[Assorted-commits] SF.net SVN: assorted:[1447] python-commons/trunk/src/commons/sqlhash.py

[<yan...@us...>]

Revision: 1447
          http://assorted.svn.sourceforge.net/assorted/?rev=1447&view=rev
Author:   yangzhang
Date:     2009-06-03 17:09:35 +0000 (Wed, 03 Jun 2009)

Log Message:
-----------
fixes and tweaks to shelf

Modified Paths:
--------------
    python-commons/trunk/src/commons/sqlhash.py

Modified: python-commons/trunk/src/commons/sqlhash.py
===================================================================
--- python-commons/trunk/src/commons/sqlhash.py	2009-06-03 17:08:19 UTC (rev 1446)
+++ python-commons/trunk/src/commons/sqlhash.py	2009-06-03 17:09:35 UTC (rev 1447)
@@ -64,7 +64,7 @@
         item = self.conn.execute(GET_ITEM, (sqlite3.Binary(key),)).fetchone()
         if item is None:
             raise KeyError(key)
-        return item[0]
+        return str(item[0])
 
     def __setitem__(self, key, value):       
         ADD_ITEM = 'REPLACE INTO shelf (key, value) VALUES (?,?)'
@@ -131,17 +131,40 @@
     return SQLhash()
 
 class Shelf(shelve.Shelf):
+  def __init__(self, *args, **okwargs):
+    kwargs = okwargs.copy()
+    try: del kwargs['cache']
+    except KeyError: pass
+    shelve.Shelf.__init__(self, *args, **kwargs)
+    if not okwargs.get('cache', True): self.cache = None
+  def __getitem__(self, k):
+    val = lambda: cPickle.loads(self.dict[k])
+    if self.cache is None:
+      return val()
+    else:
+      try: return self.cache[k]
+      except KeyError: return self.cache.setdefault(k, val())
   def __setitem__(self, key, value):
-    if self.writeback: self.cache[key] = value
+    if self.cache is not None and self.writeback: self.cache[key] = value
     else: self.dict[key] = cPickle.dumps(value, self._protocol)
   def __delitem__(self, key):
     try:
       del self.dict[key]
     except:
+      if not self.writeback: raise
+      # If writeback is enabled then it's OK if it's missing in the
+      # underlying dict but present in the cache; it just means that
+      # we only recently inserted it so it's only in the cache.  If
+      # it's not in the cache either then we should end with a
+      # KeyError.
       del self.cache[key]
     else:
+      # Also make sure it's removed from the cache.
       try: del self.cache[key]
       except KeyError: pass
+  def iteritems(self):
+    for i,k in enumerate(self.keys()):
+      yield k, self[k]
   def sync(self):
     if self.cache:
       self.dict.update( (k, cPickle.dumps(v, self._protocol)) for k,v in self.cache.items() )


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