1 files changed, 142 insertions, 0 deletions
diff --git a/gfx/layers/apz/util/APZTaskRunnable.cpp b/gfx/layers/apz/util/APZTaskRunnable.cpp
new file mode 100644
index 0000000000..6192f385a7
--- /dev/null
+++ b/gfx/layers/apz/util/APZTaskRunnable.cpp
@@ -0,0 +1,142 @@
+/* -*- 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 "APZTaskRunnable.h"
+
+#include "mozilla/PresShell.h"
+#include "nsRefreshDriver.h"
+
+namespace mozilla::layers {
+
+NS_IMETHODIMP
+APZTaskRunnable::Run() {
+  if (!mController) {
+    mRegisteredPresShellId = 0;
+    return NS_OK;
+  }
+
+  // Move these variables first since below RequestContentPaint and
+  // NotifyFlushComplete might spin event loop so that any new incoming requests
+  // will be properly queued and run in the next refresh driver's tick.
+  const bool needsFlushCompleteNotification = mNeedsFlushCompleteNotification;
+  auto requests = std::move(mPendingRepaintRequestQueue);
+  mPendingRepaintRequestMap.clear();
+  mNeedsFlushCompleteNotification = false;
+  mRegisteredPresShellId = 0;
+  RefPtr<GeckoContentController> controller = mController;
+
+  // We need to process pending RepaintRequests first.
+  while (!requests.empty()) {
+    controller->RequestContentRepaint(requests.front());
+    requests.pop_front();
+  }
+
+  if (needsFlushCompleteNotification) {
+    // Then notify "apz-repaints-flushed" so that we can ensure that all pending
+    // scroll position updates have finished when the "apz-repaints-flushed"
+    // arrives.
+    controller->NotifyFlushComplete();
+  }
+
+  return NS_OK;
+}
+
+void APZTaskRunnable::QueueRequest(const RepaintRequest& aRequest) {
+  // If we are in test-controlled refreshes mode, process this |aRequest|
+  // synchronously.
+  if (IsTestControllingRefreshesEnabled()) {
+    // Flush all pending requests and notification just in case the refresh
+    // driver mode was changed before flushing them.
+    RefPtr<GeckoContentController> controller = mController;
+    Run();
+    controller->RequestContentRepaint(aRequest);
+    return;
+  }
+  EnsureRegisterAsEarlyRunner();
+
+  RepaintRequestKey key{aRequest.GetScrollId(), aRequest.GetScrollUpdateType()};
+
+  auto lastDiscardableRequest = mPendingRepaintRequestMap.find(key);
+  // If there's an existing request with the same key, we can discard it and we
+  // push the incoming one into the queue's tail so that we can ensure the order
+  // of processing requests.
+  if (lastDiscardableRequest != mPendingRepaintRequestMap.end()) {
+    for (auto it = mPendingRepaintRequestQueue.begin();
+         it != mPendingRepaintRequestQueue.end(); it++) {
+      if (RepaintRequestKey{it->GetScrollId(), it->GetScrollUpdateType()} ==
+          key) {
+        mPendingRepaintRequestQueue.erase(it);
+        break;
+      }
+    }
+  }
+  mPendingRepaintRequestMap.insert(key);
+  mPendingRepaintRequestQueue.push_back(aRequest);
+}
+
+void APZTaskRunnable::QueueFlushCompleteNotification() {
+  // If we are in test-controlled refreshes mode, notify apz-repaints-flushed
+  // synchronously.
+  if (IsTestControllingRefreshesEnabled()) {
+    // Flush all pending requests and notification just in case the refresh
+    // driver mode was changed before flushing them.
+    RefPtr<GeckoContentController> controller = mController;
+    Run();
+    controller->NotifyFlushComplete();
+    return;
+  }
+
+  EnsureRegisterAsEarlyRunner();
+
+  mNeedsFlushCompleteNotification = true;
+}
+
+bool APZTaskRunnable::IsRegisteredWithCurrentPresShell() const {
+  MOZ_ASSERT(mController);
+
+  uint32_t current = 0;
+  if (PresShell* presShell = mController->GetTopLevelPresShell()) {
+    current = presShell->GetPresShellId();
+  }
+  return mRegisteredPresShellId == current;
+}
+
+void APZTaskRunnable::EnsureRegisterAsEarlyRunner() {
+  if (IsRegisteredWithCurrentPresShell()) {
+    return;
+  }
+
+  // If the registered presshell id has been changed, we need to discard pending
+  // requests and notification since all of them are for documents which
+  // have been torn down.
+  if (mRegisteredPresShellId) {
+    mPendingRepaintRequestMap.clear();
+    mPendingRepaintRequestQueue.clear();
+    mNeedsFlushCompleteNotification = false;
+  }
+
+  if (PresShell* presShell = mController->GetTopLevelPresShell()) {
+    if (nsRefreshDriver* driver = presShell->GetRefreshDriver()) {
+      driver->AddEarlyRunner(this);
+      mRegisteredPresShellId = presShell->GetPresShellId();
+    }
+  }
+}
+
+bool APZTaskRunnable::IsTestControllingRefreshesEnabled() const {
+  if (!mController) {
+    return false;
+  }
+
+  if (PresShell* presShell = mController->GetTopLevelPresShell()) {
+    if (nsRefreshDriver* driver = presShell->GetRefreshDriver()) {
+      return driver->IsTestControllingRefreshesEnabled();
+    }
+  }
+  return false;
+}
+
+}  // namespace mozilla::layers