From 491e5794fea450235f0bab35bcd4862e0d4195e9 Mon Sep 17 00:00:00 2001
From: Mark Sapiro <msapiro@value.net>
Date: Wed, 2 Jan 2008 20:25:11 -0800
Subject: Switchboard.py - Moved the counting of the number of recoveries of a
 .bak file                  from the dequeue() method to the
 recover_backup_files() method                  in order to minimize added
 i/o.

---
 Mailman/Queue/Switchboard.py | 60 ++++++++++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/Mailman/Queue/Switchboard.py b/Mailman/Queue/Switchboard.py
index 895d6df2..a774c580 100644
--- a/Mailman/Queue/Switchboard.py
+++ b/Mailman/Queue/Switchboard.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2001-2007 by the Free Software Foundation, Inc.
+# Copyright (C) 2001-2008 by the Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -63,10 +63,9 @@ SAVE_MSGS_AS_PICKLES = True
 # Small increment to add to time in case two entries have the same time.  This
 # prevents skipping one of two entries with the same time until the next pass.
 DELTA = .0001
-# We count the number of times a file has been dequeued.  This can be more
-# than one if the file has been moved to .bak and recovered.  In order to
-# prevent loops and a message flood, when the count reaches this value, we
-# move the file to the shunt queue as a .psv.
+# We count the number of times a file has been moved to .bak and recovered.
+# In order to prevent loops and a message flood, when the count reaches this
+# value, we move the file to the shunt queue as a .psv.
 MAX_BAK_COUNT = 3
 
 
@@ -152,34 +151,16 @@ class Switchboard:
         filename = os.path.join(self.__whichq, filebase + '.pck')
         backfile = os.path.join(self.__whichq, filebase + '.bak')
         # Read the message object and metadata.
-        fp = open(filename, 'rb+')
+        fp = open(filename)
         # Move the file to the backup file name for processing.  If this
         # process crashes uncleanly the .bak file will be used to re-instate
-        # the .pck file in order to try again.  We keep count in _bak_count
-        # in the metadata which we rewrite of the number of times we recover
-        # and dequeue this file.  When the count reaches MAX_BAK_COUNT, we
-        # move the .bak file to a .psv file in the shunt queue.
+        # the .pck file in order to try again.
         os.rename(filename, backfile)
         try:
             msg = cPickle.load(fp)
-            data_pos = fp.tell()
             data = cPickle.load(fp)
-            data['_bak_count'] = data.setdefault('_bak_count', 0) + 1
-            fp.seek(data_pos)
-            if data.get('_parsemsg'):
-                protocol = 0
-            else:
-                protocol = 1
-            cPickle.dump(data, fp, protocol)
-            fp.truncate()
-            fp.flush()
-            os.fsync(fp.fileno())
         finally:
             fp.close()
-        if data['_bak_count'] >= MAX_BAK_COUNT:
-            syslog('error', '.bak file max count, preserving file: %s',
-                   filebase)
-            self.finish(filebase, preserve=True)
         if data.get('_parsemsg'):
             msg = email.message_from_string(msg, Message.Message)
         return msg, data
@@ -233,8 +214,33 @@ class Switchboard:
     def recover_backup_files(self):
         # Move all .bak files in our slice to .pck.  It's impossible for both
         # to exist at the same time, so the move is enough to ensure that our
-        # normal dequeuing process will handle them.
+        # normal dequeuing process will handle them.  We keep count in
+        # _bak_count in the metadata of the number of times we recover this
+        # file.  When the count reaches MAX_BAK_COUNT, we move the .bak file
+        # to a .psv file in the shunt queue.
         for filebase in self.files('.bak'):
             src = os.path.join(self.__whichq, filebase + '.bak')
             dst = os.path.join(self.__whichq, filebase + '.pck')
-            os.rename(src, dst)
+            fp = open(src, 'rb+')
+            try:
+                msg = cPickle.load(fp)
+                data_pos = fp.tell()
+                data = cPickle.load(fp)
+                data['_bak_count'] = data.setdefault('_bak_count', 0) + 1
+                fp.seek(data_pos)
+                if data.get('_parsemsg'):
+                    protocol = 0
+                else:
+                    protocol = 1
+                cPickle.dump(data, fp, protocol)
+                fp.truncate()
+                fp.flush()
+                os.fsync(fp.fileno())
+            finally:
+                fp.close()
+            if data['_bak_count'] >= MAX_BAK_COUNT:
+                syslog('error', '.bak file max count, preserving file: %s',
+                         filebase)
+                self.finish(filebase, preserve=True)
+            else:
+                os.rename(src, dst)
-- 
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