On 12/17/2010 10:22 AM, Gregg Wonderly wrote:
On 12/16/2010 9:35 PM, Patricia Shanahan wrote:
I would love to be able to base it on a ConcurrentMap, but I don't see
how it
would work.
As far as I can tell, there is no clean split between key and non-key
among the
entry's public fields. A template can specify values for any subset of
the
fields, and different templates used in reading from the same space
may choose
different sets of fields.
Any ideas how to work around that?
One of the things I did in Griddle was to create a CHM for each key
field name. I then put every entry into the appropriate map based on it
having a key value pair with a name.
Matching is then a matter of querying each map with the provided key's
value, and only if the same entry exists in all tables does a match
begin processing.
...
Yes, I see what you mean. I've used similar techniques with
java.util.HashMap to deal with multiple entries for the same key.
It raises a question about Outrigger functionality. As currently
implemented, it is FIFO. For example, a single Entry read gets the
oldest Entry in the space that matches the template.
The net.jini.space.JavaSpace interface does not require FIFO behavior.
It says things like "Read any matching entry from the space, blocking
until one exists."
In a CHM-based implementation keeping the FIFO behavior might involve a
sort taking O(k log k) time, where k is the number of elements that match.
Or k may be the number of entries in the smallest contents for any match
field. One possible sequence is find the matching entries for the most
restrictive field, sort them in time order, and search the sorted result
for the first Entry that meets the rest of the template rules.
Any thoughts on this.
Patricia
