1 files changed, 103 insertions, 0 deletions
diff --git a/dom/canvas/WebGLContextLossHandler.cpp b/dom/canvas/WebGLContextLossHandler.cpp
new file mode 100644
index 000000000..1f50896a5
--- /dev/null
+++ b/dom/canvas/WebGLContextLossHandler.cpp
@@ -0,0 +1,103 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 "WebGLContextLossHandler.h"
+
+#include "mozilla/DebugOnly.h"
+#include "nsISupportsImpl.h"
+#include "nsITimer.h"
+#include "nsThreadUtils.h"
+#include "WebGLContext.h"
+
+namespace mozilla {
+
+class WatchdogTimerEvent final : public nsITimerCallback
+{
+    const WeakPtr<WebGLContextLossHandler> mHandler;
+
+public:
+    NS_DECL_ISUPPORTS
+
+    explicit WatchdogTimerEvent(WebGLContextLossHandler* handler)
+        : mHandler(handler)
+    { }
+
+private:
+    virtual ~WatchdogTimerEvent() { }
+
+    NS_IMETHOD Notify(nsITimer*) override {
+        if (mHandler) {
+            mHandler->TimerCallback();
+        }
+        return NS_OK;
+    }
+};
+
+NS_IMPL_ISUPPORTS(WatchdogTimerEvent, nsITimerCallback, nsISupports)
+
+////////////////////////////////////////
+
+WebGLContextLossHandler::WebGLContextLossHandler(WebGLContext* webgl)
+    : mWebGL(webgl)
+    , mTimer(do_CreateInstance(NS_TIMER_CONTRACTID))
+    , mTimerPending(false)
+    , mShouldRunTimerAgain(false)
+#ifdef DEBUG
+    , mThread(NS_GetCurrentThread())
+#endif
+{
+    MOZ_ASSERT(mThread);
+}
+
+WebGLContextLossHandler::~WebGLContextLossHandler()
+{
+    // NS_GetCurrentThread() returns null during shutdown.
+    const DebugOnly<nsIThread*> callingThread = NS_GetCurrentThread();
+    MOZ_ASSERT(callingThread == mThread || !callingThread);
+}
+
+////////////////////
+
+void
+WebGLContextLossHandler::RunTimer()
+{
+    MOZ_ASSERT(NS_GetCurrentThread() == mThread);
+
+    // If the timer was already running, don't restart it here. Instead,
+    // wait until the previous call is done, then fire it one more time.
+    // This is also an optimization to prevent unnecessary
+    // cross-communication between threads.
+    if (mTimerPending) {
+        mShouldRunTimerAgain = true;
+        return;
+    }
+
+    const RefPtr<WatchdogTimerEvent> event = new WatchdogTimerEvent(this);
+    const uint32_t kDelayMS = 1000;
+    mTimer->InitWithCallback(event, kDelayMS, nsITimer::TYPE_ONE_SHOT);
+
+    mTimerPending = true;
+}
+
+////////////////////
+
+void
+WebGLContextLossHandler::TimerCallback()
+{
+    MOZ_ASSERT(NS_GetCurrentThread() == mThread);
+
+    mTimerPending = false;
+
+    const bool runOnceMore = mShouldRunTimerAgain;
+    mShouldRunTimerAgain = false;
+
+    mWebGL->UpdateContextLossStatus();
+
+    if (runOnceMore && !mTimerPending) {
+        RunTimer();
+    }
+}
+
+} // namespace mozilla