comparison tests/test-branches.t @ 29744:0d588332ad2c

branchmap: acquires lock before writting the rev branch cache

We now attempt to acquire a lock and write the branch cache within that lock.
This would prevent cache corruption when multiple processes try to write the cache
at the same time.

29743:9f3c49ee4486

  $ mkdir .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n'
  5
  $ rmdir .hg/cache/rbc-revs-v1
  $ mv .hg/cache/rbc-revs-v1_ .hg/cache/rbc-revs-v1

recovery from invalid cache revs file with trailing data
  $ echo >> .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5

29744:0d588332ad2c

  $ mkdir .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n'
  5
  $ rmdir .hg/cache/rbc-revs-v1
  $ mv .hg/cache/rbc-revs-v1_ .hg/cache/rbc-revs-v1

no errors when wlock cannot be acquired

#if unix-permissions
  $ mv .hg/cache/rbc-revs-v1 .hg/cache/rbc-revs-v1_
  $ rm -f .hg/cache/branch*
  $ chmod 555 .hg
  $ hg head a -T '{rev}\n'
  5
  $ chmod 755 .hg
  $ mv .hg/cache/rbc-revs-v1_ .hg/cache/rbc-revs-v1
#endif

recovery from invalid cache revs file with trailing data
  $ echo >> .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5