[FLINK-18905] Add runtime support for multiple input operator chained with sources

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.12.0
• Component/s: Runtime / Task
• Labels: pull-request-available
• Assignee: Piotr Nowojski
• Reporter: Piotr Nowojski
• Created: 12/Aug/20 15:28
• Updated: 19/Feb/21 07:26
• Resolved: 03/Sep/20 13:01

Description

Raw runtime support, ignoring watermarks, metrics and checkpointing.

Requires rewrite of `OperatorChain` class, dealing with `StreamTask#headOperator` field and generalisation of `StreamMultipleInputProcessor`.

Issue Links

• links to: GitHub Pull Request #3
• links to: GitHub Pull Request #13234