commit 4d2dd189b5eeb1bc1997f6cc4f90ed53c7a4d4ab
author Patrick Hiesel <hiesel@google.com> Tue May 09 17:35:18 2017 +0200
committer Patrick Hiesel <hiesel@google.com> Tue May 30 09:42:34 2017 +0200
tree 48e0f75c91fd5005ae5d75af5865a6667a307978
parent 1ead0c68f14e8e686244795cb44d511116470544

Add project~changeNumber as changeId pattern

This change adds support for a new change identifier in the /changes
REST API endpoint. It follows the discussion on
Idac92e61ee1471b074034eef39901b1b8e961706 and the two recent Gerrit
Hackathons.

The new change identifier serves multiple purposes:

1) Since it contains the project name, we can directly construct the
   ChangeApi without a secondary index lookup. This means that we can
   still serve requests to some endpoints, even in case of a complete
   index failure.
   When the project is added in the UI, we will still be able to serve
   change pages in case of an index failure. While the triplet also
   contains the project, it is unfeasible for the UI since it requires a
   branch name (which we don't want to have in the UI URLs) and has the
   changeId instead of the change number.
2) Reducing the number of secondary index lookups is a performance gain.
3) The project name being contained in the URL enables load balancers
   to shard requests based on the project without a need for an index
   lookup (which most load balancers do not support). The sharding
   configuration can then be as easy as a regular expression and a
   static project-to-machine mapping.
4) This change is also a first step in deprecating the other three
   change identifiers and unifying our API access pattern. This will
   happen gradually in upcoming changes. Also the UI will be adapted.

This change also adds extensive testing to both the new parsing logic as
well as all change identifiers in both the Java and the REST API.

Change-Id: I7a904fdd001c065af9897d9c08edce1cfbd43a14