RTCStatsReport: Take ownership of other's stats with TakeMembersFrom

webrtc/stats/rtcstatsreport_unittest.cc

Index: webrtc/stats/rtcstatsreport_unittest.cc
diff --git a/webrtc/stats/rtcstatsreport_unittest.cc b/webrtc/stats/rtcstatsreport_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b4722ab156858a58ceb67bf15cf3c600b09224e2
--- /dev/null
+++ b/webrtc/stats/rtcstatsreport_unittest.cc
@@ -0,0 +1,131 @@
+/*
+ *  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.
+ */
+
+#include "webrtc/api/rtcstatsreport.h"
+
+#include "webrtc/api/rtcstats.h"
+#include "webrtc/base/checks.h"
+#include "webrtc/base/gunit.h"
+
+namespace webrtc {
+
+class RTCTestStats1 : public RTCStats {
+ public:
+  RTCTestStats1(const std::string& id, double timestamp)
+      : RTCStats(id, timestamp),
+        integer("integer") {}
+
+  WEBRTC_RTCSTATS_IMPL(RTCStats, RTCTestStats1,
+      &integer);
+
+  RTCStatsMember<int32_t> integer;
+};
+
+const char RTCTestStats1::kType[] = "test-stats-1";
+
+class RTCTestStats2 : public RTCStats {
+ public:
+  RTCTestStats2(const std::string& id, double timestamp)
+      : RTCStats(id, timestamp),
+        number("number") {}
+
+  WEBRTC_RTCSTATS_IMPL(RTCStats, RTCTestStats2,
+      &number);
+
+  RTCStatsMember<double> number;
+};
+
+const char RTCTestStats2::kType[] = "test-stats-2";
+
+class RTCTestStats3 : public RTCStats {
+ public:
+  RTCTestStats3(const std::string& id, double timestamp)
+      : RTCStats(id, timestamp),
+        string("string") {}
+
+  WEBRTC_RTCSTATS_IMPL(RTCStats, RTCTestStats3,
+      &string);
+
+  RTCStatsMember<std::string> string;
+};
+
+const char RTCTestStats3::kType[] = "test-stats-3";
+
+TEST(RTCStatsReport, AddAndGetStats) {
+  rtc::scoped_refptr<RTCStatsReport> report = RTCStatsReport::Create();
+  EXPECT_EQ(report->size(), static_cast<size_t>(0));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("a0", 1.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("a1", 2.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("b0", 4.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("b1", 8.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("a2", 16.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("b2", 32.0)));
+  EXPECT_EQ(report->size(), static_cast<size_t>(6));
+
+  EXPECT_EQ(report->Get("missing"), nullptr);
+  EXPECT_EQ(report->Get("a0")->id(), "a0");
+  EXPECT_EQ(report->Get("b2")->id(), "b2");
+
+  std::vector<const RTCTestStats1*> a = report->GetStatsOfType<RTCTestStats1>();
+  EXPECT_EQ(a.size(), static_cast<size_t>(3));
+  uint32_t mask = 0;
+  for (const RTCTestStats1* stats : a)
+    mask |= static_cast<uint32_t>(stats->timestamp());
+  EXPECT_EQ(mask, static_cast<uint32_t>(1 | 2 | 16));
+
+  std::vector<const RTCTestStats2*> b = report->GetStatsOfType<RTCTestStats2>();
+  EXPECT_EQ(b.size(), static_cast<size_t>(3));
+  mask = 0;
+  for (const RTCTestStats2* stats : b)
+    mask |= static_cast<uint32_t>(stats->timestamp());
+  EXPECT_EQ(mask, static_cast<uint32_t>(4 | 8 | 32));
+
+  EXPECT_EQ(report->GetStatsOfType<RTCTestStats3>().size(),
+            static_cast<size_t>(0));
+}
+
+TEST(RTCStatsReport, StatsOrder) {

[hta-webrtc, 2016/08/26 08:50:31]

This test verifies a property of RTCStatsReport that isn't mentioned in its API.
Can you add a statement to the .h file that the elements are returned in
lexicographic order on key?

(if we were to use a hashmap to hold them rather than std::map, this property
would change - but this is documented by implementation leaking into interface
due to C++ limitations, I'd prefer it to be explict).

[hbos, 2016/08/29 09:52:45]

"Objects implementing an interface that is declared to be maplike represent an
ordered list of key–value pairs known as its map entries."
https://heycam.github.io/webidl/#idl-maplike

I've interpreted ordered list of key-value pairs as ordered by key, and the key
being a string as lexiographical order. Is this not what is meant?

[hbos, 2016/08/29 11:58:42]

Done, added a comment. Talked offline, ordered in that context typically just
means that the order is consistent, without specifying how it is ordered.

+  rtc::scoped_refptr<RTCStatsReport> report = RTCStatsReport::Create();
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("C", 2.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("D", 3.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("B", 1.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("A", 0.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("E", 4.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("F", 5.0)));
+  report->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats2("G", 6.0)));
+  size_t i = 0;
+  for (const RTCStats& stats : *report) {
+    EXPECT_EQ(static_cast<size_t>(stats.timestamp()), i);
+    ++i;
+  }
+  EXPECT_EQ(i, static_cast<size_t>(7));
+}
+
+TEST(RTCStatsReport, TakeMembersFrom) {
+  rtc::scoped_refptr<RTCStatsReport> a = RTCStatsReport::Create();
+  a->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("B", 1.0)));
+  a->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("C", 2.0)));
+  a->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("E", 4.0)));
+  rtc::scoped_refptr<RTCStatsReport> b = RTCStatsReport::Create();
+  b->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("A", 0.0)));
+  b->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("D", 3.0)));
+  b->AddStats(std::unique_ptr<RTCStats>(new RTCTestStats1("F", 5.0)));
+
+  a->TakeMembersFrom(b);
+  EXPECT_EQ(b->size(), static_cast<size_t>(0));
+  size_t i = 0;
+  for (const RTCStats& stats : *a) {
+    EXPECT_EQ(static_cast<size_t>(stats.timestamp()), i);
+    ++i;
+  }
+  EXPECT_EQ(i, static_cast<size_t>(6));
+}
+
+}  // namespace webrtc