better conflict retry in postgresql backend [SF#1552809]

fix time log example [SF#1554630]

Author: Richard Jones

CHANGES.txt

@@ -55,6 +55,8 @@ Fixed:
   in classic template (sf patch 1424576)
 - "as" is a keyword in Python 2.6
 - "from __future__" statments need to be first line of file in Python 2.6
+- better conflict retry in postgresql backend (sf bug 1552809)
+- fix time log example (sf bug 1554630)
 
 
 2006-04-27 1.1.2

doc/customizing.txt

@@ -2,7 +2,7 @@
 Customising Roundup
 ===================
 
-:Version: $Revision: 1.207 $
+:Version: $Revision: 1.208 $
 
 .. This document borrows from the ZopeBook section on ZPT. The original is at:
    http://www.zope.org/Documentation/Books/ZopeBook/current/ZPT.stx
@@ -3373,11 +3373,13 @@ be able to give a summary of the total time spent on a particular issue.
    to the ``extensions`` directory in our tracker. The contents of this
    file is as follows::
 
+    from roundup import date
+
     def totalTimeSpent(times):
         ''' Call me with a list of timelog items (which have an
             Interval "period" property)
         '''
-        total = Interval('0d')
+        total = date.Interval('0d')
         for time in times:
             total += time.period._value
         return total

doc/index.txt

@@ -63,6 +63,7 @@ letting me implement this system on their time.
 Thanks also to the many people on the mailing list, in the sourceforge
 project and those who just report bugs:
 Thomas Arendsen Hein,
+Nerijus Baliunas,
 Anthony Baxter,
 Marlon van den Berg,
 Bo Berglund,

roundup/backends/back_postgresql.py

@@ -1,4 +1,4 @@
-#$Id: back_postgresql.py,v 1.35 2006-10-03 23:15:09 richard Exp $
+#$Id: back_postgresql.py,v 1.36 2006-10-03 23:28:51 richard Exp $
 #
 # Copyright (c) 2003 Martynas Sklyzmantas, Andrey Lebedev <[email protected]>
 #
@@ -70,6 +70,8 @@ def db_command(config, command):
 def pg_command(cursor, command):
     '''Execute the postgresql command, which may be blocked by some other
     user connecting to the database, and return a true value if it succeeds.
+    
+    If there is a concurrent update, retry the command.
     '''
     try:
         cursor.execute(command)
@@ -78,10 +80,18 @@ def pg_command(cursor, command):
         if response.find('FATAL') != -1:
             raise RuntimeError, response
         elif response.find('ERROR') != -1:
-            if response.find('is being accessed by other users') == -1:
-                raise RuntimeError, response
-            time.sleep(1)
-            return 0
+            msgs = [
+                'is being accessed by other users',
+                'could not serialize access due to concurrent update',
+            ]
+            can_retry = 0
+            for msg in msgs:
+                if response.find(msg) == -1:
+                    can_retry = 1
+            if can_retry:
+                time.sleep(1)
+                return 0
+            raise RuntimeError, response
     return 1
 
 def db_exists(config):