Summary:
We want to migrate the tests to run using treemanifest. As part of
that, we want to first transition to using treemanifest without actually
changing the hash, so we can check that the tests still work first, then update
the hashes second.
This diff adds the flatcompat mode and enables it by default. A future diff will
start enabling treemanifest for existing tests.
Reviewed By: quark-zju
Differential Revision: D15030252
fbshipit-source-id: 06c82be749282d62f1d9cfb43246695c427f8165
Summary:
When requesting trees from the server we try to provide a base tree
that we already have. In the hybrid manifest days, when we were fetching
manifest X, we would look up the linknode for X in the flat manifest revlog,
then scan the changelog up and down from that linknode. In the treeonly world we
don't have that revlog anymore though, so the current algorithm just searches from
the tip. This ended up being a really bad algorithm, since if you have tip and you
request tip~1000, then tip~2000, then tip~3000, you end up basing them all
against tip and redownloading a lot of data. This makes hg blame and hg log -p
super slow.
Let's change the algorithm to base off of a hint linknode, and let's change
changectx to set that hint every time it attempts to read a manifest. In manual
testing this significantly sped up hg log -p
Reviewed By: phillco
Differential Revision: D8399613
fbshipit-source-id: 771a94ee8b82be682ea0091b8d6c0fcd5f4e6646
