1/*
2 * Copyright (C) 2007 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 _LIBS_UTILS_THREAD_H
18#define _LIBS_UTILS_THREAD_H
19
20#include <stdint.h>
21#include <sys/types.h>
22#include <time.h>
23
24#if !defined(_WIN32)
25# include <pthread.h>
26#endif
27
28#include <utils/Condition.h>
29#include <utils/Errors.h>
30#include <utils/Mutex.h>
31#include <utils/RefBase.h>
32#include <utils/Timers.h>
33#include <utils/ThreadDefs.h>
34
35// ---------------------------------------------------------------------------
36namespace android {
37// ---------------------------------------------------------------------------
38
39// DO NOT USE: please use std::thread
40
41class Thread : virtual public RefBase
42{
43public:
44    // Create a Thread object, but doesn't create or start the associated
45    // thread. See the run() method.
46    explicit            Thread(bool canCallJava = true);
47    virtual             ~Thread();
48
49    // Start the thread in threadLoop() which needs to be implemented.
50    virtual status_t    run(    const char* name,
51                                int32_t priority = PRIORITY_DEFAULT,
52                                size_t stack = 0);
53
54    // Ask this object's thread to exit. This function is asynchronous, when the
55    // function returns the thread might still be running. Of course, this
56    // function can be called from a different thread.
57    virtual void        requestExit();
58
59    // Good place to do one-time initializations
60    virtual status_t    readyToRun();
61
62    // Call requestExit() and wait until this object's thread exits.
63    // BE VERY CAREFUL of deadlocks. In particular, it would be silly to call
64    // this function from this object's thread. Will return WOULD_BLOCK in
65    // that case.
66            status_t    requestExitAndWait();
67
68    // Wait until this object's thread exits. Returns immediately if not yet running.
69    // Do not call from this object's thread; will return WOULD_BLOCK in that case.
70            status_t    join();
71
72    // Indicates whether this thread is running or not.
73            bool        isRunning() const;
74
75#if defined(__ANDROID__)
76    // Return the thread's kernel ID, same as the thread itself calling gettid(),
77    // or -1 if the thread is not running.
78            pid_t       getTid() const;
79#endif
80
81protected:
82    // exitPending() returns true if requestExit() has been called.
83            bool        exitPending() const;
84
85private:
86    // Derived class must implement threadLoop(). The thread starts its life
87    // here. There are two ways of using the Thread object:
88    // 1) loop: if threadLoop() returns true, it will be called again if
89    //          requestExit() wasn't called.
90    // 2) once: if threadLoop() returns false, the thread will exit upon return.
91    virtual bool        threadLoop() = 0;
92
93private:
94    Thread& operator=(const Thread&);
95    static  int             _threadLoop(void* user);
96    const   bool            mCanCallJava;
97    // always hold mLock when reading or writing
98            thread_id_t     mThread;
99    mutable Mutex           mLock;
100            Condition       mThreadExitedCondition;
101            status_t        mStatus;
102    // note that all accesses of mExitPending and mRunning need to hold mLock
103    volatile bool           mExitPending;
104    volatile bool           mRunning;
105            sp<Thread>      mHoldSelf;
106#if defined(__ANDROID__)
107    // legacy for debugging, not used by getTid() as it is set by the child thread
108    // and so is not initialized until the child reaches that point
109            pid_t           mTid;
110#endif
111};
112
113
114}; // namespace android
115
116// ---------------------------------------------------------------------------
117#endif // _LIBS_UTILS_THREAD_H
118// ---------------------------------------------------------------------------
119