commit f6e546490b98e6b772677ec02659250338f39cda
author Youssef Elghareeb <ghareeb@google.com> Tue Oct 26 17:26:57 2021 +0200
committer Youssef Elghareeb <ghareeb@google.com> Thu Oct 28 14:42:16 2021 +0200
tree 54b9c0ee249c9003465837be27fd46ddcc130f76
parent 56944f825d89211c264de45a0a83bd54eabcd9c7

Add a "count=$count" argument to the label predicate

In this change we implement a "count" argument for the label predicate.
Example usages:
  * label:Code-Review=+2,count=2
  * label:Verified=MIN,count=1

The "count" argument can only be used in conjuction with numeric or
MAX/MIN/ANY votes. It can neither be used with Submit record predicates
(e.g. label:Code-Review=NEED), nor in conjunction with the user/group
args. We disallow these use cases to avoid extra complexity. For
example, the following usage is forbidden and will throw a
QueryParseException:
  * label:Code-Review=+2,user=non_uploader,count=2

The "=" operator does exact matching for count, for example
`label:Code-Review=1,count=2` will only match with changes having
exactly two +1 votes. We also support all other (>, >=, <, <=)
operators. For the "less than" operators, we don't match against any
change where count=0, i.e. label:cr=+1,count<2 will not match with a
change that does not have any +1 votes for CR. We do that deliberately
since it is computationally expensive to compute and store all formats
for non-voted values for all label types.

For less/greater than operators, we expand the query to a an OR'ed list
of predicates. For example, count>1 is expanded to count=2 OR count=3 OR
... OR count=5. We hardcoded a limit of 5 since this is reasonnable.
This same expansion is already implemented for label votes, i.e. for
search queries like: `label:code-review>-1`. This expansion is made so
that only exact count formats are stored in the index to optimize the
storage and avoid extra computation while indexing a change.

This new argument can be used in search queries and in submit
requirements expressions.

Bug: Google b/196337375
Change-Id: Ic14af9f7c1881414424e5bc77d3e3e0ce1f374f5