1 files changed, 171 insertions, 0 deletions
diff --git a/docshell/base/timeline/ObservedDocShell.cpp b/docshell/base/timeline/ObservedDocShell.cpp
new file mode 100644
index 0000000000..e4a2b319f5
--- /dev/null
+++ b/docshell/base/timeline/ObservedDocShell.cpp
@@ -0,0 +1,171 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ObservedDocShell.h"
+
+#include <utility>
+
+#include "AbstractTimelineMarker.h"
+#include "LayerTimelineMarker.h"
+#include "MainThreadUtils.h"
+#include "mozilla/AutoRestore.h"
+#include "nsIDocShell.h"
+
+namespace mozilla {
+
+ObservedDocShell::ObservedDocShell(nsIDocShell* aDocShell)
+    : mDocShell(aDocShell), mLock("ObservedDocShellMutex") {
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+void ObservedDocShell::AddMarker(UniquePtr<AbstractTimelineMarker>&& aMarker) {
+  // Only allow main thread markers to go into this list. No need to lock
+  // here since `mTimelineMarkers` will only be accessed or modified on the
+  // main thread only.
+  MOZ_ASSERT(NS_IsMainThread());
+  // Don't accept any markers generated by the process of popping
+  // markers.
+  if (!mPopping) {
+    mTimelineMarkers.AppendElement(std::move(aMarker));
+  }
+}
+
+void ObservedDocShell::AddOTMTMarker(
+    UniquePtr<AbstractTimelineMarker>&& aMarker) {
+  // Only allow off the main thread markers to go into this list. Since most
+  // of our markers come from the main thread, be a little more efficient and
+  // avoid dealing with multithreading scenarios until all the markers are
+  // actually cleared or popped in `ClearMarkers` or `PopMarkers`.
+  MOZ_ASSERT(!NS_IsMainThread());
+  MutexAutoLock lock(mLock);  // for `mOffTheMainThreadTimelineMarkers`.
+  mOffTheMainThreadTimelineMarkers.AppendElement(std::move(aMarker));
+}
+
+void ObservedDocShell::ClearMarkers() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MutexAutoLock lock(mLock);  // for `mOffTheMainThreadTimelineMarkers`.
+  mTimelineMarkers.Clear();
+  mOffTheMainThreadTimelineMarkers.Clear();
+}
+
+void ObservedDocShell::PopMarkers(
+    JSContext* aCx, nsTArray<dom::ProfileTimelineMarker>& aStore) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  MOZ_RELEASE_ASSERT(!mPopping);
+  AutoRestore<bool> resetPopping(mPopping);
+  mPopping = true;
+
+  {
+    MutexAutoLock lock(mLock);  // for `mOffTheMainThreadTimelineMarkers`.
+
+    // First, move all of our markers into a single array. We'll chose
+    // the `mTimelineMarkers` store because that's where we expect most of
+    // our markers to be, and we can access it without holding the lock.
+    mTimelineMarkers.AppendElements(
+        std::move(mOffTheMainThreadTimelineMarkers));
+  }
+
+  // If we see an unpaired START, we keep it around for the next call
+  // to ObservedDocShell::PopMarkers. We store the kept START objects here.
+  nsTArray<UniquePtr<AbstractTimelineMarker>> keptStartMarkers;
+
+  for (uint32_t i = 0; i < mTimelineMarkers.Length(); ++i) {
+    UniquePtr<AbstractTimelineMarker>& startPayload =
+        mTimelineMarkers.ElementAt(i);
+
+    // If this is a TIMESTAMP marker, there's no corresponding END,
+    // as it's a single unit of time, not a duration.
+    if (startPayload->GetTracingType() == MarkerTracingType::TIMESTAMP) {
+      dom::ProfileTimelineMarker* marker = aStore.AppendElement();
+      marker->mName = NS_ConvertUTF8toUTF16(startPayload->GetName());
+      marker->mStart = startPayload->GetTime();
+      marker->mEnd = startPayload->GetTime();
+      marker->mStack = startPayload->GetStack();
+      startPayload->AddDetails(aCx, *marker);
+      continue;
+    }
+
+    // Whenever a START marker is found, look for the corresponding END
+    // and build a {name,start,end} JS object.
+    if (startPayload->GetTracingType() == MarkerTracingType::START) {
+      bool hasSeenEnd = false;
+
+      // "Paint" markers are different because painting is handled at root
+      // docshell level. The information that a paint was done is stored at
+      // sub-docshell level, but we can only be sure that a paint did actually
+      // happen in if a "Layer" marker was recorded too.
+      bool startIsPaintType = strcmp(startPayload->GetName(), "Paint") == 0;
+      bool hasSeenLayerType = false;
+
+      // If we are processing a "Paint" marker, we append information from
+      // all the embedded "Layer" markers to this array.
+      dom::Sequence<dom::ProfileTimelineLayerRect> layerRectangles;
+
+      // DOM events can be nested, so we must take care when searching
+      // for the matching end. It doesn't hurt to apply this logic to
+      // all event types.
+      uint32_t markerDepth = 0;
+
+      // The assumption is that the devtools timeline flushes markers frequently
+      // enough for the amount of markers to always be small enough that the
+      // nested for loop isn't going to be a performance problem.
+      for (uint32_t j = i + 1; j < mTimelineMarkers.Length(); ++j) {
+        UniquePtr<AbstractTimelineMarker>& endPayload =
+            mTimelineMarkers.ElementAt(j);
+        bool endIsLayerType = strcmp(endPayload->GetName(), "Layer") == 0;
+
+        // Look for "Layer" markers to stream out "Paint" markers.
+        if (startIsPaintType && endIsLayerType) {
+          AbstractTimelineMarker* raw = endPayload.get();
+          LayerTimelineMarker* layerPayload =
+              static_cast<LayerTimelineMarker*>(raw);
+          layerPayload->AddLayerRectangles(layerRectangles);
+          hasSeenLayerType = true;
+        }
+        if (!startPayload->Equals(*endPayload)) {
+          continue;
+        }
+        if (endPayload->GetTracingType() == MarkerTracingType::START) {
+          ++markerDepth;
+          continue;
+        }
+        if (endPayload->GetTracingType() == MarkerTracingType::END) {
+          if (markerDepth > 0) {
+            --markerDepth;
+            continue;
+          }
+          if (!startIsPaintType || (startIsPaintType && hasSeenLayerType)) {
+            dom::ProfileTimelineMarker* marker = aStore.AppendElement();
+            marker->mName = NS_ConvertUTF8toUTF16(startPayload->GetName());
+            marker->mStart = startPayload->GetTime();
+            marker->mEnd = endPayload->GetTime();
+            marker->mStack = startPayload->GetStack();
+            if (hasSeenLayerType) {
+              marker->mRectangles.Construct(layerRectangles);
+            }
+            startPayload->AddDetails(aCx, *marker);
+            endPayload->AddDetails(aCx, *marker);
+          }
+          hasSeenEnd = true;
+          break;
+        }
+      }
+
+      // If we did not see the corresponding END, keep the START.
+      if (!hasSeenEnd) {
+        keptStartMarkers.AppendElement(
+            std::move(mTimelineMarkers.ElementAt(i)));
+        mTimelineMarkers.RemoveElementAt(i);
+        --i;
+      }
+    }
+  }
+
+  mTimelineMarkers = std::move(keptStartMarkers);
+}
+
+}  // namespace mozilla