[Stats] Migrate RTCStats/Test to Attributes.

One in series of CLs to migrate from Members() to Attributes() to
unblock code deletion.

Adds and makes use of has_value(), holds_alternative<T>() and get<T>()
convenience methods.

Bug: webrtc:15164
Change-Id: I2ae9869a5d1de3f3875c70494c9781d69da7f936
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/334160
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Evan Shrubsole <eshr@google.com>
Cr-Commit-Position: refs/heads/main@{#41510}

api/stats/attribute.h

@@ -53,6 +53,18 @@ class RTC_EXPORT Attribute : public RTCStatsMemberInterface {
   const char* name() const;
   const StatVariant& as_variant() const;
 
+  bool has_value() const;
+  template <typename T>
+  bool holds_alternative() const {
+    return absl::holds_alternative<const RTCStatsMember<T>*>(attribute_);
+  }
+  template <typename T>
+  const T& get() const {
+    RTC_CHECK(holds_alternative<T>());
+    RTC_CHECK(has_value());
+    return absl::get<const RTCStatsMember<T>*>(attribute_)->value();
+  }
+
   static Attribute FromMemberInterface(const RTCStatsMemberInterface* member);
   // RTCStatsMemberInterface implementation.
   // TODO(https://crbug.com/webrtc/15164): Delete RTCStatsMemberInterface in

stats/attribute.cc

@@ -99,6 +99,11 @@ const Attribute::StatVariant& Attribute::as_variant() const {
   return attribute_;
 }
 
+bool Attribute::has_value() const {
+  return absl::visit([](const auto* attr) { return attr->has_value(); },
+                     attribute_);
+}
+
 RTCStatsMemberInterface::Type Attribute::type() const {
   return absl::visit([](const auto* attr) { return attr->type(); }, attribute_);
 }

stats/rtc_stats.cc

@@ -24,16 +24,13 @@ RTCStats::~RTCStats() {}
 bool RTCStats::operator==(const RTCStats& other) const {
   if (type() != other.type() || id() != other.id())
     return false;
-  std::vector<const RTCStatsMemberInterface*> members = Members();
+  std::vector<Attribute> attributes = Attributes();
-  std::vector<const RTCStatsMemberInterface*> other_members = other.Members();
+  std::vector<Attribute> other_attributes = other.Attributes();
-  RTC_DCHECK_EQ(members.size(), other_members.size());
+  RTC_DCHECK_EQ(attributes.size(), other_attributes.size());
-  for (size_t i = 0; i < members.size(); ++i) {
+  for (size_t i = 0; i < attributes.size(); ++i) {
-    const RTCStatsMemberInterface* member = members[i];
+    if (attributes[i] != other_attributes[i]) {
-    const RTCStatsMemberInterface* other_member = other_members[i];
-    RTC_DCHECK_EQ(member->type(), other_member->type());
-    RTC_DCHECK_EQ(member->name(), other_member->name());
-    if (*member != *other_member)
       return false;
+    }
   }
   return true;
 }
@@ -51,13 +48,17 @@ std::string RTCStats::ToJson() const {
      << "\","
         "\"timestamp\":"
      << timestamp_.us();
-  for (const RTCStatsMemberInterface* member : Members()) {
+  for (const Attribute& attribute : Attributes()) {
-    if (member->is_defined()) {
+    if (attribute.has_value()) {
-      sb << ",\"" << member->name() << "\":";
+      sb << ",\"" << attribute.name() << "\":";
-      if (member->is_string())
+      if (attribute.holds_alternative<std::string>()) {
-        sb << "\"" << member->ValueToJson() << "\"";
+        sb << "\"";
-      else
+      }
-        sb << member->ValueToJson();
+      sb << absl::visit([](const auto* attr) { return attr->ValueToJson(); },
+                        attribute.as_variant());
+      if (attribute.holds_alternative<std::string>()) {
+        sb << "\"";
+      }
     }
   }
   sb << "}";

stats/rtc_stats_unittest.cc

@@ -66,14 +66,14 @@ WEBRTC_RTCSTATS_IMPL(RTCGrandChildStats,
                      "grandchild-stats",
                      &grandchild_int)
 
-TEST(RTCStatsTest, RTCStatsAndMembers) {
+TEST(RTCStatsTest, RTCStatsAndAttributes) {
   RTCTestStats stats("testId", Timestamp::Micros(42));
   EXPECT_EQ(stats.id(), "testId");
   EXPECT_EQ(stats.timestamp().us(), static_cast<int64_t>(42));
-  std::vector<const RTCStatsMemberInterface*> members = stats.Members();
+  std::vector<Attribute> attributes = stats.Attributes();
-  EXPECT_EQ(members.size(), static_cast<size_t>(16));
+  EXPECT_EQ(attributes.size(), static_cast<size_t>(16));
-  for (const RTCStatsMemberInterface* member : members) {
+  for (const auto& attribute : attributes) {
-    EXPECT_FALSE(member->is_defined());
+    EXPECT_FALSE(attribute.has_value());
   }
   stats.m_bool = true;
   stats.m_int32 = 123;
@@ -111,8 +111,8 @@ TEST(RTCStatsTest, RTCStatsAndMembers) {
   stats.m_sequence_string = sequence_string;
   stats.m_map_string_uint64 = map_string_uint64;
   stats.m_map_string_double = map_string_double;
-  for (const RTCStatsMemberInterface* member : members) {
+  for (const auto& attribute : attributes) {
-    EXPECT_TRUE(member->is_defined());
+    EXPECT_TRUE(attribute.has_value());
   }
   EXPECT_EQ(*stats.m_bool, true);
   EXPECT_EQ(*stats.m_int32, static_cast<int32_t>(123));
@@ -217,8 +217,8 @@ TEST(RTCStatsTest, RTCStatsGrandChild) {
   stats.child_int = 1;
   stats.grandchild_int = 2;
   int32_t sum = 0;
-  for (const RTCStatsMemberInterface* member : stats.Members()) {
+  for (const auto& attribute : stats.Attributes()) {
-    sum += *member->cast_to<const RTCStatsMember<int32_t>>();
+    sum += attribute.get<int32_t>();
   }
   EXPECT_EQ(sum, static_cast<int32_t>(3));