Bug 1583646 - make WebCryptoTask dispatch tasks to our background thread; r=keeler,jcj

Since background threads get shut down near `xpcom-shutdown-threads`,
there's no need to have `WebCryptoThreadPool` anymore; we can rely on
the background thread dispatching to fail to dispatch our task as
appropriate.

Differential Revision: https://phabricator.services.mozilla.com/D47006

--HG--
extra : moz-landing-system : lando

dom/crypto/WebCryptoTask.cpp

@@ -19,7 +19,6 @@
 #include "mozilla/dom/TypedArray.h"
 #include "mozilla/dom/WebCryptoCommon.h"
 #include "mozilla/dom/WebCryptoTask.h"
-#include "mozilla/dom/WebCryptoThreadPool.h"
 #include "mozilla/dom/WorkerRef.h"
 #include "mozilla/dom/WorkerPrivate.h"
 
@@ -339,7 +338,13 @@ void WebCryptoTask::DispatchWithPromise(Promise* aResultPromise) {
   MAYBE_EARLY_FAIL(mEarlyRv);
 
   // dispatch to thread pool
-  mEarlyRv = WebCryptoThreadPool::Dispatch(this);
+
+  if (!EnsureNSSInitializedChromeOrContent()) {
+    mEarlyRv = NS_ERROR_FAILURE;
+  }
+  MAYBE_EARLY_FAIL(mEarlyRv);
+
+  mEarlyRv = NS_DispatchToBackgroundThread(this);
   MAYBE_EARLY_FAIL(mEarlyRv)
 }
 

dom/crypto/WebCryptoThreadPool.cpp

@@ -1,125 +0,0 @@
-/* -*- 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 "mozilla/dom/WebCryptoThreadPool.h"
-
-#include "MainThreadUtils.h"
-#include "mozilla/Services.h"
-#include "mozilla/StaticPtr.h"
-#include "nsComponentManagerUtils.h"
-#include "nsNSSComponent.h"
-#include "nsXPCOMCIDInternal.h"
-#include "nsXPCOMPrivate.h"
-#include "nsIObserverService.h"
-#include "nsThreadPool.h"
-
-namespace mozilla {
-namespace dom {
-
-StaticRefPtr<WebCryptoThreadPool> gInstance;
-
-NS_IMPL_ISUPPORTS(WebCryptoThreadPool, nsIObserver)
-
-/* static */
-void WebCryptoThreadPool::Initialize() {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-  MOZ_ASSERT(!gInstance, "More than one instance!");
-
-  gInstance = new WebCryptoThreadPool();
-  NS_WARNING_ASSERTION(gInstance, "Failed create thread pool!");
-
-  if (gInstance && NS_FAILED(gInstance->Init())) {
-    NS_WARNING("Failed to initialize thread pool!");
-    gInstance = nullptr;
-  }
-}
-
-/* static */
-nsresult WebCryptoThreadPool::Dispatch(nsIRunnable* aRunnable) {
-  if (gInstance) {
-    return gInstance->DispatchInternal(aRunnable);
-  }
-
-  // Fail if called on shutdown.
-  return NS_ERROR_FAILURE;
-}
-
-nsresult WebCryptoThreadPool::Init() {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-
-  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
-  NS_ENSURE_TRUE(obs, NS_ERROR_FAILURE);
-
-  // Need this observer to know when to shut down the thread pool.
-  return obs->AddObserver(this, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID, false);
-}
-
-nsresult WebCryptoThreadPool::DispatchInternal(nsIRunnable* aRunnable) {
-  MutexAutoLock lock(mMutex);
-
-  if (mShutdown) {
-    return NS_ERROR_FAILURE;
-  }
-
-  if (!mPool) {
-    NS_ENSURE_TRUE(EnsureNSSInitializedChromeOrContent(), NS_ERROR_FAILURE);
-
-    nsCOMPtr<nsIThreadPool> pool(new nsThreadPool());
-
-    nsresult rv = pool->SetName(NS_LITERAL_CSTRING("SubtleCrypto"));
-    NS_ENSURE_SUCCESS(rv, rv);
-
-    pool.swap(mPool);
-  }
-
-  return mPool->Dispatch(aRunnable, NS_DISPATCH_NORMAL);
-}
-
-void WebCryptoThreadPool::Shutdown() {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-
-  // Limit the scope of locking to avoid deadlocking if DispatchInternal ends
-  // up getting called during shutdown event processing.
-  nsCOMPtr<nsIThreadPool> pool;
-  {
-    MutexAutoLock lock(mMutex);
-    if (mShutdown) {
-      return;
-    }
-    pool = mPool;
-    mShutdown = true;
-  }
-
-  if (pool) {
-    pool->Shutdown();
-  }
-
-  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
-  NS_WARNING_ASSERTION(obs, "Failed to retrieve observer service!");
-
-  if (obs) {
-    if (NS_FAILED(
-            obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID))) {
-      NS_WARNING("Failed to remove shutdown observer!");
-    }
-  }
-}
-
-NS_IMETHODIMP
-WebCryptoThreadPool::Observe(nsISupports* aSubject, const char* aTopic,
-                             const char16_t* aData) {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-
-  if (gInstance) {
-    gInstance->Shutdown();
-    gInstance = nullptr;
-  }
-
-  return NS_OK;
-}
-
-}  // namespace dom
-}  // namespace mozilla

dom/crypto/WebCryptoThreadPool.h

@@ -1,50 +0,0 @@
-/* -*- 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/. */
-
-#ifndef mozilla_dom_WebCryptoThreadPool_h
-#define mozilla_dom_WebCryptoThreadPool_h
-
-#include "mozilla/Mutex.h"
-#include "nsIObserver.h"
-#include "nsIObserverService.h"
-#include "nsIThreadPool.h"
-
-namespace mozilla {
-namespace dom {
-
-class WebCryptoThreadPool final : nsIObserver {
- public:
-  NS_DECL_THREADSAFE_ISUPPORTS
-
-  static void Initialize();
-
-  static nsresult Dispatch(nsIRunnable* aRunnable);
-
- private:
-  WebCryptoThreadPool()
-      : mMutex("WebCryptoThreadPool::mMutex"),
-        mPool(nullptr),
-        mShutdown(false) {}
-  virtual ~WebCryptoThreadPool() {}
-
-  nsresult Init();
-
-  nsresult DispatchInternal(nsIRunnable* aRunnable);
-
-  void Shutdown();
-
-  NS_IMETHOD Observe(nsISupports* aSubject, const char* aTopic,
-                     const char16_t* aData) override;
-
-  mozilla::Mutex mMutex;
-  nsCOMPtr<nsIThreadPool> mPool;
-  bool mShutdown;
-};
-
-}  // namespace dom
-}  // namespace mozilla
-
-#endif  // mozilla_dom_WebCryptoThreadPool_h

dom/crypto/moz.build

@@ -13,7 +13,6 @@ EXPORTS.mozilla.dom += [
     'KeyAlgorithmProxy.h',
     'WebCryptoCommon.h',
     'WebCryptoTask.h',
-    'WebCryptoThreadPool.h'
 ]
 
 UNIFIED_SOURCES += [
@@ -21,7 +20,6 @@ UNIFIED_SOURCES += [
     'CryptoKey.cpp',
     'KeyAlgorithmProxy.cpp',
     'WebCryptoTask.cpp',
-    'WebCryptoThreadPool.cpp',
 ]
 
 include('/ipc/chromium/chromium-config.mozbuild')

layout/build/nsLayoutStatics.cpp

@@ -70,7 +70,6 @@
 
 #include "AudioChannelService.h"
 #include "mozilla/dom/PromiseDebugging.h"
-#include "mozilla/dom/WebCryptoThreadPool.h"
 
 #ifdef MOZ_XUL
 #  include "nsXULPopupManager.h"
@@ -278,8 +277,6 @@ nsresult nsLayoutStatics::Initialize() {
 
   PromiseDebugging::Init();
 
-  mozilla::dom::WebCryptoThreadPool::Initialize();
-
   if (XRE_IsParentProcess() || XRE_IsContentProcess()) {
     InitializeServo();
   }