view tests/test-simple-update.t @ 27475:a2e2a8fa5fd1

revlog: avoid string slice when decompressing u* chunks

Revlog chunks can be stored uncompressed. If the first byte of the
raw data is \0, we store the data as is. Else we prefix it with 'u'.

Before, we performed a string slice to strip out the 'u' prefix.
With this patch, we use a buffer to avoid an extra memory copy and
associated garbage collection overhead.

I was unable to verify any performance impact of this patch. For both
mozilla-central and the hg repos, the number of manifest revisions
with 'u' prefixes is very small - under 1%. So this change likely
isn't called enough to have an impact on manifest reading. However,
the reasoning behind this change is solid, so it should be safe.

  $ hg init test
  $ cd test
  $ echo foo>foo
  $ hg addremove
  adding foo
  $ hg commit -m "1"

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ hg clone . ../branch
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ../branch
  $ hg co
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo bar>>foo
  $ hg commit -m "2"

  $ cd ../test

  $ hg pull ../branch
  pulling from ../branch
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  (run 'hg update' to get a working copy)

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 2 changesets, 2 total revisions

  $ hg co
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cat foo
  foo
  bar

  $ hg manifest --debug
  6f4310b00b9a147241b071a60c28a650827fb03d 644   foo

update to rev 0 with a date

  $ hg upd -d foo 0
  abort: you can't specify a revision and a date
  [255]

  $ cd ..