1 /* 2 * Copyright (C) 2012 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 #include "barrier.h" 18 19 #include "base/mutex.h" 20 #include "thread.h" 21 22 namespace art { 23 24 Barrier::Barrier(int count) 25 : count_(count), 26 lock_("GC barrier lock"), 27 condition_("GC barrier condition", lock_) { 28 } 29 30 void Barrier::Pass(Thread* self) { 31 MutexLock mu(self, lock_); 32 SetCountLocked(self, count_ - 1); 33 } 34 35 void Barrier::Wait(Thread* self) { 36 Increment(self, -1); 37 } 38 39 void Barrier::Init(Thread* self, int count) { 40 MutexLock mu(self, lock_); 41 SetCountLocked(self, count); 42 } 43 44 void Barrier::Increment(Thread* self, int delta) { 45 MutexLock mu(self, lock_); 46 SetCountLocked(self, count_ + delta); 47 48 // Increment the count. If it becomes zero after the increment 49 // then all the threads have already passed the barrier. If 50 // it is non-zero then there is still one or more threads 51 // that have not yet called the Pass function. When the 52 // Pass function is called by the last thread, the count will 53 // be decremented to zero and a Broadcast will be made on the 54 // condition variable, thus waking this up. 55 if (count_ != 0) { 56 condition_.Wait(self); 57 } 58 } 59 60 void Barrier::Increment(Thread* self, int delta, uint32_t timeout_ms) { 61 MutexLock mu(self, lock_); 62 SetCountLocked(self, count_ + delta); 63 if (count_ != 0) { 64 condition_.TimedWait(self, timeout_ms, 0); 65 } 66 } 67 68 void Barrier::SetCountLocked(Thread* self, int count) { 69 count_ = count; 70 if (count_ == 0) { 71 condition_.Broadcast(self); 72 } 73 } 74 75 Barrier::~Barrier() { 76 CHECK(!count_) << "Attempted to destroy barrier with non zero count"; 77 } 78 79 } // namespace art 80
