1 /* 2 * Copyright (C) 2016 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 CHRE_UTIL_FIXED_SIZE_BLOCKING_QUEUE_H_ 18 #define CHRE_UTIL_FIXED_SIZE_BLOCKING_QUEUE_H_ 19 20 #include <deque> 21 22 #include "chre/platform/condition_variable.h" 23 #include "chre/platform/mutex.h" 24 #include "chre/util/array_queue.h" 25 #include "chre/util/non_copyable.h" 26 27 namespace chre { 28 29 /** 30 * Implements a thread-safe blocking queue that blocks when popping an element 31 * if necessary. 32 */ 33 template <typename ElementType, size_t kSize> 34 class FixedSizeBlockingQueue : public NonCopyable { 35 public: 36 /** 37 * Pushes an element into the queue and notifies any waiting threads that an 38 * element is available. 39 * 40 * @param The element to be pushed. 41 * 42 * @return true if the element is pushed successfully. 43 */ 44 bool push(const ElementType& element); 45 bool push(ElementType&& element); 46 47 /** 48 * Pops one element from the queue. If the queue is empty, the thread will 49 * block until an element has been pushed. 50 * 51 * @return The element that was popped. 52 */ 53 ElementType pop(); 54 55 /** 56 * Determines whether or not the BlockingQueue is empty. 57 */ 58 bool empty(); 59 60 /** 61 * Determines the current size of the BlockingQueue. 62 */ 63 size_t size(); 64 65 /** 66 * Removes an element from the array queue given an index. It returns false if 67 * the index is out of bounds of the underlying array queue. 68 * 69 * @param index Requested index in range [0,size()-1] 70 * @return true if the indexed element has been removed successfully. 71 */ 72 bool remove(size_t index); 73 74 /** 75 * Obtains an element of the array queue given an index. It is illegal to 76 * index this array queue out of bounds and the user of the API must check the 77 * size() function prior to indexing this array queue to ensure that they will 78 * not read out of bounds. 79 * 80 * @param index Requested index in range [0,size()-1] 81 * @return The element. 82 */ 83 ElementType& operator[](size_t index); 84 85 /** 86 * Obtains a const element of the queue given an index. It is illegal to index 87 * this queue out of bounds and the user of the API must check the size() 88 * function prior to indexing this queue to ensure that they will not read out 89 * of bounds. 90 * 91 * @param index Requested index in the rante [0,size()-1] 92 * @return The element. 93 */ 94 const ElementType& operator[](size_t index) const; 95 96 private: 97 //! The mutex used to ensure thread-safety. 98 Mutex mMutex; 99 100 //! The condition variable used to implement the blocking behavior of the 101 //! queue. 102 ConditionVariable mConditionVariable; 103 104 //! The underlying fixed size container backing the queue. 105 ArrayQueue<ElementType, kSize> mQueue; 106 }; 107 108 } // namespace chre 109 110 #include "chre/util/fixed_size_blocking_queue_impl.h" 111 112 #endif // CHRE_UTIL_FIXED_SIZE_BLOCKING_QUEUE_H_ 113
