view tests/test-push.t @ 40021:c537144fdbef

wireprotov2: support response caching

One of the things I've learned from managing VCS servers over the
years is that they are hard to scale. It is well known that some
companies have very beefy (read: very expensive) servers to power
their VCS needs. It is also known that specialized servers for
various VCS exist in order to facilitate scaling servers. (Mercurial
is in this boat.)

One of the aspects that make a VCS server hard to scale is the
high CPU load incurred by constant client clone/pull operations.

To alleviate the scaling pain associated with data retrieval
operations, I want to integrate caching into the Mercurial wire
protocol server as robustly as possible such that servers can
aggressively cache responses and defer as much server load as
possible.

This commit represents the initial implementation of a general
caching layer in wire protocol version 2.

We define a new interface and behavior for a wire protocol cacher
in repository.py. (This is probably where a reviewer should look
first to understand what is going on.)

The bulk of the added code is in wireprotov2server.py, where we
define how a command can opt in to being cached and integrate
caching into command dispatching.

From a very high-level:

* A command can declare itself as cacheable by providing a callable
  that can be used to derive a cache key.
* At dispatch time, if a command is cacheable, we attempt to
  construct a cacher and use it for serving the request and/or
  caching the request.
* The dispatch layer handles the bulk of the business logic for
  caching, making cachers mostly "dumb content stores."
* The mechanism for invalidating cached entries (one of the harder
  parts about caching in general) is by varying the cache key when
  state changes. As such, cachers don't need to be concerned with
  cache invalidation.

Initially, we've hooked up support for caching "manifestdata" and
"filedata" commands. These are the simplest to cache, as they should
be immutable over time. Caching of commands related to changeset
data is a bit harder (because cache validation is impacted by
changes to bookmarks, phases, etc). This will be implemented later.
(Strictly speaking, censoring a file should invalidate caches. I've
added an inline TODO to track this edge case.)

To prove it works, this commit implements a test-only extension
providing in-memory caching backed by an lrucachedict. A new test
showing this extension behaving properly is added. FWIW, the
cacher is ~50 lines of code, demonstrating the relative ease with
which a cache can be added to a server.

While the test cacher is not suitable for production workloads, just
for kicks I performed a clone of just the changeset and manifest data
for the mozilla-unified repository. With a fully warmed cache (of just
the manifest data since changeset data is not cached), server-side
CPU usage dropped from ~73s to ~28s. That's pretty significant and
demonstrates the potential that response caching has on server
scalability!

Differential Revision: https://phab.mercurial-scm.org/D4773

==================================
Basic testing for the push command
==================================

Testing of the '--rev' flag
===========================

  $ hg init test-revflag
  $ hg -R test-revflag unbundle "$TESTDIR/bundles/remote.hg"
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 7 changes to 4 files (+1 heads)
  new changesets bfaf4b5cbf01:916f1afdef90 (9 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ for i in 0 1 2 3 4 5 6 7 8; do
  >    echo
  >    hg init test-revflag-"$i"
  >    hg -R test-revflag push -r "$i" test-revflag-"$i"
  >    hg -R test-revflag-"$i" verify
  > done
  
  pushing to test-revflag-0
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files
  
  pushing to test-revflag-1
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 2 changes to 1 files
  
  pushing to test-revflag-2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 3 changes to 1 files
  
  pushing to test-revflag-3
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 4 changes to 1 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 4 changesets with 4 changes to 1 files
  
  pushing to test-revflag-4
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 2 changes to 1 files
  
  pushing to test-revflag-5
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 3 changes to 1 files
  
  pushing to test-revflag-6
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 5 changes to 2 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 4 changesets with 5 changes to 2 files
  
  pushing to test-revflag-7
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 6 changes to 3 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 6 changes to 3 files
  
  pushing to test-revflag-8
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 5 changes to 2 files
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 5 changes to 2 files

  $ cd test-revflag-8

  $ hg pull ../test-revflag-7
  pulling from ../test-revflag-7
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 2 changes to 3 files (+1 heads)
  new changesets c70afb1ee985:faa2e4234c7a
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 9 changesets with 7 changes to 4 files

  $ cd ..

Test server side validation during push
=======================================

  $ hg init test-validation
  $ cd test-validation

  $ cat > .hg/hgrc <<EOF
  > [server]
  > validate=1
  > EOF

  $ echo alpha > alpha
  $ echo beta > beta
  $ hg addr
  adding alpha
  adding beta
  $ hg ci -m 1

  $ cd ..
  $ hg clone test-validation test-validation-clone
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

#if reporevlogstore

Test spurious filelog entries:

  $ cd test-validation-clone
  $ echo blah >> beta
  $ cp .hg/store/data/beta.i tmp1
  $ hg ci -m 2
  $ cp .hg/store/data/beta.i tmp2
  $ hg -q rollback
  $ mv tmp2 .hg/store/data/beta.i
  $ echo blah >> beta
  $ hg ci -m '2 (corrupt)'

Expected to fail:

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   beta@1: dddc47b3ba30 not in manifests
  checked 2 changesets with 4 changes to 2 files
  1 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]

  $ hg push
  pushing to $TESTTMP/test-validation
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  transaction abort!
  rollback completed
  abort: received spurious file revlog entry
  [255]

  $ hg -q rollback
  $ mv tmp1 .hg/store/data/beta.i
  $ echo beta > beta

Test missing filelog entries:

  $ cp .hg/store/data/beta.i tmp
  $ echo blah >> beta
  $ hg ci -m '2 (corrupt)'
  $ mv tmp .hg/store/data/beta.i

Expected to fail:

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   beta@1: manifest refers to unknown revision dddc47b3ba30
  checked 2 changesets with 2 changes to 2 files
  1 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]

  $ hg push
  pushing to $TESTTMP/test-validation
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  transaction abort!
  rollback completed
  abort: missing file data for beta:dddc47b3ba30e54484720ce0f4f768a0f4b6efb9 - run hg verify
  [255]

  $ cd ..

#endif

Test push hook locking
=====================

  $ hg init 1

  $ echo '[ui]' >> 1/.hg/hgrc
  $ echo 'timeout = 10' >> 1/.hg/hgrc

  $ echo foo > 1/foo
  $ hg --cwd 1 ci -A -m foo
  adding foo

  $ hg clone 1 2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg clone 2 3
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cat <<EOF > $TESTTMP/debuglocks-pretxn-hook.sh
  > hg debuglocks
  > true
  > EOF
  $ echo '[hooks]' >> 2/.hg/hgrc
  $ echo "pretxnchangegroup.a = sh $TESTTMP/debuglocks-pretxn-hook.sh" >> 2/.hg/hgrc
  $ echo 'changegroup.push = hg push -qf ../1' >> 2/.hg/hgrc

  $ echo bar >> 3/foo
  $ hg --cwd 3 ci -m bar

  $ hg --cwd 3 push ../2 --config devel.legacy.exchange=bundle1
  pushing to ../2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  lock:  user *, process * (*s) (glob)
  wlock: free

  $ hg --cwd 1 --config extensions.strip= strip tip -q
  $ hg --cwd 2 --config extensions.strip= strip tip -q
  $ hg --cwd 3 push ../2 # bundle2+
  pushing to ../2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  lock:  user *, process * (*s) (glob)
  wlock: user *, process * (*s) (glob)

Test bare push with multiple race checking options
--------------------------------------------------

  $ hg init test-bare-push-no-concurrency
  $ hg init test-bare-push-unrelated-concurrency
  $ hg -R test-revflag push -r 0 test-bare-push-no-concurrency --config server.concurrent-push-mode=strict
  pushing to test-bare-push-no-concurrency
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  $ hg -R test-revflag push -r 0 test-bare-push-unrelated-concurrency --config server.concurrent-push-mode=check-related
  pushing to test-bare-push-unrelated-concurrency
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

SEC: check for unsafe ssh url

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

  $ hg -R test-revflag push 'ssh://-oProxyCommand=touch${IFS}owned/path'
  pushing to ssh://-oProxyCommand%3Dtouch%24%7BIFS%7Downed/path
  abort: potentially unsafe url: 'ssh://-oProxyCommand=touch${IFS}owned/path'
  [255]
  $ hg -R test-revflag push 'ssh://%2DoProxyCommand=touch${IFS}owned/path'
  pushing to ssh://-oProxyCommand%3Dtouch%24%7BIFS%7Downed/path
  abort: potentially unsafe url: 'ssh://-oProxyCommand=touch${IFS}owned/path'
  [255]
  $ hg -R test-revflag push 'ssh://fakehost|touch${IFS}owned/path'
  pushing to ssh://fakehost%7Ctouch%24%7BIFS%7Downed/path
  abort: no suitable response from remote hg!
  [255]
  $ hg -R test-revflag push 'ssh://fakehost%7Ctouch%20owned/path'
  pushing to ssh://fakehost%7Ctouch%20owned/path
  abort: no suitable response from remote hg!
  [255]

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