view tests/test-issue842.t @ 25774:4f8c20fe66f0

shelve: keep old backups if timestamp can't decide exact order of them

Before this patch, backups to be discarded are decided by steps below
at 'hg unshelve' or so:

  1. list '(st_mtime, filename)' tuples of each backups up
  2. sort list of these tuples, and
  3. discard backups other than 'maxbackups' ones at the end of list

This doesn't work well in the case below:

  - "sort by name" order differs from actual backup-ing order, and
  - some of backups have same timestamp

For example, 'test-shelve.t' satisfies the former condition:

  - 'default-01' < 'default-1' in "sort by name" order
  - 'default-1'  < 'default-01' in actual backup-ing order

Then, 'default-01' is discarded instead of 'default-1' unexpectedly,
if they have same timestamp. This failure appears occasionally,
because the most important condition "same timestamp" is timing
critical.

To avoid such unexpected discarding, this patch keeps old backups if
timestamp can't decide exact order of them.

Timestamp of the border backup (= the oldest one of recent
'maxbackups' ones) as 'bordermtime' is used to examine whether
timestamp can decide exact order of backups.

http://mercurial.selenic.com/bts/issue842

  $ hg init
  $ echo foo > a
  $ hg ci -Ama
  adding a

  $ hg up -r0000
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo bar > a

Should issue new head warning:

  $ hg ci -Amb
  adding a
  created new head

  $ hg up -r0000
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo stuffy > a

Should not issue new head warning:

  $ hg ci -q -Amc

  $ hg up -r0000
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo crap > a
  $ hg branch testing
  marked working directory as branch testing
  (branches are permanent and global, did you want a bookmark?)

Should not issue warning:

  $ hg ci -q -Amd