view tests/test-config.t @ 35793:4fb2bb61597c

bundle2: increase payload part chunk size to 32kb

Bundle2 payload parts are framed chunks. Esentially, we obtain
data in equal size chunks of size `preferedchunksize` and emit those
to a generator. That generator is fed into a compressor (which can
be the no-op compressor, which just re-emits the generator). And
the output from the compressor likely goes to a file descriptor
or socket.

What this means is that small chunk sizes create more Python objects
and Python function calls than larger chunk sizes. And as we know,
Python object and function call overhead in performance sensitive
code matters (at least with CPython).

This commit increases the bundle2 part payload chunk size from 4k
to 32k. Practically speaking, this means that the chunks we feed
into a compressor (implemented in C code) or feed directly into a
file handle or socket write() are larger. It's possible the chunks
might be larger than what the receiver can handle in one logical
operation. But at that point, we're in C code, which is much more
efficient at dealing with splitting up the chunk and making multiple
function calls than Python is.

A downside to larger chunks is that the receiver has to wait for that
much data to arrive (either raw or from a decompressor) before it
can process the chunk. But 32kb still feels like a small buffer to
have to wait for. And in many cases, the client will convert from
8 read(4096) to 1 read(32768). That's happening in Python land. So
we cut down on the number of Python objects and function calls,
making the client faster as well. I don't think there are any
significant concerns to increasing the payload chunk size to 32kb.

The impact of this change on performance significant. Using `curl`
to obtain a stream clone bundle2 payload from a server on localhost
serving the mozilla-unified repository:

before: 20.78 user; 7.71 system;  80.5 MB/s
after:  13.90 user; 3.51 system; 132 MB/s
legacy:  9.72 user; 8.16 system; 132 MB/s

bundle2 stream clone generation is still more resource intensive than
legacy stream clone (that's likely because of the use of a
util.chunkbuffer). But the throughput is the same. We might
be in territory we're this is effectively a benchmark of the
networking stack or Python's syscall throughput.

From the client perspective, `hg clone -U --stream`:

before: 33.50 user; 7.95 system; 53.3 MB/s
after:  22.82 user; 7.33 system; 72.7 MB/s
legacy: 29.96 user; 7.94 system; 58.0 MB/s

And for `hg clone --stream` with a working directory update of
~230k files:

after:  119.55 user; 26.47 system; 0:57.08 wall
legacy: 126.98 user; 26.94 system; 1:05.56 wall

So, it appears that bundle2's stream clone is now definitively faster
than legacy stream clone!

Differential Revision: https://phab.mercurial-scm.org/D1932

hide outer repo
  $ hg init

Invalid syntax: no value

  $ cat > .hg/hgrc << EOF
  > novaluekey
  > EOF
  $ hg showconfig
  hg: parse error at $TESTTMP/.hg/hgrc:1: novaluekey
  [255]

Invalid syntax: no key

  $ cat > .hg/hgrc << EOF
  > =nokeyvalue
  > EOF
  $ hg showconfig
  hg: parse error at $TESTTMP/.hg/hgrc:1: =nokeyvalue
  [255]

Test hint about invalid syntax from leading white space

  $ cat > .hg/hgrc << EOF
  >  key=value
  > EOF
  $ hg showconfig
  hg: parse error at $TESTTMP/.hg/hgrc:1:  key=value
  unexpected leading whitespace
  [255]

  $ cat > .hg/hgrc << EOF
  >  [section]
  > key=value
  > EOF
  $ hg showconfig
  hg: parse error at $TESTTMP/.hg/hgrc:1:  [section]
  unexpected leading whitespace
  [255]

Reset hgrc

  $ echo > .hg/hgrc

Test case sensitive configuration

  $ cat <<EOF >> $HGRCPATH
  > [Section]
  > KeY = Case Sensitive
  > key = lower case
  > EOF

  $ hg showconfig Section
  Section.KeY=Case Sensitive
  Section.key=lower case

  $ hg showconfig Section -Tjson
  [
   {
    "name": "Section.KeY",
    "source": "*.hgrc:*", (glob)
    "value": "Case Sensitive"
   },
   {
    "name": "Section.key",
    "source": "*.hgrc:*", (glob)
    "value": "lower case"
   }
  ]
  $ hg showconfig Section.KeY -Tjson
  [
   {
    "name": "Section.KeY",
    "source": "*.hgrc:*", (glob)
    "value": "Case Sensitive"
   }
  ]
  $ hg showconfig -Tjson | tail -7
   },
   {
    "name": "*", (glob)
    "source": "*", (glob)
    "value": "*" (glob)
   }
  ]

Test empty config source:

  $ cat <<EOF > emptysource.py
  > def reposetup(ui, repo):
  >     ui.setconfig('empty', 'source', 'value')
  > EOF
  $ cp .hg/hgrc .hg/hgrc.orig
  $ cat <<EOF >> .hg/hgrc
  > [extensions]
  > emptysource = `pwd`/emptysource.py
  > EOF

  $ hg config --debug empty.source
  read config from: * (glob)
  none: value
  $ hg config empty.source -Tjson
  [
   {
    "name": "empty.source",
    "source": "",
    "value": "value"
   }
  ]

  $ cp .hg/hgrc.orig .hg/hgrc

Test "%unset"

  $ cat >> $HGRCPATH <<EOF
  > [unsettest]
  > local-hgrcpath = should be unset (HGRCPATH)
  > %unset local-hgrcpath
  > 
  > global = should be unset (HGRCPATH)
  > 
  > both = should be unset (HGRCPATH)
  > 
  > set-after-unset = should be unset (HGRCPATH)
  > EOF

  $ cat >> .hg/hgrc <<EOF
  > [unsettest]
  > local-hgrc = should be unset (.hg/hgrc)
  > %unset local-hgrc
  > 
  > %unset global
  > 
  > both = should be unset (.hg/hgrc)
  > %unset both
  > 
  > set-after-unset = should be unset (.hg/hgrc)
  > %unset set-after-unset
  > set-after-unset = should be set (.hg/hgrc)
  > EOF

  $ hg showconfig unsettest
  unsettest.set-after-unset=should be set (.hg/hgrc)

Test exit code when no config matches

  $ hg config Section.idontexist
  [1]

sub-options in [paths] aren't expanded

  $ cat > .hg/hgrc << EOF
  > [paths]
  > foo = ~/foo
  > foo:suboption = ~/foo
  > EOF

  $ hg showconfig paths
  paths.foo:suboption=~/foo
  paths.foo=$TESTTMP/foo

edit failure

  $ HGEDITOR=false hg config --edit
  abort: edit failed: false exited with status 1
  [255]

config affected by environment variables

  $ EDITOR=e1 VISUAL=e2 hg config --debug | grep 'ui\.editor'
  $VISUAL: ui.editor=e2

  $ VISUAL=e2 hg config --debug --config ui.editor=e3 | grep 'ui\.editor'
  --config: ui.editor=e3

  $ PAGER=p1 hg config --debug | grep 'pager\.pager'
  $PAGER: pager.pager=p1

  $ PAGER=p1 hg config --debug --config pager.pager=p2 | grep 'pager\.pager'
  --config: pager.pager=p2

verify that aliases are evaluated as well

  $ hg init aliastest
  $ cd aliastest
  $ cat > .hg/hgrc << EOF
  > [ui]
  > user = repo user
  > EOF
  $ touch index
  $ unset HGUSER
  $ hg ci -Am test
  adding index
  $ hg log --template '{author}\n'
  repo user
  $ cd ..

alias has lower priority

  $ hg init aliaspriority
  $ cd aliaspriority
  $ cat > .hg/hgrc << EOF
  > [ui]
  > user = alias user
  > username = repo user
  > EOF
  $ touch index
  $ unset HGUSER
  $ hg ci -Am test
  adding index
  $ hg log --template '{author}\n'
  repo user
  $ cd ..