view tests/test-push-http.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

#require no-chg

#testcases bundle1 bundle2

#if bundle1
  $ cat << EOF >> $HGRCPATH
  > [devel]
  > # This test is dedicated to interaction through old bundle
  > legacy.exchange = bundle1
  > EOF
#endif

  $ hg init test
  $ cd test
  $ echo a > a
  $ hg ci -Ama
  adding a
  $ cd ..
  $ hg clone test test2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd test2
  $ echo a >> a
  $ hg ci -mb
  $ req() {
  >     hg $1 serve -p $HGPORT -d --pid-file=hg.pid -E errors.log
  >     cat hg.pid >> $DAEMON_PIDS
  >     hg --cwd ../test2 push http://localhost:$HGPORT/
  >     exitstatus=$?
  >     killdaemons.py
  >     echo % serve errors
  >     cat errors.log
  >     return $exitstatus
  > }
  $ cd ../test

expect ssl error

  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  abort: HTTP Error 403: ssl required
  % serve errors
  [255]

expect authorization error

  $ echo '[web]' > .hg/hgrc
  $ echo 'push_ssl = false' >> .hg/hgrc
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  abort: authorization failed
  % serve errors
  [255]

expect authorization error: must have authorized user

  $ echo 'allow_push = unperson' >> .hg/hgrc
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  abort: authorization failed
  % serve errors
  [255]

expect success

  $ cat > $TESTTMP/hook.sh <<'EOF'
  > echo "phase-move: $HG_NODE:  $HG_OLDPHASE -> $HG_PHASE"
  > EOF

#if bundle1
  $ cat >> .hg/hgrc <<EOF
  > allow_push = *
  > [hooks]
  > changegroup = sh -c "printenv.py changegroup 0"
  > pushkey = sh -c "printenv.py pushkey 0"
  > txnclose-phase.test = sh $TESTTMP/hook.sh 
  > EOF
  $ req "--debug --config extensions.blackbox="
  listening at http://*:$HGPORT/ (bound to $LOCALIP:$HGPORT) (glob) (?)
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: redirecting incoming bundle to */hg-unbundle-* (glob)
  remote: adding changesets
  remote: add changeset ba677d0156c1
  remote: adding manifests
  remote: adding file changes
  remote: adding a revisions
  remote: added 1 changesets with 1 changes to 1 files
  remote: updating the branch cache
  remote: running hook txnclose-phase.test: sh $TESTTMP/hook.sh
  remote: phase-move: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b:  draft -> public
  remote: running hook txnclose-phase.test: sh $TESTTMP/hook.sh
  remote: phase-move: ba677d0156c1196c1a699fa53f390dcfc3ce3872:   -> public
  remote: running hook changegroup: sh -c "printenv.py changegroup 0"
  remote: changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob)
  % serve errors
  $ hg rollback
  repository tip rolled back to revision 0 (undo serve)
  $ req "--debug --config server.streamunbundle=True --config extensions.blackbox="
  listening at http://*:$HGPORT/ (bound to $LOCALIP:$HGPORT) (glob) (?)
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: add changeset ba677d0156c1
  remote: adding manifests
  remote: adding file changes
  remote: adding a revisions
  remote: added 1 changesets with 1 changes to 1 files
  remote: updating the branch cache
  remote: running hook txnclose-phase.test: sh $TESTTMP/hook.sh
  remote: phase-move: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b:  draft -> public
  remote: running hook txnclose-phase.test: sh $TESTTMP/hook.sh
  remote: phase-move: ba677d0156c1196c1a699fa53f390dcfc3ce3872:   -> public
  remote: running hook changegroup: sh -c "printenv.py changegroup 0"
  remote: changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob)
  % serve errors
  $ hg rollback
  repository tip rolled back to revision 0 (undo serve)
#endif

#if bundle2
  $ cat >> .hg/hgrc <<EOF
  > allow_push = *
  > [hooks]
  > changegroup = sh -c "printenv.py changegroup 0"
  > pushkey = sh -c "printenv.py pushkey 0"
  > txnclose-phase.test = sh $TESTTMP/hook.sh 
  > EOF
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: phase-move: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b:  draft -> public
  remote: phase-move: ba677d0156c1196c1a699fa53f390dcfc3ce3872:   -> public
  remote: changegroup hook: HG_BUNDLE2=1 HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob)
  % serve errors
  $ hg rollback
  repository tip rolled back to revision 0 (undo serve)
#endif

expect success, server lacks the httpheader capability

  $ CAP=httpheader
  $ . "$TESTDIR/notcapable"
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: phase-move: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b:  draft -> public
  remote: phase-move: ba677d0156c1196c1a699fa53f390dcfc3ce3872:   -> public
  remote: changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob) (bundle1 !)
  remote: changegroup hook: HG_BUNDLE2=1 HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob) (bundle2 !)
  % serve errors
  $ hg rollback
  repository tip rolled back to revision 0 (undo serve)

expect success, server lacks the unbundlehash capability

  $ CAP=unbundlehash
  $ . "$TESTDIR/notcapable"
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: phase-move: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b:  draft -> public
  remote: phase-move: ba677d0156c1196c1a699fa53f390dcfc3ce3872:   -> public
  remote: changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob) (bundle1 !)
  remote: changegroup hook: HG_BUNDLE2=1 HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob) (bundle2 !)
  % serve errors
  $ hg rollback
  repository tip rolled back to revision 0 (undo serve)

expect success, pre-d1b16a746db6 server supports the unbundle capability, but
has no parameter

  $ cat <<EOF > notcapable-unbundleparam.py
  > from mercurial import extensions, httppeer
  > def capable(orig, self, name):
  >     if name == 'unbundle':
  >         return True
  >     return orig(self, name)
  > def uisetup(ui):
  >     extensions.wrapfunction(httppeer.httppeer, 'capable', capable)
  > EOF
  $ cp $HGRCPATH $HGRCPATH.orig
  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > notcapable-unbundleparam = `pwd`/notcapable-unbundleparam.py
  > EOF
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: phase-move: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b:  draft -> public
  remote: phase-move: ba677d0156c1196c1a699fa53f390dcfc3ce3872:   -> public
  remote: changegroup hook: * (glob)
  % serve errors
  $ hg rollback
  repository tip rolled back to revision 0 (undo serve)
  $ mv $HGRCPATH.orig $HGRCPATH

Test pushing to a publishing repository with a failing prepushkey hook

  $ cat > .hg/hgrc <<EOF
  > [web]
  > push_ssl = false
  > allow_push = *
  > [hooks]
  > prepushkey = sh -c "printenv.py prepushkey 1"
  > [devel]
  > legacy.exchange=phases
  > EOF

#if bundle1
Bundle1 works because a) phases are updated as part of changegroup application
and b) client checks phases after the "unbundle" command. Since it sees no
phase changes are necessary, it doesn't send the "pushkey" command and the
prepushkey hook never has to fire.

  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  % serve errors

#endif

#if bundle2
Bundle2 sends a "pushkey" bundle2 part. This runs as part of the transaction
and fails the entire push.
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: prepushkey hook: HG_BUNDLE2=1 HG_HOOKNAME=prepushkey HG_HOOKTYPE=prepushkey HG_KEY=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NAMESPACE=phases HG_NEW=0 HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_OLD=1 HG_PENDING=$TESTTMP/test HG_PHASES_MOVED=1 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob)
  remote: pushkey-abort: prepushkey hook exited with status 1
  remote: transaction abort!
  remote: rollback completed
  abort: updating ba677d0156c1 to public failed
  % serve errors
  [255]

#endif

Now remove the failing prepushkey hook.

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > prepushkey = sh -c "printenv.py prepushkey 0"
  > EOF

We don't need to test bundle1 because it succeeded above.

#if bundle2
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: prepushkey hook: HG_BUNDLE2=1 HG_HOOKNAME=prepushkey HG_HOOKTYPE=prepushkey HG_KEY=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NAMESPACE=phases HG_NEW=0 HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_OLD=1 HG_PENDING=$TESTTMP/test HG_PHASES_MOVED=1 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob)
  % serve errors
#endif

  $ hg --config extensions.strip= strip -r 1:
  saved backup bundle to $TESTTMP/test/.hg/strip-backup/ba677d0156c1-eea704d7-backup.hg

Now do a variant of the above, except on a non-publishing repository

  $ cat >> .hg/hgrc <<EOF
  > [phases]
  > publish = false
  > [hooks]
  > prepushkey = sh -c "printenv.py prepushkey 1"
  > EOF

#if bundle1
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: prepushkey hook: HG_HOOKNAME=prepushkey HG_HOOKTYPE=prepushkey HG_KEY=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NAMESPACE=phases HG_NEW=0 HG_OLD=1
  remote: pushkey-abort: prepushkey hook exited with status 1
  updating ba677d0156c1 to public failed!
  % serve errors
#endif

#if bundle2
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: prepushkey hook: HG_BUNDLE2=1 HG_HOOKNAME=prepushkey HG_HOOKTYPE=prepushkey HG_KEY=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NAMESPACE=phases HG_NEW=0 HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_OLD=1 HG_PENDING=$TESTTMP/test HG_PHASES_MOVED=1 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob)
  remote: pushkey-abort: prepushkey hook exited with status 1
  remote: transaction abort!
  remote: rollback completed
  abort: updating ba677d0156c1 to public failed
  % serve errors
  [255]
#endif

Make phases updates work

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > prepushkey = sh -c "printenv.py prepushkey 0"
  > EOF

#if bundle1
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  no changes found
  remote: prepushkey hook: HG_HOOKNAME=prepushkey HG_HOOKTYPE=prepushkey HG_KEY=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NAMESPACE=phases HG_NEW=0 HG_OLD=1
  % serve errors
  [1]
#endif

#if bundle2
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: prepushkey hook: HG_BUNDLE2=1 HG_HOOKNAME=prepushkey HG_HOOKTYPE=prepushkey HG_KEY=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NAMESPACE=phases HG_NEW=0 HG_NODE=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_NODE_LAST=ba677d0156c1196c1a699fa53f390dcfc3ce3872 HG_OLD=1 HG_PENDING=$TESTTMP/test HG_PHASES_MOVED=1 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:http:$LOCALIP: (glob)
  % serve errors
#endif

  $ hg --config extensions.strip= strip -r 1:
  saved backup bundle to $TESTTMP/test/.hg/strip-backup/ba677d0156c1-eea704d7-backup.hg

#if bundle2

  $ cat > .hg/hgrc <<EOF
  > [web]
  > push_ssl = false
  > allow_push = *
  > [experimental]
  > httppostargs=true
  > EOF
  $ req
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  % serve errors

#endif

  $ cd ..

Pushing via hgwebdir works

  $ hg init hgwebdir
  $ cd hgwebdir
  $ echo 0 > a
  $ hg -q commit -A -m initial
  $ cd ..

  $ cat > web.conf << EOF
  > [paths]
  > / = *
  > [web]
  > push_ssl = false
  > allow_push = *
  > EOF

  $ hg serve --web-conf web.conf -p $HGPORT -d --pid-file hg.pid
  $ cat hg.pid >> $DAEMON_PIDS

  $ hg clone http://localhost:$HGPORT/hgwebdir hgwebdir-local
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 98a3f8f02ba7
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd hgwebdir-local
  $ echo commit > a
  $ hg commit -m 'local commit'

  $ hg push
  pushing to http://localhost:$HGPORT/hgwebdir
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files

  $ killdaemons.py

  $ cd ..