1 files changed, 74 insertions, 0 deletions
diff --git a/gfx/angle/src/libANGLE/signal_utils.h b/gfx/angle/src/libANGLE/signal_utils.h
new file mode 100755
index 000000000..835f2c602
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+++ b/gfx/angle/src/libANGLE/signal_utils.h
@@ -0,0 +1,74 @@
+//
+// Copyright 2016 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// signal_utils:
+//   Helper classes for tracking dependent state changes between objects.
+//   These changes are signaled to the dependent class via channels.
+
+#ifndef LIBANGLE_SIGNAL_UTILS_H_
+#define LIBANGLE_SIGNAL_UTILS_H_
+
+#include <set>
+
+#include "common/angleutils.h"
+
+namespace angle
+{
+
+// Message token passed to the receiver;
+using SignalToken = uint32_t;
+
+// Interface that the depending class inherits from.
+class SignalReceiver
+{
+  public:
+    virtual ~SignalReceiver() = default;
+    virtual void signal(SignalToken token) = 0;
+};
+
+class ChannelBinding;
+
+// The host class owns the channel. It uses the channel to fire signals to the receiver.
+class BroadcastChannel final : NonCopyable
+{
+  public:
+    BroadcastChannel();
+    ~BroadcastChannel();
+
+    void signal() const;
+    void reset();
+
+  private:
+    // Only the ChannelBinding class should add or remove receivers.
+    friend class ChannelBinding;
+    void addReceiver(ChannelBinding *receiver);
+    void removeReceiver(ChannelBinding *receiver);
+
+    std::vector<ChannelBinding *> mReceivers;
+};
+
+// The dependent class keeps bindings to the host's BroadcastChannel.
+class ChannelBinding final
+{
+  public:
+    ChannelBinding(SignalReceiver *receiver, SignalToken token);
+    ~ChannelBinding();
+    ChannelBinding(const ChannelBinding &other) = default;
+    ChannelBinding &operator=(const ChannelBinding &other) = default;
+
+    void bind(BroadcastChannel *channel);
+    void reset();
+    void signal() const;
+    void onChannelClosed();
+
+  private:
+    BroadcastChannel *mChannel;
+    SignalReceiver *mReceiver;
+    SignalToken mToken;
+};
+
+}  // namespace angle
+
+#endif  // LIBANGLE_SIGNAL_UTILS_H_