Abstracted some common and annoying logic from FileStorage.

src/ZODB/BaseStorage.py

+##############################################################################
+# 
+# Zope Public License (ZPL) Version 1.0
+# -------------------------------------
+# 
+# Copyright (c) Digital Creations.  All rights reserved.
+# 
+# This license has been certified as Open Source(tm).
+# 
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+# 
+# 1. Redistributions in source code must retain the above copyright
+#    notice, this list of conditions, and the following disclaimer.
+# 
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions, and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 
+# 3. Digital Creations requests that attribution be given to Zope
+#    in any manner possible. Zope includes a "Powered by Zope"
+#    button that is installed by default. While it is not a license
+#    violation to remove this button, it is requested that the
+#    attribution remain. A significant investment has been put
+#    into Zope, and this effort will continue if the Zope community
+#    continues to grow. This is one way to assure that growth.
+# 
+# 4. All advertising materials and documentation mentioning
+#    features derived from or use of this software must display
+#    the following acknowledgement:
+# 
+#      "This product includes software developed by Digital Creations
+#      for use in the Z Object Publishing Environment
+#      (http://www.zope.org/)."
+# 
+#    In the event that the product being advertised includes an
+#    intact Zope distribution (with copyright and license included)
+#    then this clause is waived.
+# 
+# 5. Names associated with Zope or Digital Creations must not be used to
+#    endorse or promote products derived from this software without
+#    prior written permission from Digital Creations.
+# 
+# 6. Modified redistributions of any form whatsoever must retain
+#    the following acknowledgment:
+# 
+#      "This product includes software developed by Digital Creations
+#      for use in the Z Object Publishing Environment
+#      (http://www.zope.org/)."
+# 
+#    Intact (re-)distributions of any official Zope release do not
+#    require an external acknowledgement.
+# 
+# 7. Modifications are encouraged but must be packaged separately as
+#    patches to official Zope releases.  Distributions that do not
+#    clearly separate the patches from the original work must be clearly
+#    labeled as unofficial distributions.  Modifications which do not
+#    carry the name Zope may be packaged in any form, as long as they
+#    conform to all of the clauses above.
+# 
+# 
+# Disclaimer
+# 
+#   THIS SOFTWARE IS PROVIDED BY DIGITAL CREATIONS ``AS IS'' AND ANY
+#   EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+#   PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL DIGITAL CREATIONS OR ITS
+#   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+#   USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+#   ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+#   OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+#   OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+#   SUCH DAMAGE.
+# 
+# 
+# This software consists of contributions made by Digital Creations and
+# many individuals on behalf of Digital Creations.  Specific
+# attributions are listed in the accompanying credits file.
+# 
+##############################################################################
+"""Handy standard storage machinery
+"""
+__version__='$Revision: 1.1 $'[11:-2]
+
+import time, bpthread
+from POSException import UndoError
+from TimeStamp import TimeStamp
+z64='\0'*8
+
+class BaseStorage:
+    _transaction=None
+    _serial=z64
+
+    def __init__(self, name):
+        
+        self.__name__=name
+
+        # Allocate locks:
+        l=bpthread.allocate_lock()
+        self._lock_acquire=l.acquire
+        self._lock_release=l.release
+        l=bpthread.allocate_lock()
+        self._commit_lock_acquire=l.acquire
+        self._commit_lock_release=l.release
+
+        t=time.time()
+        t=self._ts=apply(TimeStamp,(time.gmtime(t)[:5]+(t%60,)))
+        self._serial=`t`
+        self._oid='\0\0\0\0\0\0\0\1'
+
+    def close(self): pass
+
+    def getName(self): return self.__name__
+    def getSize(self): return len(self)*300 # WAG!
+    def history(self, oid, version, length=1): pass
+
+    def new_oid(self, last=None):
+        if last is None:
+            self._lock_acquire()
+            try:
+                last=self._oid
+                d=ord(last[-1])
+                if d < 255: last=last[:-1]+chr(d+1)
+                else:       last=self.new_oid(last[:-1])
+                self._oid=last
+                return last
+            finally: self._lock_release()
+        else:
+            d=ord(last[-1])
+            if d < 255: return last[:-1]+chr(d+1)+'\0'*(8-len(last))
+            else:       return self.new_oid(last[:-1])
+
+    def registerDB(self, db, limit): pass # we don't care
+
+    def supportsUndo(self): return 0
+    def supportsVersions(self): return 0
+        
+    def tpc_abort(self, transaction):
+        self._lock_acquire()
+        try:
+            if transaction is not self._transaction: return
+            self._clear_temp()
+            self._transaction=None
+            self._commit_lock_release()
+        finally: self._lock_release()
+
+    def tpc_begin(self, transaction):
+        self._lock_acquire()
+        try:
+            if self._transaction is transaction: return
+            self._lock_release()
+            self._commit_lock_acquire()
+            self._lock_acquire()
+            self._transaction=transaction
+            self._clear_temp()
+
+            user=transaction.user
+            desc=transaction.description
+            ext=transaction._extension
+            if ext: ext=dumps(ext,1)
+            else: ext=""
+            self._ude=user, desc, ext
+
+            t=time.time()
+            t=apply(TimeStamp,(time.gmtime(t)[:5]+(t%60,)))
+            self._ts=t=t.laterThan(self._ts)
+            self._serial=`t`
+
+            self._begin(self._serial, user, desc, ext)
+            
+        finally: self._lock_release()
+
+    def _begin(self, tid, u, d, e):
+        pass
+
+    def tpc_finish(self, transaction, f=None):
+        self._lock_acquire()
+        try:
+            if transaction is not self._transaction: return
+            if f is not None: f()
+
+            u,d,e=self._ude
+            self._finish(self._serial, u, d, e)
+
+            self._clear_temp()
+            self._ude=None
+            self._transaction=None
+            self._commit_lock_release()
+        finally: self._lock_release()
+
+    def _finish(self, tid, u, d, e):
+        pass
+
+    def undo(self, transaction_id):
+        raise UndoError, 'Undoable transaction'
+
+    def undoLog(self, first, last, filter=None): return ()
+
+    def versionEmpty(self, version): return 1
+
+    def versions(self, max=None): return ()
+
+    def pack(self, t, referencesf): pass
+