view contrib/fixpax.py @ 27650:e7222d326ea2

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.

#!/usr/bin/env python
# fixpax - fix ownership in bdist_mpkg output
#
# Copyright 2015 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# MIT license (http://opensource.org/licenses/MIT)

"""Set file ownership to 0 in an Archive.pax.gz.
Suitable for fixing files bdist_mpkg output:
*.mpkg/Contents/Packages/*.pkg/Contents/Archive.pax.gz
"""

import sys, os, gzip

def fixpax(iname, oname):
    i = gzip.GzipFile(iname)
    o = gzip.GzipFile(oname, "w")

    while True:
        magic = i.read(6)
        dev = i.read(6)
        ino = i.read(6)
        mode = i.read(6)
        i.read(6) # uid
        i.read(6) # gid
        nlink = i.read(6)
        rdev = i.read(6)
        mtime = i.read(11)
        namesize = i.read(6)
        filesize = i.read(11)
        name = i.read(int(namesize, 8))
        data = i.read(int(filesize, 8))

        o.write(magic)
        o.write(dev)
        o.write(ino)
        o.write(mode)
        o.write("000000")
        o.write("000000")
        o.write(nlink)
        o.write(rdev)
        o.write(mtime)
        o.write(namesize)
        o.write(filesize)
        o.write(name)
        o.write(data)

        if name.startswith("TRAILER!!!"):
            o.write(i.read())
            break

    o.close()
    i.close()

if __name__ == '__main__':
    for iname in sys.argv[1:]:
        print 'fixing file ownership in %s' % iname
        oname = sys.argv[1] + '.tmp'
        fixpax(iname, oname)
        os.rename(oname, iname)