[80] | 1 | // |
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| 2 | // PriorityNotificationQueue.h |
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| 3 | // |
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| 4 | // $Id: //poco/1.3/Foundation/include/Poco/PriorityNotificationQueue.h#3 $ |
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| 5 | // |
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| 6 | // Library: Foundation |
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| 7 | // Package: Notifications |
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| 8 | // Module: PriorityNotificationQueue |
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| 9 | // |
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| 10 | // Definition of the PriorityNotificationQueue class. |
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| 11 | // |
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| 12 | // Copyright (c) 2009, Applied Informatics Software Engineering GmbH. |
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| 13 | // and Contributors. |
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| 14 | // |
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| 15 | // Permission is hereby granted, free of charge, to any person or organization |
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| 16 | // obtaining a copy of the software and accompanying documentation covered by |
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| 17 | // this license (the "Software") to use, reproduce, display, distribute, |
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| 18 | // execute, and transmit the Software, and to prepare derivative works of the |
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| 19 | // Software, and to permit third-parties to whom the Software is furnished to |
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| 20 | // do so, all subject to the following: |
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| 21 | // |
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| 22 | // The copyright notices in the Software and this entire statement, including |
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| 23 | // the above license grant, this restriction and the following disclaimer, |
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| 24 | // must be included in all copies of the Software, in whole or in part, and |
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| 25 | // all derivative works of the Software, unless such copies or derivative |
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| 26 | // works are solely in the form of machine-executable object code generated by |
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| 27 | // a source language processor. |
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| 28 | // |
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| 29 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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| 30 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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| 31 | // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT |
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| 32 | // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE |
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| 33 | // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, |
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| 34 | // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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| 35 | // DEALINGS IN THE SOFTWARE. |
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| 36 | // |
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| 37 | |
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| 38 | |
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| 39 | #ifndef Foundation_PriorityNotificationQueue_INCLUDED |
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| 40 | #define Foundation_PriorityNotificationQueue_INCLUDED |
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| 41 | |
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| 42 | |
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| 43 | #include "Poco/Foundation.h" |
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| 44 | #include "Poco/Notification.h" |
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| 45 | #include "Poco/Mutex.h" |
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| 46 | #include "Poco/Event.h" |
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| 47 | #include <map> |
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| 48 | #include <deque> |
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| 49 | |
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| 50 | |
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| 51 | namespace Poco { |
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| 52 | |
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| 53 | |
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| 54 | class NotificationCenter; |
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| 55 | |
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| 56 | |
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| 57 | class Foundation_API PriorityNotificationQueue |
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| 58 | /// A PriorityNotificationQueue object provides a way to implement asynchronous |
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| 59 | /// notifications. This is especially useful for sending notifications |
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| 60 | /// from one thread to another, for example from a background thread to |
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| 61 | /// the main (user interface) thread. |
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| 62 | /// |
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| 63 | /// The PriorityNotificationQueue is quite similar to the NotificationQueue class. |
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| 64 | /// The only difference to NotificationQueue is that each Notification is tagged |
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| 65 | /// with a priority value. When inserting a Notification into the queue, the |
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| 66 | /// Notification is inserted according to the given priority value, with |
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| 67 | /// lower priority values being inserted before higher priority |
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| 68 | /// values. Therefore, the lower the numerical priority value, the higher |
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| 69 | /// the actual notification priority. |
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| 70 | /// |
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| 71 | /// Notifications are dequeued in order of their priority. |
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| 72 | /// |
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| 73 | /// The PriorityNotificationQueue can also be used to distribute work from |
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| 74 | /// a controlling thread to one or more worker threads. Each worker thread |
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| 75 | /// repeatedly calls waitDequeueNotification() and processes the |
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| 76 | /// returned notification. Special care must be taken when shutting |
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| 77 | /// down a queue with worker threads waiting for notifications. |
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| 78 | /// The recommended sequence to shut down and destroy the queue is to |
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| 79 | /// 1. set a termination flag for every worker thread |
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| 80 | /// 2. call the wakeUpAll() method |
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| 81 | /// 3. join each worker thread |
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| 82 | /// 4. destroy the notification queue. |
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| 83 | { |
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| 84 | public: |
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| 85 | PriorityNotificationQueue(); |
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| 86 | /// Creates the PriorityNotificationQueue. |
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| 87 | |
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| 88 | ~PriorityNotificationQueue(); |
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| 89 | /// Destroys the PriorityNotificationQueue. |
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| 90 | |
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| 91 | void enqueueNotification(Notification::Ptr pNotification, int priority); |
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| 92 | /// Enqueues the given notification by adding it to |
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| 93 | /// the queue according to the given priority. |
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| 94 | /// Lower priority values are inserted before higher priority values. |
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| 95 | /// The queue takes ownership of the notification, thus |
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| 96 | /// a call like |
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| 97 | /// notificationQueue.enqueueNotification(new MyNotification, 1); |
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| 98 | /// does not result in a memory leak. |
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| 99 | |
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| 100 | Notification* dequeueNotification(); |
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| 101 | /// Dequeues the next pending notification. |
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| 102 | /// Returns 0 (null) if no notification is available. |
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| 103 | /// The caller gains ownership of the notification and |
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| 104 | /// is expected to release it when done with it. |
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| 105 | /// |
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| 106 | /// It is highly recommended that the result is immediately |
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| 107 | /// assigned to a Notification::Ptr, to avoid potential |
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| 108 | /// memory management issues. |
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| 109 | |
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| 110 | Notification* waitDequeueNotification(); |
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| 111 | /// Dequeues the next pending notification. |
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| 112 | /// If no notification is available, waits for a notification |
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| 113 | /// to be enqueued. |
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| 114 | /// The caller gains ownership of the notification and |
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| 115 | /// is expected to release it when done with it. |
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| 116 | /// This method returns 0 (null) if wakeUpAll() |
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| 117 | /// has been called by another thread. |
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| 118 | /// |
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| 119 | /// It is highly recommended that the result is immediately |
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| 120 | /// assigned to a Notification::Ptr, to avoid potential |
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| 121 | /// memory management issues. |
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| 122 | |
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| 123 | Notification* waitDequeueNotification(long milliseconds); |
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| 124 | /// Dequeues the next pending notification. |
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| 125 | /// If no notification is available, waits for a notification |
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| 126 | /// to be enqueued up to the specified time. |
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| 127 | /// Returns 0 (null) if no notification is available. |
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| 128 | /// The caller gains ownership of the notification and |
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| 129 | /// is expected to release it when done with it. |
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| 130 | /// |
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| 131 | /// It is highly recommended that the result is immediately |
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| 132 | /// assigned to a Notification::Ptr, to avoid potential |
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| 133 | /// memory management issues. |
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| 134 | |
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| 135 | void dispatch(NotificationCenter& notificationCenter); |
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| 136 | /// Dispatches all queued notifications to the given |
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| 137 | /// notification center. |
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| 138 | |
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| 139 | void wakeUpAll(); |
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| 140 | /// Wakes up all threads that wait for a notification. |
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| 141 | |
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| 142 | bool empty() const; |
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| 143 | /// Returns true iff the queue is empty. |
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| 144 | |
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| 145 | int size() const; |
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| 146 | /// Returns the number of notifications in the queue. |
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| 147 | |
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| 148 | void clear(); |
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| 149 | /// Removes all notifications from the queue. |
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| 150 | |
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| 151 | bool hasIdleThreads() const; |
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| 152 | /// Returns true if the queue has at least one thread waiting |
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| 153 | /// for a notification. |
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| 154 | |
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| 155 | static PriorityNotificationQueue& defaultQueue(); |
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| 156 | /// Returns a reference to the default |
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| 157 | /// PriorityNotificationQueue. |
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| 158 | |
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| 159 | protected: |
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| 160 | Notification::Ptr dequeueOne(); |
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| 161 | |
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| 162 | private: |
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| 163 | typedef std::multimap<int, Notification::Ptr> NfQueue; |
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| 164 | struct WaitInfo |
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| 165 | { |
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| 166 | Notification::Ptr pNf; |
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| 167 | Event nfAvailable; |
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| 168 | }; |
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| 169 | typedef std::deque<WaitInfo*> WaitQueue; |
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| 170 | |
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| 171 | NfQueue _nfQueue; |
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| 172 | WaitQueue _waitQueue; |
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| 173 | mutable FastMutex _mutex; |
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| 174 | }; |
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| 175 | |
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| 176 | |
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| 177 | } // namespace Poco |
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| 178 | |
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| 179 | |
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| 180 | #endif // Foundation_PriorityNotificationQueue_INCLUDED |
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