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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ANDROID_MESSAGE_QUEUE_H
     18 #define ANDROID_MESSAGE_QUEUE_H
     19 
     20 #include <stdint.h>
     21 #include <errno.h>
     22 #include <sys/types.h>
     23 
     24 #include <utils/threads.h>
     25 #include <utils/Timers.h>
     26 #include <utils/List.h>
     27 
     28 #include "Barrier.h"
     29 
     30 namespace android {
     31 
     32 // ---------------------------------------------------------------------------
     33 
     34 class MessageBase;
     35 
     36 class MessageList
     37 {
     38     List< sp<MessageBase> > mList;
     39     typedef List< sp<MessageBase> > LIST;
     40 public:
     41     inline LIST::iterator begin()                { return mList.begin(); }
     42     inline LIST::const_iterator begin() const    { return mList.begin(); }
     43     inline LIST::iterator end()                  { return mList.end(); }
     44     inline LIST::const_iterator end() const      { return mList.end(); }
     45     inline bool isEmpty() const { return mList.empty(); }
     46     void insert(const sp<MessageBase>& node);
     47     void remove(LIST::iterator pos);
     48 };
     49 
     50 // ============================================================================
     51 
     52 class MessageBase :
     53     public LightRefBase<MessageBase>
     54 {
     55 public:
     56     nsecs_t     when;
     57     uint32_t    what;
     58     int32_t     arg0;
     59 
     60     MessageBase() : when(0), what(0), arg0(0) { }
     61     MessageBase(uint32_t what, int32_t arg0=0)
     62         : when(0), what(what), arg0(arg0) { }
     63 
     64     // return true if message has a handler
     65     virtual bool handler() { return false; }
     66 
     67     // waits for the handler to be processed
     68     void wait() const { barrier.wait(); }
     69 
     70     // releases all waiters. this is done automatically if
     71     // handler returns true
     72     void notify() const { barrier.open(); }
     73 
     74 protected:
     75     virtual ~MessageBase() { }
     76 
     77 private:
     78     mutable Barrier barrier;
     79     friend class LightRefBase<MessageBase>;
     80 };
     81 
     82 inline bool operator < (const MessageBase& lhs, const MessageBase& rhs) {
     83     return lhs.when < rhs.when;
     84 }
     85 
     86 // ---------------------------------------------------------------------------
     87 
     88 class MessageQueue
     89 {
     90     typedef List< sp<MessageBase> > LIST;
     91 public:
     92 
     93     MessageQueue();
     94     ~MessageQueue();
     95 
     96     // pre-defined messages
     97     enum {
     98         INVALIDATE = '_upd'
     99     };
    100 
    101     sp<MessageBase> waitMessage(nsecs_t timeout = -1);
    102 
    103     status_t postMessage(const sp<MessageBase>& message,
    104             nsecs_t reltime=0, uint32_t flags = 0);
    105 
    106     status_t invalidate();
    107 
    108     void dump(const sp<MessageBase>& message);
    109 
    110 private:
    111     status_t queueMessage(const sp<MessageBase>& message,
    112             nsecs_t reltime, uint32_t flags);
    113     void dumpLocked(const sp<MessageBase>& message);
    114 
    115     Mutex           mLock;
    116     Condition       mCondition;
    117     MessageList     mMessages;
    118     bool            mInvalidate;
    119     sp<MessageBase> mInvalidateMessage;
    120 };
    121 
    122 // ---------------------------------------------------------------------------
    123 
    124 }; // namespace android
    125 
    126 #endif /* ANDROID_MESSAGE_QUEUE_H */
    127