tests/test-pull-network.t

hgwebdir: avoid systematic full garbage collection

Forcing a systematic full garbage collection upon each request
can serioulsy harm performance. This is reported as
https://bz.mercurial-scm.org/show_bug.cgi?id=6075

With this change we're performing the full collection according
to a new setting, `experimental.web.full-garbage-collection-rate`.
The default value is 1, which doesn't change the behavior and will
allow us to test on real use cases. If the value is 0, no full garbage
collection occurs.

Regardless of the value of the setting, a partial garbage collection
still occurs upon each request (not attempting to collect objects from
the oldest generation). This should be enough to take care of
reference cycles that have been created by the last request
(assessment of this requires changing the setting, not to be 1).

In my experience chasing memory leaks in Mercurial servers,
the full collection never reclaimed any memory, but this is with
Python 3 and biased towards small repositories.

On the other hand, as explained in the Python developer docs [1],
frequent full collections are very harmful in terms of performance if
lots of objects survive the collection, and hence stay in the
oldest generation. Note that `gc.collect()` is indeed trying to
collect the oldest generation [2]. This happens usually in two cases:

- unwanted lingering objects (i.e., an actual memory leak that
  the GC cannot do anything about). Sadly, we have lots of those
  these days.
- desireable long-term objects, typically in caches (not inner caches
  carried by repositories, which should be collected with them). This
  is a subject of interest for the Heptapod project.

In short, the flat rate that this change still permits is
probably a bad idea in most cases, and the default value can
be tweaked later on (or even be set to 0) according to experiments
in the wild.

The test is inspired from test-hgwebdir-paths.py

[1] https://devguide.python.org/garbage_collector/#collecting-the-oldest-generation
[2] https://docs.python.org/3/library/gc.html#gc.collect

Differential Revision: https://phab.mercurial-scm.org/D11204

#require serve

#testcases sshv1 sshv2

#if sshv2
  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > sshpeer.advertise-v2 = true
  > sshserver.support-v2 = true
  > EOF
#endif

  $ 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
  checked 1 changesets with 1 changes to 1 files

  $ hg serve -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid >> $DAEMON_PIDS
  $ cd ..

  $ hg clone --pull http://foo:bar@localhost:$HGPORT/ copy
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 340e38bdcde4
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd copy
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files

  $ hg co
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat foo
  foo

  $ hg manifest --debug
  2ed2a3912a0b24502043eae84ee4b279c18b90dd 644   foo

  $ hg pull
  pulling from http://foo@localhost:$HGPORT/
  searching for changes
  no changes found

  $ hg rollback --dry-run --verbose
  repository tip rolled back to revision -1 (undo pull: http://foo:***@localhost:$HGPORT/)

Test pull of non-existing 20 character revision specification, making sure plain ascii identifiers
not are encoded like a node:

  $ hg pull -r 'xxxxxxxxxxxxxxxxxxxy'
  pulling from http://foo@localhost:$HGPORT/
  abort: unknown revision 'xxxxxxxxxxxxxxxxxxxy'
  [255]
  $ hg pull -r 'xxxxxxxxxxxxxxxxxx y'
  pulling from http://foo@localhost:$HGPORT/
  abort: unknown revision 'xxxxxxxxxxxxxxxxxx y'
  [255]

Test pull of working copy revision
  $ hg pull -r 'ffffffffffff'
  pulling from http://foo@localhost:$HGPORT/
  abort: unknown revision 'ffffffffffff'
  [255]

Test 'file:' uri handling:

  $ hg pull -q file://../test-does-not-exist
  abort: file:// URLs can only refer to localhost
  [255]

  $ hg pull -q file://../test
  abort: file:// URLs can only refer to localhost
  [255]

MSYS changes 'file:' into 'file;'

#if no-msys
  $ hg pull -q file:../test  # no-msys
#endif

It's tricky to make file:// URLs working on every platform with
regular shell commands.

  $ URL=`"$PYTHON" -c "from __future__ import print_function; import os; print('file://foobar' + ('/' + os.getcwd().replace(os.sep, '/')).replace('//', '/') + '/../test')"`
  $ hg pull -q "$URL"
  abort: file:// URLs can only refer to localhost
  [255]

  $ URL=`"$PYTHON" -c "from __future__ import print_function; import os; print('file://localhost' + ('/' + os.getcwd().replace(os.sep, '/')).replace('//', '/') + '/../test')"`
  $ hg pull -q "$URL"

SEC: check for unsafe ssh url

  $ cat >> $HGRCPATH << EOF
  > [ui]
  > ssh = sh -c "read l; read l; read l"
  > EOF

  $ hg pull 'ssh://-oProxyCommand=touch${IFS}owned/path'
  pulling from ssh://-oProxyCommand%3Dtouch%24%7BIFS%7Downed/path
  abort: potentially unsafe url: 'ssh://-oProxyCommand=touch${IFS}owned/path'
  [255]
  $ hg pull 'ssh://%2DoProxyCommand=touch${IFS}owned/path'
  pulling from ssh://-oProxyCommand%3Dtouch%24%7BIFS%7Downed/path
  abort: potentially unsafe url: 'ssh://-oProxyCommand=touch${IFS}owned/path'
  [255]
  $ hg pull 'ssh://fakehost|touch${IFS}owned/path'
  pulling from ssh://fakehost%7Ctouch%24%7BIFS%7Downed/path
  abort: no suitable response from remote hg
  [255]
  $ hg --config ui.timestamp-output=true pull 'ssh://fakehost%7Ctouch%20owned/path'
  \[20[2-9][0-9]-[01][0-9]-[0-3][0-9]T[0-5][0-9]:[0-5][0-9]:[0-5][0-9]\.[0-9][0-9][0-9][0-9][0-9][0-9]\] pulling from ssh://fakehost%7Ctouch%20owned/path (re)
  \[20[2-9][0-9]-[01][0-9]-[0-3][0-9]T[0-5][0-9]:[0-5][0-9]:[0-5][0-9]\.[0-9][0-9][0-9][0-9][0-9][0-9]\] abort: no suitable response from remote hg (re)
  [255]

  $ [ ! -f owned ] || echo 'you got owned'

  $ cd ..