[HDFS-11437] libhdfs++: Handler for FileSystem async connect can be invoked before successful communication with active NN

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: hdfs-client
• Assignee: James Clampffer
• Reporter: James Clampffer
• Created: 21/Feb/17 21:59
• Updated: 26/Oct/18 13:29

Description

The handler provided to FileSystem::Connect can be invoked as soon as the FS makes a connection to the standby NN rather than waiting until it connects to the active NN. This allows RPC requests to be enqueued before a real connection is made and if the active NN isn't reachable for some reason the only way to cancel is to delete the FS from another thread which kills all pending requests.

The underlying issue is that currently the only thing that must happen for the connect handler to be invoked is a successful handshake with a NN. Connecting to the standby NN and receiving a StandbyException satisfies this requirement but it should wait until it is able to get a handshake from the active NN.