diff options
Diffstat (limited to 'Lib/Queue.py')
| -rw-r--r-- | Lib/Queue.py | 246 |
1 files changed, 130 insertions, 116 deletions
diff --git a/Lib/Queue.py b/Lib/Queue.py index 5125fd5..1cec4e3 100644 --- a/Lib/Queue.py +++ b/Lib/Queue.py @@ -1,121 +1,135 @@ # A multi-producer, multi-consumer queue. -Empty = 'Queue.Empty' # Exception raised by get_nowait() +# define this exception to be compatible with Python 1.5's class +# exceptions, but also when -X option is used. +try: + class Empty(Exception): + pass +except TypeError: + # string based exceptions + Empty = 'Queue.Empty' # Exception raised by get_nowait() class Queue: - - # Initialize a queue object with a given maximum size - # (If maxsize is <= 0, the maximum size is infinite) - def __init__(self, maxsize): - import thread - self._init(maxsize) - self.mutex = thread.allocate_lock() - self.esema = thread.allocate_lock() - self.esema.acquire_lock() - self.fsema = thread.allocate_lock() - - # Get an approximation of the queue size (not reliable!) - def qsize(self): - self.mutex.acquire_lock() - n = self._qsize() - self.mutex.release_lock() - return n - - # Check if the queue is empty (not reliable!) - def empty(self): - self.mutex.acquire_lock() - n = self._empty() - self.mutex.release_lock() - return n - - # Check if the queue is full (not reliable!) - def full(self): - self.mutex.acquire_lock() - n = self._full() - self.mutex.release_lock() - return n - - # Put a new item into the queue - def put(self, item): - self.fsema.acquire_lock() - self.mutex.acquire_lock() - was_empty = self._empty() - self._put(item) - if was_empty: - self.esema.release_lock() - if not self._full(): - self.fsema.release_lock() - self.mutex.release_lock() - - # Get an item from the queue, - # blocking if necessary until one is available - def get(self): - self.esema.acquire_lock() - self.mutex.acquire_lock() - was_full = self._full() - item = self._get() - if was_full: - self.fsema.release_lock() - if not self._empty(): - self.esema.release_lock() - self.mutex.release_lock() - return item - - # Get an item from the queue if one is immediately available, - # raise Empty if the queue is empty or temporarily unavailable - def get_nowait(self): - locked = self.esema.acquire_lock(0) - self.mutex.acquire_lock() - if self._empty(): - # The queue is empyt -- we can't have esema - self.mutex.release_lock() - raise Empty - if not locked: - locked = self.esema.acquire_lock(0) - if not locked: - # Somebody else has esema - # but we have mutex -- - # go out of their way - self.mutex.release_lock() - raise Empty - was_full = self._full() - item = self._get() - if was_full: - self.fsema.release_lock() - if not self._empty(): - self.esema.release_lock() + def __init__(self, maxsize): + """Initialize a queue object with a given maximum size. + + If maxsize is <= 0, the queue size is infinite. + """ + import thread + self._init(maxsize) + self.mutex = thread.allocate_lock() + self.esema = thread.allocate_lock() + self.esema.acquire_lock() + self.fsema = thread.allocate_lock() + + def qsize(self): + """Returns the approximate size of the queue (not reliable!).""" + self.mutex.acquire_lock() + n = self._qsize() + self.mutex.release_lock() + return n + + def empty(self): + """Returns 1 if the queue is empty, 0 otherwise (not reliable!).""" + self.mutex.acquire_lock() + n = self._empty() + self.mutex.release_lock() + return n + + def full(self): + """Returns 1 if the queue is full, 0 otherwise (not reliable!).""" + self.mutex.acquire_lock() + n = self._full() + self.mutex.release_lock() + return n + + def put(self, item): + """Put an item into the queue.""" + self.fsema.acquire_lock() + self.mutex.acquire_lock() + was_empty = self._empty() + self._put(item) + if was_empty: + self.esema.release_lock() + if not self._full(): + self.fsema.release_lock() + self.mutex.release_lock() + + def get(self): + """Gets and returns an item from the queue. + This method blocks if necessary until an item is available. + """ + self.esema.acquire_lock() + self.mutex.acquire_lock() + was_full = self._full() + item = self._get() + if was_full: + self.fsema.release_lock() + if not self._empty(): + self.esema.release_lock() + self.mutex.release_lock() + return item + + # Get an item from the queue if one is immediately available, + # raise Empty if the queue is empty or temporarily unavailable + def get_nowait(self): + """Gets and returns an item from the queue. + Only gets an item if one is immediately available, Otherwise + this raises the Empty exception if the queue is empty or + temporarily unavailable. + """ + locked = self.esema.acquire_lock(0) + self.mutex.acquire_lock() + if self._empty(): + # The queue is empty -- we can't have esema + self.mutex.release_lock() + raise Empty + if not locked: + locked = self.esema.acquire_lock(0) + if not locked: + # Somebody else has esema + # but we have mutex -- + # go out of their way self.mutex.release_lock() - return item - - # XXX Need to define put_nowait() as well. - - - # Override these methods to implement other queue organizations - # (e.g. stack or priority queue). - # These will only be called with appropriate locks held - - # Initialize the queue representation - def _init(self, maxsize): - self.maxsize = maxsize - self.queue = [] - - def _qsize(self): - return len(self.queue) - - # Check wheter the queue is empty - def _empty(self): - return not self.queue - - # Check whether the queue is full - def _full(self): - return self.maxsize > 0 and len(self.queue) == self.maxsize - - # Put a new item in the queue - def _put(self, item): - self.queue.append(item) - - # Get an item from the queue - def _get(self): - item = self.queue[0] - del self.queue[0] - return item + raise Empty + was_full = self._full() + item = self._get() + if was_full: + self.fsema.release_lock() + if not self._empty(): + self.esema.release_lock() + self.mutex.release_lock() + return item + + # XXX Need to define put_nowait() as well. + + + # Override these methods to implement other queue organizations + # (e.g. stack or priority queue). + # These will only be called with appropriate locks held + + # Initialize the queue representation + def _init(self, maxsize): + self.maxsize = maxsize + self.queue = [] + + def _qsize(self): + return len(self.queue) + + # Check wheter the queue is empty + def _empty(self): + return not self.queue + + # Check whether the queue is full + def _full(self): + return self.maxsize > 0 and len(self.queue) == self.maxsize + + # Put a new item in the queue + def _put(self, item): + self.queue.append(item) + + # Get an item from the queue + def _get(self): + item = self.queue[0] + del self.queue[0] + return item |