Additional fan_in attribute conditions (in addition to 'time in seconds')

[GoogleCodeExporter]

At present, the fan_in attribute accepts an integer representing 
time-in-seconds for how often the "boxcars should ship" 
http://code.google.com/p/fantasm/wiki/AdvancedConcepts.

Additional conditions could be very useful. Examples include:

- size: if the total size of the machine contexts is greater than 'size', batch 
the relevant machines.
- number: analogous to 'size', except the condition is number of some specified 
entity in each machine contexts (this can be distinct from the number of 
machines in cases where each machines operates on >1 entity).

These are extremely useful constructs when batching datastore and memcache 
operations. This is essential how the AppEngine mapreduce framework's mutation 
pool works. 
http://code.google.com/p/appengine-mapreduce/source/browse/trunk/python/src/mapr
educe/context.py#108

Original issue reported on code.google.com by saidimu on 6 Apr 2011 at 6:40

[GoogleCodeExporter]

I should clarify that the 'size' attribute is mostly useful only for memcache 
batch operations (which have a 32MB aggregate limit since SDK 1.4.0). Batch 
datastore operations have no aggregate size limit (also since SDK 1.4.0)

http://code.google.com/p/googleappengine/wiki/SdkReleaseNotes

Original comment by saidimu on 7 Apr 2011 at 3:10

[GoogleCodeExporter]

Original comment by shawn.ru...@gmail.com on 15 Apr 2011 at 8:31

• Added labels: Type-Enhancement
• Removed labels: Type-Defect