Alexander Zarei created DRILL-1537:
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Summary: C++ Client: Passing the listener context to
queryResultListener function
Key: DRILL-1537
URL: https://issues.apache.org/jira/browse/DRILL-1537
Project: Apache Drill
Issue Type: Bug
Components: Client - ODBC
Reporter: Alexander Zarei
When submitting queries by the function `SubmitQuery(QueryType t, string& plan,
pfnQueryResultsListener l, void* lCtx)` of drillClientImp class, the
listenerContext parameter provides a convenient way of associating returned
results with submitted queries.
The way it works is that the calling application passes the context to
`SubmitQuery` and when returning results, `processQueryResult` passes the
context to the `queryResultListener` callback function. As such, the callback
function can associate the returned result with the context.
When we were updating QuerySubmitter example to showcase usage of `SubmitQuery`
with context, we noticed `processQueryResult` function does not pass the
context directly to the `queryResultListener` callback function; Instead, an
instance of DrillClientQueryResult which contains the context as a data member
is passed to the `queryResultListener`. This requires the `queryResultListener`
function, which is implemented in consumers of the C++ Client, to know about
the DrillClientQueryResult.
However, DrillClientQueryResult is not in the public API of the DrillClient.
Two solutions are imaginable at the first glance: First, passing the context
instead of a DrillClientQueryResult, which we implemented and tested it;
Second, moving DrillClientQueryResult to the public API; Moving
DrillClientQueryResult to the public API does not seem to be desirable as it is
internal detail for the C++ Client.
I was wondering what your thoughts are on this.
Thanks,
Alex
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