revlog: remove unnecessary cache validation in _chunks
Previously, we likely called _chunkraw() multiple times in order to
ensure it didn't change out from under us. I'm pretty certain this code
had its origins in the days where we attempted to have thread safety of
localrepository and thus revlog instances.
revlog instances are already not thread safe for writing. And, as of
Mercurial 3.6, hgweb uses a separate localrepository instance per
request, so there should only be a single thread reading a revlog at
a time. We more or less decided that attempting to make classes like
revlog thread safe is a lost cause.
So, this patch removes thread safety from _chunks. As a result, we make
one less call into _chunkraw() when the initial read isn't serviced
by the cache. This translates to savings of 4 function calls overall
and possibly prevents the creation of an additional buffer view into the
cache. I doubt this translates into any real world performance wins
because decompression will almost certainly dwarf time spent in
_chunks(). But it does make the code simpler, so it is an improvement.
#!/bin/sh -e
#
# Build a Mercurial debian package from the current repo
#
# Tested on Jessie (stable as of original script authoring.)
. $(dirname $0)/packagelib.sh
BUILD=1
CLEANUP=1
DISTID=`(lsb_release -is 2> /dev/null | tr '[:upper:]' '[:lower:]') || echo debian`
CODENAME=`lsb_release -cs 2> /dev/null || echo unknown`
while [ "$1" ]; do
case "$1" in
--distid )
shift
DISTID="$1"
shift
;;
--codename )
shift
CODENAME="$1"
shift
;;
--cleanup )
shift
BUILD=
;;
--build )
shift
CLEANUP=
;;
* )
echo "Invalid parameter $1!" 1>&2
exit 1
;;
esac
done
trap "if [ '$CLEANUP' ] ; then rm -r '$PWD/debian' ; fi" EXIT
set -u
if [ ! -d .hg ]; then
echo 'You are not inside a Mercurial repository!' 1>&2
exit 1
fi
gethgversion
debver="$version"
if [ -n "$type" ] ; then
debver="$debver~$type"
fi
if [ -n "$distance" ] ; then
debver="$debver+$distance-$node"
fi
control=debian/control
changelog=debian/changelog
if [ "$BUILD" ]; then
if [ -d debian ] ; then
echo "Error! debian control directory already exists!"
exit 1
fi
cp -r $PWD/contrib/debian debian
chmod -R 0755 debian
# This looks like sed -i, but sed -i behaves just differently enough
# between BSD and GNU sed that I gave up and did the dumb thing.
sed "s/__VERSION__/$debver/" < $changelog > $changelog.tmp
date=$(date --rfc-2822)
sed "s/__DATE__/$date/" < $changelog.tmp > $changelog
rm $changelog.tmp
debuild -us -uc -b
if [ $? != 0 ]; then
echo 'debuild failed!'
exit 1
fi
fi
if [ "$CLEANUP" ] ; then
echo
OUTPUTDIR=${OUTPUTDIR:=packages/$DISTID-$CODENAME}
mkdir -p "$OUTPUTDIR"
find ../mercurial*.deb ../mercurial_*.build ../mercurial_*.changes \
-type f -newer $control -print0 | \
xargs -Inarf -0 mv narf "$OUTPUTDIR"
echo "Built packages for $debver:"
find "$OUTPUTDIR" -type f -newer $control -name '*.deb'
fi