view tests/test-audit-path.t @ 30212:260af19891f2

changegroup: increase write buffer size to 128k

By default, Python defers to the operating system for choosing the
default buffer size on opened files. On my Linux machine, the default
is 4k, which is really small for 2016.

This patch bumps the write buffer size when writing
changegroups/bundles to 128k. This matches the 128k read buffer
we already use on revlogs.

It's worth noting that this only impacts when writing to an explicit
file (such as during `hg bundle`). Buffers when writing to bundle
files via the repo vfs or to a temporary file are not impacted.

When producing a none-v2 bundle file of the mozilla-unified repository,
this change caused the number of write() system calls to drop from
952,449 to 29,788. After this change, the most frequent system
calls are fstat(), read(), lseek(), and open(). There were
2,523,672 system calls after this patch (so a net decrease of
~950k is statistically significant).

This change shows no performance change on my system. But I have a
high-end system with a fast SSD. It is quite possible this change
will have a significant impact on network file systems, where
extra network round trips due to excessive I/O system calls could
introduce significant latency.

  $ hg init

audit of .hg

  $ hg add .hg/00changelog.i
  abort: path contains illegal component: .hg/00changelog.i (glob)
  [255]

#if symlink

Symlinks

  $ mkdir a
  $ echo a > a/a
  $ hg ci -Ama
  adding a/a
  $ ln -s a b
  $ echo b > a/b
  $ hg add b/b
  abort: path 'b/b' traverses symbolic link 'b' (glob)
  [255]
  $ hg add b

should still fail - maybe

  $ hg add b/b
  abort: path 'b/b' traverses symbolic link 'b' (glob)
  [255]

  $ hg commit -m 'add symlink b'


Test symlink traversing when accessing history:
-----------------------------------------------

(build a changeset where the path exists as a directory)

  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkdir b
  $ echo c > b/a
  $ hg add b/a
  $ hg ci -m 'add directory b'
  created new head

Test that hg cat does not do anything wrong the working copy has 'b' as directory

  $ hg cat b/a
  c
  $ hg cat -r "desc(directory)" b/a
  c
  $ hg cat -r "desc(symlink)" b/a
  b/a: no such file in rev bc151a1f53bd
  [1]

Test that hg cat does not do anything wrong the working copy has 'b' as a symlink (issue4749)

  $ hg up 'desc(symlink)'
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg cat b/a
  b/a: no such file in rev bc151a1f53bd
  [1]
  $ hg cat -r "desc(directory)" b/a
  c
  $ hg cat -r "desc(symlink)" b/a
  b/a: no such file in rev bc151a1f53bd
  [1]

#endif


unbundle tampered bundle

  $ hg init target
  $ cd target
  $ hg unbundle "$TESTDIR/bundles/tampered.hg"
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 6 changes to 6 files (+4 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)

attack .hg/test

  $ hg manifest -r0
  .hg/test
  $ hg update -Cr0
  abort: path contains illegal component: .hg/test (glob)
  [255]

attack foo/.hg/test

  $ hg manifest -r1
  foo/.hg/test
  $ hg update -Cr1
  abort: path 'foo/.hg/test' is inside nested repo 'foo' (glob)
  [255]

attack back/test where back symlinks to ..

  $ hg manifest -r2
  back
  back/test
#if symlink
  $ hg update -Cr2
  abort: path 'back/test' traverses symbolic link 'back'
  [255]
#else
('back' will be a file and cause some other system specific error)
  $ hg update -Cr2
  abort: * (glob)
  [255]
#endif

attack ../test

  $ hg manifest -r3
  ../test
  $ hg update -Cr3
  abort: path contains illegal component: ../test (glob)
  [255]

attack /tmp/test

  $ hg manifest -r4
  /tmp/test
  $ hg update -Cr4
  abort: path contains illegal component: /tmp/test (glob)
  [255]

  $ cd ..