1 files changed, 279 insertions, 0 deletions
diff --git a/gfx/ipc/CanvasRenderThread.cpp b/gfx/ipc/CanvasRenderThread.cpp
new file mode 100644
index 0000000000..853806a222
--- /dev/null
+++ b/gfx/ipc/CanvasRenderThread.cpp
@@ -0,0 +1,279 @@
+/* -*- 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 "CanvasRenderThread.h"
+
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/SharedThreadPool.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/TaskQueue.h"
+#include "mozilla/gfx/CanvasManagerParent.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/layers/CanvasTranslator.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/webrender/RenderThread.h"
+#include "nsThread.h"
+#include "prsystem.h"
+#include "transport/runnable_utils.h"
+
+bool NS_IsInCanvasThreadOrWorker() {
+  return mozilla::gfx::CanvasRenderThread::IsInCanvasRenderOrWorkerThread();
+}
+
+namespace mozilla::gfx {
+
+static StaticRefPtr<CanvasRenderThread> sCanvasRenderThread;
+static mozilla::BackgroundHangMonitor* sBackgroundHangMonitor;
+#ifdef DEBUG
+static bool sCanvasRenderThreadEverStarted = false;
+#endif
+
+CanvasRenderThread::CanvasRenderThread(nsCOMPtr<nsIThread>&& aThread,
+                                       nsCOMPtr<nsIThreadPool>&& aWorkers,
+                                       bool aCreatedThread)
+    : mMutex("CanvasRenderThread::mMutex"),
+      mThread(std::move(aThread)),
+      mWorkers(std::move(aWorkers)),
+      mCreatedThread(aCreatedThread) {}
+
+CanvasRenderThread::~CanvasRenderThread() = default;
+
+// static
+void CanvasRenderThread::Start() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!sCanvasRenderThread);
+
+#ifdef DEBUG
+  // Check to ensure nobody will try to ever start us more than once during
+  // the process' lifetime (in particular after Stop).
+  MOZ_ASSERT(!sCanvasRenderThreadEverStarted);
+  sCanvasRenderThreadEverStarted = true;
+#endif
+
+  int32_t threadPref =
+      StaticPrefs::gfx_canvas_remote_worker_threads_AtStartup();
+  uint32_t threadLimit;
+  if (threadPref < 0) {
+    // 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.
+    threadLimit = std::max(2, PR_GetNumberOfProcessors() / 2);
+  } else {
+    threadLimit = uint32_t(threadPref);
+  }
+
+  // We don't spawn any workers if the user set the limit to 0. Instead we will
+  // use the CanvasRenderThread virtual thread.
+  nsCOMPtr<nsIThreadPool> workers;
+  if (threadLimit > 0) {
+    workers = SharedThreadPool::Get("CanvasWorkers"_ns, threadLimit);
+    if (NS_WARN_IF(!workers)) {
+      return;
+    }
+  }
+
+  nsCOMPtr<nsIThread> thread;
+  if (!gfxVars::SupportsThreadsafeGL()) {
+    thread = wr::RenderThread::GetRenderThread();
+    MOZ_ASSERT(thread);
+  } else if (!gfxVars::UseCanvasRenderThread()) {
+    thread = layers::CompositorThread();
+    MOZ_ASSERT(thread);
+  }
+
+  if (thread) {
+    sCanvasRenderThread = new CanvasRenderThread(
+        std::move(thread), std::move(workers), /* aCreatedThread */ false);
+    return;
+  }
+
+  // This is 4M, which is higher than the default 256K.
+  // Increased with bug 1753349 to accommodate the `chromium/5359` branch of
+  // ANGLE, which has large peak stack usage for some pathological shader
+  // compilations.
+  //
+  // Previously increased to 512K to accommodate Mesa in bug 1753340.
+  //
+  // Previously increased to 320K to avoid a stack overflow in the
+  // Intel Vulkan driver initialization in bug 1716120.
+  //
+  // Note: we only override it if it's limited already.
+  const uint32_t stackSize =
+      nsIThreadManager::DEFAULT_STACK_SIZE ? 4096 << 10 : 0;
+
+  nsresult rv = NS_NewNamedThread(
+      "CanvasRenderer", getter_AddRefs(thread),
+      NS_NewRunnableFunction(
+          "CanvasRender::BackgroundHangSetup",
+          []() {
+            sBackgroundHangMonitor = new mozilla::BackgroundHangMonitor(
+                "CanvasRendererBHM",
+                /* Timeout values are powers-of-two to enable us get better
+                   data. 128ms is chosen for transient hangs because 8Hz should
+                   be the minimally acceptable goal for Compositor
+                   responsiveness (normal goal is 60Hz). */
+                128,
+                /* 2048ms is chosen for permanent hangs because it's longer than
+                 * most Compositor hangs seen in the wild, but is short enough
+                 * to not miss getting native hang stacks. */
+                2048);
+            nsCOMPtr<nsIThread> thread = NS_GetCurrentThread();
+            nsThread* nsthread = static_cast<nsThread*>(thread.get());
+            nsthread->SetUseHangMonitor(true);
+            nsthread->SetPriority(nsISupportsPriority::PRIORITY_HIGH);
+          }),
+      {.stackSize = stackSize});
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return;
+  }
+
+  sCanvasRenderThread = new CanvasRenderThread(
+      std::move(thread), std::move(workers), /* aCreatedThread */ true);
+}
+
+// static
+void CanvasRenderThread::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // It is possible we never initialized this thread in the parent process,
+  // because we used the GPU process instead.
+  if (!sCanvasRenderThread) {
+    MOZ_ASSERT(XRE_IsParentProcess());
+    return;
+  }
+
+  // This closes all of the IPDL actors with possibly active task queues.
+  CanvasManagerParent::Shutdown();
+
+  // Any task queues that are in the process of shutting down are tracked in
+  // mPendingShutdownTaskQueues. We need to block on each one until all events
+  // are flushed so that we can safely teardown RemoteTextureMap afterwards.
+  while (true) {
+    RefPtr<TaskQueue> taskQueue;
+    {
+      MutexAutoLock lock(sCanvasRenderThread->mMutex);
+
+      auto& pendingQueues = sCanvasRenderThread->mPendingShutdownTaskQueues;
+      if (pendingQueues.IsEmpty()) {
+        break;
+      }
+
+      taskQueue = pendingQueues.PopLastElement();
+    }
+    taskQueue->AwaitShutdownAndIdle();
+  }
+
+  bool createdThread = sCanvasRenderThread->mCreatedThread;
+  nsCOMPtr<nsIThread> oldThread = sCanvasRenderThread->GetCanvasRenderThread();
+  nsCOMPtr<nsIThreadPool> oldWorkers = sCanvasRenderThread->mWorkers;
+
+  // Ensure that we flush the CanvasRenderThread event queue before clearing our
+  // singleton.
+  NS_DispatchAndSpinEventLoopUntilComplete(
+      "CanvasRenderThread::Shutdown"_ns, oldThread,
+      NS_NewRunnableFunction("CanvasRenderThread::Shutdown", []() -> void {}));
+
+  // Null out sCanvasRenderThread before we enter synchronous Shutdown,
+  // from here on we are to be considered shut down for our consumers.
+  sCanvasRenderThread = nullptr;
+
+  if (oldWorkers) {
+    oldWorkers->Shutdown();
+  }
+
+  // We do a synchronous shutdown here while spinning the MT event loop, but
+  // only if we created a dedicated CanvasRender thread.
+  if (createdThread) {
+    oldThread->Shutdown();
+  }
+}
+
+// static
+bool CanvasRenderThread::IsInCanvasRenderThread() {
+  return sCanvasRenderThread &&
+         sCanvasRenderThread->mThread == NS_GetCurrentThread();
+}
+
+/* static */ bool CanvasRenderThread::IsInCanvasWorkerThread() {
+  // It is possible there are no worker threads, and the worker is the same as
+  // the CanvasRenderThread itself.
+  return sCanvasRenderThread &&
+         ((sCanvasRenderThread->mWorkers &&
+           sCanvasRenderThread->mWorkers->IsOnCurrentThread()) ||
+          (!sCanvasRenderThread->mWorkers &&
+           sCanvasRenderThread->mThread == NS_GetCurrentThread()));
+}
+
+/* static */ bool CanvasRenderThread::IsInCanvasRenderOrWorkerThread() {
+  // It is possible there are no worker threads, and the worker is the same as
+  // the CanvasRenderThread itself.
+  return sCanvasRenderThread &&
+         (sCanvasRenderThread->mThread == NS_GetCurrentThread() ||
+          (sCanvasRenderThread->mWorkers &&
+           sCanvasRenderThread->mWorkers->IsOnCurrentThread()));
+}
+
+// static
+already_AddRefed<nsIThread> CanvasRenderThread::GetCanvasRenderThread() {
+  nsCOMPtr<nsIThread> thread;
+  if (sCanvasRenderThread) {
+    thread = sCanvasRenderThread->mThread;
+  }
+  return thread.forget();
+}
+
+/* static */ already_AddRefed<TaskQueue>
+CanvasRenderThread::CreateWorkerTaskQueue() {
+  if (!sCanvasRenderThread || !sCanvasRenderThread->mWorkers) {
+    return nullptr;
+  }
+
+  return TaskQueue::Create(do_AddRef(sCanvasRenderThread->mWorkers),
+                           "CanvasWorker")
+      .forget();
+}
+
+/* static */ void CanvasRenderThread::ShutdownWorkerTaskQueue(
+    TaskQueue* aTaskQueue) {
+  MOZ_ASSERT(aTaskQueue);
+
+  aTaskQueue->BeginShutdown();
+
+  if (!sCanvasRenderThread) {
+    MOZ_ASSERT_UNREACHABLE("No CanvasRenderThread!");
+    return;
+  }
+
+  MutexAutoLock lock(sCanvasRenderThread->mMutex);
+  auto& pendingQueues = sCanvasRenderThread->mPendingShutdownTaskQueues;
+  pendingQueues.AppendElement(aTaskQueue);
+}
+
+/* static */ void CanvasRenderThread::FinishShutdownWorkerTaskQueue(
+    TaskQueue* aTaskQueue) {
+  if (!sCanvasRenderThread) {
+    return;
+  }
+
+  MutexAutoLock lock(sCanvasRenderThread->mMutex);
+  sCanvasRenderThread->mPendingShutdownTaskQueues.RemoveElement(aTaskQueue);
+}
+
+/* static */ void CanvasRenderThread::Dispatch(
+    already_AddRefed<nsIRunnable> aRunnable) {
+  if (!sCanvasRenderThread) {
+    MOZ_DIAGNOSTIC_ASSERT(false,
+                          "Dispatching after CanvasRenderThread shutdown!");
+    return;
+  }
+  sCanvasRenderThread->mThread->Dispatch(std::move(aRunnable));
+}
+
+}  // namespace mozilla::gfx