phabricator: try to fetch differential revisions in batch...
phabricator: try to fetch differential revisions in batch
Previously, we read Differential Revisions one by one by calling
`differential.query`.
Fetching them one by one is suboptimal. Unfortunately, there is no Conduit
API that allows us to get a stack of diffids using a single API call.
This patch tries to be smarter using a simple heuristic: when fetching D59
as a stack, previous IDs like D51, D52, D53, ..., D58 are likely belonging
to a same stack so just fetch them as well. Since `differential.query` only
returns cheap metadata without expensive diff content, it shouldn't be a big
problem for the server.
Using a test Phabricator instance, this patch reduces `phabread` reading a
10 patch stack from about 13 to 30 seconds to 8 seconds.
