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 // NOLINTNEXTLINE(google-default-arguments) 51 virtual status_t run( const char* name, 52 int32_t priority = PRIORITY_DEFAULT, 53 size_t stack = 0); 54 55 // Ask this object's thread to exit. This function is asynchronous, when the 56 // function returns the thread might still be running. Of course, this 57 // function can be called from a different thread. 58 virtual void requestExit(); 59 60 // Good place to do one-time initializations 61 virtual status_t readyToRun(); 62 63 // Call requestExit() and wait until this object's thread exits. 64 // BE VERY CAREFUL of deadlocks. In particular, it would be silly to call 65 // this function from this object's thread. Will return WOULD_BLOCK in 66 // that case. 67 status_t requestExitAndWait(); 68 69 // Wait until this object's thread exits. Returns immediately if not yet running. 70 // Do not call from this object's thread; will return WOULD_BLOCK in that case. 71 status_t join(); 72 73 // Indicates whether this thread is running or not. 74 bool isRunning() const; 75 76 #if defined(__ANDROID__) 77 // Return the thread's kernel ID, same as the thread itself calling gettid(), 78 // or -1 if the thread is not running. 79 pid_t getTid() const; 80 #endif 81 82 protected: 83 // exitPending() returns true if requestExit() has been called. 84 bool exitPending() const; 85 86 private: 87 // Derived class must implement threadLoop(). The thread starts its life 88 // here. There are two ways of using the Thread object: 89 // 1) loop: if threadLoop() returns true, it will be called again if 90 // requestExit() wasn't called. 91 // 2) once: if threadLoop() returns false, the thread will exit upon return. 92 virtual bool threadLoop() = 0; 93 94 private: 95 Thread& operator=(const Thread&); 96 static int _threadLoop(void* user); 97 const bool mCanCallJava; 98 // always hold mLock when reading or writing 99 thread_id_t mThread; 100 mutable Mutex mLock; 101 Condition mThreadExitedCondition; 102 status_t mStatus; 103 // note that all accesses of mExitPending and mRunning need to hold mLock 104 volatile bool mExitPending; 105 volatile bool mRunning; 106 sp<Thread> mHoldSelf; 107 #if defined(__ANDROID__) 108 // legacy for debugging, not used by getTid() as it is set by the child thread 109 // and so is not initialized until the child reaches that point 110 pid_t mTid; 111 #endif 112 }; 113 114 } // namespace android 115 116 // --------------------------------------------------------------------------- 117 #endif // _LIBS_UTILS_THREAD_H 118 // --------------------------------------------------------------------------- 119