/* -*-  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"

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