diff --git a/libs/surfaceflinger/MessageQueue.h b/libs/surfaceflinger/MessageQueue.h
new file mode 100644
index 0000000..d894fe2
--- /dev/null
+++ b/libs/surfaceflinger/MessageQueue.h
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_MESSAGE_QUEUE_H
+#define ANDROID_MESSAGE_QUEUE_H
+
+#include <stdint.h>
+#include <errno.h>
+#include <sys/types.h>
+
+#include <utils/threads.h>
+#include <utils/Timers.h>
+
+
+namespace android {
+
+// ---------------------------------------------------------------------------
+
+template<typename NODE_PTR_TYPE>
+class DoublyLinkedList
+{
+protected:
+    typedef NODE_PTR_TYPE NODE_PTR;
+    
+    NODE_PTR  mFirst;
+    NODE_PTR  mLast;
+
+public:
+    class Node {
+        friend class DoublyLinkedList;
+        mutable NODE_PTR next;
+        mutable NODE_PTR prev;
+    public:
+        typedef NODE_PTR PTR;
+        inline NODE_PTR getNext() const { return next; }
+        inline NODE_PTR getPrev() const { return prev; }
+        void detach() { 
+            prev = 0;
+            next = 0;
+        }
+    };
+
+    DoublyLinkedList() : mFirst(0), mLast(0) { }
+    ~DoublyLinkedList() { }
+    
+    bool        isEmpty() const { return mFirst == 0; }
+    const NODE_PTR& head() const { return mFirst; }
+    const NODE_PTR& tail() const { return mLast; }
+    const NODE_PTR& head() { return mFirst; }
+    const NODE_PTR& tail() { return mLast; }
+
+    void insertAfter(const NODE_PTR& node, const NODE_PTR& newNode) {
+        newNode->prev = node;
+        newNode->next = node->next;
+        if (node->next == 0) mLast = newNode;
+        else                 node->next->prev = newNode;
+        node->next = newNode;
+    }
+
+    void insertBefore(const NODE_PTR& node, const NODE_PTR& newNode) {
+        newNode->prev = node->prev;
+        newNode->next = node;
+        if (node->prev == 0)   mFirst = newNode;
+        else                   node->prev->next = newNode;
+        node->prev = newNode;
+    }
+
+    void insertHead(const NODE_PTR& newNode) {
+        if (mFirst == 0) {
+            mFirst = mLast = newNode;
+            newNode->prev = newNode->next = 0;
+        } else {
+            newNode->prev = 0;
+            newNode->next = mFirst;
+            mFirst->prev = newNode;
+            mFirst = newNode;
+        }
+    }
+
+    void insertTail(const NODE_PTR& newNode) {
+        if (mLast == 0) {
+            insertHead(newNode);
+        } else {
+            newNode->prev = mLast;
+            newNode->next = 0;
+            mLast->next = newNode;
+            mLast = newNode;
+        }
+    }
+
+    NODE_PTR remove(const NODE_PTR& node) {
+        if (node->prev == 0)    mFirst = node->next;
+        else                    node->prev->next = node->next;
+        if (node->next == 0)    mLast = node->prev;
+        else                    node->next->prev = node->prev;
+        return node;
+    }
+};
+
+// ---------------------------------------------------------------------------
+
+template<typename NODE_PTR_TYPE>
+class SortedList : protected DoublyLinkedList< NODE_PTR_TYPE > 
+{
+    typedef DoublyLinkedList< NODE_PTR_TYPE > forward;
+public:
+    typedef NODE_PTR_TYPE NODE_PTR;
+    inline bool isEmpty() const { return forward::isEmpty(); }
+    inline const NODE_PTR& head() const { return forward::head(); }
+    inline const NODE_PTR& tail() const { return forward::tail(); }
+    inline const NODE_PTR& head() { return forward::head(); }
+    inline const NODE_PTR& tail() { return forward::tail(); }
+    inline NODE_PTR remove(const NODE_PTR& node) { return forward::remove(node); }
+    void insert(const NODE_PTR& node) {
+        NODE_PTR l(head());
+        while (l != 0) {
+            if (*node < *l) {
+                insertBefore(l, node);
+                return;
+            }
+            l = l->getNext();
+        }
+        insertTail(node);
+    }
+};
+
+// ============================================================================
+
+class MessageBase : 
+    public LightRefBase<MessageBase>, 
+    public DoublyLinkedList< sp<MessageBase> >::Node
+{
+public:
+    nsecs_t     when;
+    uint32_t    what;
+    int32_t     arg0;    
+
+    MessageBase(uint32_t what=0, int32_t arg0=0)
+    : when(0), what(what), arg0(arg0) { }
+    
+    // return true if message has a handler
+    virtual bool handler() { return false; }
+    
+protected:
+    virtual ~MessageBase() { }
+
+private:
+    friend class LightRefBase<MessageBase>;
+};
+
+inline bool operator < (const MessageBase& lhs, const MessageBase& rhs) {
+    return lhs.when < rhs.when;
+}
+
+// ---------------------------------------------------------------------------
+
+/*
+ * MessageList is a sorted list of sp<MessageBase>
+ */
+    
+typedef SortedList< MessageBase::Node::PTR > MessageList; 
+
+// ---------------------------------------------------------------------------
+
+class MessageQueue
+{
+public:
+
+    // this is a work-around the multichar constant warning. A macro would
+    // work too, but would pollute the namespace.
+    template <int a, int b, int c, int d>
+    struct WHAT {
+        static const uint32_t Value = 
+            (uint32_t(a&0xff)<<24)|(uint32_t(b&0xff)<<16)|
+            (uint32_t(c&0xff)<<8)|uint32_t(d&0xff);
+    };
+    
+    MessageQueue();
+    ~MessageQueue();
+
+    // pre-defined messages
+    enum {
+        INVALIDATE = WHAT<'_','p','d','t'>::Value
+    };
+
+    MessageList::NODE_PTR waitMessage(nsecs_t timeout = -1);
+    
+    status_t postMessage(const MessageList::NODE_PTR& message, 
+            nsecs_t reltime=0, uint32_t flags = 0);
+        
+    status_t invalidate();
+    
+    void dump(const MessageList::NODE_PTR& message);
+
+private:
+    status_t queueMessage(const MessageList::NODE_PTR& message,
+            nsecs_t reltime, uint32_t flags);
+    void dumpLocked(const MessageList::NODE_PTR& message);
+    
+    Mutex           mLock;
+    Condition       mCondition;
+    MessageList     mMessages;
+    bool            mInvalidate;
+    MessageList::NODE_PTR mInvalidateMessage;
+};
+
+// ---------------------------------------------------------------------------
+
+}; // namespace android
+
+#endif /* ANDROID_MESSAGE_QUEUE_H */