Split off from PickleJar.

src/ZODB/PickleCache.py

+#!/usr/local/bin/python 
+# $What$
+
+__doc__='''PickleJar Object Cache
+
+$Id: PickleCache.py,v 1.1 1997/12/15 17:51:55 jim Exp $'''
+#     Copyright 
+#
+#       Copyright 1996 Digital Creations, L.C., 910 Princess Anne
+#       Street, Suite 300, Fredericksburg, Virginia 22401 U.S.A. All
+#       rights reserved.  Copyright in this software is owned by DCLC,
+#       unless otherwise indicated. Permission to use, copy and
+#       distribute this software is hereby granted, provided that the
+#       above copyright notice appear in all copies and that both that
+#       copyright notice and this permission notice appear. Note that
+#       any product, process or technology described in this software
+#       may be the subject of other Intellectual Property rights
+#       reserved by Digital Creations, L.C. and are not licensed
+#       hereunder.
+#
+#     Trademarks 
+#
+#       Digital Creations & DCLC, are trademarks of Digital Creations, L.C..
+#       All other trademarks are owned by their respective companies. 
+#
+#     No Warranty 
+#
+#       The software is provided "as is" without warranty of any kind,
+#       either express or implied, including, but not limited to, the
+#       implied warranties of merchantability, fitness for a particular
+#       purpose, or non-infringement. This software could include
+#       technical inaccuracies or typographical errors. Changes are
+#       periodically made to the software; these changes will be
+#       incorporated in new editions of the software. DCLC may make
+#       improvements and/or changes in this software at any time
+#       without notice.
+#
+#     Limitation Of Liability 
+#
+#       In no event will DCLC be liable for direct, indirect, special,
+#       incidental, economic, cover, or consequential damages arising
+#       out of the use of or inability to use this software even if
+#       advised of the possibility of such damages. Some states do not
+#       allow the exclusion or limitation of implied warranties or
+#       limitation of liability for incidental or consequential
+#       damages, so the above limitation or exclusion may not apply to
+#       you.
+#  
+#
+# If you have questions regarding this software,
+# contact:
+#
+#   Digital Creations, bobo@digicool.com
+#
+#   (540) 371-6909
+# 
+__version__='$Revision: 1.1 $'[11:-2]
+	
+class PickleCache:
+
+    def __init__(self, cache_size, cache_age=1000):
+        if cache_size < 1: cache_size=1
+        self.cache_size=cache_size
+        self.data, self.cache_ids, self.cache_location ={}, [], 0
+	for a in 'keys', 'items', 'values', 'has_key':
+	    setattr(self,a,getattr(self.data,a))
+
+
+    def __getitem__(self, key):
+        cache=self.data
+        v=cache[key]
+
+        # Do cache GC
+        n=min(len(cache)/self.cache_size,10)
+        if n:
+            l=self.cache_location
+            ids=self.cache_ids
+            while n:
+                if not l:
+                    ids=self.cache_ids=cache.keys()
+                    l=len(ids)
+                l=l-1
+                n=n-1
+                id=ids[l]
+                if getrefcount(cache[id]) <= 2:
+                    del cache[id]
+            self.cache_location=l
+
+        return v
+
+    def __setitem__(self, key, v): self.data[key]=v
+
+    def __delitem__(self, key): del self.data[key]
+
+    def values(self): return self.data.values()
+
+    def full_sweep(self):
+        cache=self.data
+        for id in cache.keys():
+            if getrefcount(cache[id]) <= 2: del cache[id]
+    
+    minimize=full_sweep
+
+############################################################################
+#
+# $Log: PickleCache.py,v $
+# Revision 1.1  1997/12/15 17:51:55  jim
+# Split off from PickleJar.
+#
+#
+#