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