view mercurial/changegroup.py @ 2735:07026da25ed8

hbisect.py: don't rely on __del__ to write the current state.

This is yet another page of the "Thou shalt not do too much inside
__del__ methods" book, in the "demandload and __del__ don't go well
together" chapter.

The bisect extension is broken in 0.9.1:

$ hg bisect init
$ hg bisect bad
Fatal Python error: Interpreter not initialized (version mismatch?)
Aborted

(yes, I tripled checked my instalation to make sure the problem is not
there)

It's been broken since revision fe1689273f84 moved the import of the
binascii module into a demandload.

(In details: the first time that "hg bisect bad" (or good) is called,
there are still no revisions saved in .hg/bisect/*, so bisect.__init__
doesn't call hg.bin on anything.  So, when we reach __del__, the
binascii module still hasn't been imported and we get that "nice"
message above.)

"""
changegroup.py - Mercurial changegroup manipulation functions

 Copyright 2006 Matt Mackall <[e-mail]>

This software may be used and distributed according to the terms
of the GNU General Public License, incorporated herein by reference.
"""
from i18n import gettext as _
from demandload import *
demandload(globals(), "struct util")

def getchunk(source):
    """get a chunk from a changegroup"""
    d = source.read(4)
    if not d:
        return ""
    l = struct.unpack(">l", d)[0]
    if l <= 4:
        return ""
    d = source.read(l - 4)
    if len(d) < l - 4:
        raise util.Abort(_("premature EOF reading chunk"
                           " (got %d bytes, expected %d)")
                          % (len(d), l - 4))
    return d

def chunkiter(source):
    """iterate through the chunks in source"""
    while 1:
        c = getchunk(source)
        if not c:
            break
        yield c

def genchunk(data):
    """build a changegroup chunk"""
    header = struct.pack(">l", len(data)+ 4)
    return "%s%s" % (header, data)

def closechunk():
    return struct.pack(">l", 0)