MessageQueue.h revision 81bac09fa6b01dd1495644d9c825c3666762fced 
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
30namespace android {
31
32// ---------------------------------------------------------------------------
33
34class MessageBase;
35
36class MessageList
37{
38    List< sp<MessageBase> > mList;
39    typedef List< sp<MessageBase> > LIST;
40public:
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
52class MessageBase :
53    public LightRefBase<MessageBase>
54{
55public:
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
74protected:
75    virtual ~MessageBase() { }
76
77private:
78    mutable Barrier barrier;
79    friend class LightRefBase<MessageBase>;
80};
81
82inline bool operator < (const MessageBase& lhs, const MessageBase& rhs) {
83    return lhs.when < rhs.when;
84}
85
86// ---------------------------------------------------------------------------
87
88class MessageQueue
89{
90    typedef List< sp<MessageBase> > LIST;
91public:
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
110private:
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