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_CONDITION_H 18 #define _LIBS_UTILS_CONDITION_H 19 20 #include <stdint.h> 21 #include <sys/types.h> 22 #include <time.h> 23 24 #if defined(HAVE_PTHREADS) 25 # include <pthread.h> 26 #endif 27 28 #include <utils/Errors.h> 29 #include <utils/Mutex.h> 30 #include <utils/Timers.h> 31 32 // --------------------------------------------------------------------------- 33 namespace android { 34 // --------------------------------------------------------------------------- 35 36 /* 37 * Condition variable class. The implementation is system-dependent. 38 * 39 * Condition variables are paired up with mutexes. Lock the mutex, 40 * call wait(), then either re-wait() if things aren't quite what you want, 41 * or unlock the mutex and continue. All threads calling wait() must 42 * use the same mutex for a given Condition. 43 */ 44 class Condition { 45 public: 46 enum { 47 PRIVATE = 0, 48 SHARED = 1 49 }; 50 51 Condition(); 52 Condition(int type); 53 ~Condition(); 54 // Wait on the condition variable. Lock the mutex before calling. 55 status_t wait(Mutex& mutex); 56 // same with relative timeout 57 status_t waitRelative(Mutex& mutex, nsecs_t reltime); 58 // Signal the condition variable, allowing one thread to continue. 59 void signal(); 60 // Signal the condition variable, allowing all threads to continue. 61 void broadcast(); 62 63 private: 64 #if defined(HAVE_PTHREADS) 65 pthread_cond_t mCond; 66 #else 67 void* mState; 68 #endif 69 }; 70 71 // --------------------------------------------------------------------------- 72 73 #if defined(HAVE_PTHREADS) 74 75 inline Condition::Condition() { 76 pthread_cond_init(&mCond, NULL); 77 } 78 inline Condition::Condition(int type) { 79 if (type == SHARED) { 80 pthread_condattr_t attr; 81 pthread_condattr_init(&attr); 82 pthread_condattr_setpshared(&attr, PTHREAD_PROCESS_SHARED); 83 pthread_cond_init(&mCond, &attr); 84 pthread_condattr_destroy(&attr); 85 } else { 86 pthread_cond_init(&mCond, NULL); 87 } 88 } 89 inline Condition::~Condition() { 90 pthread_cond_destroy(&mCond); 91 } 92 inline status_t Condition::wait(Mutex& mutex) { 93 return -pthread_cond_wait(&mCond, &mutex.mMutex); 94 } 95 inline status_t Condition::waitRelative(Mutex& mutex, nsecs_t reltime) { 96 #if defined(HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE) 97 struct timespec ts; 98 ts.tv_sec = reltime/1000000000; 99 ts.tv_nsec = reltime%1000000000; 100 return -pthread_cond_timedwait_relative_np(&mCond, &mutex.mMutex, &ts); 101 #else // HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE 102 struct timespec ts; 103 #if defined(HAVE_POSIX_CLOCKS) 104 clock_gettime(CLOCK_REALTIME, &ts); 105 #else // HAVE_POSIX_CLOCKS 106 // we don't support the clocks here. 107 struct timeval t; 108 gettimeofday(&t, NULL); 109 ts.tv_sec = t.tv_sec; 110 ts.tv_nsec= t.tv_usec*1000; 111 #endif // HAVE_POSIX_CLOCKS 112 ts.tv_sec += reltime/1000000000; 113 ts.tv_nsec+= reltime%1000000000; 114 if (ts.tv_nsec >= 1000000000) { 115 ts.tv_nsec -= 1000000000; 116 ts.tv_sec += 1; 117 } 118 return -pthread_cond_timedwait(&mCond, &mutex.mMutex, &ts); 119 #endif // HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE 120 } 121 inline void Condition::signal() { 122 pthread_cond_signal(&mCond); 123 } 124 inline void Condition::broadcast() { 125 pthread_cond_broadcast(&mCond); 126 } 127 128 #endif // HAVE_PTHREADS 129 130 // --------------------------------------------------------------------------- 131 }; // namespace android 132 // --------------------------------------------------------------------------- 133 134 #endif // _LIBS_UTILS_CONDITON_H 135