1 files changed, 286 insertions, 0 deletions
diff --git a/dom/serviceworkers/ServiceWorkerShutdownBlocker.cpp b/dom/serviceworkers/ServiceWorkerShutdownBlocker.cpp
new file mode 100644
index 0000000000..2aa19653ec
--- /dev/null
+++ b/dom/serviceworkers/ServiceWorkerShutdownBlocker.cpp
@@ -0,0 +1,286 @@
+/* -*- 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 "ServiceWorkerShutdownBlocker.h"
+
+#include <chrono>
+#include <utility>
+
+#include "MainThreadUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsDebug.h"
+#include "nsError.h"
+#include "nsIWritablePropertyBag2.h"
+#include "nsThreadUtils.h"
+#include "ServiceWorkerManager.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_ISUPPORTS(ServiceWorkerShutdownBlocker, nsIAsyncShutdownBlocker)
+
+NS_IMETHODIMP ServiceWorkerShutdownBlocker::GetName(nsAString& aNameOut) {
+  aNameOut = nsLiteralString(
+      u"ServiceWorkerShutdownBlocker: shutting down Service Workers");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ServiceWorkerShutdownBlocker::BlockShutdown(nsIAsyncShutdownClient* aClient) {
+  AssertIsOnMainThread();
+  MOZ_ASSERT(!mShutdownClient);
+  MOZ_ASSERT(mServiceWorkerManager);
+
+  mShutdownClient = aClient;
+
+  (*mServiceWorkerManager)->MaybeStartShutdown();
+  mServiceWorkerManager.destroy();
+
+  MaybeUnblockShutdown();
+  MaybeInitUnblockShutdownTimer();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP ServiceWorkerShutdownBlocker::GetState(nsIPropertyBag** aBagOut) {
+  AssertIsOnMainThread();
+  MOZ_ASSERT(aBagOut);
+
+  nsCOMPtr<nsIWritablePropertyBag2> propertyBag =
+      do_CreateInstance("@mozilla.org/hash-property-bag;1");
+
+  if (NS_WARN_IF(!propertyBag)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv = propertyBag->SetPropertyAsBool(u"acceptingPromises"_ns,
+                                               IsAcceptingPromises());
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = propertyBag->SetPropertyAsUint32(u"pendingPromises"_ns,
+                                        GetPendingPromises());
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsAutoCString shutdownStates;
+
+  for (auto iter = mShutdownStates.iter(); !iter.done(); iter.next()) {
+    shutdownStates.Append(iter.get().value().GetProgressString());
+    shutdownStates.Append(", ");
+  }
+
+  rv = propertyBag->SetPropertyAsACString(u"shutdownStates"_ns, shutdownStates);
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  propertyBag.forget(aBagOut);
+
+  return NS_OK;
+}
+
+/* static */ already_AddRefed<ServiceWorkerShutdownBlocker>
+ServiceWorkerShutdownBlocker::CreateAndRegisterOn(
+    nsIAsyncShutdownClient& aShutdownBarrier,
+    ServiceWorkerManager& aServiceWorkerManager) {
+  AssertIsOnMainThread();
+
+  RefPtr<ServiceWorkerShutdownBlocker> blocker =
+      new ServiceWorkerShutdownBlocker(aServiceWorkerManager);
+
+  nsresult rv = aShutdownBarrier.AddBlocker(
+      blocker.get(), NS_LITERAL_STRING_FROM_CSTRING(__FILE__), __LINE__,
+      u"Service Workers shutdown"_ns);
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return nullptr;
+  }
+
+  return blocker.forget();
+}
+
+void ServiceWorkerShutdownBlocker::WaitOnPromise(
+    GenericNonExclusivePromise* aPromise, uint32_t aShutdownStateId) {
+  AssertIsOnMainThread();
+  MOZ_DIAGNOSTIC_ASSERT(IsAcceptingPromises());
+  MOZ_ASSERT(aPromise);
+  MOZ_ASSERT(mShutdownStates.has(aShutdownStateId));
+
+  ++mState.as<AcceptingPromises>().mPendingPromises;
+
+  RefPtr<ServiceWorkerShutdownBlocker> self = this;
+
+  aPromise->Then(GetCurrentSerialEventTarget(), __func__,
+                 [self = std::move(self), shutdownStateId = aShutdownStateId](
+                     const GenericNonExclusivePromise::ResolveOrRejectValue&) {
+                   // Progress reporting might race with aPromise settling.
+                   self->mShutdownStates.remove(shutdownStateId);
+
+                   if (!self->PromiseSettled()) {
+                     self->MaybeUnblockShutdown();
+                   }
+                 });
+}
+
+void ServiceWorkerShutdownBlocker::StopAcceptingPromises() {
+  AssertIsOnMainThread();
+  MOZ_ASSERT(IsAcceptingPromises());
+
+  mState = AsVariant(NotAcceptingPromises(mState.as<AcceptingPromises>()));
+
+  MaybeUnblockShutdown();
+  MaybeInitUnblockShutdownTimer();
+}
+
+uint32_t ServiceWorkerShutdownBlocker::CreateShutdownState() {
+  AssertIsOnMainThread();
+
+  static uint32_t nextShutdownStateId = 1;
+
+  MOZ_ALWAYS_TRUE(mShutdownStates.putNew(nextShutdownStateId,
+                                         ServiceWorkerShutdownState()));
+
+  return nextShutdownStateId++;
+}
+
+void ServiceWorkerShutdownBlocker::ReportShutdownProgress(
+    uint32_t aShutdownStateId, Progress aProgress) {
+  AssertIsOnMainThread();
+  MOZ_RELEASE_ASSERT(aShutdownStateId != kInvalidShutdownStateId);
+
+  auto lookup = mShutdownStates.lookup(aShutdownStateId);
+
+  // Progress reporting might race with the promise that WaitOnPromise is called
+  // with settling.
+  if (!lookup) {
+    return;
+  }
+
+  // This will check for a valid progress transition with assertions.
+  lookup->value().SetProgress(aProgress);
+
+  if (aProgress == Progress::ShutdownCompleted) {
+    mShutdownStates.remove(lookup);
+  }
+}
+
+ServiceWorkerShutdownBlocker::ServiceWorkerShutdownBlocker(
+    ServiceWorkerManager& aServiceWorkerManager)
+    : mState(VariantType<AcceptingPromises>()),
+      mServiceWorkerManager(WrapNotNull(&aServiceWorkerManager)) {
+  AssertIsOnMainThread();
+}
+
+ServiceWorkerShutdownBlocker::~ServiceWorkerShutdownBlocker() {
+  MOZ_ASSERT(!IsAcceptingPromises());
+  MOZ_ASSERT(!GetPendingPromises());
+  MOZ_ASSERT(!mShutdownClient);
+  MOZ_ASSERT(!mServiceWorkerManager);
+}
+
+void ServiceWorkerShutdownBlocker::MaybeUnblockShutdown() {
+  AssertIsOnMainThread();
+
+  if (!mShutdownClient || IsAcceptingPromises() || GetPendingPromises()) {
+    return;
+  }
+
+  UnblockShutdown();
+}
+
+void ServiceWorkerShutdownBlocker::UnblockShutdown() {
+  MOZ_ASSERT(mShutdownClient);
+
+  mShutdownClient->RemoveBlocker(this);
+  mShutdownClient = nullptr;
+
+  if (mTimer) {
+    mTimer->Cancel();
+  }
+}
+
+uint32_t ServiceWorkerShutdownBlocker::PromiseSettled() {
+  AssertIsOnMainThread();
+  MOZ_ASSERT(GetPendingPromises());
+
+  if (IsAcceptingPromises()) {
+    return --mState.as<AcceptingPromises>().mPendingPromises;
+  }
+
+  return --mState.as<NotAcceptingPromises>().mPendingPromises;
+}
+
+bool ServiceWorkerShutdownBlocker::IsAcceptingPromises() const {
+  AssertIsOnMainThread();
+
+  return mState.is<AcceptingPromises>();
+}
+
+uint32_t ServiceWorkerShutdownBlocker::GetPendingPromises() const {
+  AssertIsOnMainThread();
+
+  if (IsAcceptingPromises()) {
+    return mState.as<AcceptingPromises>().mPendingPromises;
+  }
+
+  return mState.as<NotAcceptingPromises>().mPendingPromises;
+}
+
+ServiceWorkerShutdownBlocker::NotAcceptingPromises::NotAcceptingPromises(
+    AcceptingPromises aPreviousState)
+    : mPendingPromises(aPreviousState.mPendingPromises) {
+  AssertIsOnMainThread();
+}
+
+NS_IMETHODIMP ServiceWorkerShutdownBlocker::Notify(nsITimer*) {
+  // TODO: this method being called indicates that there are ServiceWorkers
+  // that did not complete shutdown before the timer expired - there should be
+  // a telemetry ping or some other way of recording the state of when this
+  // happens (e.g. what's returned by GetState()).
+  UnblockShutdown();
+  return NS_OK;
+}
+
+#ifdef RELEASE_OR_BETA
+#  define SW_UNBLOCK_SHUTDOWN_TIMER_DURATION 10s
+#else
+// In Nightly, we do want a shutdown hang to be reported so we pick a value
+// notably longer than the 60s of the RunWatchDog timeout.
+#  define SW_UNBLOCK_SHUTDOWN_TIMER_DURATION 200s
+#endif
+
+void ServiceWorkerShutdownBlocker::MaybeInitUnblockShutdownTimer() {
+  AssertIsOnMainThread();
+
+  if (mTimer || !mShutdownClient || IsAcceptingPromises()) {
+    return;
+  }
+
+  MOZ_ASSERT(GetPendingPromises(),
+             "Shouldn't be blocking shutdown with zero pending promises.");
+
+  using namespace std::chrono_literals;
+
+  static constexpr auto delay =
+      std::chrono::duration_cast<std::chrono::milliseconds>(
+          SW_UNBLOCK_SHUTDOWN_TIMER_DURATION);
+
+  mTimer = NS_NewTimer();
+
+  mTimer->InitWithCallback(this, delay.count(), nsITimer::TYPE_ONE_SHOT);
+}
+
+}  // namespace dom
+}  // namespace mozilla