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00001 /********************************************************************* 00002 * Software License Agreement (BSD License) 00003 * 00004 * Copyright (c) 2010, Willow Garage, Inc. 00005 * All rights reserved. 00006 * 00007 * Redistribution and use in source and binary forms, with or without 00008 * modification, are permitted provided that the following conditions 00009 * are met: 00010 * 00011 * * Redistributions of source code must retain the above copyright 00012 * notice, this list of conditions and the following disclaimer. 00013 * * Redistributions in binary form must reproduce the above 00014 * copyright notice, this list of conditions and the following 00015 * disclaimer in the documentation and/or other materials provided 00016 * with the distribution. 00017 * * Neither the name of the Willow Garage nor the names of its 00018 * contributors may be used to endorse or promote products derived 00019 * from this software without specific prior written permission. 00020 * 00021 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00022 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00023 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00024 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 00025 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00026 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00027 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00028 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 00029 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00030 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 00031 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00032 * POSSIBILITY OF SUCH DAMAGE. 00033 *********************************************************************/ 00034 00035 #ifndef ROSRT_DETAIL_MWSR_QUEUE_H 00036 #define ROSRT_DETAIL_MWSR_QUEUE_H 00037 00038 #include "lockfree/object_pool.h" 00039 #include <ros/atomic.h> 00040 00041 namespace rosrt 00042 { 00043 namespace detail 00044 { 00045 00046 template<typename T> 00047 class MWSRQueue 00048 { 00049 public: 00050 struct Node 00051 { 00052 T val; 00053 Node* next; 00054 }; 00055 00056 MWSRQueue(uint32_t size) 00057 : pool_(size, Node()) 00058 , head_(0) 00059 { 00060 00061 } 00062 00063 bool push(const T& val) 00064 { 00065 Node* n = pool_.allocate(); 00066 if (!n) 00067 { 00068 return false; 00069 } 00070 00071 n->val = val; 00072 Node* stale_head = head_.load(ros::memory_order_relaxed); 00073 do 00074 { 00075 n->next = stale_head; 00076 } while(!head_.compare_exchange_weak(stale_head, n, ros::memory_order_release)); 00077 00078 return true; 00079 } 00080 00081 Node* popAll() 00082 { 00083 Node* last = head_.exchange(0, ros::memory_order_consume); 00084 Node* first = 0; 00085 00086 // Reverse the list to get it back in push() order 00087 while (last) 00088 { 00089 Node* tmp = last; 00090 last = last->next; 00091 tmp->next = first; 00092 first = tmp; 00093 } 00094 00095 return first; 00096 } 00097 00098 void free(Node* node) 00099 { 00100 pool_.free(node); 00101 } 00102 00103 private: 00104 lockfree::ObjectPool<Node> pool_; 00105 ros::atomic<Node*> head_; 00106 }; 00107 00108 } // namespace detail 00109 } // namespace rosrt 00110 00111 #endif // ROSRT_DETAIL_MWSR_QUEUE_H