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 ANDROID_BARRIER_H 18 #define ANDROID_BARRIER_H 19 20 #include <stdint.h> 21 #include <sys/types.h> 22 #include <utils/threads.h> 23 24 namespace android { 25 26 class Barrier 27 { 28 public: Barrier()29 inline Barrier() : state(CLOSED) { } ~Barrier()30 inline ~Barrier() { } open()31 void open() { 32 // gcc memory barrier, this makes sure all memory writes 33 // have been issued by gcc. On an SMP system we'd need a real 34 // h/w barrier. 35 asm volatile ("":::"memory"); 36 Mutex::Autolock _l(lock); 37 state = OPENED; 38 cv.broadcast(); 39 } close()40 void close() { 41 Mutex::Autolock _l(lock); 42 state = CLOSED; 43 } wait()44 void wait() const { 45 Mutex::Autolock _l(lock); 46 while (state == CLOSED) { 47 cv.wait(lock); 48 } 49 } 50 private: 51 enum { OPENED, CLOSED }; 52 mutable Mutex lock; 53 mutable Condition cv; 54 volatile int state; 55 }; 56 57 }; // namespace android 58 59 #endif // ANDROID_BARRIER_H 60