Home | History | Annotate | Download | only in utils 
      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 // ---------------------------------------------------------------------------
     36 namespace android {
     37 // ---------------------------------------------------------------------------
     38 
     39 // DO NOT USE: please use std::thread
     40 
     41 class Thread : virtual public RefBase
     42 {
     43 public:
     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 
     81 protected:
     82     // exitPending() returns true if requestExit() has been called.
     83             bool        exitPending() const;
     84 
     85 private:
     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 
     93 private:
     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