Bug 1225722 - Modularize RTCStatsIdGenerator::RewriteIds somewhat. r=bwc

Differential Revision: https://phabricator.services.mozilla.com/D135864

dom/media/webrtc/jsapi/PeerConnectionImpl.cpp

@@ -2979,9 +2979,8 @@ RefPtr<dom::RTCStatsReportPromise> PeerConnectionImpl::GetStats(
       ->Then(
           mThread, __func__,
           [report = std::move(report), idGen = mIdGenerator](
-              const nsTArray<UniquePtr<dom::RTCStatsCollection>>&
-                  aStats) mutable {
-            idGen->RewriteIds(aStats, report.get());
+              nsTArray<UniquePtr<dom::RTCStatsCollection>> aStats) mutable {
+            idGen->RewriteIds(std::move(aStats), report.get());
             return dom::RTCStatsReportPromise::CreateAndResolve(
                 std::move(report), __func__);
           },

dom/media/webrtc/jsapi/RTCRtpReceiver.cpp

@@ -166,9 +166,9 @@ already_AddRefed<Promise> RTCRtpReceiver::GetStats() {
       ->Then(
           mMainThread, __func__,
           [promise, window = mWindow, idGen = mIdGenerator](
-              const nsTArray<UniquePtr<RTCStatsCollection>>& aStats) {
+              nsTArray<UniquePtr<RTCStatsCollection>> aStats) {
             RTCStatsCollection opaqueStats;
-            idGen->RewriteIds(aStats, &opaqueStats);
+            idGen->RewriteIds(std::move(aStats), &opaqueStats);
 
             RefPtr<RTCStatsReport> report(new RTCStatsReport(window));
             report->Incorporate(opaqueStats);

dom/media/webrtc/jsapi/RTCStatsIdGenerator.cpp

@@ -8,8 +8,8 @@
 
 #include <iostream>
 
-#include "mozilla/dom/RTCStatsReportBinding.h"
 #include "mozilla/RandomNum.h"
+#include "RTCStatsReport.h"
 
 namespace mozilla {
 
@@ -17,7 +17,7 @@ RTCStatsIdGenerator::RTCStatsIdGenerator()
     : mSalt(RandomUint64().valueOr(0xa5a5a5a5)), mCounter(0) {}
 
 void RTCStatsIdGenerator::RewriteIds(
-    const nsTArray<UniquePtr<dom::RTCStatsCollection>>& aFromStats,
+    nsTArray<UniquePtr<dom::RTCStatsCollection>> aFromStats,
     dom::RTCStatsCollection* aIntoReport) {
   // Rewrite an Optional id
   auto rewriteId = [&](dom::Optional<nsString>& id) {
@@ -26,13 +26,10 @@ void RTCStatsIdGenerator::RewriteIds(
     }
   };
 
-  auto assignWithOpaqueIds = [&](auto& aSource, auto& aDest) {
-    for (auto& stat : aSource) {
+  auto rewriteIds = [&](auto& aList) {
+    for (auto& stat : aList) {
       rewriteId(stat.mId);
     }
-    if (!aDest.AppendElements(aSource, fallible)) {
-      mozalloc_handle_oom(0);
-    }
   };
 
   auto rewriteRemoteIds = [&](auto& aList) {
@@ -49,54 +46,37 @@ void RTCStatsIdGenerator::RewriteIds(
 
   // Involves a lot of copying, since webidl dictionaries don't have
   // move semantics. Oh well.
-  for (const auto& stats : aFromStats) {
-    for (auto& stat : stats->mIceCandidatePairStats) {
-      rewriteId(stat.mLocalCandidateId);
-      rewriteId(stat.mRemoteCandidateId);
-    };
-    assignWithOpaqueIds(stats->mIceCandidatePairStats,
-                        aIntoReport->mIceCandidatePairStats);
 
-    assignWithOpaqueIds(stats->mIceCandidateStats,
-                        aIntoReport->mIceCandidateStats);
+  // Create a temporary to avoid double-rewriting any stats already in
+  // aIntoReport.
+  auto stats = MakeUnique<dom::RTCStatsCollection>();
+  dom::FlattenStats(std::move(aFromStats), stats.get());
 
-    rewriteRemoteIds(stats->mInboundRtpStreamStats);
-    assignWithOpaqueIds(stats->mInboundRtpStreamStats,
-                        aIntoReport->mInboundRtpStreamStats);
+  for (auto& stat : stats->mIceCandidatePairStats) {
+    rewriteId(stat.mLocalCandidateId);
+    rewriteId(stat.mRemoteCandidateId);
+  };
+  rewriteIds(stats->mIceCandidatePairStats);
 
-    rewriteRemoteIds(stats->mOutboundRtpStreamStats);
-    assignWithOpaqueIds(stats->mOutboundRtpStreamStats,
-                        aIntoReport->mOutboundRtpStreamStats);
+  rewriteIds(stats->mIceCandidateStats);
 
-    rewriteLocalIds(stats->mRemoteInboundRtpStreamStats);
-    assignWithOpaqueIds(stats->mRemoteInboundRtpStreamStats,
-                        aIntoReport->mRemoteInboundRtpStreamStats);
+  rewriteRemoteIds(stats->mInboundRtpStreamStats);
+  rewriteIds(stats->mInboundRtpStreamStats);
 
-    rewriteLocalIds(stats->mRemoteOutboundRtpStreamStats);
-    assignWithOpaqueIds(stats->mRemoteOutboundRtpStreamStats,
-                        aIntoReport->mRemoteOutboundRtpStreamStats);
+  rewriteRemoteIds(stats->mOutboundRtpStreamStats);
+  rewriteIds(stats->mOutboundRtpStreamStats);
 
-    assignWithOpaqueIds(stats->mRtpContributingSourceStats,
-                        aIntoReport->mRtpContributingSourceStats);
-    assignWithOpaqueIds(stats->mTrickledIceCandidateStats,
-                        aIntoReport->mTrickledIceCandidateStats);
-    assignWithOpaqueIds(stats->mDataChannelStats,
-                        aIntoReport->mDataChannelStats);
-    if (!aIntoReport->mRawLocalCandidates.AppendElements(
-            stats->mRawLocalCandidates, fallible) ||
-        !aIntoReport->mRawRemoteCandidates.AppendElements(
-            stats->mRawRemoteCandidates, fallible) ||
-        !aIntoReport->mVideoFrameHistories.AppendElements(
-            stats->mVideoFrameHistories, fallible) ||
-        !aIntoReport->mBandwidthEstimations.AppendElements(
-            stats->mBandwidthEstimations, fallible)) {
-      // XXX(Bug 1632090) Instead of extending the array 1-by-1
-      // (which might involve multiple reallocations) and
-      // potentially crashing here, SetCapacity could be called
-      // outside the loop once.
-      mozalloc_handle_oom(0);
-    }
-  }
+  rewriteLocalIds(stats->mRemoteInboundRtpStreamStats);
+  rewriteIds(stats->mRemoteInboundRtpStreamStats);
+
+  rewriteLocalIds(stats->mRemoteOutboundRtpStreamStats);
+  rewriteIds(stats->mRemoteOutboundRtpStreamStats);
+
+  rewriteIds(stats->mRtpContributingSourceStats);
+  rewriteIds(stats->mTrickledIceCandidateStats);
+  rewriteIds(stats->mDataChannelStats);
+
+  dom::MergeStats(std::move(stats), aIntoReport);
 }
 
 nsString RTCStatsIdGenerator::Id(const nsString& aKey) {

dom/media/webrtc/jsapi/RTCStatsIdGenerator.h

@@ -25,9 +25,8 @@ class RTCStatsIdGenerator {
   RTCStatsIdGenerator();
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RTCStatsIdGenerator);
 
-  void RewriteIds(
-      const nsTArray<UniquePtr<dom::RTCStatsCollection>>& aFromStats,
-      dom::RTCStatsCollection* aIntoReport);
+  void RewriteIds(nsTArray<UniquePtr<dom::RTCStatsCollection>> aFromStats,
+                  dom::RTCStatsCollection* aIntoReport);
 
  private:
   virtual ~RTCStatsIdGenerator(){};

dom/media/webrtc/jsapi/RTCStatsReport.cpp

@@ -130,4 +130,40 @@ void RTCStatsReport::Set(const nsAString& aKey, JS::Handle<JSObject*> aValue,
   RTCStatsReport_Binding::MaplikeHelpers::Set(this, aKey, aValue, aRv);
 }
 
+void MergeStats(UniquePtr<dom::RTCStatsCollection> aFromStats,
+                dom::RTCStatsCollection* aIntoStats) {
+  auto move = [&](auto& aSource, auto& aDest) {
+    if (!aDest.AppendElements(std::move(aSource), fallible)) {
+      mozalloc_handle_oom(0);
+    }
+  };
+
+  move(aFromStats->mIceCandidatePairStats, aIntoStats->mIceCandidatePairStats);
+  move(aFromStats->mIceCandidateStats, aIntoStats->mIceCandidateStats);
+  move(aFromStats->mInboundRtpStreamStats, aIntoStats->mInboundRtpStreamStats);
+  move(aFromStats->mOutboundRtpStreamStats,
+       aIntoStats->mOutboundRtpStreamStats);
+  move(aFromStats->mRemoteInboundRtpStreamStats,
+       aIntoStats->mRemoteInboundRtpStreamStats);
+  move(aFromStats->mRemoteOutboundRtpStreamStats,
+       aIntoStats->mRemoteOutboundRtpStreamStats);
+  move(aFromStats->mCodecStats, aIntoStats->mCodecStats);
+  move(aFromStats->mRtpContributingSourceStats,
+       aIntoStats->mRtpContributingSourceStats);
+  move(aFromStats->mTrickledIceCandidateStats,
+       aIntoStats->mTrickledIceCandidateStats);
+  move(aFromStats->mDataChannelStats, aIntoStats->mDataChannelStats);
+  move(aFromStats->mRawLocalCandidates, aIntoStats->mRawLocalCandidates);
+  move(aFromStats->mRawRemoteCandidates, aIntoStats->mRawRemoteCandidates);
+  move(aFromStats->mVideoFrameHistories, aIntoStats->mVideoFrameHistories);
+  move(aFromStats->mBandwidthEstimations, aIntoStats->mBandwidthEstimations);
+}
+
+void FlattenStats(nsTArray<UniquePtr<dom::RTCStatsCollection>> aFromStats,
+                  dom::RTCStatsCollection* aIntoStats) {
+  for (auto& stats : aFromStats) {
+    MergeStats(std::move(stats), aIntoStats);
+  }
+}
+
 }  // namespace mozilla::dom

dom/media/webrtc/jsapi/RTCStatsReport.h

@@ -143,6 +143,12 @@ class RTCStatsReport final : public nsWrapperCache {
   nsCOMPtr<nsPIDOMWindowInner> mParent;
 };
 
+void MergeStats(UniquePtr<dom::RTCStatsCollection> aFromStats,
+                dom::RTCStatsCollection* aIntoStats);
+
+void FlattenStats(nsTArray<UniquePtr<dom::RTCStatsCollection>> aFromStats,
+                  dom::RTCStatsCollection* aIntoStats);
+
 }  // namespace dom
 }  // namespace mozilla