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This patch adds an output parameter 'already_unregistered' to FindRecvrOrWait() to signal to the caller in which of two cases it may have returned NULL. If 'already_unregistered' is true, the receiver has already been setup and closed (possibly by cancellation, possibly by the fragment deliberately closing its inputs in the case of a limit). This is not an error - cancellation will be signalled to the sender from the coordinator, and deliberate closure means the coordinator will tear down the query shortly. If 'already_unregistered' is set to false by FindRecvrOrWait(), the DataStreamMgr has never seen the intended receiver. This means the sender has waited for a full timeout period without the upstream receiver being established; this signals a likely query setup problem (as long as datastream_sender_timeout_ms is set sufficiently large) and so we return an error. We need to tweak the two timeout parameters here: * datastream_sender_timeout_ms needs to be large enough to avoid false negatives for problems during query setup (otherwise queries will unexpectedly cancel that would otherwise have succeeded, if slowly). * STREAM_EXPIRATION_TIME_MS needs to be set high enough that a query will not continue executing for longer than STREAM_EXPIRATION_TIME_MS after it closes its input (otherwise the sender will get already_unregistered=false, and cancel). This case will only trigger when a sender tries to call TransmitData() after the receiver has been closed for STREAM_EXPIRATION_TIME_MS; this should not happen in non-error cases as receivers are not closed before consuming their entire input. In this patch the former has been set to 2 minutes, and the latter to 5 minutes. Change-Id: Ib1734992c7199b9dd4b03afca5372022051b6fbd Reviewed-on: http://gerrit.cloudera.org:8080/2305 Reviewed-by: Henry Robinson <henry@cloudera.com> Tested-by: Henry Robinson <henry@cloudera.com>