[CalendarServer-changes] [6530] CalendarServer/branches/users/glyph/sharedpool/txdav/base/datastore/ asyncsqlpool.py

[source_changes at macosforge.org]

Revision: 6530
          http://trac.macosforge.org/projects/calendarserver/changeset/6530
Author:   glyph at apple.com
Date:     2010-11-01 14:25:02 -0700 (Mon, 01 Nov 2010)
Log Message:
-----------
Allow pickles to be big.

Modified Paths:
--------------
    CalendarServer/branches/users/glyph/sharedpool/txdav/base/datastore/asyncsqlpool.py

Modified: CalendarServer/branches/users/glyph/sharedpool/txdav/base/datastore/asyncsqlpool.py
===================================================================
--- CalendarServer/branches/users/glyph/sharedpool/txdav/base/datastore/asyncsqlpool.py	2010-11-01 21:24:35 UTC (rev 6529)
+++ CalendarServer/branches/users/glyph/sharedpool/txdav/base/datastore/asyncsqlpool.py	2010-11-01 21:25:02 UTC (rev 6530)
@@ -20,6 +20,7 @@
 """
 
 import sys
+from cStringIO import StringIO
 from cPickle import dumps, loads
 from itertools import count
 
@@ -268,15 +269,45 @@
     return [('transactionID', Integer())]
 
 
+CHUNK_MAX = 0xffff
 
-class Pickle(Argument):
+class BigArgument(Argument):
     """
+    An argument whose payload can be larger than L{CHUNK_MAX}, by splitting
+    across multiple AMP keys.
+    """
+    def fromBox(self, name, strings, objects, proto):
+        value = StringIO()
+        for counter in count():
+            chunk = strings.get("%s.%d" % (name, counter))
+            if chunk is None:
+                break
+            value.write(chunk)
+        objects[name] = self.fromString(value.getvalue())
+
+
+    def toBox(self, name, strings, objects, proto):
+        value = StringIO(self.toString(objects[name]))
+        for counter in count():
+            nextChunk = value.read(CHUNK_MAX)
+            if not nextChunk:
+                break
+            strings["%s.%d" % (name, counter)] = nextChunk
+
+
+
+class Pickle(BigArgument):
+    """
     A pickle sent over AMP.  This is to serialize the 'args' argument to
-    execSQL, which is the dynamically-typed 'args' list argument to a DB-API
+    C{execSQL}, which is the dynamically-typed 'args' list argument to a DB-API
     C{execute} function, as well as its dynamically-typed result ('rows').
 
     This should be cleaned up into a nicer structure, but this is not a network
     protocol, so we can be a little relaxed about security.
+
+    This is a L{BigArgument} rather than a regular L{Argument} because
+    individual arguments and query results need to contain entire vCard or
+    iCalendar documents, which can easily be greater than 64k.
     """
 
     def toString(self, inObject):
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