view tests/test-incoming-outgoing.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.

#require serve

  $ hg init test
  $ cd test
  $ for i in 0 1 2 3 4 5 6 7 8; do
  >     echo $i >> foo
  >     hg commit -A -m $i
  > done
  adding foo
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 9 changesets, 9 total revisions
  $ hg serve -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid >> $DAEMON_PIDS
  $ cd ..

  $ hg init new

http incoming

  $ hg -R new incoming http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R new incoming -r 4 http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  

local incoming

  $ hg -R new incoming test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R new incoming -r 4 test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  

limit to 2 changesets

  $ hg -R new incoming -l 2 test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  

limit to 2 changesets, test with -p --git

  $ hg -R new incoming -l 2 -p --git test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,1 @@
  +0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -1,1 +1,2 @@
   0
  +1
  

test with --bundle

  $ hg -R new incoming --bundle test.hg http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R new incoming --bundle test2.hg test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  


test the resulting bundles

  $ hg init temp
  $ hg init temp2
  $ hg -R temp unbundle test.hg
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 9 changes to 1 files
  (run 'hg update' to get a working copy)
  $ hg -R temp2 unbundle test2.hg
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 9 changes to 1 files
  (run 'hg update' to get a working copy)
  $ hg -R temp tip
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R temp2 tip
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  

  $ rm -r temp temp2 new

test outgoing

  $ hg clone test test-dev
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd test-dev
  $ for i in 9 10 11 12 13; do
  >     echo $i >> foo
  >     hg commit -A -m $i
  > done
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 14 changesets, 14 total revisions
  $ cd ..
  $ hg -R test-dev outgoing test
  comparing with test
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  
  changeset:   12:e576b1bed305
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     12
  
  changeset:   13:96bbff09a7cc
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     13
  
test outgoing with secret changesets

  $ hg -R test-dev phase --force --secret 9
  $ hg -R test-dev outgoing test
  comparing with test
  searching for changes
  no changes found (ignored 5 secret changesets)
  [1]
  $ hg -R test-dev phase --draft -r 'head()'

limit to 3 changesets

  $ hg -R test-dev outgoing -l 3 test
  comparing with test
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  
  $ hg -R test-dev outgoing http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  
  changeset:   12:e576b1bed305
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     12
  
  changeset:   13:96bbff09a7cc
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     13
  
  $ hg -R test-dev outgoing -r 11 http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  

incoming from empty remote repository

  $ hg init r1
  $ hg init r2
  $ echo a > r1/foo
  $ hg -R r1 ci -Ama
  adding foo
  $ hg -R r1 incoming r2 --bundle x.hg
  comparing with r2
  searching for changes
  no changes found
  [1]