1 files changed, 137 insertions, 0 deletions
diff --git a/xpcom/threads/ThreadEventTarget.cpp b/xpcom/threads/ThreadEventTarget.cpp
new file mode 100644
index 0000000000..17844d4886
--- /dev/null
+++ b/xpcom/threads/ThreadEventTarget.cpp
@@ -0,0 +1,137 @@
+/* -*- 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 "ThreadEventTarget.h"
+#include "mozilla/ThreadEventQueue.h"
+
+#include "LeakRefPtr.h"
+#include "mozilla/DelayedRunnable.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/TimeStamp.h"
+#include "nsComponentManagerUtils.h"
+#include "nsITimer.h"
+#include "nsThreadManager.h"
+#include "nsThreadSyncDispatch.h"
+#include "nsThreadUtils.h"
+#include "ThreadDelay.h"
+
+using namespace mozilla;
+
+#ifdef DEBUG
+// This flag will be set right after XPCOMShutdownThreads finished but before
+// we continue with other processing. It is exclusively meant to prime the
+// assertion of ThreadEventTarget::Dispatch as early as possible.
+// Please use AppShutdown::IsInOrBeyond(ShutdownPhase::???)
+// elsewhere to check for shutdown phases.
+static mozilla::Atomic<bool, mozilla::SequentiallyConsistent>
+    gXPCOMThreadsShutDownNotified(false);
+#endif
+
+ThreadEventTarget::ThreadEventTarget(ThreadTargetSink* aSink,
+                                     bool aIsMainThread, bool aBlockDispatch)
+    : mSink(aSink),
+#ifdef DEBUG
+      mIsMainThread(aIsMainThread),
+#endif
+      mBlockDispatch(aBlockDispatch) {
+  mThread = PR_GetCurrentThread();
+}
+
+ThreadEventTarget::~ThreadEventTarget() = default;
+
+void ThreadEventTarget::SetCurrentThread(PRThread* aThread) {
+  mThread = aThread;
+}
+
+void ThreadEventTarget::ClearCurrentThread() { mThread = nullptr; }
+
+NS_IMPL_ISUPPORTS(ThreadEventTarget, nsIEventTarget, nsISerialEventTarget)
+
+NS_IMETHODIMP
+ThreadEventTarget::DispatchFromScript(nsIRunnable* aRunnable, uint32_t aFlags) {
+  return Dispatch(do_AddRef(aRunnable), aFlags);
+}
+
+#ifdef DEBUG
+// static
+void ThreadEventTarget::XPCOMShutdownThreadsNotificationFinished() {
+  gXPCOMThreadsShutDownNotified = true;
+}
+#endif
+
+NS_IMETHODIMP
+ThreadEventTarget::Dispatch(already_AddRefed<nsIRunnable> aEvent,
+                            uint32_t aFlags) {
+  // We want to leak the reference when we fail to dispatch it, so that
+  // we won't release the event in a wrong thread.
+  LeakRefPtr<nsIRunnable> event(std::move(aEvent));
+  if (NS_WARN_IF(!event)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  NS_ASSERTION(!gXPCOMThreadsShutDownNotified || mIsMainThread ||
+                   PR_GetCurrentThread() == mThread ||
+                   (aFlags & NS_DISPATCH_IGNORE_BLOCK_DISPATCH),
+               "Dispatch to non-main thread after xpcom-shutdown-threads");
+
+  if (mBlockDispatch && !(aFlags & NS_DISPATCH_IGNORE_BLOCK_DISPATCH)) {
+    MOZ_DIAGNOSTIC_ASSERT(
+        false,
+        "Attempt to dispatch to thread which does not usually process "
+        "dispatched runnables until shutdown");
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  LogRunnable::LogDispatch(event.get());
+
+  NS_ASSERTION((aFlags & (NS_DISPATCH_AT_END |
+                          NS_DISPATCH_IGNORE_BLOCK_DISPATCH)) == aFlags,
+               "unexpected dispatch flags");
+  if (!mSink->PutEvent(event.take(), EventQueuePriority::Normal)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  // Delay to encourage the receiving task to run before we do work.
+  DelayForChaosMode(ChaosFeature::TaskDispatching, 1000);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ThreadEventTarget::DelayedDispatch(already_AddRefed<nsIRunnable> aEvent,
+                                   uint32_t aDelayMs) {
+  nsCOMPtr<nsIRunnable> event = aEvent;
+  NS_ENSURE_TRUE(!!aDelayMs, NS_ERROR_UNEXPECTED);
+
+  RefPtr<DelayedRunnable> r =
+      new DelayedRunnable(do_AddRef(this), event.forget(), aDelayMs);
+  nsresult rv = r->Init();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return Dispatch(r.forget(), NS_DISPATCH_NORMAL);
+}
+
+NS_IMETHODIMP
+ThreadEventTarget::RegisterShutdownTask(nsITargetShutdownTask* aTask) {
+  return mSink->RegisterShutdownTask(aTask);
+}
+
+NS_IMETHODIMP
+ThreadEventTarget::UnregisterShutdownTask(nsITargetShutdownTask* aTask) {
+  return mSink->UnregisterShutdownTask(aTask);
+}
+
+NS_IMETHODIMP
+ThreadEventTarget::IsOnCurrentThread(bool* aIsOnCurrentThread) {
+  *aIsOnCurrentThread = IsOnCurrentThread();
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(bool)
+ThreadEventTarget::IsOnCurrentThreadInfallible() {
+  // This method is only going to be called if `mThread` is null, which
+  // only happens when the thread has exited the event loop.  Therefore, when
+  // we are called, we can never be on this thread.
+  return false;
+}