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