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Posted to commits@cassandra.apache.org by "Sylvain Lebresne (JIRA)" <ji...@apache.org> on 2014/02/05 20:02:08 UTC
[jira] [Created] (CASSANDRA-6659) Allow "intercepting" query by
user provided custom classes
Sylvain Lebresne created CASSANDRA-6659:
-------------------------------------------
Summary: Allow "intercepting" query by user provided custom classes
Key: CASSANDRA-6659
URL: https://issues.apache.org/jira/browse/CASSANDRA-6659
Project: Cassandra
Issue Type: Improvement
Reporter: Sylvain Lebresne
Assignee: Sylvain Lebresne
Priority: Minor
The idea for this ticket is to abstract the main execution methods of QueryProcessor into an interface, something like:
{noformat}
public interface QueryHandler
{
public ResultSet process(String query, QueryState state, QueryOptions options);
public ResultMessage.Prepared prepare(String query, QueryState state);
public ResultSet processPrepared(CQLStatement statement, QueryState state, QueryOptions options);
public ResultSet processBatch(BatchStatement statement, QueryState state, BatchQueryOptions options);
}
{noformat}
and to allow users to provide a specific class of their own (implementing said interface) to which the native protocol would handoff queries to (so by default queries would go to QueryProcessor, but you would have a way to use a custom class instead).
A typical use case for that could be to allow some form of custom logging of incoming queries and/or of their results. But this could probably also have some application for testing as one could have a handler that completely bypass QueryProcessor if you want, say, do perf regression tests for a given driver (and don't want to actually execute the query as you're perf testing the driver, not C*) without needing to patch the sources. Those being just examples, the mechanism is generic enough to allow for other ideas.
Most importantly, it requires very little code in C*. As for how users would register their "handler", it can be as simple as a startup flag indicating the class to use, or a yaml setting, or both.
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