##// END OF EJS Templates
revlog: linearize created changegroups in generaldelta revlogs...
revlog: linearize created changegroups in generaldelta revlogs This greatly improves the speed of the bundling process, and often reduces the bundle size considerably. (Although if the repository is already ordered, this has little effect on both time and bundle size.) For non-generaldelta clients, the reduced bundle size translates to a reduced repository size, similar to shrinking the revlogs (which uses the exact same algorithm). For generaldelta clients the difference is minor. When the new bundle format comes, reordering will not be necessary since we can then store the deltaparent relationsships directly. The eventual default behavior for clients and servers is presented in the table below, where "new" implies support for GD as well as the new bundle format: old client new client old server old bundle, no reorder old bundle, no reorder new server, non-GD old bundle, no reorder[1] old bundle, no reorder[2] new server, GD old bundle, reorder[3] new bundle, no reorder[4] [1] reordering is expensive on the server in this case, skip it [2] client can choose to do its own redelta here [3] reordering is needed because otherwise the pull does a lot of extra work on the server [4] reordering isn't needed because client can get deltabase in bundle format Currently, the default is to reorder on GD-servers, and not otherwise. A new setting, bundle.reorder, has been added to override the default reordering behavior. It can be set to either 'auto' (the default), or any true or false value as a standard boolean setting, to either force the reordering on or off regardless of generaldelta. Some timing data from a relatively branch test repository follows. All bundling is done with --all --type none options. Non-generaldelta, non-shrunk repo: ----------------------------------- Size: 276M Without reorder (default): Bundle time: 14.4 seconds Bundle size: 939M With reorder: Bundle time: 1 minute, 29.3 seconds Bundle size: 381M Generaldelta, non-shrunk repo: ----------------------------------- Size: 87M Without reorder: Bundle time: 2 minutes, 1.4 seconds Bundle size: 939M With reorder (default): Bundle time: 25.5 seconds Bundle size: 381M

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changegroup.py
256 lines | 8.1 KiB | text/x-python | PythonLexer
# changegroup.py - Mercurial changegroup manipulation functions
#
# Copyright 2006 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from i18n import _
from node import nullrev
import mdiff, util
import struct, os, bz2, zlib, tempfile
_BUNDLE10_DELTA_HEADER = "20s20s20s20s"
def readexactly(stream, n):
'''read n bytes from stream.read and abort if less was available'''
s = stream.read(n)
if len(s) < n:
raise util.Abort(_("stream ended unexpectedly"
" (got %d bytes, expected %d)")
% (len(s), n))
return s
def getchunk(stream):
"""return the next chunk from stream as a string"""
d = readexactly(stream, 4)
l = struct.unpack(">l", d)[0]
if l <= 4:
if l:
raise util.Abort(_("invalid chunk length %d") % l)
return ""
return readexactly(stream, l - 4)
def chunkheader(length):
"""return a changegroup chunk header (string)"""
return struct.pack(">l", length + 4)
def closechunk():
"""return a changegroup chunk header (string) for a zero-length chunk"""
return struct.pack(">l", 0)
class nocompress(object):
def compress(self, x):
return x
def flush(self):
return ""
bundletypes = {
"": ("", nocompress), # only when using unbundle on ssh and old http servers
# since the unification ssh accepts a header but there
# is no capability signaling it.
"HG10UN": ("HG10UN", nocompress),
"HG10BZ": ("HG10", lambda: bz2.BZ2Compressor()),
"HG10GZ": ("HG10GZ", lambda: zlib.compressobj()),
}
# hgweb uses this list to communicate its 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 chunkgroup is the end of the changegroup
# a changegroup has at least 2 chunkgroups (changelog and manifest).
# after that, an empty chunkgroup is the end of the changegroup
empty = False
count = 0
while not empty or count <= 2:
empty = True
count += 1
while 1:
chunk = getchunk(cg)
if not chunk:
break
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 decompressor(fh, alg):
if alg == 'UN':
return fh
elif alg == 'GZ':
def generator(f):
zd = zlib.decompressobj()
for chunk in f:
yield zd.decompress(chunk)
elif alg == 'BZ':
def generator(f):
zd = bz2.BZ2Decompressor()
zd.decompress("BZ")
for chunk in util.filechunkiter(f, 4096):
yield zd.decompress(chunk)
else:
raise util.Abort("unknown bundle compression '%s'" % alg)
return util.chunkbuffer(generator(fh))
class unbundle10(object):
deltaheader = _BUNDLE10_DELTA_HEADER
deltaheadersize = struct.calcsize(deltaheader)
def __init__(self, fh, alg):
self._stream = decompressor(fh, alg)
self._type = alg
self.callback = None
def compressed(self):
return self._type != 'UN'
def read(self, l):
return self._stream.read(l)
def seek(self, pos):
return self._stream.seek(pos)
def tell(self):
return self._stream.tell()
def close(self):
return self._stream.close()
def chunklength(self):
d = readexactly(self._stream, 4)
l = struct.unpack(">l", d)[0]
if l <= 4:
if l:
raise util.Abort(_("invalid chunk length %d") % l)
return 0
if self.callback:
self.callback()
return l - 4
def changelogheader(self):
"""v10 does not have a changelog header chunk"""
return {}
def manifestheader(self):
"""v10 does not have a manifest header chunk"""
return {}
def filelogheader(self):
"""return the header of the filelogs chunk, v10 only has the filename"""
l = self.chunklength()
if not l:
return {}
fname = readexactly(self._stream, l)
return dict(filename=fname)
def _deltaheader(self, headertuple, prevnode):
node, p1, p2, cs = headertuple
if prevnode is None:
deltabase = p1
else:
deltabase = prevnode
return node, p1, p2, deltabase, cs
def deltachunk(self, prevnode):
l = self.chunklength()
if not l:
return {}
headerdata = readexactly(self._stream, self.deltaheadersize)
header = struct.unpack(self.deltaheader, headerdata)
delta = readexactly(self._stream, l - self.deltaheadersize)
node, p1, p2, deltabase, cs = self._deltaheader(header, prevnode)
return dict(node=node, p1=p1, p2=p2, cs=cs,
deltabase=deltabase, delta=delta)
class headerlessfixup(object):
def __init__(self, fh, h):
self._h = h
self._fh = fh
def read(self, n):
if self._h:
d, self._h = self._h[:n], self._h[n:]
if len(d) < n:
d += readexactly(self._fh, n - len(d))
return d
return readexactly(self._fh, n)
def readbundle(fh, fname):
header = readexactly(fh, 6)
if not fname:
fname = "stream"
if not header.startswith('HG') and header.startswith('\0'):
fh = headerlessfixup(fh, header)
header = "HG10UN"
magic, version, alg = header[0:2], header[2:4], header[4:6]
if magic != 'HG':
raise util.Abort(_('%s: not a Mercurial bundle') % fname)
if version != '10':
raise util.Abort(_('%s: unknown bundle version %s') % (fname, version))
return unbundle10(fh, alg)
class bundle10(object):
deltaheader = _BUNDLE10_DELTA_HEADER
def __init__(self, lookup):
self._lookup = lookup
def close(self):
return closechunk()
def fileheader(self, fname):
return chunkheader(len(fname)) + fname
def revchunk(self, revlog, rev, prev):
node = revlog.node(rev)
p1, p2 = revlog.parentrevs(rev)
base = prev
prefix = ''
if base == nullrev:
delta = revlog.revision(node)
prefix = mdiff.trivialdiffheader(len(delta))
else:
delta = revlog.revdiff(base, rev)
linknode = self._lookup(revlog, node)
p1n, p2n = revlog.parents(node)
basenode = revlog.node(base)
meta = self.builddeltaheader(node, p1n, p2n, basenode, linknode)
meta += prefix
l = len(meta) + len(delta)
yield chunkheader(l)
yield meta
yield delta
def builddeltaheader(self, node, p1n, p2n, basenode, linknode):
# do nothing with basenode, it is implicitly the previous one in HG10
return struct.pack(self.deltaheader, node, p1n, p2n, linknode)