localrepo: create new function for instantiating a local repo object
Today, there is a single local repository class - localrepository. Its
__init__ is responsible for loading the .hg/requires file and taking
different actions depending on what is present.
In addition, extensions may define a "reposetup" function that
monkeypatches constructed repository instances, often by implementing
a derived type and changing the __class__ of the repo instance.
Work around alternate storage backends and partial clone has made it
clear to me that shoehorning all this logic into __init__ and operating
on an existing instance is too convoluted. For example, localrepository
assumes revlog storage and swapping in non-revlog storage requires
overriding e.g. file() to return something that isn't a revlog. I've
authored various patches that either:
a) teach various methods (like file()) about different states and
taking the appropriate code path at run-time
b) create methods/attributes/callables used for instantiating things
and populating these in __init__
"a" incurs run-time performance penalties and makes code more
complicated since various functions have a bunch of "if storage is X"
branches.
"b" makes localrepository quickly explode in complexity.
My plan for tackling this problem is to make the local repository type
more dynamic. Instead of a static localrepository class/type that
supports all of the local repository configurations (revlogs vs other,
revlogs with ellipsis, revlog v1 versus revlog v2, etc), we'll
dynamically construct a type providing the implementations that are
needed for the repository on disk, derived from the .hg/requires file
and configuration options. The constructed repository type will be
specialized and methods won't need to be taught about different
implementations nor overloaded.
We may also leverage this functionality for building types that don't
implement all attributes. For example, the "intents" feature allows
commands to declare that they are read only. By dynamically
constructing a repository type, we could return a repository instance
with no attributes related to mutating the repository. This could
include things like a "changelog" property implementation that doesn't
check whether it needs to invalidate the hidden revisions set on every
access.
This commit establishes a function for building a local repository
instance. Future commits will start moving functionality from
localrepository.__init__ to this function. Then we'll start dynamically
changing the returned type depending on options that are present.
This change may seem radical. But it should be fully compatible with
the reposetup() model - at least for now.
Differential Revision: https://phab.mercurial-scm.org/D4563
Test UI worker interaction
$ cat > t.py <<EOF
> from __future__ import absolute_import, print_function
> import time
> from mercurial import (
> error,
> registrar,
> ui as uimod,
> worker,
> )
> def abort(ui, args):
> if args[0] == 0:
> # by first worker for test stability
> raise error.Abort(b'known exception')
> return runme(ui, [])
> def exc(ui, args):
> if args[0] == 0:
> # by first worker for test stability
> raise Exception('unknown exception')
> return runme(ui, [])
> def runme(ui, args):
> for arg in args:
> ui.status(b'run\n')
> yield 1, arg
> time.sleep(0.1) # easier to trigger killworkers code path
> functable = {
> b'abort': abort,
> b'exc': exc,
> b'runme': runme,
> }
> cmdtable = {}
> command = registrar.command(cmdtable)
> @command(b'test', [], b'hg test [COST] [FUNC]')
> def t(ui, repo, cost=1.0, func=b'runme'):
> cost = float(cost)
> func = functable[func]
> ui.status(b'start\n')
> runs = worker.worker(ui, cost, func, (ui,), range(8))
> for n, i in runs:
> pass
> ui.status(b'done\n')
> EOF
$ abspath=`pwd`/t.py
$ hg init
Run tests with worker enable by forcing a heigh cost
$ hg --config "extensions.t=$abspath" test 100000.0
start
run
run
run
run
run
run
run
run
done
Run tests without worker by forcing a low cost
$ hg --config "extensions.t=$abspath" test 0.0000001
start
run
run
run
run
run
run
run
run
done
#if no-windows
Known exception should be caught, but printed if --traceback is enabled
$ hg --config "extensions.t=$abspath" --config 'worker.numcpus=8' \
> test 100000.0 abort 2>&1
start
abort: known exception
[255]
$ hg --config "extensions.t=$abspath" --config 'worker.numcpus=8' \
> test 100000.0 abort --traceback 2>&1 | egrep '^(SystemExit|Abort)'
Abort: known exception
SystemExit: 255
Traceback must be printed for unknown exceptions
$ hg --config "extensions.t=$abspath" --config 'worker.numcpus=8' \
> test 100000.0 exc 2>&1 | grep '^Exception'
Exception: unknown exception
Workers should not do cleanups in all cases
$ cat > $TESTTMP/detectcleanup.py <<EOF
> from __future__ import absolute_import
> import atexit
> import os
> import time
> oldfork = os.fork
> count = 0
> parentpid = os.getpid()
> def delayedfork():
> global count
> count += 1
> pid = oldfork()
> # make it easier to test SIGTERM hitting other workers when they have
> # not set up error handling yet.
> if count > 1 and pid == 0:
> time.sleep(0.1)
> return pid
> os.fork = delayedfork
> def cleanup():
> if os.getpid() != parentpid:
> os.write(1, 'should never happen\n')
> atexit.register(cleanup)
> EOF
$ hg --config "extensions.t=$abspath" --config worker.numcpus=8 --config \
> "extensions.d=$TESTTMP/detectcleanup.py" test 100000 abort
start
abort: known exception
[255]
#endif