Programming to Get Function Results
The client may use the default result collector. If the client needs special results handling, code a custom
ResultsCollector implementation to replace the default. Use the
Execution::withCollector method to define the custom collector.
Note: This section applies only to functions that return results.
To program your client to get the results from a function, use the result collector returned from the function execution, like this:
ResultCollectorPtr rc = FunctionService::onRegion(region) ->withArgs(args) ->withFilter(keySet) ->withCollector(new MyCustomResultCollector()) .execute(Function); CacheableVectorPtr functionResult = rc.getResult();
getResult methods of the default result collector block until all results are received, then return the full result set.
To handle the results in a custom manner:
- Write a class that implements the
ResultCollectorinterface to handle the results in a custom manner. The methods are of two types: one handles data and information from GemFire and populates the results set, while the other returns the compiled results to the calling application:
addResultis called when results arrive from the
addResultto add a single result to the ResultCollector.
endResultsis called to signal the end of all results from the function execution.
getResultis available to your executing application (the one that calls
Execution.execute) to retrieve the results. This may block until all results are available.
clearResultsis called to clear partial results from the results collector. This is used only for highly available
onRegionfunctions where the calling application waits for the results. If the call fails, before GemFire retries the execution, it calls
clearResultsto ready the instance for a clean set of results.
- Use the
Executionobject in your executing member to call
withCollector, passing your custom collector, as shown in the example above.