view tests/test-filebranch.t @ 40393:229d23cdb203

exchangev2: support fetching shallow files history

This commit teaches the exchangev2 client code to handle fetching shallow
files data.

Only shallow fetching of files data is supported: shallow fetching of
changeset and manifest data is explicitly not yet supported.

Previously, we would fetch file revisions for changesets that were received
by the current pull operation. In the new model, we calculate the set of
"relevant" changesets given the pull depth and only fetch files data for
those changesets.

We also teach the "filesdata" command invocation to vary parameters as needed.

The implementation here is far from complete or optimal. Subsequent pulls will
end up re-fetching a lot of files data. But the application of this data should
mostly be a no-op on the client, so it isn't a big deal.

Depending on the order file revisions are fetched in, revisions could get
inserted with the wrong revision number relationships. I think the best way
to deal with this is to remove revision numbers from storage and to either
dynamically derive them (by reconstructing a DAG from nodes/parents) or remove
revision numbers from the file storage interface completely.

A missing API that we'll likely want to write pretty soon is "ensure files
for revision(s) are present." We can kind of cajole exchangev2.pull() to do
this. But it isn't very efficient. For example, in simple cases like
widening the store to obtain data for a single revision, it is probably
more efficient to walk the manifest and find exactly which file revisions
are missing and to make explicit requests for just their data. In more
advanced cases, asking the server for all files data may be more efficient,
even though it requires sending data the client already has. There is tons
of room for future experimentation here. And TBH I'm not sure what the
final state will be.

Anyway, this commit gets us pretty close to being able to have shallow
and narrow checkouts with exchangev2/sqlite storage. Close enough that a
minimal extension should be able to provide fill in the gaps until the code
in core stabilizes and there is a user-facing way to trigger the
narrow/shallow bits from `hg clone` without also implying using of the
narrow extension...

Differential Revision: https://phab.mercurial-scm.org/D5169

This test makes sure that we don't mark a file as merged with its ancestor
when we do a merge.

  $ cat <<EOF > merge
  > from __future__ import print_function
  > import sys, os
  > print("merging for", os.path.basename(sys.argv[1]))
  > EOF
  $ HGMERGE="$PYTHON ../merge"; export HGMERGE

Creating base:

  $ hg init a
  $ cd a
  $ echo 1 > foo
  $ echo 1 > bar
  $ echo 1 > baz
  $ echo 1 > quux
  $ hg add foo bar baz quux
  $ hg commit -m "base"

  $ cd ..
  $ hg clone a b
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved

Creating branch a:

  $ cd a
  $ echo 2a > foo
  $ echo 2a > bar
  $ hg commit -m "branch a"

Creating branch b:

  $ cd ..
  $ cd b
  $ echo 2b > foo
  $ echo 2b > baz
  $ hg commit -m "branch b"

We shouldn't have anything but n state here:

  $ hg debugstate --no-dates | grep -v "^n"
  [1]

Merging:

  $ hg pull ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 2 changes to 2 files (+1 heads)
  new changesets bdd988058d16
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg merge -v
  resolving manifests
  getting bar
  merging foo
  merging for foo
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ echo 2m > foo
  $ echo 2b > baz
  $ echo new > quux

  $ hg ci -m "merge"

main: we should have a merge here:

  $ hg debugindex --changelog
     rev linkrev nodeid       p1           p2
       0       0 cdca01651b96 000000000000 000000000000
       1       1 f6718a9cb7f3 cdca01651b96 000000000000
       2       2 bdd988058d16 cdca01651b96 000000000000
       3       3 d8a521142a3c f6718a9cb7f3 bdd988058d16

log should show foo and quux changed:

  $ hg log -v -r tip
  changeset:   3:d8a521142a3c
  tag:         tip
  parent:      1:f6718a9cb7f3
  parent:      2:bdd988058d16
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       foo quux
  description:
  merge
  
  

foo: we should have a merge here:

  $ hg debugindex foo
     rev linkrev nodeid       p1           p2
       0       0 b8e02f643373 000000000000 000000000000
       1       1 2ffeddde1b65 b8e02f643373 000000000000
       2       2 33d1fb69067a b8e02f643373 000000000000
       3       3 aa27919ee430 2ffeddde1b65 33d1fb69067a

bar: we should not have a merge here:

  $ hg debugindex bar
     rev linkrev nodeid       p1           p2
       0       0 b8e02f643373 000000000000 000000000000
       1       2 33d1fb69067a b8e02f643373 000000000000

baz: we should not have a merge here:

  $ hg debugindex baz
     rev linkrev nodeid       p1           p2
       0       0 b8e02f643373 000000000000 000000000000
       1       1 2ffeddde1b65 b8e02f643373 000000000000

quux: we should not have a merge here:

  $ hg debugindex quux
     rev linkrev nodeid       p1           p2
       0       0 b8e02f643373 000000000000 000000000000
       1       3 6128c0f33108 b8e02f643373 000000000000

Manifest entries should match tips of all files:

  $ hg manifest --debug
  33d1fb69067a0139622a3fa3b7ba1cdb1367972e 644   bar
  2ffeddde1b65b4827f6746174a145474129fa2ce 644   baz
  aa27919ee4303cfd575e1fb932dd64d75aa08be4 644   foo
  6128c0f33108e8cfbb4e0824d13ae48b466d7280 644   quux

Everything should be clean now:

  $ hg status

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 4 changesets with 10 changes to 4 files

  $ cd ..