Mercurial > pygame

annotate lib/threads/Py25Queue.py @ 3194:9fcb7abf3185 default tip

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Remove some gcc 4.7.2 compiler warnings
author Lenard Lindstrom <len-l@telus.net>
date Tue, 23 Apr 2013 19:53:36 -0700
parents f7ba151c33c6
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
2089
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1 """A multi-producer, multi-consumer queue."""
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2
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3 from time import time as _time
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4
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5 from collections import deque
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6
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7 __all__ = ['Empty', 'Full', 'Queue']
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8
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9 class Empty(Exception):
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10 "Exception raised by Queue.get(block=0)/get_nowait()."
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11 pass
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12
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13 class Full(Exception):
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14 "Exception raised by Queue.put(block=0)/put_nowait()."
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15 pass
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16
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17 class Queue:
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18 """Create a queue object with a given maximum size.
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19
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20 If maxsize is <= 0, the queue size is infinite.
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21 """
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22 def __init__(self, maxsize=0):
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23 try:
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24 import threading
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25 except ImportError:
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26 import dummy_threading as threading
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27 self._init(maxsize)
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28 # mutex must be held whenever the queue is mutating. All methods
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29 # that acquire mutex must release it before returning. mutex
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30 # is shared between the three conditions, so acquiring and
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31 # releasing the conditions also acquires and releases mutex.
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32 self.mutex = threading.Lock()
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33 # Notify not_empty whenever an item is added to the queue; a
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34 # thread waiting to get is notified then.
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35 self.not_empty = threading.Condition(self.mutex)
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36 # Notify not_full whenever an item is removed from the queue;
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37 # a thread waiting to put is notified then.
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38 self.not_full = threading.Condition(self.mutex)
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39 # Notify all_tasks_done whenever the number of unfinished tasks
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40 # drops to zero; thread waiting to join() is notified to resume
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41 self.all_tasks_done = threading.Condition(self.mutex)
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42 self.unfinished_tasks = 0
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43
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44 def task_done(self):
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45 """Indicate that a formerly enqueued task is complete.
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46
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47 Used by Queue consumer threads. For each get() used to fetch a task,
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48 a subsequent call to task_done() tells the queue that the processing
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49 on the task is complete.
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50
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51 If a join() is currently blocking, it will resume when all items
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52 have been processed (meaning that a task_done() call was received
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53 for every item that had been put() into the queue).
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54
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55 Raises a ValueError if called more times than there were items
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56 placed in the queue.
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57 """
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58 self.all_tasks_done.acquire()
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59 try:
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60 unfinished = self.unfinished_tasks - 1
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61 if unfinished <= 0:
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62 if unfinished < 0:
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63 raise ValueError('task_done() called too many times')
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64 self.all_tasks_done.notifyAll()
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65 self.unfinished_tasks = unfinished
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66 finally:
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67 self.all_tasks_done.release()
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68
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69 def join(self):
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70 """Blocks until all items in the Queue have been gotten and processed.
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71
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72 The count of unfinished tasks goes up whenever an item is added to the
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73 queue. The count goes down whenever a consumer thread calls task_done()
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74 to indicate the item was retrieved and all work on it is complete.
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75
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76 When the count of unfinished tasks drops to zero, join() unblocks.
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77 """
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78 self.all_tasks_done.acquire()
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79 try:
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80 while self.unfinished_tasks:
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81 self.all_tasks_done.wait()
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82 finally:
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83 self.all_tasks_done.release()
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84
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85 def qsize(self):
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86 """Return the approximate size of the queue (not reliable!)."""
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87 self.mutex.acquire()
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88 n = self._qsize()
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89 self.mutex.release()
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90 return n
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91
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92 def empty(self):
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93 """Return True if the queue is empty, False otherwise (not reliable!)."""
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94 self.mutex.acquire()
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95 n = self._empty()
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96 self.mutex.release()
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97 return n
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98
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99 def full(self):
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100 """Return True if the queue is full, False otherwise (not reliable!)."""
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101 self.mutex.acquire()
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102 n = self._full()
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103 self.mutex.release()
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104 return n
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105
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106 def put(self, item, block=True, timeout=None):
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107 """Put an item into the queue.
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108
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109 If optional args 'block' is true and 'timeout' is None (the default),
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110 block if necessary until a free slot is available. If 'timeout' is
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111 a positive number, it blocks at most 'timeout' seconds and raises
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112 the Full exception if no free slot was available within that time.
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113 Otherwise ('block' is false), put an item on the queue if a free slot
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114 is immediately available, else raise the Full exception ('timeout'
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115 is ignored in that case).
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116 """
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117 self.not_full.acquire()
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118 try:
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119 if not block:
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120 if self._full():
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121 raise Full
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122 elif timeout is None:
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123 while self._full():
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124 self.not_full.wait()
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125 else:
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126 if timeout < 0:
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127 raise ValueError("'timeout' must be a positive number")
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128 endtime = _time() + timeout
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129 while self._full():
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130 remaining = endtime - _time()
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131 if remaining <= 0.0:
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132 raise Full
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133 self.not_full.wait(remaining)
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134 self._put(item)
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135 self.unfinished_tasks += 1
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136 self.not_empty.notify()
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137 finally:
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138 self.not_full.release()
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139
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140 def put_nowait(self, item):
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141 """Put an item into the queue without blocking.
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142
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143 Only enqueue the item if a free slot is immediately available.
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144 Otherwise raise the Full exception.
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145 """
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146 return self.put(item, False)
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147
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148 def get(self, block=True, timeout=None):
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149 """Remove and return an item from the queue.
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150
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151 If optional args 'block' is true and 'timeout' is None (the default),
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152 block if necessary until an item is available. If 'timeout' is
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153 a positive number, it blocks at most 'timeout' seconds and raises
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154 the Empty exception if no item was available within that time.
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155 Otherwise ('block' is false), return an item if one is immediately
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156 available, else raise the Empty exception ('timeout' is ignored
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157 in that case).
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158 """
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159 self.not_empty.acquire()
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160 try:
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161 if not block:
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162 if self._empty():
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163 raise Empty
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164 elif timeout is None:
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165 while self._empty():
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166 self.not_empty.wait()
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167 else:
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168 if timeout < 0:
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169 raise ValueError("'timeout' must be a positive number")
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170 endtime = _time() + timeout
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171 while self._empty():
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172 remaining = endtime - _time()
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173 if remaining <= 0.0:
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174 raise Empty
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175 self.not_empty.wait(remaining)
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176 item = self._get()
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177 self.not_full.notify()
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178 return item
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179 finally:
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180 self.not_empty.release()
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181
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182 def get_nowait(self):
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183 """Remove and return an item from the queue without blocking.
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184
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185 Only get an item if one is immediately available. Otherwise
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186 raise the Empty exception.
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187 """
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188 return self.get(False)
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189
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190 # Override these methods to implement other queue organizations
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191 # (e.g. stack or priority queue).
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192 # These will only be called with appropriate locks held
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193
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194 # Initialize the queue representation
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195 def _init(self, maxsize):
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196 self.maxsize = maxsize
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197 self.queue = deque()
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198
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199 def _qsize(self):
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200 return len(self.queue)
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201
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202 # Check whether the queue is empty
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203 def _empty(self):
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204 return not self.queue
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205
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206 # Check whether the queue is full
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207 def _full(self):
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208 return self.maxsize > 0 and len(self.queue) == self.maxsize
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209
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210 # Put a new item in the queue
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211 def _put(self, item):
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212 self.queue.append(item)
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213
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214 # Get an item from the queue
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215 def _get(self):
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216 return self.queue.popleft()