streamclone: define first iteration of version 2 of stream format
(This patch is based on a first draft from Gregory Szorc, with deeper rework)
Version 1 of the stream clone format was invented many years ago and suffers
from a few deficiencies:
1) Filenames are stored in store-encoded (on filesystem) form rather than in
their internal form. This makes future compatibility with new store
filename encodings more difficult.
2) File entry "headers" consist of a newline of the file name followed by the
string file size. Converting strings to integers is avoidable overhead. We
can't store filenames with newlines (manifests have this limitation as
well, so it isn't a major concern). But the big concern here is the
necessity for readline(). Scanning for newlines means reading ahead and
that means extra buffer allocations and slicing (in Python) and this makes
performance suffer.
3) Filenames aren't compressed optimally. Filenames should be compressed well
since there is a lot of repeated data. However, since they are scattered
all over the stream (with revlog data in between), they typically fall
outside the window size of the compressor and don't compress.
4) It can only exchange stored based content, being able to exchange caches
too would be nice.
5) It is limited to a stream-based protocol and isn't suitable for an on-disk
format for general repository reading because the offset of individual file
entries requires scanning the entire file to find file records.
As part of enabling streaming clones to work in bundle2, #2 proved to have a
significant negative impact on performance. Since bundle2 provides the
opportunity to start fresh, Gregory Szorc figured he would take the
opportunity to invent a new streaming clone data format.
The new format devised in this series addresses #1, #2, and #4. It punts on #3
because it was complex without yielding a significant gain and on #5 because
devising a new store format that "packs" multiple revlogs into a single
"packed revlog" is massive scope bloat. However, this v2 format might be
suitable for streaming into a "packed revlog" with minimal processing. If it
works, great. If not, we can always invent stream format when it is needed.
This patch only introduces the bases of the format. We'll get it usable through
bundle2 first, then we'll extend the format in future patches to bring it to its
full potential (especially #4).
"""This unit test primarily tests parsers.parse_index2().
It also checks certain aspects of the parsers module as a whole.
"""
from __future__ import absolute_import, print_function
import struct
import subprocess
import sys
from mercurial.node import (
nullid,
nullrev,
)
from mercurial import (
policy,
)
parsers = policy.importmod(r'parsers')
# original python implementation
def gettype(q):
return int(q & 0xFFFF)
def offset_type(offset, type):
return long(long(offset) << 16 | type)
indexformatng = ">Qiiiiii20s12x"
def py_parseindex(data, inline) :
s = 64
cache = None
index = []
nodemap = {nullid: nullrev}
n = off = 0
l = len(data) - s
append = index.append
if inline:
cache = (0, data)
while off <= l:
e = struct.unpack(indexformatng, data[off:off + s])
nodemap[e[7]] = n
append(e)
n += 1
if e[1] < 0:
break
off += e[1] + s
else:
while off <= l:
e = struct.unpack(indexformatng, data[off:off + s])
nodemap[e[7]] = n
append(e)
n += 1
off += s
e = list(index[0])
type = gettype(e[0])
e[0] = offset_type(0, type)
index[0] = tuple(e)
# add the magic null revision at -1
index.append((0, 0, 0, -1, -1, -1, -1, nullid))
return index, cache
data_inlined = '\x00\x01\x00\x01\x00\x00\x00\x00\x00\x00\x01\x8c' \
'\x00\x00\x04\x07\x00\x00\x00\x00\x00\x00\x15\x15\xff\xff\xff' \
'\xff\xff\xff\xff\xff\xebG\x97\xb7\x1fB\x04\xcf\x13V\x81\tw\x1b' \
'w\xdduR\xda\xc6\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' \
'x\x9c\x9d\x93?O\xc30\x10\xc5\xf7|\x8a\xdb\x9a\xa8m\x06\xd8*\x95' \
'\x81B\xa1\xa2\xa2R\xcb\x86Pd\x9a\x0b5$vd_\x04\xfd\xf6\x9c\xff@' \
'\x11!\x0b\xd9\xec\xf7\xbbw\xe7gG6\xad6\x04\xdaN\xc0\x92\xa0$)' \
'\xb1\x82\xa2\xd1%\x16\xa4\x8b7\xa9\xca\xd4-\xb2Y\x02\xfc\xc9' \
'\xcaS\xf9\xaeX\xed\xb6\xd77Q\x02\x83\xd4\x19\xf5--Y\xea\xe1W' \
'\xab\xed\x10\xceR\x0f_\xdf\xdf\r\xe1,\xf5\xf0\xcb\xf5 \xceR\x0f' \
'_\xdc\x0e\x0e\xc3R\x0f_\xae\x96\x9b!\x9e\xa5\x1e\xbf\xdb,\x06' \
'\xc7q\x9a/\x88\x82\xc3B\xea\xb5\xb4TJ\x93\xb6\x82\x0e\xe16\xe6' \
'KQ\xdb\xaf\xecG\xa3\xd1 \x01\xd3\x0b_^\xe8\xaa\xa0\xae\xad\xd1' \
'&\xbef\x1bz\x08\xb0|\xc9Xz\x06\xf6Z\x91\x90J\xaa\x17\x90\xaa' \
'\xd2\xa6\x11$5C\xcf\xba#\xa0\x03\x02*2\x92-\xfc\xb1\x94\xdf\xe2' \
'\xae\xb8\'m\x8ey0^\x85\xd3\x82\xb4\xf0`:\x9c\x00\x8a\xfd\x01' \
'\xb0\xc6\x86\x8b\xdd\xae\x80\xf3\xa9\x9fd\x16\n\x00R%\x1a\x06' \
'\xe9\xd8b\x98\x1d\xf4\xf3+\x9bf\x01\xd8p\x1b\xf3.\xed\x9f^g\xc3' \
'^\xd9W81T\xdb\xd5\x04sx|\xf2\xeb\xd6`%?x\xed"\x831\xbf\xf3\xdc' \
'b\xeb%gaY\xe1\xad\x9f\xb9f\'1w\xa9\xa5a\x83s\x82J\xb98\xbc4\x8b' \
'\x83\x00\x9f$z\xb8#\xa5\xb1\xdf\x98\xd9\xec\x1b\x89O\xe3Ts\x9a4' \
'\x17m\x8b\xfc\x8f\xa5\x95\x9a\xfc\xfa\xed,\xe5|\xa1\xfe\x15\xb9' \
'\xbc\xb2\x93\x1f\xf2\x95\xff\xdf,\x1a\xc5\xe7\x17*\x93Oz:>\x0e'
data_non_inlined = '\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01D\x19' \
'\x00\x07e\x12\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff' \
'\xff\xff\xff\xff\xd1\xf4\xbb\xb0\xbe\xfc\x13\xbd\x8c\xd3\x9d' \
'\x0f\xcd\xd9;\x8c\x07\x8cJ/\x00\x00\x00\x00\x00\x00\x00\x00\x00' \
'\x00\x00\x00\x00\x00\x00\x01D\x19\x00\x00\x00\x00\x00\xdf\x00' \
'\x00\x01q\x00\x00\x00\x01\x00\x00\x00\x01\x00\x00\x00\x00\xff' \
'\xff\xff\xff\xc1\x12\xb9\x04\x96\xa4Z1t\x91\xdfsJ\x90\xf0\x9bh' \
'\x07l&\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' \
'\x00\x01D\xf8\x00\x00\x00\x00\x01\x1b\x00\x00\x01\xb8\x00\x00' \
'\x00\x01\x00\x00\x00\x02\x00\x00\x00\x01\xff\xff\xff\xff\x02\n' \
'\x0e\xc6&\xa1\x92\xae6\x0b\x02i\xfe-\xe5\xbao\x05\xd1\xe7\x00' \
'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01F' \
'\x13\x00\x00\x00\x00\x01\xec\x00\x00\x03\x06\x00\x00\x00\x01' \
'\x00\x00\x00\x03\x00\x00\x00\x02\xff\xff\xff\xff\x12\xcb\xeby1' \
'\xb6\r\x98B\xcb\x07\xbd`\x8f\x92\xd9\xc4\x84\xbdK\x00\x00\x00' \
'\x00\x00\x00\x00\x00\x00\x00\x00\x00'
def parse_index2(data, inline):
index, chunkcache = parsers.parse_index2(data, inline)
return list(index), chunkcache
def importparsers(hexversion):
"""Import mercurial.parsers with the given sys.hexversion."""
# The file parsers.c inspects sys.hexversion to determine the version
# of the currently-running Python interpreter, so we monkey-patch
# sys.hexversion to simulate using different versions.
code = ("import sys; sys.hexversion=%s; "
"import mercurial.cext.parsers" % hexversion)
cmd = "python -c \"%s\"" % code
# We need to do these tests inside a subprocess because parser.c's
# version-checking code happens inside the module init function, and
# when using reload() to reimport an extension module, "The init function
# of extension modules is not called a second time"
# (from http://docs.python.org/2/library/functions.html?#reload).
p = subprocess.Popen(cmd, shell=True,
stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
return p.communicate() # returns stdout, stderr
def printhexfail(testnumber, hexversion, stdout, expected):
try:
hexstring = hex(hexversion)
except TypeError:
hexstring = None
print("FAILED: version test #%s with Python %s and patched "
"sys.hexversion %r (%r):\n Expected %s but got:\n-->'%s'\n" %
(testnumber, sys.version_info, hexversion, hexstring, expected,
stdout))
def testversionokay(testnumber, hexversion):
stdout, stderr = importparsers(hexversion)
if stdout:
printhexfail(testnumber, hexversion, stdout, expected="no stdout")
def testversionfail(testnumber, hexversion):
stdout, stderr = importparsers(hexversion)
# We include versionerrortext to distinguish from other ImportErrors.
errtext = "ImportError: %s" % parsers.versionerrortext
if errtext not in stdout:
printhexfail(testnumber, hexversion, stdout,
expected="stdout to contain %r" % errtext)
def makehex(major, minor, micro):
return int("%x%02x%02x00" % (major, minor, micro), 16)
def runversiontests():
"""Check the version-detection logic when importing parsers."""
info = sys.version_info
major, minor, micro = info[0], info[1], info[2]
# Test same major-minor versions.
testversionokay(1, makehex(major, minor, micro))
testversionokay(2, makehex(major, minor, micro + 1))
# Test different major-minor versions.
testversionfail(3, makehex(major + 1, minor, micro))
testversionfail(4, makehex(major, minor + 1, micro))
testversionfail(5, "'foo'")
def runtest() :
# Only test the version-detection logic if it is present.
try:
parsers.versionerrortext
except AttributeError:
pass
else:
runversiontests()
# Check that parse_index2() raises TypeError on bad arguments.
try:
parse_index2(0, True)
except TypeError:
pass
else:
print("Expected to get TypeError.")
# Check parsers.parse_index2() on an index file against the original
# Python implementation of parseindex, both with and without inlined data.
py_res_1 = py_parseindex(data_inlined, True)
c_res_1 = parse_index2(data_inlined, True)
py_res_2 = py_parseindex(data_non_inlined, False)
c_res_2 = parse_index2(data_non_inlined, False)
if py_res_1 != c_res_1:
print("Parse index result (with inlined data) differs!")
if py_res_2 != c_res_2:
print("Parse index result (no inlined data) differs!")
ix = parsers.parse_index2(data_inlined, True)[0]
for i, r in enumerate(ix):
if r[7] == nullid:
i = -1
try:
if ix[r[7]] != i:
print('Reverse lookup inconsistent for %r'
% r[7].encode('hex'))
except TypeError:
# pure version doesn't support this
break
print("done")
runtest()