gecko-dev/dom/broadcastchannel/BroadcastChannelService.cpp

/* -*- 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 "BroadcastChannelService.h"
#include "BroadcastChannelParent.h"
#include "mozilla/dom/File.h"
#include "mozilla/dom/IPCBlobUtils.h"
#include "mozilla/ipc/BackgroundParent.h"

#ifdef XP_WIN
#undef PostMessage
#endif

namespace mozilla {

using namespace ipc;

namespace dom {

namespace {

BroadcastChannelService* sInstance = nullptr;

} // namespace

BroadcastChannelService::BroadcastChannelService()
{
  AssertIsOnBackgroundThread();

  // sInstance is a raw BroadcastChannelService*.
  MOZ_ASSERT(!sInstance);
  sInstance = this;
}

BroadcastChannelService::~BroadcastChannelService()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(sInstance == this);
  MOZ_ASSERT(mAgents.Count() == 0);

  sInstance = nullptr;
}

// static
already_AddRefed<BroadcastChannelService>
BroadcastChannelService::GetOrCreate()
{
  AssertIsOnBackgroundThread();

  RefPtr<BroadcastChannelService> instance = sInstance;
  if (!instance) {
    instance = new BroadcastChannelService();
  }
  return instance.forget();
}

void
BroadcastChannelService::RegisterActor(BroadcastChannelParent* aParent,
                                       const nsAString& aOriginChannelKey)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aParent);

  nsTArray<BroadcastChannelParent*>* parents =
    mAgents.LookupForAdd(aOriginChannelKey).OrInsert(
      [] () { return new nsTArray<BroadcastChannelParent*>(); });

  MOZ_ASSERT(!parents->Contains(aParent));
  parents->AppendElement(aParent);
}

void
BroadcastChannelService::UnregisterActor(BroadcastChannelParent* aParent,
                                         const nsAString& aOriginChannelKey)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aParent);

  DebugOnly<bool> found = false;
  mAgents.LookupRemoveIf(aOriginChannelKey,
    [&found, aParent] (nsTArray<BroadcastChannelParent*>* aValue) {
      found = true;
      aValue->RemoveElement(aParent);
      return aValue->IsEmpty();  // remove the entry if the array is now empty
    });
  MOZ_ASSERT(found, "Invalid state");
}

void
BroadcastChannelService::PostMessage(BroadcastChannelParent* aParent,
                                     const ClonedMessageData& aData,
                                     const nsAString& aOriginChannelKey)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aParent);

  nsTArray<BroadcastChannelParent*>* parents;
  if (!mAgents.Get(aOriginChannelKey, &parents)) {
    MOZ_CRASH("Invalid state");
  }

  // We need to keep the array alive for the life-time of this operation.
  nsTArray<RefPtr<BlobImpl>> blobImpls;
  if (!aData.blobs().IsEmpty()) {
    blobImpls.SetCapacity(aData.blobs().Length());

    for (uint32_t i = 0, len = aData.blobs().Length(); i < len; ++i) {
      RefPtr<BlobImpl> impl = IPCBlobUtils::Deserialize(aData.blobs()[i]);

      MOZ_ASSERT(impl);
      blobImpls.AppendElement(impl);
    }
  }

  // For each parent actor, we notify the message.
  for (uint32_t i = 0; i < parents->Length(); ++i) {
    BroadcastChannelParent* parent = parents->ElementAt(i);
    MOZ_ASSERT(parent);

    if (parent == aParent) {
      continue;
    }

    // We need to have a copy of the data for this parent.
    ClonedMessageData newData(aData);
    MOZ_ASSERT(blobImpls.Length() == newData.blobs().Length());

    if (!blobImpls.IsEmpty()) {
      // Serialize Blob objects for this message.
      for (uint32_t i = 0, len = blobImpls.Length(); i < len; ++i) {
        nsresult rv = IPCBlobUtils::Serialize(blobImpls[i], parent->Manager(),
                                              newData.blobs()[i]);
        if (NS_WARN_IF(NS_FAILED(rv))) {
          return;
        }
      }
    }

    Unused << parent->SendNotify(newData);
  }
}

} // namespace dom
} // namespace mozilla