branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
Test UI worker interaction
$ cat > t.py <<EOF
> import sys
> import time
> from mercurial import (
> error,
> registrar,
> ui as uimod,
> worker,
> )
> sys.unraisablehook = lambda x: None
> 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 | grep -E '(WorkerError|Abort)'
raise error.Abort(b'known exception')
mercurial.error.Abort: known exception
raise error.WorkerError(status)
mercurial.error.WorkerError: 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
> import atexit
> import os
> import sys
> import time
> sys.unraisablehook = lambda x: None
> 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]
Do not crash on partially read result
$ cat > $TESTTMP/detecttruncated.py <<EOF
> import os
> import sys
> import time
> sys.unraisablehook = lambda x: None
> oldwrite = os.write
> def splitwrite(fd, string):
> ret = oldwrite(fd, string[:9])
> if ret == 9:
> time.sleep(0.1)
> ret += oldwrite(fd, string[9:])
> return ret
> os.write = splitwrite
> EOF
$ hg --config "extensions.t=$abspath" --config worker.numcpus=8 --config \
> "extensions.d=$TESTTMP/detecttruncated.py" test 100000.0
start
run
run
run
run
run
run
run
run
done
#endif