LibWeb: Make DOM timers cancellable and stop leaking them

This patch adds a Web::Timer object that represents a single timer
registration made with window.setTimeout() or window.setInterval().
All live timers are owned by the DOM Window object.

The timers can be stopped via clearTimeout() or clearInterval().
Note that those API's are actually interchangeable, but we have to
support both.

1 files changed, 63 insertions, 0 deletions

diff --git a/Libraries/LibWeb/DOM/Timer.h b/Libraries/LibWeb/DOM/Timer.h
new file mode 100644
index 0000000000..562a3cf542
--- /dev/null
+++ b/Libraries/LibWeb/DOM/Timer.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Forward.h>
+#include <LibCore/Forward.h>
+#include <LibJS/Heap/Handle.h>
+#include <LibWeb/Forward.h>
+
+namespace Web {
+
+class Timer final : public RefCounted<Timer> {
+public:
+    enum class Type {
+        Interval,
+        Timeout,
+    };
+
+    static NonnullRefPtr<Timer> create_interval(Window&, int milliseconds, JS::Function&);
+    static NonnullRefPtr<Timer> create_timeout(Window&, int milliseconds, JS::Function&);
+
+    ~Timer();
+
+    i32 id() const { return m_id; }
+    Type type() const { return m_type; }
+
+    JS::Function& callback() { return *m_callback.cell(); }
+
+private:
+    Timer(Window&, Type, int ms, JS::Function&);
+
+    Window& m_window;
+    RefPtr<Core::Timer> m_timer;
+    Type m_type;
+    int m_id { 0 };
+    JS::Handle<JS::Function> m_callback;
+};
+
+}