view tests/test-import-bypass.t @ 51681:522b4d729e89

mmap: populate the mapping by default

Without pre-population, accessing all data through a mmap can result in many
pagefault, reducing performance significantly. If the mmap is prepopulated, the
performance can no longer get slower than a full read.
(See benchmark number below)

In some cases were very few data is read, prepopulating can be overkill and
slower than populating on access (through page fault). So that behavior can be
controlled when the caller can pre-determine the best behavior.
(See benchmark number below)

In addition, testing with populating in a secondary thread yield great result
combining the best of each approach. This might be implemented in later
changesets.

In all cases, using mmap has a great effect on memory usage when many processes
run in parallel on the same machine.

### Benchmarks

# What did I run

A couple of month back I ran a large benchmark campaign to assess the impact of
various approach for using mmap with the revlog (and other files), it
highlighted a few benchmarks that capture the impact of the changes well. So to
validate this change I checked the following:

- log command displaying various revisions
  (read the changelog index)
- log command displaying the patch of listed revisions
  (read the changelog index, the manifest index and a few files indexes)
- unbundling a few revisions
  (read and write changelog, manifest and few files indexes, and walk the graph
  to update some cache)
- pushing a few revisions
  (read and write changelog, manifest and few files indexes, walk the graph to
  update some cache, performs various accesses locally and remotely during
  discovery)

Benchmarks were run using the default module policy (c+py) and the rust one. No
significant difference were found between the two implementation, so we will
present result using the default policy (unless otherwise specified).

I ran them on a few repositories :

- mercurial: a "public changeset only" copy of mercurial from 2018-08-01 using
  zstd compression and sparse-revlog

- pypy: a copy of pypy from 2018-08-01 using zstd compression and sparse-revlog

- netbeans: a copy of netbeans from 2018-08-01 using zstd compression and
  sparse-revlog

- mozilla-try: a copy of mozilla-try from 2019-02-18 using zstd compression and
  sparse-revlog

- mozilla-try persistent-nodemap: Same as the above but with a persistent
  nodemap. Used for the log --patch benchmark only

# Results

For the smaller repositories (mercurial, pypy), the impact of mmap is almost
imperceptible, other cost dominating the operation. The impact of prepopulating
is undiscernible in the benchmark we ran.

For larger repositories the benchmark support explanation given above:

On netbeans, the log can be about 1% faster without repopulation (for a
difference < 100ms) but unbundle becomes a bit slower, even when small.

### data-env-vars.name                             = netbeans-2018-08-01-zstd-sparse-revlog
  # benchmark.name                                 = hg.command.unbundle
  # benchmark.variants.issue6528                   = disabled
  # benchmark.variants.reuse-external-delta-parent = yes
  # benchmark.variants.revs                        = any-1-extra-rev
  # benchmark.variants.source                      = unbundle
  # benchmark.variants.verbosity                   = quiet
with-populate: 0.240157
no-populate:   0.265087  (+10.38%, +0.02)
  # benchmark.variants.revs                        = any-100-extra-rev
with-populate: 1.459518
no-populate:   1.481290   (+1.49%, +0.02)
 ## benchmark.name                                 = hg.command.push
  # benchmark.variants.explicit-rev                = none
  # benchmark.variants.issue6528                   = disabled
  # benchmark.variants.protocol                    = ssh
  # benchmark.variants.reuse-external-delta-parent = yes
  # benchmark.variants.revs                        = any-1-extra-rev
with-populate: 0.771919
no-populate:   0.792025   (+2.60%, +0.02)
  # benchmark.variants.revs                        = any-100-extra-rev
with-populate: 1.459518
no-populate:   1.481290   (+1.49%, +0.02)


For mozilla-try, the "slow down" from pre-populate for small `hg log` is more
visible, but still small in absolute time. (using rust value for the persistent
nodemap value to be relevant).

### data-env-vars.name            = mozilla-try-2019-02-18-ds2-pnm
  # benchmark.name                = hg.command.log
  # bin-env-vars.hg.flavor        = rust
  # benchmark.variants.patch      = yes
  # benchmark.variants.limit-rev  = 1
with-populate: 0.237813
no-populate:   0.229452   (-3.52%, -0.01)
  # benchmark.variants.limit-rev  = 10
  # benchmark.variants.patch      = yes
with-populate: 1.213578
no-populate:   1.205189
### data-env-vars.name            = mozilla-try-2019-02-18-zstd-sparse-revlog
  # benchmark.variants.limit-rev  = 1000
  # benchmark.variants.patch      = no
  # benchmark.variants.rev        = tip
with-populate: 0.198607
no-populate:   0.195038   (-1.80%, -0.00)

However pre-populating provide a significant boost on more complex operations
like unbundle or push:

### data-env-vars.name                             = mozilla-try-2019-02-18-zstd-sparse-revlog
  # benchmark.name                                 = hg.command.push
  # benchmark.variants.explicit-rev                = none
  # benchmark.variants.issue6528                   = disabled
  # benchmark.variants.protocol                    = ssh
  # benchmark.variants.reuse-external-delta-parent = yes
  # benchmark.variants.revs                        = any-1-extra-rev
with-populate: 4.798632
no-populate:   4.953295   (+3.22%, +0.15)
  # benchmark.variants.revs                        = any-100-extra-rev
with-populate: 4.903618
no-populate:   5.014963   (+2.27%, +0.11)
 ## benchmark.name                                 = hg.command.unbundle
  # benchmark.variants.revs                        = any-1-extra-rev
with-populate: 1.423411
no-populate:   1.585365  (+11.38%, +0.16)
  # benchmark.variants.revs                        = any-100-extra-rev
with-populate: 1.537909
no-populate:   1.688489   (+9.79%, +0.15)

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "purge=" >> $HGRCPATH

  $ shortlog() {
  >     hg log -G --template '{rev}:{node|short} {author} {date|hgdate} - {branch} - {desc|firstline}\n'
  > }

Test --bypass with other options

  $ hg init repo-options
  $ cd repo-options
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ echo a >> a
  $ hg branch foo
  marked working directory as branch foo
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -Am changea
  $ hg export . > ../test.diff
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

Test importing an existing revision
(this also tests that "hg import" disallows combination of '--exact'
and '--edit')

  $ hg import --bypass --exact --edit ../test.diff
  abort: cannot specify both --exact and --edit
  [10]
  $ hg import --bypass --exact ../test.diff
  applying ../test.diff
  $ shortlog
  o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |
  o  0:07f494440405 test 0 0 - default - adda
  

Test failure without --exact

  $ hg import --bypass ../test.diff
  applying ../test.diff
  unable to find 'a' for patching
  (use '--prefix' to apply patch relative to the current directory)
  abort: patch failed to apply
  [20]
  $ hg st
  $ shortlog
  o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |
  o  0:07f494440405 test 0 0 - default - adda
  

Test --user, --date and --message

  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg import --bypass --u test2 -d '1 0' -m patch2 ../test.diff
  applying ../test.diff
  $ cat .hg/last-message.txt
  patch2 (no-eol)
  $ shortlog
  o  2:2e127d1da504 test2 1 0 - default - patch2
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  @  0:07f494440405 test 0 0 - default - adda
  
  $ hg rollback
  repository tip rolled back to revision 1 (undo import)

Test --import-branch
(this also tests that editor is not invoked for '--bypass', if the
patch contains the commit message, regardless of '--edit')

  $ HGEDITOR=cat hg import --bypass --import-branch --edit ../test.diff
  applying ../test.diff
  $ shortlog
  o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |
  @  0:07f494440405 test 0 0 - default - adda
  
  $ hg rollback
  repository tip rolled back to revision 1 (undo import)

Test --strip

  $ hg import --bypass --strip 0 - <<EOF
  > # HG changeset patch
  > # User test
  > # Date 0 0
  > # Branch foo
  > # Node ID 4e322f7ce8e3e4203950eac9ece27bf7e45ffa6c
  > # Parent  07f4944404050f47db2e5c5071e0e84e7a27bba9
  > changea
  > 
  > diff -r 07f494440405 -r 4e322f7ce8e3 a
  > --- a	Thu Jan 01 00:00:00 1970 +0000
  > +++ a	Thu Jan 01 00:00:00 1970 +0000
  > @@ -1,1 +1,2 @@
  >  a
  > +a
  > EOF
  applying patch from stdin
  $ hg rollback
  repository tip rolled back to revision 1 (undo import)

Test --strip with --bypass

  $ mkdir -p dir/dir2
  $ echo bb > dir/dir2/b
  $ echo cc > dir/dir2/c
  $ echo d > dir/d
  $ hg ci -Am 'addabcd'
  adding dir/d
  adding dir/dir2/b
  adding dir/dir2/c
  $ shortlog
  @  2:d805bc8236b6 test 0 0 - default - addabcd
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  
  $ hg import --bypass --strip 2 --prefix dir/ - <<EOF
  > # HG changeset patch
  > # User test
  > # Date 0 0
  > # Branch foo
  > changeabcd
  > 
  > diff --git a/foo/a b/foo/a
  > new file mode 100644
  > --- /dev/null
  > +++ b/foo/a
  > @@ -0,0 +1 @@
  > +a
  > diff --git a/foo/dir2/b b/foo/dir2/b2
  > rename from foo/dir2/b
  > rename to foo/dir2/b2
  > diff --git a/foo/dir2/c b/foo/dir2/c
  > --- a/foo/dir2/c
  > +++ b/foo/dir2/c
  > @@ -0,0 +1 @@
  > +cc
  > diff --git a/foo/d b/foo/d
  > deleted file mode 100644
  > --- a/foo/d
  > +++ /dev/null
  > @@ -1,1 +0,0 @@
  > -d
  > EOF
  applying patch from stdin

  $ shortlog
  o  3:5bd46886ca3e test 0 0 - default - changeabcd
  |
  @  2:d805bc8236b6 test 0 0 - default - addabcd
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  
  $ hg diff --change 3 --git
  diff --git a/dir/a b/dir/a
  new file mode 100644
  --- /dev/null
  +++ b/dir/a
  @@ -0,0 +1,1 @@
  +a
  diff --git a/dir/d b/dir/d
  deleted file mode 100644
  --- a/dir/d
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -d
  diff --git a/dir/dir2/b b/dir/dir2/b2
  rename from dir/dir2/b
  rename to dir/dir2/b2
  diff --git a/dir/dir2/c b/dir/dir2/c
  --- a/dir/dir2/c
  +++ b/dir/dir2/c
  @@ -1,1 +1,2 @@
   cc
  +cc
  $ hg -q --config extensions.strip= strip .

Test unsupported combinations

  $ hg import --bypass --no-commit ../test.diff
  abort: cannot specify both --no-commit and --bypass
  [10]
  $ hg import --bypass --similarity 50 ../test.diff
  abort: cannot use --similarity with --bypass
  [10]
  $ hg import --exact --prefix dir/ ../test.diff
  abort: cannot specify both --exact and --prefix
  [10]

Test commit editor
(this also tests that editor is invoked, if the patch doesn't contain
the commit message, regardless of '--edit')

  $ cat > ../test.diff <<EOF
  > diff -r 07f494440405 -r 4e322f7ce8e3 a
  > --- a/a	Thu Jan 01 00:00:00 1970 +0000
  > +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  > @@ -1,1 +1,2 @@
  > -a
  > +b
  > +c
  > EOF
  $ HGEDITOR=cat hg import --bypass ../test.diff
  applying ../test.diff
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: changed a
  abort: empty commit message
  [10]

Test patch.eol is handled
(this also tests that editor is not invoked for '--bypass', if the
commit message is explicitly specified, regardless of '--edit')

  $ "$PYTHON" -c 'open("a", "wb").write(b"a\r\n")'
  $ hg ci -m makeacrlf
  $ HGEDITOR=cat hg import -m 'should fail because of eol' --edit --bypass ../test.diff
  applying ../test.diff
  patching file a
  Hunk #1 FAILED at 0
  abort: patch failed to apply
  [20]
  $ hg --config patch.eol=auto import -d '0 0' -m 'test patch.eol' --bypass ../test.diff
  applying ../test.diff
  $ shortlog
  o  3:c606edafba99 test 0 0 - default - test patch.eol
  |
  @  2:872023de769d test 0 0 - default - makeacrlf
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  

Test applying multiple patches

  $ hg up -qC 0
  $ echo e > e
  $ hg ci -Am adde
  adding e
  created new head
  $ hg export . > ../patch1.diff
  $ hg up -qC 1
  $ echo f > f
  $ hg ci -Am addf
  adding f
  $ hg export . > ../patch2.diff
  $ cd ..
  $ hg clone -r1 repo-options repo-multi1
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 07f494440405:4e322f7ce8e3
  updating to branch foo
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd repo-multi1
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg import --bypass ../patch1.diff ../patch2.diff
  applying ../patch1.diff
  applying ../patch2.diff
  $ shortlog
  o  3:bc8ca3f8a7c4 test 0 0 - default - addf
  |
  o  2:16581080145e test 0 0 - default - adde
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  @  0:07f494440405 test 0 0 - default - adda
  

Test applying multiple patches with --exact

  $ cd ..
  $ hg clone -r1 repo-options repo-multi2
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 07f494440405:4e322f7ce8e3
  updating to branch foo
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd repo-multi2
  $ hg import --bypass --exact ../patch1.diff ../patch2.diff
  applying ../patch1.diff
  applying ../patch2.diff
  $ shortlog
  o  3:d60cb8989666 test 0 0 - foo - addf
  |
  | o  2:16581080145e test 0 0 - default - adde
  | |
  @ |  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  

  $ cd ..

Test avoiding editor invocation at applying the patch with --exact
even if commit message is empty

  $ cd repo-options

  $ echo a >> a
  $ hg commit -m ' '
  $ hg tip -T "{node}\n"
  1b77bc7d1db9f0e7f1716d515b630516ab386c89
  $ hg export -o ../empty-log.diff .
  $ hg update -q -C ".^1"
  $ hg --config extensions.strip= strip -q tip
  $ HGEDITOR=cat hg import --exact --bypass ../empty-log.diff
  applying ../empty-log.diff
  $ hg tip -T "{node}\n"
  1b77bc7d1db9f0e7f1716d515b630516ab386c89

  $ cd ..

#if symlink execbit

Test complicated patch with --exact

  $ hg init repo-exact
  $ cd repo-exact
  $ echo a > a
  $ echo c > c
  $ echo d > d
  $ echo e > e
  $ echo f > f
  $ chmod +x f
  $ ln -s c linkc
  $ hg ci -Am t
  adding a
  adding c
  adding d
  adding e
  adding f
  adding linkc
  $ hg cp a aa1
  $ echo b >> a
  $ echo b > b
  $ hg add b
  $ hg cp a aa2
  $ echo aa >> aa2
  $ chmod +x e
  $ chmod -x f
  $ ln -s a linka
  $ hg rm d
  $ hg rm linkc
  $ hg mv c cc
  $ hg ci -m patch
  $ hg export --git . > ../test.diff
  $ hg up -C null
  0 files updated, 0 files merged, 7 files removed, 0 files unresolved
  $ hg purge
  $ hg st
  $ hg import --bypass --exact ../test.diff
  applying ../test.diff

The patch should have matched the exported revision and generated no additional
data. If not, diff both heads to debug it.

  $ shortlog
  o  1:2978fd5c8aa4 test 0 0 - default - patch
  |
  o  0:a0e19e636a43 test 0 0 - default - t
  
#endif

  $ cd ..