annotate mercurial/changegroup.py @ 6858:8f256bf98219

Add support for multiple possible bisect results (issue1228, issue1182)

The real reason for both issue is that bisect can not handle cases where there
are multiple possibilities for the result.

Example (from issue1228):
rev 0 -> good
rev 1 -> skipped
rev 2 -> skipped
rev 3 -> skipped
rev 4 -> bad

Note that this patch does not only fix the reported Assertion Error but also
the problem of a non converging bisect:

hg init
for i in `seq 3`; do echo $i > $i; hg add $i; hg ci -m$i; done
hg bisect -b 2
hg bisect -g 0
hg bisect -s

From this state on, you can:
 a) mark as bad forever (non converging!)
 b) mark as good to get an inconsistent state
 c) skip for the Assertion Error

Minor description and code edits by pmezard.

"""
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 _
import struct, os, bz2, zlib, util, tempfile

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 chunkheader(length):
    """build a changegroup chunk header"""
    return struct.pack(">l", length + 4)

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

class nocompress(object):
    def compress(self, x):
        return x
    def flush(self):
        return ""

bundletypes = {
    "": ("", nocompress),
    "HG10UN": ("HG10UN", nocompress),
    "HG10BZ": ("HG10", lambda: bz2.BZ2Compressor()),
    "HG10GZ": ("HG10GZ", lambda: zlib.compressobj()),
}

# hgweb uses this list to communicate it's preferred type
bundlepriority = ['HG10GZ', 'HG10BZ', 'HG10UN']

def writebundle(cg, filename, bundletype):
    """Write a bundle file and return its filename.

    Existing files will not be overwritten.
    If no filename is specified, a temporary file is created.
    bz2 compression can be turned off.
    The bundle file will be deleted in case of errors.
    """

    fh = None
    cleanup = None
    try:
        if filename:
            fh = open(filename, "wb")
        else:
            fd, filename = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg")
            fh = os.fdopen(fd, "wb")
        cleanup = filename

        header, compressor = bundletypes[bundletype]
        fh.write(header)
        z = compressor()

        # parse the changegroup data, otherwise we will block
        # in case of sshrepo because we don't know the end of the stream

        # an empty chunkiter is the end of the changegroup
        # a changegroup has at least 2 chunkiters (changelog and manifest).
        # after that, an empty chunkiter is the end of the changegroup
        empty = False
        count = 0
        while not empty or count <= 2:
            empty = True
            count += 1
            for chunk in chunkiter(cg):
                empty = False
                fh.write(z.compress(chunkheader(len(chunk))))
                pos = 0
                while pos < len(chunk):
                    next = pos + 2**20
                    fh.write(z.compress(chunk[pos:next]))
                    pos = next
            fh.write(z.compress(closechunk()))
        fh.write(z.flush())
        cleanup = None
        return filename
    finally:
        if fh is not None:
            fh.close()
        if cleanup is not None:
            os.unlink(cleanup)

def unbundle(header, fh):
    if header == 'HG10UN':
        return fh
    elif not header.startswith('HG'):
        # old client with uncompressed bundle
        def generator(f):
            yield header
            for chunk in f:
                yield chunk
    elif header == 'HG10GZ':
        def generator(f):
            zd = zlib.decompressobj()
            for chunk in f:
                yield zd.decompress(chunk)
    elif header == 'HG10BZ':
        def generator(f):
            zd = bz2.BZ2Decompressor()
            zd.decompress("BZ")
            for chunk in util.filechunkiter(f, 4096):
                yield zd.decompress(chunk)
    return util.chunkbuffer(generator(fh))

def readbundle(fh, fname):
    header = fh.read(6)
    if not header.startswith('HG'):
        raise util.Abort(_('%s: not a Mercurial bundle file') % fname)
    if not header.startswith('HG10'):
        raise util.Abort(_('%s: unknown bundle version') % fname)
    elif header not in bundletypes:
        raise util.Abort(_('%s: unknown bundle compression type') % fname)
    return unbundle(header, fh)