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Comment to new IProcessor method

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This commit is contained in:
Igor Nikonov 2024-07-23 07:57:03 +00:00
parent 6c9d037730
commit 223eee3f46
1 changed files with 15 additions and 0 deletions
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15
src/Processors/IProcessor.h
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@ -221,6 +221,21 @@ public:
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method 'schedule' is not implemented for {} processor", getName());
}
/* The method is called right after asynchronous job is done
* i.e. when file descriptor returned by schedule() is readable.
* The sequence of method calls:
* ... prepare() -> schedule() -> onAsyncJobReady() -> work() ...
* See also comment to schedule() method
*
* It allows doing some preprocessing immediately after asynchronous job is done.
* The implementation should return control quickly, to avoid blocking another asynchronous completed jobs
* created by the same pipeline.
*
* Example, scheduling tasks for remote workers (file descriptor in this case is a socket)
* When the remote worker asks for the next task, doing it in onAsyncJobReady() we can provide it immediately.
* Otherwise, the returning of the next task for the remote worker can be delayed by current work done in the pipeline
* i.e. processor->work(), which will create unnecessary latency in query processing by remote workers Not Committed Yet
*/
virtual void onAsyncJobReady() {}
/** You must call this method if 'prepare' returned ExpandPipeline.