1 files changed, 133 insertions, 0 deletions
diff --git a/devtools/shared/heapsnapshot/DominatorTree.cpp b/devtools/shared/heapsnapshot/DominatorTree.cpp
new file mode 100644
index 0000000000..e78aad43d2
--- /dev/null
+++ b/devtools/shared/heapsnapshot/DominatorTree.cpp
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* 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 "mozilla/devtools/DominatorTree.h"
+#include "mozilla/dom/DominatorTreeBinding.h"
+#include "mozilla/ErrorResult.h"
+
+namespace mozilla {
+namespace devtools {
+
+dom::Nullable<uint64_t> DominatorTree::GetRetainedSize(uint64_t aNodeId,
+                                                       ErrorResult& aRv) {
+  JS::ubi::Node::Id id(aNodeId);
+  auto node = mHeapSnapshot->getNodeById(id);
+  if (node.isNothing()) return dom::Nullable<uint64_t>();
+
+  auto mallocSizeOf = GetCurrentThreadDebuggerMallocSizeOf();
+  JS::ubi::Node::Size size = 0;
+  if (!mDominatorTree.getRetainedSize(*node, mallocSizeOf, size)) {
+    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+    return dom::Nullable<uint64_t>();
+  }
+
+  MOZ_ASSERT(size != 0,
+             "The node should not have been unknown since we got it from the "
+             "heap snapshot.");
+  return dom::Nullable<uint64_t>(size);
+}
+
+struct NodeAndRetainedSize {
+  JS::ubi::Node mNode;
+  JS::ubi::Node::Size mSize;
+
+  NodeAndRetainedSize(const JS::ubi::Node& aNode, JS::ubi::Node::Size aSize)
+      : mNode(aNode), mSize(aSize) {}
+
+  struct Comparator {
+    static bool Equals(const NodeAndRetainedSize& aLhs,
+                       const NodeAndRetainedSize& aRhs) {
+      return aLhs.mSize == aRhs.mSize;
+    }
+
+    static bool LessThan(const NodeAndRetainedSize& aLhs,
+                         const NodeAndRetainedSize& aRhs) {
+      // Use > because we want to sort from greatest to least retained size.
+      return aLhs.mSize > aRhs.mSize;
+    }
+  };
+};
+
+void DominatorTree::GetImmediatelyDominated(
+    uint64_t aNodeId, dom::Nullable<nsTArray<uint64_t>>& aOutResult,
+    ErrorResult& aRv) {
+  MOZ_ASSERT(aOutResult.IsNull());
+
+  JS::ubi::Node::Id id(aNodeId);
+  Maybe<JS::ubi::Node> node = mHeapSnapshot->getNodeById(id);
+  if (node.isNothing()) return;
+
+  // Get all immediately dominated nodes and their retained sizes.
+  MallocSizeOf mallocSizeOf = GetCurrentThreadDebuggerMallocSizeOf();
+  Maybe<JS::ubi::DominatorTree::DominatedSetRange> range =
+      mDominatorTree.getDominatedSet(*node);
+  MOZ_ASSERT(
+      range.isSome(),
+      "The node should be known, since we got it from the heap snapshot.");
+  size_t length = range->length();
+  nsTArray<NodeAndRetainedSize> dominatedNodes(length);
+  for (const JS::ubi::Node& dominatedNode : *range) {
+    JS::ubi::Node::Size retainedSize = 0;
+    if (NS_WARN_IF(!mDominatorTree.getRetainedSize(dominatedNode, mallocSizeOf,
+                                                   retainedSize))) {
+      aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+      return;
+    }
+    MOZ_ASSERT(retainedSize != 0,
+               "retainedSize should not be zero since we know the node is in "
+               "the dominator tree.");
+
+    dominatedNodes.AppendElement(
+        NodeAndRetainedSize(dominatedNode, retainedSize));
+  }
+
+  // Sort them by retained size.
+  NodeAndRetainedSize::Comparator comparator;
+  dominatedNodes.Sort(comparator);
+
+  // Fill the result with the nodes' ids.
+  JS::ubi::Node root = mDominatorTree.root();
+  aOutResult.SetValue(nsTArray<uint64_t>(length));
+  for (const NodeAndRetainedSize& entry : dominatedNodes) {
+    // The root dominates itself, but we don't want to expose that to JS.
+    if (entry.mNode == root) continue;
+
+    aOutResult.Value().AppendElement(entry.mNode.identifier());
+  }
+}
+
+dom::Nullable<uint64_t> DominatorTree::GetImmediateDominator(
+    uint64_t aNodeId) const {
+  JS::ubi::Node::Id id(aNodeId);
+  Maybe<JS::ubi::Node> node = mHeapSnapshot->getNodeById(id);
+  if (node.isNothing()) return dom::Nullable<uint64_t>();
+
+  JS::ubi::Node dominator = mDominatorTree.getImmediateDominator(*node);
+  if (!dominator || dominator == *node) return dom::Nullable<uint64_t>();
+
+  return dom::Nullable<uint64_t>(dominator.identifier());
+}
+
+/*** Cycle Collection Boilerplate
+ * *****************************************************************/
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(DominatorTree, mParent, mHeapSnapshot)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(DominatorTree)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(DominatorTree)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DominatorTree)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+/* virtual */
+JSObject* DominatorTree::WrapObject(JSContext* aCx,
+                                    JS::HandleObject aGivenProto) {
+  return dom::DominatorTree_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace devtools
+}  // namespace mozilla