tests/test-pull-branch.t

lock: block signal interrupt while making a lock file

On Windows where symlink isn't supported, util.makelock() could leave an empty
file if interrupted immediately after os.open(). This empty lock never dies
as it has no process id recorded.

    ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
    # an interrupt may occur here
    os.write(ld, info)
    os.close(ld)

This was a long-standing bug of TortoiseHg which runs a command-server and
kills it by CTRL_C_EVENT, reported by random Windows users.

https://bitbucket.org/tortoisehg/thg/issues/4873/#comment-43591129

At first, I tried to fix makelock() to clean up a stale lock file, which
turned out to be hard because any instructions may be interrupted by a
signal.

    ld = None
    try:
        # CALL_FUNCTION  # os.open(...)
        # an interrupt may occur here
        # STORE_FAST     # ld = ...
        ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
        os.write(ld, info)
        ...
        return True
    except:
        if ld:
            ...
            os.unlink(pathname)
        return False

So I decided to block signals by temporarily replacing the signal handlers
so makelcok() and held = 1 will never be interrupted.

Many thanks to Fernando Najera for investigating the issue.

  $ hg init t
  $ cd t
  $ echo 1 > foo
  $ hg ci -Am1 # 0
  adding foo
  $ hg branch branchA
  marked working directory as branch branchA
  (branches are permanent and global, did you want a bookmark?)
  $ echo a1 > foo
  $ hg ci -ma1 # 1

  $ cd ..
  $ hg init tt
  $ cd tt
  $ hg pull ../t
  pulling from ../t
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 495a0ec48aaf:50e089d141b7
  (run 'hg update' to get a working copy)
  $ hg up branchA
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd ../t
  $ echo a2 > foo
  $ hg ci -ma2 # 2

Create branch B:

  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch branchB
  marked working directory as branch branchB
  $ echo b1 > foo
  $ hg ci -mb1 # 3

  $ cd ../tt

A new branch is there

  $ hg pull -u ../t
  pulling from ../t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files (+1 heads)
  new changesets 9f878dea0b96:5be59ce5067b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Develop both branches:

  $ cd ../t
  $ hg up branchA
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a3 > foo
  $ hg ci -ma3 # 4
  $ hg up branchB
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b2 > foo
  $ hg ci -mb2 # 5

  $ cd ../tt

Should succeed, no new heads:

  $ hg pull -u ../t
  pulling from ../t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 7c8fe7e20c32:453e93fa00a5
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Add a head on other branch:

  $ cd ../t
  $ hg up branchA
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a4 > foo
  $ hg ci -ma4 # 6
  $ hg up branchB
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b3.1 > foo
  $ hg ci -m b3.1 # 7
  $ hg up 5
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b3.2 > foo
  $ hg ci -m b3.2 # 8
  created new head

  $ cd ../tt

Should succeed because there is only one head on our branch:

  $ hg pull -u ../t
  pulling from ../t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files (+1 heads)
  new changesets da3a8a0161c6:b61cab8fe4e8
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd ../t
  $ hg up -C branchA
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a5.1 > foo
  $ hg ci -ma5.1 # 9
  $ hg up 6
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a5.2 > foo
  $ hg ci -ma5.2 # 10
  created new head
  $ hg up 7
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b4.1 > foo
  $ hg ci -m b4.1 # 11
  $ hg up -C 8
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b4.2 > foo
  $ hg ci -m b4.2 # 12

  $ cd ../tt

  $ hg pull -u ../t
  pulling from ../t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 4 changes to 1 files (+1 heads)
  new changesets 0c4d148ae29e:ecfc3f4a6fd9
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updated to "d740e1a584e7: a5.2"
  1 other heads for branch "branchA"

Make changes on new branch on tt

  $ hg up 6
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch branchC
  marked working directory as branch branchC
  $ echo b1 > bar
  $ hg ci -Am "commit on branchC on tt"
  adding bar

Make changes on default branch on t

  $ cd ../t
  $ hg up -C default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a1 > bar
  $ hg ci -Am "commit on default on t"
  adding bar

Pull branchC from tt

  $ hg pull ../tt
  pulling from ../tt
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 7d8ffa4c0b22
  (run 'hg heads' to see heads)

Make changes on default and branchC on tt

  $ cd ../tt
  $ hg pull ../t
  pulling from ../t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 2b94b54b6b5f
  (run 'hg heads' to see heads)
  $ hg up -C default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a1 > bar1
  $ hg ci -Am "commit on default on tt"
  adding bar1
  $ hg up branchC
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a1 > bar2
  $ hg ci -Am "commit on branchC on tt"
  adding bar2

Make changes on default and branchC on t

  $ cd ../t
  $ hg up default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a1 > bar3
  $ hg ci -Am "commit on default on t"
  adding bar3
  $ hg up branchC
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a1 > bar4
  $ hg ci -Am "commit on branchC on tt"
  adding bar4

Pull from tt

  $ hg pull ../tt
  pulling from ../tt
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+2 heads)
  new changesets eed40c14b407:e634733b0309
  (run 'hg heads .' to see heads, 'hg merge' to merge)

  $ cd ..