[Python-checkins] r59987 - in python/trunk: Doc/library/collections.rst Lib/Queue.py

Tue Jan 15 21:52:42 CET 2008

Author: raymond.hettinger
Date: Tue Jan 15 21:52:42 2008
New Revision: 59987
Modified:
 python/trunk/Doc/library/collections.rst
 python/trunk/Lib/Queue.py
Log:
Refactor if/elif chain for clarity and speed. Remove dependency on subclasses having to implement _empty and _full.
Modified: python/trunk/Doc/library/collections.rst
==============================================================================

--- python/trunk/Doc/library/collections.rst	(original)
+++ python/trunk/Doc/library/collections.rst	Tue Jan 15 21:52:42 2008
@@ -535,6 +535,14 @@
 def _replace(self, _map=map, **kwds):
 return self._make(_map(kwds.get, ('x', 'y'), self))
 
+Note, subclasses should set ``__slots__`` to an empty tuple so that
+an instance dictionary will not be created and the memory overhead
+will be kept to zero.
+
+Note, subclasses should set ``__slots__`` to an empty tuple. This
+reduces memory usage by 
+
+
 Subclassing is not useful for adding new, stored fields. Instead, simply
 create a new named tuple type from the :attr:`_fields` attribute::
 
Modified: python/trunk/Lib/Queue.py
==============================================================================
--- python/trunk/Lib/Queue.py	(original)
+++ python/trunk/Lib/Queue.py	Tue Jan 15 21:52:42 2008
@@ -23,6 +23,7 @@
 import threading
 except ImportError:
 import dummy_threading as threading
+ self.maxsize = maxsize
 self._init(maxsize)
 # mutex must be held whenever the queue is mutating. All methods
 # that acquire mutex must release it before returning. mutex
@@ -91,14 +92,14 @@
 def empty(self):
 """Return True if the queue is empty, False otherwise (not reliable!)."""
 self.mutex.acquire()
- n = self._empty()
+ n = not self._qsize()
 self.mutex.release()
 return n
 
 def full(self):
 """Return True if the queue is full, False otherwise (not reliable!)."""
 self.mutex.acquire()
- n = self._full()
+ n = 0 < self.maxsize == self._qsize()
 self.mutex.release()
 return n
 
@@ -115,21 +116,22 @@
 """
 self.not_full.acquire()
 try:
- if not block:
- if self._full():
- raise Full
- elif timeout is None:
- while self._full():
- self.not_full.wait()
- else:
- if timeout < 0:
- raise ValueError("'timeout' must be a positive number")
- endtime = _time() + timeout
- while self._full():
- remaining = endtime - _time()
- if remaining <= 0.0:
+ if self.maxsize > 0:
+ if not block:
+ if self._qsize() == self.maxsize:
 raise Full
- self.not_full.wait(remaining)
+ elif timeout is None:
+ while self._qsize() == self.maxsize:
+ self.not_full.wait()
+ elif timeout < 0:
+ raise ValueError("'timeout' must be a positive number")
+ else:
+ endtime = _time() + timeout
+ while self._qsize() == self.maxsize:
+ remaining = endtime - _time()
+ if remaining <= 0.0:
+ raise Full
+ self.not_full.wait(remaining)
 self._put(item)
 self.unfinished_tasks += 1
 self.not_empty.notify()
@@ -158,16 +160,16 @@
 self.not_empty.acquire()
 try:
 if not block:
- if self._empty():
+ if not self._qsize():
 raise Empty
 elif timeout is None:
- while self._empty():
+ while not self._qsize():
 self.not_empty.wait()
+ elif timeout < 0:
+ raise ValueError("'timeout' must be a positive number")
 else:
- if timeout < 0:
- raise ValueError("'timeout' must be a positive number")
 endtime = _time() + timeout
- while self._empty():
+ while not self._qsize():
 remaining = endtime - _time()
 if remaining <= 0.0:
 raise Empty
@@ -192,20 +194,11 @@
 
 # Initialize the queue representation
 def _init(self, maxsize):
- self.maxsize = maxsize
 self.queue = deque()
 
 def _qsize(self):
 return len(self.queue)
 
- # Check whether 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)
