1 files changed, 238 insertions, 0 deletions
diff --git a/dom/file/ipc/RemoteLazyInputStreamThread.cpp b/dom/file/ipc/RemoteLazyInputStreamThread.cpp
new file mode 100644
index 0000000000..5883c44d4c
--- /dev/null
+++ b/dom/file/ipc/RemoteLazyInputStreamThread.cpp
@@ -0,0 +1,238 @@
+/* -*- 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 "RemoteLazyInputStreamThread.h"
+
+#include "ErrorList.h"
+#include "mozilla/AppShutdown.h"
+#include "mozilla/SchedulerGroup.h"
+#include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/ipc/BackgroundChild.h"
+#include "mozilla/ipc/PBackgroundChild.h"
+#include "nsXPCOMPrivate.h"
+
+using namespace mozilla::ipc;
+
+namespace mozilla {
+
+namespace {
+
+StaticMutex gRemoteLazyThreadMutex;
+StaticRefPtr<RemoteLazyInputStreamThread> gRemoteLazyThread;
+
+class ThreadInitializeRunnable final : public Runnable {
+ public:
+  ThreadInitializeRunnable() : Runnable("dom::ThreadInitializeRunnable") {}
+
+  NS_IMETHOD
+  Run() override {
+    StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+    MOZ_ASSERT(gRemoteLazyThread);
+    if (NS_WARN_IF(!gRemoteLazyThread->InitializeOnMainThread())) {
+      // RemoteLazyInputStreamThread::GetOrCreate might have handed out a
+      // pointer to our thread already at this point such that we cannot
+      // just do gRemoteLazyThread = nullptr; here.
+      MOZ_DIAGNOSTIC_ASSERT(
+          false, "Async gRemoteLazyThread->InitializeOnMainThread() failed.");
+      return NS_ERROR_FAILURE;
+    }
+    return NS_OK;
+  }
+};
+
+}  // namespace
+
+NS_IMPL_ISUPPORTS(RemoteLazyInputStreamThread, nsIObserver, nsIEventTarget,
+                  nsISerialEventTarget, nsIDirectTaskDispatcher)
+
+bool RLISThreadIsInOrBeyondShutdown() {
+  // ShutdownPhase::XPCOMShutdownThreads matches
+  // obs->AddObserver(this, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID, false);
+  return AppShutdown::IsInOrBeyond(ShutdownPhase::XPCOMShutdownThreads);
+}
+
+/* static */
+RemoteLazyInputStreamThread* RemoteLazyInputStreamThread::Get() {
+  if (RLISThreadIsInOrBeyondShutdown()) {
+    return nullptr;
+  }
+
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+
+  return gRemoteLazyThread;
+}
+
+/* static */
+RemoteLazyInputStreamThread* RemoteLazyInputStreamThread::GetOrCreate() {
+  if (RLISThreadIsInOrBeyondShutdown()) {
+    return nullptr;
+  }
+
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+
+  if (!gRemoteLazyThread) {
+    gRemoteLazyThread = new RemoteLazyInputStreamThread();
+    if (!gRemoteLazyThread->Initialize()) {
+      gRemoteLazyThread = nullptr;
+    }
+  }
+
+  return gRemoteLazyThread;
+}
+
+bool RemoteLazyInputStreamThread::Initialize() {
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_NewNamedThread("RemoteLzyStream", getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return false;
+  }
+
+  mThread = thread;
+
+  if (!NS_IsMainThread()) {
+    RefPtr<Runnable> runnable = new ThreadInitializeRunnable();
+    nsresult rv = SchedulerGroup::Dispatch(runnable.forget());
+    return !NS_WARN_IF(NS_FAILED(rv));
+  }
+
+  return InitializeOnMainThread();
+}
+
+bool RemoteLazyInputStreamThread::InitializeOnMainThread() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
+  if (NS_WARN_IF(!obs)) {
+    return false;
+  }
+
+  nsresult rv =
+      obs->AddObserver(this, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID, false);
+  return !NS_WARN_IF(NS_FAILED(rv));
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::Observe(nsISupports* aSubject, const char* aTopic,
+                                     const char16_t* aData) {
+  MOZ_ASSERT(!strcmp(aTopic, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID));
+
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+
+  if (mThread) {
+    mThread->Shutdown();
+    mThread = nullptr;
+  }
+
+  gRemoteLazyThread = nullptr;
+
+  return NS_OK;
+}
+
+// nsIEventTarget
+
+NS_IMETHODIMP_(bool)
+RemoteLazyInputStreamThread::IsOnCurrentThreadInfallible() {
+  return mThread->IsOnCurrentThread();
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::IsOnCurrentThread(bool* aRetval) {
+  return mThread->IsOnCurrentThread(aRetval);
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::Dispatch(already_AddRefed<nsIRunnable> aRunnable,
+                                      uint32_t aFlags) {
+  nsCOMPtr<nsIRunnable> runnable(aRunnable);
+
+  if (RLISThreadIsInOrBeyondShutdown()) {
+    // nsIEventTarget::Dispatch must leak the runnable if the dispatch fails.
+    (void)runnable.forget();
+
+    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
+  }
+
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+
+  return mThread->Dispatch(runnable.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::DispatchFromScript(nsIRunnable* aRunnable,
+                                                uint32_t aFlags) {
+  nsCOMPtr<nsIRunnable> runnable(aRunnable);
+  return Dispatch(runnable.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::DelayedDispatch(already_AddRefed<nsIRunnable>,
+                                             uint32_t) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::RegisterShutdownTask(nsITargetShutdownTask*) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::UnregisterShutdownTask(nsITargetShutdownTask*) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+RemoteLazyInputStreamThread::DispatchDirectTask(
+    already_AddRefed<nsIRunnable> aRunnable) {
+  nsCOMPtr<nsIRunnable> runnable(aRunnable);
+
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+
+  nsCOMPtr<nsIDirectTaskDispatcher> dispatcher = do_QueryInterface(mThread);
+
+  if (dispatcher) {
+    return dispatcher->DispatchDirectTask(runnable.forget());
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP RemoteLazyInputStreamThread::DrainDirectTasks() {
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+
+  nsCOMPtr<nsIDirectTaskDispatcher> dispatcher = do_QueryInterface(mThread);
+
+  if (dispatcher) {
+    return dispatcher->DrainDirectTasks();
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP RemoteLazyInputStreamThread::HaveDirectTasks(bool* aValue) {
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+
+  nsCOMPtr<nsIDirectTaskDispatcher> dispatcher = do_QueryInterface(mThread);
+
+  if (dispatcher) {
+    return dispatcher->HaveDirectTasks(aValue);
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+bool IsOnDOMFileThread() {
+  MOZ_ASSERT(!RLISThreadIsInOrBeyondShutdown());
+
+  StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
+  MOZ_ASSERT(gRemoteLazyThread);
+
+  return gRemoteLazyThread->IsOnCurrentThreadInfallible();
+}
+
+void AssertIsOnDOMFileThread() { MOZ_ASSERT(IsOnDOMFileThread()); }
+
+}  // namespace mozilla