
class RTCStatsMemberInterface;
// Abstract base class for RTCStats-derived dictionaries, see
// https://w3c.github.io/webrtc-stats/.
//
// All derived classes must have the following static variable defined:
// static const char kType[];
// It is used as a unique class identifier and a string representation of the
// class type, see https://w3c.github.io/webrtc-stats/#rtcstatstype-str*.
// Use the |WEBRTC_RTCSTATS_IMPL| macro when implementing subclasses, see macro
// for details.
//
// Derived classes list their dictionary members, RTCStatsMember<T>, as public
// fields, allowing the following:
//
// RTCFooStats foo("fooId", GetCurrentTime());
// foo.bar = 42;
// foo.baz = std::vector<std::string>();
// foo.baz->push_back("hello world");
// uint32_t x = *foo.bar;
//
// Pointers to all the members are available with |Members|, allowing iteration:
//
// for (const RTCStatsMemberInterface* member : foo.Members()) {
// printf("%s = %s\n", member->name(), member->ValueToString().c_str());
// }
class RTCStats {
public:
RTCStats(const std::string& id, double timestamp)
: id_(id), timestamp_(timestamp) {}
RTCStats(std::string&& id, double timestamp)
: id_(std::move(id)), timestamp_(timestamp) {}
virtual ~RTCStats() {}
virtual std::unique_ptr<RTCStats> copy() const = 0;
const std::string& id() const { return id_; }
// Time relative to the UNIX epoch (Jan 1, 1970, UTC), in seconds.
double timestamp() const { return timestamp_; }
// Returns the static member variable |kType| of the implementing class.
virtual const char* type() const = 0;
// Returns a vector of pointers to all the RTCStatsMemberInterface members of
// this class. This allows for iteration of members.
std::vector<const RTCStatsMemberInterface*> Members() const;
// Creates a human readable string representation of the report, listing all
// of its members (names and values).
std::string ToString() const;
// Downcasts the stats object to an |RTCStats| subclass |T|. DCHECKs that the
// object is of type |T|.
template<typename T>
const T& cast_to() const {
RTC_DCHECK_EQ(type(), T::kType);
return static_cast<const T&>(*this);
}
protected:
// Gets a vector of all members of this |RTCStats| object, including members
// derived from parent classes. |additional_capacity| is how many more members
// shall be reserved in the vector (so that subclasses can allocate a vector
// with room for both parent and child members without it having to resize).
virtual std::vector<const RTCStatsMemberInterface*>
MembersOfThisObjectAndAncestors(
size_t additional_capacity) const;
std::string const id_;
double timestamp_;
};
// All |RTCStats| classes should use this macro in a public section of the class
// definition.
//
// This macro declares the static |kType| and overrides methods as required by
// subclasses of |RTCStats|: |copy|, |type|, and
// |MembersOfThisObjectAndAncestors|. The |...| argument is a list of addresses
// to each member defined in the implementing class (list cannot be empty, must
// have at least one new member).
//
// (Since class names need to be known to implement these methods this cannot be
// part of the base |RTCStats|. While these methods could be implemented using
// templates, that would only work for immediate subclasses. Subclasses of
// subclasses also have to override these methods, resulting in boilerplate
// code. Using a macro avoids this and works for any |RTCStats| class, including
// grandchildren.)
//
// Sample usage:
//
// rtcfoostats.h:
// class RTCFooStats : public RTCStats {
// public:
// RTCFooStats(const std::string& id, double timestamp)
// : RTCStats(id, timestamp),
// foo("foo"),
// bar("bar") {
// }
//
// WEBRTC_RTCSTATS_IMPL(RTCStats, RTCFooStats,
// &foo,
// &bar);
//
// RTCStatsMember<int32_t> foo;
// RTCStatsMember<int32_t> bar;
// };
//
// rtcfoostats.cc:
// const char RTCFooStats::kType[] = "foo-stats";
//
#define WEBRTC_RTCSTATS_IMPL(parent_class, this_class, ...) \
public: \
static const char kType[]; \
std::unique_ptr<webrtc::RTCStats> copy() const override { \
return std::unique_ptr<webrtc::RTCStats>(new this_class(*this)); \
} \
const char* type() const override { return this_class::kType; } \
protected: \
std::vector<const webrtc::RTCStatsMemberInterface*> \
MembersOfThisObjectAndAncestors( \
size_t local_var_additional_capacity) const override { \
const webrtc::RTCStatsMemberInterface* local_var_members[] = { \
__VA_ARGS__ \
}; \
size_t local_var_members_count = \
sizeof(local_var_members) / sizeof(local_var_members[0]); \
std::vector<const webrtc::RTCStatsMemberInterface*> local_var_members_vec =\
parent_class::MembersOfThisObjectAndAncestors( \
local_var_members_count + local_var_additional_capacity); \
RTC_DCHECK_GE( \
local_var_members_vec.capacity() - local_var_members_vec.size(), \
local_var_members_count + local_var_additional_capacity); \
local_var_members_vec.insert(local_var_members_vec.end(), \
&local_var_members[0], \
&local_var_members[local_var_members_count]); \
return local_var_members_vec; \
} \
public:
// Interface for |RTCStats| members, which have a name and a value of a type
// defined in a subclass. Only the types listed in |Type| are supported, these
// are implemented by |RTCStatsMember<T>|. The value of a member may be
// undefined, the value can only be read if |is_defined|.
class RTCStatsMemberInterface {
public:
// Member value types.
enum Type {
kInt32, // int32_t
kUint32, // uint32_t
kInt64, // int64_t
kUint64, // uint64_t
kDouble, // double
kStaticString, // const char*
kString, // std::string
kSequenceInt32, // std::vector<int32_t>
kSequenceUint32, // std::vector<uint32_t>
kSequenceInt64, // std::vector<int64_t>
kSequenceUint64, // std::vector<uint64_t>
kSequenceDouble, // std::vector<double>
kSequenceStaticString, // std::vector<const char*>
kSequenceString, // std::vector<std::string>
};
virtual ~RTCStatsMemberInterface() {}
const char* name() const { return name_; }
virtual Type type() const = 0;
virtual bool is_sequence() const = 0;
virtual bool is_string() const = 0;
bool is_defined() const { return is_defined_; }
virtual std::string ValueToString() const = 0;
template<typename T>
const T& cast_to() const {
RTC_DCHECK_EQ(type(), T::kType);
return static_cast<const T&>(*this);
}
protected:
RTCStatsMemberInterface(const char* name, bool is_defined)
: name_(name), is_defined_(is_defined) {}
const char* const name_;
bool is_defined_;
};
// Template implementation of |RTCStatsMemberInterface|. Every possible |T| is
// specialized in rtcstats.cc, using a different |T| results in a linker error
// (undefined reference to |kType|). The supported types are the ones described
// by |RTCStatsMemberInterface::Type|.
template<typename T>
class RTCStatsMember : public RTCStatsMemberInterface {
public:
static const Type kType;
explicit RTCStatsMember(const char* name)
: RTCStatsMemberInterface(name, false),
value_() {}
RTCStatsMember(const char* name, const T& value)
: RTCStatsMemberInterface(name, true),
value_(value) {}
RTCStatsMember(const char* name, T&& value)
: RTCStatsMemberInterface(name, true),
value_(std::move(value)) {}
explicit RTCStatsMember(const RTCStatsMember<T>& other)
: RTCStatsMemberInterface(other.name_, other.is_defined_),
value_(other.value_) {}
explicit RTCStatsMember(RTCStatsMember<T>&& other)
: RTCStatsMemberInterface(other.name_, other.is_defined_),
value_(std::move(other.value_)) {}
Type type() const override { return kType; }
bool is_sequence() const override;
bool is_string() const override;
std::string ValueToString() const override;
// Assignment operators.
T& operator=(const T& value) {
value_ = value;
is_defined_ = true;
return value_;
}
T& operator=(const T&& value) {
value_ = std::move(value);
is_defined_ = true;
return value_;
}
T& operator=(const RTCStatsMember<T>& other) {
RTC_DCHECK(other.is_defined_);
value_ = other.is_defined_;
is_defined_ = true;
return value_;
}
// Value getters.
T& operator*() {
RTC_DCHECK(is_defined_);
return value_;
}
const T& operator*() const {
RTC_DCHECK(is_defined_);
return value_;
}
// Value getters, arrow operator.
T* operator->() {
RTC_DCHECK(is_defined_);
return &value_;
}
const T* operator->() const {
RTC_DCHECK(is_defined_);
return &value_;
}
private:
T value_;
};
} // namespace webrtc
#endif // WEBRTC_API_RTCSTATS_H_