view tests/test-tags.t @ 30442:41a8106789ca

util: implement zstd compression engine

Now that zstd is vendored and being built (in some configurations), we
can implement a compression engine for zstd!

The zstd engine is a little different from existing engines. Because
it may not always be present, we have to defer load the module in case
importing it fails. We facilitate this via a cached property that holds
a reference to the module or None. The "available" method is
implemented to reflect reality.

The zstd engine declares its ability to handle bundles using the
"zstd" human name and the "ZS" internal name. The latter was chosen
because internal names are 2 characters (by only convention I think)
and "ZS" seems reasonable.

The engine, like others, supports specifying the compression level.
However, there are no consumers of this API that yet pass in that
argument. I have plans to change that, so stay tuned.

Since all we need to do to support bundle generation with a new
compression engine is implement and register the compression engine,
bundle generation with zstd "just works!" Tests demonstrating this
have been added.

How does performance of zstd for bundle generation compare? On the
mozilla-unified repo, `hg bundle --all -t <engine>-v2` yields the
following on my i7-6700K on Linux:

engine        CPU time     bundle size   vs orig size   throughput
none            97.0s     4,054,405,584     100.0%       41.8 MB/s
bzip2 (l=9)    393.6s       975,343,098      24.0%       10.3 MB/s
gzip (l=6)     184.0s     1,140,533,074      28.1%       22.0 MB/s
zstd (l=1)     108.2s     1,119,434,718      27.6%       37.5 MB/s
zstd (l=2)     111.3s     1,078,328,002      26.6%       36.4 MB/s
zstd (l=3)     113.7s     1,011,823,727      25.0%       35.7 MB/s
zstd (l=4)     116.0s     1,008,965,888      24.9%       35.0 MB/s
zstd (l=5)     121.0s       977,203,148      24.1%       33.5 MB/s
zstd (l=6)     131.7s       927,360,198      22.9%       30.8 MB/s
zstd (l=7)     139.0s       912,808,505      22.5%       29.2 MB/s
zstd (l=12)    198.1s       854,527,714      21.1%       20.5 MB/s
zstd (l=18)    681.6s       789,750,690      19.5%        5.9 MB/s

On compression, zstd for bundle generation delivers:

* better compression than gzip with significantly less CPU utilization
* better than bzip2 compression ratios while still being significantly
  faster than gzip
* ability to aggressively tune compression level to achieve
  significantly smaller bundles

That last point is important. With clone bundles, a server can
pre-generate a bundle file, upload it to a static file server, and
redirect clients to transparently download it during clone. The server
could choose to produce a zstd bundle with the highest compression
settings possible. This would take a very long time - a magnitude
longer than a typical zstd bundle generation - but the result would
be hundreds of megabytes smaller! For the clone volume we do at
Mozilla, this could translate to petabytes of bandwidth savings
per year and faster clones (due to smaller transfer size).

I don't have detailed numbers to report on decompression. However,
zstd decompression is fast: >1 GB/s output throughput on this machine,
even through the Python bindings. And it can do that regardless of the
compression level of the input. By the time you have enough data to
worry about overhead of decompression, you have plenty of other things
to worry about performance wise.

zstd is wins all around. I can't wait to implement support for it
on the wire protocol and in revlogs.

setup

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > blackbox=
  > mock=$TESTDIR/mockblackbox.py
  > EOF

Helper functions:

  $ cacheexists() {
  >   [ -f .hg/cache/tags2-visible ] && echo "tag cache exists" || echo "no tag cache"
  > }

  $ fnodescacheexists() {
  >   [ -f .hg/cache/hgtagsfnodes1 ] && echo "fnodes cache exists" || echo "no fnodes cache"
  > }

  $ dumptags() {
  >     rev=$1
  >     echo "rev $rev: .hgtags:"
  >     hg cat -r$rev .hgtags
  > }

# XXX need to test that the tag cache works when we strip an old head
# and add a new one rooted off non-tip: i.e. node and rev of tip are the
# same, but stuff has changed behind tip.

Setup:

  $ hg init t
  $ cd t
  $ cacheexists
  no tag cache
  $ fnodescacheexists
  no fnodes cache
  $ hg id
  000000000000 tip
  $ cacheexists
  no tag cache
  $ fnodescacheexists
  no fnodes cache
  $ echo a > a
  $ hg add a
  $ hg commit -m "test"
  $ hg co
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg identify
  acb14030fe0a tip
  $ hg identify -r 'wdir()'
  acb14030fe0a tip
  $ cacheexists
  tag cache exists
No fnodes cache because .hgtags file doesn't exist
(this is an implementation detail)
  $ fnodescacheexists
  no fnodes cache

Try corrupting the cache

  $ printf 'a b' > .hg/cache/tags2-visible
  $ hg identify
  acb14030fe0a tip
  $ cacheexists
  tag cache exists
  $ fnodescacheexists
  no fnodes cache
  $ hg identify
  acb14030fe0a tip

Create local tag with long name:

  $ T=`hg identify --debug --id`
  $ hg tag -l "This is a local tag with a really long name!"
  $ hg tags
  tip                                0:acb14030fe0a
  This is a local tag with a really long name!     0:acb14030fe0a
  $ rm .hg/localtags

Create a tag behind hg's back:

  $ echo "$T first" > .hgtags
  $ cat .hgtags
  acb14030fe0a21b60322c440ad2d20cf7685a376 first
  $ hg add .hgtags
  $ hg commit -m "add tags"
  $ hg tags
  tip                                1:b9154636be93
  first                              0:acb14030fe0a
  $ hg identify
  b9154636be93 tip

We should have a fnodes cache now that we have a real tag
The cache should have an empty entry for rev 0 and a valid entry for rev 1.


  $ fnodescacheexists
  fnodes cache exists
  $ f --size --hexdump .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=48
  0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0010: ff ff ff ff ff ff ff ff b9 15 46 36 26 b7 b4 a7 |..........F6&...|
  0020: 73 e0 9e e3 c5 2f 51 0e 19 e0 5e 1f f9 66 d8 59 |s..../Q...^..f.Y|

Repeat with cold tag cache:

  $ rm -f .hg/cache/tags2-visible .hg/cache/hgtagsfnodes1
  $ hg identify
  b9154636be93 tip

  $ fnodescacheexists
  fnodes cache exists
  $ f --size --hexdump .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=48
  0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0010: ff ff ff ff ff ff ff ff b9 15 46 36 26 b7 b4 a7 |..........F6&...|
  0020: 73 e0 9e e3 c5 2f 51 0e 19 e0 5e 1f f9 66 d8 59 |s..../Q...^..f.Y|

And again, but now unable to write tag cache or lock file:

#if unix-permissions
  $ rm -f .hg/cache/tags2-visible .hg/cache/hgtagsfnodes1
  $ chmod 555 .hg/cache
  $ hg identify
  b9154636be93 tip
  $ chmod 755 .hg/cache

  $ chmod 555 .hg
  $ hg identify
  b9154636be93 tip
  $ chmod 755 .hg
#endif

Tag cache debug info written to blackbox log

  $ rm -f .hg/cache/tags2-visible .hg/cache/hgtagsfnodes1
  $ hg identify
  b9154636be93 tip
  $ hg blackbox -l 6
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> identify
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> writing 48 bytes to cache/hgtagsfnodes1
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> 0/1 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> identify exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> blackbox -l 6

Failure to acquire lock results in no write

  $ rm -f .hg/cache/tags2-visible .hg/cache/hgtagsfnodes1
  $ echo 'foo:1' > .hg/wlock
  $ hg identify
  b9154636be93 tip
  $ hg blackbox -l 6
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> identify
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> not writing .hg/cache/hgtagsfnodes1 because lock cannot be acquired
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> 0/1 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> identify exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @b9154636be938d3d431e75a7c906504a079bfe07 (5000)> blackbox -l 6

  $ fnodescacheexists
  no fnodes cache

  $ rm .hg/wlock

  $ rm -f .hg/cache/tags2-visible .hg/cache/hgtagsfnodes1
  $ hg identify
  b9154636be93 tip

Create a branch:

  $ echo bb > a
  $ hg status
  M a
  $ hg identify
  b9154636be93+ tip
  $ hg co first
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg id
  acb14030fe0a+ first
  $ hg id -r 'wdir()'
  acb14030fe0a+ first
  $ hg -v id
  acb14030fe0a+ first
  $ hg status
  M a
  $ echo 1 > b
  $ hg add b
  $ hg commit -m "branch"
  created new head

Creating a new commit shouldn't append the .hgtags fnodes cache until
tags info is accessed

  $ f --size --hexdump .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=48
  0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0010: ff ff ff ff ff ff ff ff b9 15 46 36 26 b7 b4 a7 |..........F6&...|
  0020: 73 e0 9e e3 c5 2f 51 0e 19 e0 5e 1f f9 66 d8 59 |s..../Q...^..f.Y|

  $ hg id
  c8edf04160c7 tip

First 4 bytes of record 3 are changeset fragment

  $ f --size --hexdump .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=72
  0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0010: ff ff ff ff ff ff ff ff b9 15 46 36 26 b7 b4 a7 |..........F6&...|
  0020: 73 e0 9e e3 c5 2f 51 0e 19 e0 5e 1f f9 66 d8 59 |s..../Q...^..f.Y|
  0030: c8 ed f0 41 00 00 00 00 00 00 00 00 00 00 00 00 |...A............|
  0040: 00 00 00 00 00 00 00 00                         |........|

Merge the two heads:

  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg blackbox -l3
  1970/01/01 00:00:00 bob @c8edf04160c7f731e4589d66ab3ab3486a64ac28 (5000)> merge 1
  1970/01/01 00:00:00 bob @c8edf04160c7f731e4589d66ab3ab3486a64ac28+b9154636be938d3d431e75a7c906504a079bfe07 (5000)> merge 1 exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @c8edf04160c7f731e4589d66ab3ab3486a64ac28+b9154636be938d3d431e75a7c906504a079bfe07 (5000)> blackbox -l3
  $ hg id
  c8edf04160c7+b9154636be93+ tip
  $ hg status
  M .hgtags
  $ hg commit -m "merge"

Create a fake head, make sure tag not visible afterwards:

  $ cp .hgtags tags
  $ hg tag last
  $ hg rm .hgtags
  $ hg commit -m "remove"

  $ mv tags .hgtags
  $ hg add .hgtags
  $ hg commit -m "readd"
  $ 
  $ hg tags
  tip                                6:35ff301afafe
  first                              0:acb14030fe0a

Add invalid tags:

  $ echo "spam" >> .hgtags
  $ echo >> .hgtags
  $ echo "foo bar" >> .hgtags
  $ echo "a5a5 invalid" >> .hg/localtags
  $ cat .hgtags
  acb14030fe0a21b60322c440ad2d20cf7685a376 first
  spam
  
  foo bar
  $ hg commit -m "tags"

Report tag parse error on other head:

  $ hg up 3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo 'x y' >> .hgtags
  $ hg commit -m "head"
  created new head

  $ hg tags --debug
  .hgtags@75d9f02dfe28, line 2: cannot parse entry
  .hgtags@75d9f02dfe28, line 4: node 'foo' is not well formed
  .hgtags@c4be69a18c11, line 2: node 'x' is not well formed
  tip                                8:c4be69a18c11e8bc3a5fdbb576017c25f7d84663
  first                              0:acb14030fe0a21b60322c440ad2d20cf7685a376
  $ hg tip
  changeset:   8:c4be69a18c11
  tag:         tip
  parent:      3:ac5e980c4dc0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     head
  

Test tag precedence rules:

  $ cd ..
  $ hg init t2
  $ cd t2
  $ echo foo > foo
  $ hg add foo
  $ hg ci -m 'add foo'      # rev 0
  $ hg tag bar              # rev 1
  $ echo >> foo
  $ hg ci -m 'change foo 1' # rev 2
  $ hg up -C 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tag -r 1 -f bar      # rev 3
  $ hg up -C 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo >> foo
  $ hg ci -m 'change foo 2' # rev 4
  created new head
  $ hg tags
  tip                                4:0c192d7d5e6b
  bar                                1:78391a272241

Repeat in case of cache effects:

  $ hg tags
  tip                                4:0c192d7d5e6b
  bar                                1:78391a272241

Detailed dump of tag info:

  $ hg heads -q             # expect 4, 3, 2
  4:0c192d7d5e6b
  3:6fa450212aeb
  2:7a94127795a3
  $ dumptags 2
  rev 2: .hgtags:
  bbd179dfa0a71671c253b3ae0aa1513b60d199fa bar
  $ dumptags 3
  rev 3: .hgtags:
  bbd179dfa0a71671c253b3ae0aa1513b60d199fa bar
  bbd179dfa0a71671c253b3ae0aa1513b60d199fa bar
  78391a272241d70354aa14c874552cad6b51bb42 bar
  $ dumptags 4
  rev 4: .hgtags:
  bbd179dfa0a71671c253b3ae0aa1513b60d199fa bar

Dump cache:

  $ cat .hg/cache/tags2-visible
  4 0c192d7d5e6b78a714de54a2e9627952a877e25a
  bbd179dfa0a71671c253b3ae0aa1513b60d199fa bar
  bbd179dfa0a71671c253b3ae0aa1513b60d199fa bar
  78391a272241d70354aa14c874552cad6b51bb42 bar

  $ f --size --hexdump .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=120
  0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0010: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0020: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0030: 7a 94 12 77 0c 04 f2 a8 af 31 de 17 fa b7 42 28 |z..w.....1....B(|
  0040: 78 ee 5a 2d ad bc 94 3d 6f a4 50 21 7d 3b 71 8c |x.Z-...=o.P!};q.|
  0050: 96 4e f3 7b 89 e5 50 eb da fd 57 89 e7 6c e1 b0 |.N.{..P...W..l..|
  0060: 0c 19 2d 7d 0c 04 f2 a8 af 31 de 17 fa b7 42 28 |..-}.....1....B(|
  0070: 78 ee 5a 2d ad bc 94 3d                         |x.Z-...=|

Corrupt the .hgtags fnodes cache
Extra junk data at the end should get overwritten on next cache update

  $ echo extra >> .hg/cache/hgtagsfnodes1
  $ echo dummy1 > foo
  $ hg commit -m throwaway1

  $ hg tags
  tip                                5:8dbfe60eff30
  bar                                1:78391a272241

  $ hg blackbox -l 6
  1970/01/01 00:00:00 bob @8dbfe60eff306a54259cfe007db9e330e7ecf866 (5000)> tags
  1970/01/01 00:00:00 bob @8dbfe60eff306a54259cfe007db9e330e7ecf866 (5000)> writing 24 bytes to cache/hgtagsfnodes1
  1970/01/01 00:00:00 bob @8dbfe60eff306a54259cfe007db9e330e7ecf866 (5000)> 2/3 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @8dbfe60eff306a54259cfe007db9e330e7ecf866 (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @8dbfe60eff306a54259cfe007db9e330e7ecf866 (5000)> tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @8dbfe60eff306a54259cfe007db9e330e7ecf866 (5000)> blackbox -l 6

#if unix-permissions no-root
Errors writing to .hgtags fnodes cache are silently ignored

  $ echo dummy2 > foo
  $ hg commit -m throwaway2

  $ chmod a-w .hg/cache/hgtagsfnodes1
  $ rm -f .hg/cache/tags2-visible

  $ hg tags
  tip                                6:b968051b5cf3
  bar                                1:78391a272241

  $ hg blackbox -l 6
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> tags
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> couldn't write cache/hgtagsfnodes1: [Errno 13] Permission denied: '$TESTTMP/t2/.hg/cache/hgtagsfnodes1'
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> 2/3 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> blackbox -l 6

  $ chmod a+w .hg/cache/hgtagsfnodes1

  $ rm -f .hg/cache/tags2-visible
  $ hg tags
  tip                                6:b968051b5cf3
  bar                                1:78391a272241

  $ hg blackbox -l 6
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> tags
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> writing 24 bytes to cache/hgtagsfnodes1
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> 2/3 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @b968051b5cf3f624b771779c6d5f84f1d4c3fb5d (5000)> blackbox -l 6

  $ f --size .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=168

  $ hg -q --config extensions.strip= strip -r 6 --no-backup
#endif

Stripping doesn't truncate the tags cache until new data is available

  $ rm -f .hg/cache/hgtagsfnodes1 .hg/cache/tags2-visible
  $ hg tags
  tip                                5:8dbfe60eff30
  bar                                1:78391a272241

  $ f --size .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=144

  $ hg -q --config extensions.strip= strip -r 5 --no-backup
  $ hg tags
  tip                                4:0c192d7d5e6b
  bar                                1:78391a272241

  $ hg blackbox -l 5
  1970/01/01 00:00:00 bob @0c192d7d5e6b78a714de54a2e9627952a877e25a (5000)> writing 24 bytes to cache/hgtagsfnodes1
  1970/01/01 00:00:00 bob @0c192d7d5e6b78a714de54a2e9627952a877e25a (5000)> 2/3 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @0c192d7d5e6b78a714de54a2e9627952a877e25a (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @0c192d7d5e6b78a714de54a2e9627952a877e25a (5000)> tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @0c192d7d5e6b78a714de54a2e9627952a877e25a (5000)> blackbox -l 5

  $ f --size .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=120

  $ echo dummy > foo
  $ hg commit -m throwaway3

  $ hg tags
  tip                                5:035f65efb448
  bar                                1:78391a272241

  $ hg blackbox -l 6
  1970/01/01 00:00:00 bob @035f65efb448350f4772141702a81ab1df48c465 (5000)> tags
  1970/01/01 00:00:00 bob @035f65efb448350f4772141702a81ab1df48c465 (5000)> writing 24 bytes to cache/hgtagsfnodes1
  1970/01/01 00:00:00 bob @035f65efb448350f4772141702a81ab1df48c465 (5000)> 2/3 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @035f65efb448350f4772141702a81ab1df48c465 (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @035f65efb448350f4772141702a81ab1df48c465 (5000)> tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @035f65efb448350f4772141702a81ab1df48c465 (5000)> blackbox -l 6
  $ f --size .hg/cache/hgtagsfnodes1
  .hg/cache/hgtagsfnodes1: size=144

  $ hg -q --config extensions.strip= strip -r 5 --no-backup

Test tag removal:

  $ hg tag --remove bar     # rev 5
  $ hg tip -vp
  changeset:   5:5f6e8655b1c7
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       .hgtags
  description:
  Removed tag bar
  
  
  diff -r 0c192d7d5e6b -r 5f6e8655b1c7 .hgtags
  --- a/.hgtags	Thu Jan 01 00:00:00 1970 +0000
  +++ b/.hgtags	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,3 @@
   bbd179dfa0a71671c253b3ae0aa1513b60d199fa bar
  +78391a272241d70354aa14c874552cad6b51bb42 bar
  +0000000000000000000000000000000000000000 bar
  
  $ hg tags
  tip                                5:5f6e8655b1c7
  $ hg tags                 # again, try to expose cache bugs
  tip                                5:5f6e8655b1c7

Remove nonexistent tag:

  $ hg tag --remove foobar
  abort: tag 'foobar' does not exist
  [255]
  $ hg tip
  changeset:   5:5f6e8655b1c7
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Removed tag bar
  

Undo a tag with rollback:

  $ hg rollback             # destroy rev 5 (restore bar)
  repository tip rolled back to revision 4 (undo commit)
  working directory now based on revision 4
  $ hg tags
  tip                                4:0c192d7d5e6b
  bar                                1:78391a272241
  $ hg tags
  tip                                4:0c192d7d5e6b
  bar                                1:78391a272241

Test tag rank:

  $ cd ..
  $ hg init t3
  $ cd t3
  $ echo foo > foo
  $ hg add foo
  $ hg ci -m 'add foo'       # rev 0
  $ hg tag -f bar            # rev 1 bar -> 0
  $ hg tag -f bar            # rev 2 bar -> 1
  $ hg tag -fr 0 bar         # rev 3 bar -> 0
  $ hg tag -fr 1 bar         # rev 4 bar -> 1
  $ hg tag -fr 0 bar         # rev 5 bar -> 0
  $ hg tags
  tip                                5:85f05169d91d
  bar                                0:bbd179dfa0a7
  $ hg co 3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo barbar > foo
  $ hg ci -m 'change foo'    # rev 6
  created new head
  $ hg tags
  tip                                6:735c3ca72986
  bar                                0:bbd179dfa0a7

Don't allow moving tag without -f:

  $ hg tag -r 3 bar
  abort: tag 'bar' already exists (use -f to force)
  [255]
  $ hg tags
  tip                                6:735c3ca72986
  bar                                0:bbd179dfa0a7

Strip 1: expose an old head:

  $ hg --config extensions.mq= strip 5
  saved backup bundle to $TESTTMP/t3/.hg/strip-backup/*-backup.hg (glob)
  $ hg tags                  # partly stale cache
  tip                                5:735c3ca72986
  bar                                1:78391a272241
  $ hg tags                  # up-to-date cache
  tip                                5:735c3ca72986
  bar                                1:78391a272241

Strip 2: destroy whole branch, no old head exposed

  $ hg --config extensions.mq= strip 4
  saved backup bundle to $TESTTMP/t3/.hg/strip-backup/*-backup.hg (glob)
  $ hg tags                  # partly stale
  tip                                4:735c3ca72986
  bar                                0:bbd179dfa0a7
  $ rm -f .hg/cache/tags2-visible
  $ hg tags                  # cold cache
  tip                                4:735c3ca72986
  bar                                0:bbd179dfa0a7

Test tag rank with 3 heads:

  $ cd ..
  $ hg init t4
  $ cd t4
  $ echo foo > foo
  $ hg add
  adding foo
  $ hg ci -m 'add foo'                 # rev 0
  $ hg tag bar                         # rev 1 bar -> 0
  $ hg tag -f bar                      # rev 2 bar -> 1
  $ hg up -qC 0
  $ hg tag -fr 2 bar                   # rev 3 bar -> 2
  $ hg tags
  tip                                3:197c21bbbf2c
  bar                                2:6fa450212aeb
  $ hg up -qC 0
  $ hg tag -m 'retag rev 0' -fr 0 bar  # rev 4 bar -> 0, but bar stays at 2

Bar should still point to rev 2:

  $ hg tags
  tip                                4:3b4b14ed0202
  bar                                2:6fa450212aeb

Test that removing global/local tags does not get confused when trying
to remove a tag of type X which actually only exists as a type Y:

  $ cd ..
  $ hg init t5
  $ cd t5
  $ echo foo > foo
  $ hg add
  adding foo
  $ hg ci -m 'add foo'                 # rev 0

  $ hg tag -r 0 -l localtag
  $ hg tag --remove localtag
  abort: tag 'localtag' is not a global tag
  [255]
  $ 
  $ hg tag -r 0 globaltag
  $ hg tag --remove -l globaltag
  abort: tag 'globaltag' is not a local tag
  [255]
  $ hg tags -v
  tip                                1:a0b6fe111088
  localtag                           0:bbd179dfa0a7 local
  globaltag                          0:bbd179dfa0a7

Test for issue3911

  $ hg tag -r 0 -l localtag2
  $ hg tag -l --remove localtag2
  $ hg tags -v
  tip                                1:a0b6fe111088
  localtag                           0:bbd179dfa0a7 local
  globaltag                          0:bbd179dfa0a7

  $ hg tag -r 1 -f localtag
  $ hg tags -v
  tip                                2:5c70a037bb37
  localtag                           1:a0b6fe111088
  globaltag                          0:bbd179dfa0a7

  $ hg tags -v
  tip                                2:5c70a037bb37
  localtag                           1:a0b6fe111088
  globaltag                          0:bbd179dfa0a7

  $ hg tag -r 1 localtag2
  $ hg tags -v
  tip                                3:bbfb8cd42be2
  localtag2                          1:a0b6fe111088
  localtag                           1:a0b6fe111088
  globaltag                          0:bbd179dfa0a7

  $ hg tags -v
  tip                                3:bbfb8cd42be2
  localtag2                          1:a0b6fe111088
  localtag                           1:a0b6fe111088
  globaltag                          0:bbd179dfa0a7

  $ cd ..

Create a repository with tags data to test .hgtags fnodes transfer

  $ hg init tagsserver
  $ cd tagsserver
  $ touch foo
  $ hg -q commit -A -m initial
  $ hg tag -m 'tag 0.1' 0.1
  $ echo second > foo
  $ hg commit -m second
  $ hg tag -m 'tag 0.2' 0.2
  $ hg tags
  tip                                3:40f0358cb314
  0.2                                2:f63cc8fe54e4
  0.1                                0:96ee1d7354c4
  $ cd ..

Cloning should pull down hgtags fnodes mappings and write the cache file

  $ hg clone --pull tagsserver tagsclient
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 4 changes to 2 files
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

Missing tags2* files means the cache wasn't written through the normal mechanism.

  $ ls tagsclient/.hg/cache
  branch2-served
  hgtagsfnodes1
  rbc-names-v1
  rbc-revs-v1

Cache should contain the head only, even though other nodes have tags data

  $ f --size --hexdump tagsclient/.hg/cache/hgtagsfnodes1
  tagsclient/.hg/cache/hgtagsfnodes1: size=96
  0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0010: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0020: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0030: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0040: ff ff ff ff ff ff ff ff 40 f0 35 8c 19 e0 a7 d3 |........@.5.....|
  0050: 8a 5c 6a 82 4d cf fb a5 87 d0 2f a3 1e 4f 2f 8a |.\j.M...../..O/.|

Running hg tags should produce tags2* file and not change cache

  $ hg -R tagsclient tags
  tip                                3:40f0358cb314
  0.2                                2:f63cc8fe54e4
  0.1                                0:96ee1d7354c4

  $ ls tagsclient/.hg/cache
  branch2-served
  hgtagsfnodes1
  rbc-names-v1
  rbc-revs-v1
  tags2-visible

  $ f --size --hexdump tagsclient/.hg/cache/hgtagsfnodes1
  tagsclient/.hg/cache/hgtagsfnodes1: size=96
  0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0010: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0020: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0030: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
  0040: ff ff ff ff ff ff ff ff 40 f0 35 8c 19 e0 a7 d3 |........@.5.....|
  0050: 8a 5c 6a 82 4d cf fb a5 87 d0 2f a3 1e 4f 2f 8a |.\j.M...../..O/.|