Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 1 | """Queues""" |
| 2 | |
Victor Stinner | eaf16ab | 2015-07-25 02:40:40 +0200 | [diff] [blame] | 3 | __all__ = ['Queue', 'PriorityQueue', 'LifoQueue', 'QueueFull', 'QueueEmpty'] |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 4 | |
| 5 | import collections |
| 6 | import heapq |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 7 | |
Victor Stinner | eaf16ab | 2015-07-25 02:40:40 +0200 | [diff] [blame] | 8 | from . import compat |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 9 | from . import events |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 10 | from . import locks |
Victor Stinner | e6ecea5 | 2015-07-09 23:13:50 +0200 | [diff] [blame] | 11 | from .coroutines import coroutine |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 12 | |
| 13 | |
Guido van Rossum | fef7098 | 2014-01-25 17:24:51 -0800 | [diff] [blame] | 14 | class QueueEmpty(Exception): |
Victor Stinner | 17d87f8 | 2015-02-03 15:09:24 +0100 | [diff] [blame] | 15 | """Exception raised when Queue.get_nowait() is called on a Queue object |
| 16 | which is empty. |
| 17 | """ |
Guido van Rossum | fef7098 | 2014-01-25 17:24:51 -0800 | [diff] [blame] | 18 | pass |
| 19 | |
| 20 | |
| 21 | class QueueFull(Exception): |
Victor Stinner | 17d87f8 | 2015-02-03 15:09:24 +0100 | [diff] [blame] | 22 | """Exception raised when the Queue.put_nowait() method is called on a Queue |
| 23 | object which is full. |
| 24 | """ |
Guido van Rossum | fef7098 | 2014-01-25 17:24:51 -0800 | [diff] [blame] | 25 | pass |
| 26 | |
| 27 | |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 28 | class Queue: |
| 29 | """A queue, useful for coordinating producer and consumer coroutines. |
| 30 | |
| 31 | If maxsize is less than or equal to zero, the queue size is infinite. If it |
| 32 | is an integer greater than 0, then "yield from put()" will block when the |
| 33 | queue reaches maxsize, until an item is removed by get(). |
| 34 | |
| 35 | Unlike the standard library Queue, you can reliably know this Queue's size |
Victor Stinner | 2748bc7 | 2013-12-13 10:57:04 +0100 | [diff] [blame] | 36 | with qsize(), since your single-threaded asyncio application won't be |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 37 | interrupted between calling qsize() and doing an operation on the Queue. |
| 38 | """ |
| 39 | |
| 40 | def __init__(self, maxsize=0, *, loop=None): |
| 41 | if loop is None: |
| 42 | self._loop = events.get_event_loop() |
| 43 | else: |
| 44 | self._loop = loop |
| 45 | self._maxsize = maxsize |
| 46 | |
| 47 | # Futures. |
| 48 | self._getters = collections.deque() |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 49 | # Futures. |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 50 | self._putters = collections.deque() |
Victor Stinner | 4cb814c | 2015-02-17 22:53:28 +0100 | [diff] [blame] | 51 | self._unfinished_tasks = 0 |
| 52 | self._finished = locks.Event(loop=self._loop) |
| 53 | self._finished.set() |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 54 | self._init(maxsize) |
| 55 | |
Guido van Rossum | 0bd16bc | 2015-04-20 09:24:24 -0700 | [diff] [blame] | 56 | # These three are overridable in subclasses. |
| 57 | |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 58 | def _init(self, maxsize): |
| 59 | self._queue = collections.deque() |
| 60 | |
| 61 | def _get(self): |
| 62 | return self._queue.popleft() |
| 63 | |
| 64 | def _put(self, item): |
| 65 | self._queue.append(item) |
Guido van Rossum | 0bd16bc | 2015-04-20 09:24:24 -0700 | [diff] [blame] | 66 | |
| 67 | # End of the overridable methods. |
| 68 | |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 69 | def _wakeup_next(self, waiters): |
| 70 | # Wake up the next waiter (if any) that isn't cancelled. |
| 71 | while waiters: |
| 72 | waiter = waiters.popleft() |
| 73 | if not waiter.done(): |
| 74 | waiter.set_result(None) |
| 75 | break |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 76 | |
| 77 | def __repr__(self): |
| 78 | return '<{} at {:#x} {}>'.format( |
| 79 | type(self).__name__, id(self), self._format()) |
| 80 | |
| 81 | def __str__(self): |
| 82 | return '<{} {}>'.format(type(self).__name__, self._format()) |
| 83 | |
| 84 | def _format(self): |
| 85 | result = 'maxsize={!r}'.format(self._maxsize) |
| 86 | if getattr(self, '_queue', None): |
| 87 | result += ' _queue={!r}'.format(list(self._queue)) |
| 88 | if self._getters: |
| 89 | result += ' _getters[{}]'.format(len(self._getters)) |
| 90 | if self._putters: |
| 91 | result += ' _putters[{}]'.format(len(self._putters)) |
Victor Stinner | 4cb814c | 2015-02-17 22:53:28 +0100 | [diff] [blame] | 92 | if self._unfinished_tasks: |
| 93 | result += ' tasks={}'.format(self._unfinished_tasks) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 94 | return result |
| 95 | |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 96 | def qsize(self): |
| 97 | """Number of items in the queue.""" |
| 98 | return len(self._queue) |
| 99 | |
| 100 | @property |
| 101 | def maxsize(self): |
| 102 | """Number of items allowed in the queue.""" |
| 103 | return self._maxsize |
| 104 | |
| 105 | def empty(self): |
| 106 | """Return True if the queue is empty, False otherwise.""" |
| 107 | return not self._queue |
| 108 | |
| 109 | def full(self): |
| 110 | """Return True if there are maxsize items in the queue. |
| 111 | |
| 112 | Note: if the Queue was initialized with maxsize=0 (the default), |
| 113 | then full() is never True. |
| 114 | """ |
| 115 | if self._maxsize <= 0: |
| 116 | return False |
| 117 | else: |
Victor Stinner | 66dc6b0 | 2014-06-17 23:36:21 +0200 | [diff] [blame] | 118 | return self.qsize() >= self._maxsize |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 119 | |
| 120 | @coroutine |
| 121 | def put(self, item): |
| 122 | """Put an item into the queue. |
| 123 | |
Victor Stinner | 952ec98 | 2014-12-22 22:09:50 +0100 | [diff] [blame] | 124 | Put an item into the queue. If the queue is full, wait until a free |
| 125 | slot is available before adding item. |
| 126 | |
| 127 | This method is a coroutine. |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 128 | """ |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 129 | while self.full(): |
Yury Selivanov | 7661db6 | 2016-05-16 15:38:39 -0400 | [diff] [blame] | 130 | putter = self._loop.create_future() |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 131 | self._putters.append(putter) |
| 132 | try: |
| 133 | yield from putter |
| 134 | except: |
| 135 | putter.cancel() # Just in case putter is not done yet. |
| 136 | if not self.full() and not putter.cancelled(): |
| 137 | # We were woken up by get_nowait(), but can't take |
| 138 | # the call. Wake up the next in line. |
| 139 | self._wakeup_next(self._putters) |
| 140 | raise |
| 141 | return self.put_nowait(item) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 142 | |
| 143 | def put_nowait(self, item): |
| 144 | """Put an item into the queue without blocking. |
| 145 | |
Guido van Rossum | fef7098 | 2014-01-25 17:24:51 -0800 | [diff] [blame] | 146 | If no free slot is immediately available, raise QueueFull. |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 147 | """ |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 148 | if self.full(): |
Guido van Rossum | fef7098 | 2014-01-25 17:24:51 -0800 | [diff] [blame] | 149 | raise QueueFull |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 150 | self._put(item) |
| 151 | self._unfinished_tasks += 1 |
| 152 | self._finished.clear() |
| 153 | self._wakeup_next(self._getters) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 154 | |
| 155 | @coroutine |
| 156 | def get(self): |
| 157 | """Remove and return an item from the queue. |
| 158 | |
Victor Stinner | 952ec98 | 2014-12-22 22:09:50 +0100 | [diff] [blame] | 159 | If queue is empty, wait until an item is available. |
| 160 | |
| 161 | This method is a coroutine. |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 162 | """ |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 163 | while self.empty(): |
Yury Selivanov | 7661db6 | 2016-05-16 15:38:39 -0400 | [diff] [blame] | 164 | getter = self._loop.create_future() |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 165 | self._getters.append(getter) |
Yury Selivanov | 3fc0f2d | 2015-08-05 13:52:33 -0400 | [diff] [blame] | 166 | try: |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 167 | yield from getter |
| 168 | except: |
| 169 | getter.cancel() # Just in case getter is not done yet. |
| 170 | if not self.empty() and not getter.cancelled(): |
| 171 | # We were woken up by put_nowait(), but can't take |
| 172 | # the call. Wake up the next in line. |
| 173 | self._wakeup_next(self._getters) |
Yury Selivanov | 3fc0f2d | 2015-08-05 13:52:33 -0400 | [diff] [blame] | 174 | raise |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 175 | return self.get_nowait() |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 176 | |
| 177 | def get_nowait(self): |
| 178 | """Remove and return an item from the queue. |
| 179 | |
Guido van Rossum | fef7098 | 2014-01-25 17:24:51 -0800 | [diff] [blame] | 180 | Return an item if one is immediately available, else raise QueueEmpty. |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 181 | """ |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 182 | if self.empty(): |
Guido van Rossum | fef7098 | 2014-01-25 17:24:51 -0800 | [diff] [blame] | 183 | raise QueueEmpty |
Guido van Rossum | 99f96c5 | 2015-09-28 07:42:34 -0700 | [diff] [blame] | 184 | item = self._get() |
| 185 | self._wakeup_next(self._putters) |
| 186 | return item |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 187 | |
Victor Stinner | 4cb814c | 2015-02-17 22:53:28 +0100 | [diff] [blame] | 188 | def task_done(self): |
| 189 | """Indicate that a formerly enqueued task is complete. |
| 190 | |
| 191 | Used by queue consumers. For each get() used to fetch a task, |
| 192 | a subsequent call to task_done() tells the queue that the processing |
| 193 | on the task is complete. |
| 194 | |
| 195 | If a join() is currently blocking, it will resume when all items have |
| 196 | been processed (meaning that a task_done() call was received for every |
| 197 | item that had been put() into the queue). |
| 198 | |
| 199 | Raises ValueError if called more times than there were items placed in |
| 200 | the queue. |
| 201 | """ |
| 202 | if self._unfinished_tasks <= 0: |
| 203 | raise ValueError('task_done() called too many times') |
| 204 | self._unfinished_tasks -= 1 |
| 205 | if self._unfinished_tasks == 0: |
| 206 | self._finished.set() |
| 207 | |
| 208 | @coroutine |
| 209 | def join(self): |
| 210 | """Block until all items in the queue have been gotten and processed. |
| 211 | |
| 212 | The count of unfinished tasks goes up whenever an item is added to the |
| 213 | queue. The count goes down whenever a consumer calls task_done() to |
| 214 | indicate that the item was retrieved and all work on it is complete. |
| 215 | When the count of unfinished tasks drops to zero, join() unblocks. |
| 216 | """ |
| 217 | if self._unfinished_tasks > 0: |
| 218 | yield from self._finished.wait() |
| 219 | |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 220 | |
| 221 | class PriorityQueue(Queue): |
| 222 | """A subclass of Queue; retrieves entries in priority order (lowest first). |
| 223 | |
| 224 | Entries are typically tuples of the form: (priority number, data). |
| 225 | """ |
| 226 | |
| 227 | def _init(self, maxsize): |
| 228 | self._queue = [] |
| 229 | |
| 230 | def _put(self, item, heappush=heapq.heappush): |
| 231 | heappush(self._queue, item) |
| 232 | |
| 233 | def _get(self, heappop=heapq.heappop): |
| 234 | return heappop(self._queue) |
| 235 | |
| 236 | |
| 237 | class LifoQueue(Queue): |
| 238 | """A subclass of Queue that retrieves most recently added entries first.""" |
| 239 | |
| 240 | def _init(self, maxsize): |
| 241 | self._queue = [] |
| 242 | |
| 243 | def _put(self, item): |
| 244 | self._queue.append(item) |
| 245 | |
| 246 | def _get(self): |
| 247 | return self._queue.pop() |
| 248 | |
| 249 | |
Victor Stinner | eaf16ab | 2015-07-25 02:40:40 +0200 | [diff] [blame] | 250 | if not compat.PY35: |
| 251 | JoinableQueue = Queue |
| 252 | """Deprecated alias for Queue.""" |
| 253 | __all__.append('JoinableQueue') |