gecko-dev/dom/workers/Navigator.cpp

/* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 40 -*- */
/* 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 "DataStore.h"

#include "mozilla/dom/DataStore.h"
#include "mozilla/dom/DataStoreBinding.h"
#include "mozilla/dom/Promise.h"
#include "mozilla/dom/PromiseWorkerProxy.h"
#include "mozilla/dom/WorkerNavigatorBinding.h"

#include "Navigator.h"
#include "nsProxyRelease.h"
#include "RuntimeService.h"

#include "WorkerPrivate.h"
#include "WorkerRunnable.h"
#include "WorkerScope.h"

BEGIN_WORKERS_NAMESPACE

NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(WorkerNavigator)

NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(WorkerNavigator, AddRef)
NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(WorkerNavigator, Release)

/* static */ already_AddRefed<WorkerNavigator>
WorkerNavigator::Create(bool aOnLine)
{
  RuntimeService* rts = RuntimeService::GetService();
  MOZ_ASSERT(rts);

  const RuntimeService::NavigatorProperties& properties =
    rts->GetNavigatorProperties();

  nsRefPtr<WorkerNavigator> navigator =
    new WorkerNavigator(properties.mAppName, properties.mAppVersion,
                        properties.mPlatform, properties.mUserAgent,
                        aOnLine);

  return navigator.forget();
}

JSObject*
WorkerNavigator::WrapObject(JSContext* aCx)
{
  return WorkerNavigatorBinding_workers::Wrap(aCx, this);
}

// A WorkerMainThreadRunnable to synchronously add DataStoreChangeEventProxy on
// the main thread. We need this because we have to access |mBackingStore| on
// the main thread.
class DataStoreAddEventListenerRunnable : public WorkerMainThreadRunnable
{
  nsMainThreadPtrHandle<DataStore> mBackingStore;
  DataStoreChangeEventProxy* mEventProxy;

protected:
  virtual bool
  MainThreadRun() MOZ_OVERRIDE
  {
    AssertIsOnMainThread();

    // Add |mEventProxy| as an event listner to DataStore.
    if (NS_FAILED(mBackingStore->AddEventListener(NS_LITERAL_STRING("change"),
                                                  mEventProxy,
                                                  false,
                                                  false,
                                                  2))) {
      MOZ_ASSERT(false, "failed to add event listener!");
      return false;
    }

    return true;
  }

public:
  DataStoreAddEventListenerRunnable(
    WorkerPrivate* aWorkerPrivate,
    const nsMainThreadPtrHandle<DataStore>& aBackingStore,
    DataStoreChangeEventProxy* aEventProxy)
    : WorkerMainThreadRunnable(aWorkerPrivate)
    , mBackingStore(aBackingStore)
    , mEventProxy(aEventProxy)
  {
    MOZ_ASSERT(aWorkerPrivate);
    aWorkerPrivate->AssertIsOnWorkerThread();
  }
};

#define WORKER_DATA_STORES_TAG JS_SCTAG_USER_MIN

static JSObject*
GetDataStoresStructuredCloneCallbacksRead(JSContext* aCx,
                                          JSStructuredCloneReader* aReader,
                                          uint32_t aTag,
                                          uint32_t aData,
                                          void* aClosure)
{
  WorkerPrivate* workerPrivate = GetWorkerPrivateFromContext(aCx);
  MOZ_ASSERT(workerPrivate);
  workerPrivate->AssertIsOnWorkerThread();

  if (aTag != WORKER_DATA_STORES_TAG) {
    MOZ_ASSERT(false, "aTag must be WORKER_DATA_STORES_TAG!");
    return nullptr;
  }

  NS_ASSERTION(!aData, "aData should be empty");

  // Read the holder from the buffer, which points to the data store.
  nsMainThreadPtrHolder<DataStore>* dataStoreholder;
  if (!JS_ReadBytes(aReader, &dataStoreholder, sizeof(dataStoreholder))) {
    MOZ_ASSERT(false, "cannot read bytes for dataStoreholder!");
    return nullptr;
  }

  // Protect workerStoreObj from moving GC during ~nsRefPtr.
  JS::Rooted<JSObject*> workerStoreObj(aCx, nullptr);
  {
    nsRefPtr<WorkerDataStore> workerStore =
      new WorkerDataStore(workerPrivate->GlobalScope());
    nsMainThreadPtrHandle<DataStore> backingStore(dataStoreholder);

    // When we're on the worker thread, prepare a DataStoreChangeEventProxy.
    nsRefPtr<DataStoreChangeEventProxy> eventProxy =
      new DataStoreChangeEventProxy(workerPrivate, workerStore);

    // Add the DataStoreChangeEventProxy as an event listener on the main thread.
    nsRefPtr<DataStoreAddEventListenerRunnable> runnable =
      new DataStoreAddEventListenerRunnable(workerPrivate,
                                            backingStore,
                                            eventProxy);
    runnable->Dispatch(aCx);

    // Point WorkerDataStore to DataStore.
    workerStore->SetBackingDataStore(backingStore);

    JS::Rooted<JSObject*> global(aCx, JS::CurrentGlobalOrNull(aCx));
    if (!global) {
      MOZ_ASSERT(false, "cannot get global!");
    } else {
      workerStoreObj = workerStore->WrapObject(aCx);
      if (!JS_WrapObject(aCx, &workerStoreObj)) {
        MOZ_ASSERT(false, "cannot wrap object for workerStoreObj!");
        workerStoreObj = nullptr;
      }
    }
  }

  return workerStoreObj;
}

static bool
GetDataStoresStructuredCloneCallbacksWrite(JSContext* aCx,
                                           JSStructuredCloneWriter* aWriter,
                                           JS::Handle<JSObject*> aObj,
                                           void* aClosure)
{
  AssertIsOnMainThread();

  PromiseWorkerProxy* proxy = static_cast<PromiseWorkerProxy*>(aClosure);
  NS_ASSERTION(proxy, "must have proxy!");

  if (!JS_WriteUint32Pair(aWriter, WORKER_DATA_STORES_TAG, 0)) {
    MOZ_ASSERT(false, "cannot write pair for WORKER_DATA_STORES_TAG!");
    return false;
  }

  JS::Rooted<JSObject*> storeObj(aCx, aObj);

  DataStore* store = nullptr;
  nsresult rv = UNWRAP_OBJECT(DataStore, storeObj, store);
  if (NS_FAILED(rv)) {
    MOZ_ASSERT(false, "cannot unwrap the DataStore object!");
    return false;
  }

  // We keep the data store alive here.
  proxy->StoreISupports(store);

  // Construct the nsMainThreadPtrHolder pointing to the data store.
  nsMainThreadPtrHolder<DataStore>* dataStoreholder =
    new nsMainThreadPtrHolder<DataStore>(store);

  // And write the dataStoreholder into the buffer.
  if (!JS_WriteBytes(aWriter, &dataStoreholder, sizeof(dataStoreholder))) {
    MOZ_ASSERT(false, "cannot write bytes for dataStoreholder!");
    return false;
  }

  return true;
}

static JSStructuredCloneCallbacks kGetDataStoresStructuredCloneCallbacks = {
  GetDataStoresStructuredCloneCallbacksRead,
  GetDataStoresStructuredCloneCallbacksWrite,
  nullptr
};

// A WorkerMainThreadRunnable to run WorkerNavigator::GetDataStores(...) on the
// main thread.
class NavigatorGetDataStoresRunnable MOZ_FINAL : public WorkerMainThreadRunnable
{
  nsRefPtr<PromiseWorkerProxy> mPromiseWorkerProxy;
  const nsString mName;
  ErrorResult& mRv;

public:
  NavigatorGetDataStoresRunnable(WorkerPrivate* aWorkerPrivate,
                                 Promise* aWorkerPromise,
                                 const nsAString& aName,
                                 ErrorResult& aRv)
    : WorkerMainThreadRunnable(aWorkerPrivate)
    , mName(aName)
    , mRv(aRv)
  {
    MOZ_ASSERT(aWorkerPrivate);
    aWorkerPrivate->AssertIsOnWorkerThread();

    mPromiseWorkerProxy =
      new PromiseWorkerProxy(aWorkerPrivate,
                             aWorkerPromise,
                             &kGetDataStoresStructuredCloneCallbacks);
  }

protected:
  virtual bool
  MainThreadRun() MOZ_OVERRIDE
  {
    AssertIsOnMainThread();

    // Walk up to the containing window.
    WorkerPrivate* wp = mWorkerPrivate;
    while (wp->GetParent()) {
      wp = wp->GetParent();
    }
    nsPIDOMWindow* window = wp->GetWindow();

    // TODO SharedWorker has null window. Don't need to worry about at this
    // point, though.
    if (!window) {
      mRv.Throw(NS_ERROR_FAILURE);
      return false;
    }

    nsRefPtr<Promise> promise = Navigator::GetDataStores(window, mName, mRv);
    promise->AppendNativeHandler(mPromiseWorkerProxy);
    return true;
  }
};

already_AddRefed<Promise>
WorkerNavigator::GetDataStores(JSContext* aCx,
                               const nsAString& aName,
                               ErrorResult& aRv)
{
  WorkerPrivate* workerPrivate = GetWorkerPrivateFromContext(aCx);
  MOZ_ASSERT(workerPrivate);
  workerPrivate->AssertIsOnWorkerThread();

  nsRefPtr<Promise> promise = Promise::Create(workerPrivate->GlobalScope(), aRv);
  if (aRv.Failed()) {
    return nullptr;
  }

  nsRefPtr<NavigatorGetDataStoresRunnable> runnable =
    new NavigatorGetDataStoresRunnable(workerPrivate, promise, aName, aRv);
  runnable->Dispatch(aCx);

  return promise.forget();
}

END_WORKERS_NAMESPACE