1 files changed, 138 insertions, 0 deletions
diff --git a/gfx/layers/ipc/CanvasThread.cpp b/gfx/layers/ipc/CanvasThread.cpp
new file mode 100644
index 0000000000..3d0a387c04
--- /dev/null
+++ b/gfx/layers/ipc/CanvasThread.cpp
@@ -0,0 +1,138 @@
+/* -*- 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 "CanvasThread.h"
+
+#include "mozilla/SharedThreadPool.h"
+#include "nsThreadUtils.h"
+#include "prsystem.h"
+
+bool NS_IsInCanvasThreadOrWorker() {
+  return mozilla::layers::CanvasThreadHolder::IsInCanvasThreadOrWorker();
+}
+
+namespace mozilla {
+namespace layers {
+
+StaticDataMutex<StaticRefPtr<CanvasThreadHolder>>
+    CanvasThreadHolder::sCanvasThreadHolder("sCanvasThreadHolder");
+
+CanvasThreadHolder::CanvasThreadHolder(
+    already_AddRefed<nsISerialEventTarget> aCanvasThread,
+    already_AddRefed<nsIThreadPool> aCanvasWorkers)
+    : mCanvasThread(aCanvasThread),
+      mCanvasWorkers(aCanvasWorkers),
+      mCompositorThreadKeepAlive(CompositorThreadHolder::GetSingleton()) {
+  MOZ_ASSERT(NS_IsInCompositorThread());
+  MOZ_ASSERT(mCanvasThread);
+  MOZ_ASSERT(mCanvasWorkers);
+}
+
+CanvasThreadHolder::~CanvasThreadHolder() {
+  // Note we can't just use NS_IsInCompositorThread() here because
+  // sCompositorThreadHolder might have already gone.
+  MOZ_ASSERT(
+      mCompositorThreadKeepAlive->GetCompositorThread()->IsOnCurrentThread());
+}
+
+/* static */
+already_AddRefed<CanvasThreadHolder> CanvasThreadHolder::EnsureCanvasThread() {
+  MOZ_ASSERT(NS_IsInCompositorThread());
+
+  auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
+  if (!lockedCanvasThreadHolder.ref()) {
+    nsCOMPtr<nsISerialEventTarget> canvasThread;
+    nsresult rv =
+        NS_CreateBackgroundTaskQueue("Canvas", getter_AddRefs(canvasThread));
+    NS_ENSURE_SUCCESS(rv, nullptr);
+
+    // Given that the canvas workers are receiving instructions from
+    // content processes, it probably doesn't make sense to have more than
+    // half the number of processors doing canvas drawing. We set the
+    // lower limit to 2, so that even on single processor systems, if
+    // there is more than one window with canvas drawing, the OS can
+    // manage the load between them.
+    uint32_t threadLimit = std::max(2, PR_GetNumberOfProcessors() / 2);
+    nsCOMPtr<nsIThreadPool> canvasWorkers =
+        SharedThreadPool::Get("CanvasWorkers"_ns, threadLimit);
+    if (!canvasWorkers) {
+      return nullptr;
+    }
+
+    lockedCanvasThreadHolder.ref() =
+        new CanvasThreadHolder(canvasThread.forget(), canvasWorkers.forget());
+  }
+
+  return do_AddRef(lockedCanvasThreadHolder.ref());
+}
+
+/* static */
+void CanvasThreadHolder::ReleaseOnCompositorThread(
+    already_AddRefed<CanvasThreadHolder> aCanvasThreadHolder) {
+  RefPtr<CanvasThreadHolder> canvasThreadHolder = aCanvasThreadHolder;
+  auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
+  lockedCanvasThreadHolder.ref()
+      ->mCompositorThreadKeepAlive->GetCompositorThread()
+      ->Dispatch(NS_NewRunnableFunction(
+          "CanvasThreadHolder::StaticRelease",
+          [canvasThreadHolder = std::move(canvasThreadHolder)]() mutable {
+            RefPtr<CanvasThreadHolder> threadHolder =
+                canvasThreadHolder.forget();
+            threadHolder = nullptr;
+
+            auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
+            if (lockedCanvasThreadHolder.ref()->mRefCnt == 1) {
+              lockedCanvasThreadHolder.ref() = nullptr;
+            }
+          }));
+}
+
+/* static */
+bool CanvasThreadHolder::IsInCanvasThread() {
+  auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
+  return lockedCanvasThreadHolder.ref() &&
+         lockedCanvasThreadHolder.ref()->mCanvasThread->IsOnCurrentThread();
+}
+
+/* static */
+bool CanvasThreadHolder::IsInCanvasWorker() {
+  auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
+  return lockedCanvasThreadHolder.ref() &&
+         lockedCanvasThreadHolder.ref()->mCanvasWorkers->IsOnCurrentThread();
+}
+
+/* static */
+bool CanvasThreadHolder::IsInCanvasThreadOrWorker() {
+  auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
+  return lockedCanvasThreadHolder.ref() &&
+         (lockedCanvasThreadHolder.ref()->mCanvasWorkers->IsOnCurrentThread() ||
+          lockedCanvasThreadHolder.ref()->mCanvasThread->IsOnCurrentThread());
+}
+
+/* static */
+void CanvasThreadHolder::MaybeDispatchToCanvasThread(
+    already_AddRefed<nsIRunnable> aRunnable) {
+  auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
+  if (!lockedCanvasThreadHolder.ref()) {
+    // There is no canvas thread just release the runnable.
+    nsCOMPtr<nsIRunnable> runnable = aRunnable;
+    return;
+  }
+
+  lockedCanvasThreadHolder.ref()->mCanvasThread->Dispatch(std::move(aRunnable));
+}
+
+void CanvasThreadHolder::DispatchToCanvasThread(
+    already_AddRefed<nsIRunnable> aRunnable) {
+  mCanvasThread->Dispatch(std::move(aRunnable));
+}
+
+already_AddRefed<TaskQueue> CanvasThreadHolder::CreateWorkerTaskQueue() {
+  return TaskQueue::Create(do_AddRef(mCanvasWorkers), "CanvasWorker").forget();
+}
+
+}  // namespace layers
+}  // namespace mozilla