RTCStats and RTCStatsReport added (webrtc/stats)

webrtc/api/rtcstats.h

+/*
+ *  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
+// http://rawgit.com/w3c/webrtc-stats/master/webrtc-stats.html.
+//
+// All derived classes must have the following static variable defined:
+//   static const char* const kType;
+// The address of |kType| is used as a unique class identifier and the value as
+// a string representation of the class type, see
+// http://rawgit.com/w3c/webrtc-stats/master/webrtc-stats.html#rtcstatstype-str*.
+//
+// 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 in milliseconds relative to the UNIX epoch (Jan 1, 1970, UTC).
+  double timestamp() const { return timestamp_; }
+  // Returns the address of the static |kType| variable of the implementing
+  // class. Comparing it to |&T::kType| tests if a stats object is of type |T|.
+  virtual const char* const* type() const = 0;
+  // Returns the value of the static |kType| variable of the implementing class.
+  virtual const char* type_name() const = 0;
+  // Returns a vector of pointers to all the RTCStatsMemberInterface members of
+  // this class. This allows for iteration of members.
+  virtual std::vector<const RTCStatsMemberInterface*> Members() const = 0;
+
+  std::string ToString() const;
+
+  template<typename T>
+  T& to() const {
+    RTC_DCHECK_EQ(type(), &T::kType);
+    return static_cast<T&>(*this);
+  }
+
+ protected:
+  static std::vector<const RTCStatsMemberInterface*> MembersVector(
+      const RTCStatsMemberInterface** members, size_t members_count);
+
+  std::string const id_;
+  double timestamp_;
+};
+
+// Interface for |RTCStats| members, which have a name and an optional value.
+// The value type is implementation-specific. Only the types listed in |Type|
+// are supported, these are implemented by |RTCStatsMember<T>|.
+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;  // true for sequences of strings too.
+  bool has_value() const { return has_value_; }
+  virtual std::string ValueToString() const = 0;
+
+  template<typename T>
+  T& to() const {
+    RTC_DCHECK_EQ(type(), T::kType);
+    return static_cast<T&>(*this);
+  }
+
+ protected:
+  RTCStatsMemberInterface(const char* name, bool has_value)
+      : name_(name), has_value_(has_value) {}
+
+  const char* const name_;
+  bool has_value_;
+};
+
+// 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.has_value_),
+        value_(other.value_) {}
+  explicit RTCStatsMember(RTCStatsMember<T>&& other)
+      : RTCStatsMemberInterface(other.name_, other.has_value_),
+        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;
+    has_value_ = true;
+    return value_;
+  }
+  T& operator=(const T&& value) {
+    value_ = std::move(value);
+    has_value_ = true;
+    return value_;
+  }
+  T& operator=(const RTCStatsMember<T>& other) {
+    RTC_DCHECK(other.has_value_);
+    value_ = other.has_value_;
+    has_value_ = true;
+    return value_;
+  }
+
+  // Value getters.
+  T& operator*() {
+    RTC_DCHECK(has_value_);
+    return value_;
+  }
+  const T& operator*() const {
+    RTC_DCHECK(has_value_);
+    return value_;
+  }
+
+  // Value getters, arrow operator.
+  T* operator->() {
+    RTC_DCHECK(has_value_);
+    return &value_;
+  }
+  const T* operator->() const {
+    RTC_DCHECK(has_value_);
+    return &value_;
+  }
+
+ private:
+  T value_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_RTCSTATS_H_