cborutil: change buffering strategy
Profiling revealed that we were spending a lot of time on the
line that was concatenating the old buffer with the incoming data
when attempting to decode long byte strings, such as manifest
revisions.
Essentially, we were feeding N chunks of size len(X) << len(Y) into
decode() and continuously allocating a new, larger buffer to hold
the undecoded input. This created substantial memory churn and
slowed down execution.
Changing the code to aggregate pending chunks in a list until we
have enough data to fully decode the next atom makes things much
more efficient.
I don't have exact data, but I recall the old code spending >1s
on manifest fulltexts from the mozilla-unified repo. The new code
doesn't significantly appear in profile output.
Differential Revision: https://phab.mercurial-scm.org/D4854
#!/usr/bin/env python
"""
Utility for inspecting files in various ways.
This tool is like the collection of tools found in a unix environment but are
cross platform and stable and suitable for our needs in the test suite.
This can be used instead of tools like:
[
dd
find
head
hexdump
ls
md5sum
readlink
sha1sum
stat
tail
test
readlink.py
md5sum.py
"""
from __future__ import absolute_import
import binascii
import glob
import hashlib
import optparse
import os
import re
import sys
# Python 3 adapters
ispy3 = (sys.version_info[0] >= 3)
if ispy3:
def iterbytes(s):
for i in range(len(s)):
yield s[i:i + 1]
else:
iterbytes = iter
def visit(opts, filenames, outfile):
"""Process filenames in the way specified in opts, writing output to
outfile."""
for f in sorted(filenames):
isstdin = f == '-'
if not isstdin and not os.path.lexists(f):
outfile.write(b'%s: file not found\n' % f.encode('utf-8'))
continue
quiet = opts.quiet and not opts.recurse or isstdin
isdir = os.path.isdir(f)
islink = os.path.islink(f)
isfile = os.path.isfile(f) and not islink
dirfiles = None
content = None
facts = []
if isfile:
if opts.type:
facts.append(b'file')
if any((opts.hexdump, opts.dump, opts.md5, opts.sha1, opts.sha256)):
with open(f, 'rb') as fobj:
content = fobj.read()
elif islink:
if opts.type:
facts.append(b'link')
content = os.readlink(f)
elif isstdin:
content = getattr(sys.stdin, 'buffer', sys.stdin).read()
if opts.size:
facts.append(b'size=%d' % len(content))
elif isdir:
if opts.recurse or opts.type:
dirfiles = glob.glob(f + '/*')
facts.append(b'directory with %d files' % len(dirfiles))
elif opts.type:
facts.append(b'type unknown')
if not isstdin:
stat = os.lstat(f)
if opts.size and not isdir:
facts.append(b'size=%d' % stat.st_size)
if opts.mode and not islink:
facts.append(b'mode=%o' % (stat.st_mode & 0o777))
if opts.links:
facts.append(b'links=%d' % stat.st_nlink)
if opts.newer:
# mtime might be in whole seconds so newer file might be same
if stat.st_mtime >= os.stat(opts.newer).st_mtime:
facts.append(b'newer than %s' % opts.newer)
else:
facts.append(b'older than %s' % opts.newer)
if opts.md5 and content is not None:
h = hashlib.md5(content)
facts.append(b'md5=%s' % binascii.hexlify(h.digest())[:opts.bytes])
if opts.sha1 and content is not None:
h = hashlib.sha1(content)
facts.append(b'sha1=%s' % binascii.hexlify(h.digest())[:opts.bytes])
if opts.sha256 and content is not None:
h = hashlib.sha256(content)
facts.append(b'sha256=%s' %
binascii.hexlify(h.digest())[:opts.bytes])
if isstdin:
outfile.write(b', '.join(facts) + b'\n')
elif facts:
outfile.write(b'%s: %s\n' % (f.encode('utf-8'), b', '.join(facts)))
elif not quiet:
outfile.write(b'%s:\n' % f.encode('utf-8'))
if content is not None:
chunk = content
if not islink:
if opts.lines:
if opts.lines >= 0:
chunk = b''.join(chunk.splitlines(True)[:opts.lines])
else:
chunk = b''.join(chunk.splitlines(True)[opts.lines:])
if opts.bytes:
if opts.bytes >= 0:
chunk = chunk[:opts.bytes]
else:
chunk = chunk[opts.bytes:]
if opts.hexdump:
for i in range(0, len(chunk), 16):
s = chunk[i:i + 16]
outfile.write(b'%04x: %-47s |%s|\n' %
(i, b' '.join(
b'%02x' % ord(c) for c in iterbytes(s)),
re.sub(b'[^ -~]', b'.', s)))
if opts.dump:
if not quiet:
outfile.write(b'>>>\n')
outfile.write(chunk)
if not quiet:
if chunk.endswith(b'\n'):
outfile.write(b'<<<\n')
else:
outfile.write(b'\n<<< no trailing newline\n')
if opts.recurse and dirfiles:
assert not isstdin
visit(opts, dirfiles, outfile)
if __name__ == "__main__":
parser = optparse.OptionParser("%prog [options] [filenames]")
parser.add_option("-t", "--type", action="store_true",
help="show file type (file or directory)")
parser.add_option("-m", "--mode", action="store_true",
help="show file mode")
parser.add_option("-l", "--links", action="store_true",
help="show number of links")
parser.add_option("-s", "--size", action="store_true",
help="show size of file")
parser.add_option("-n", "--newer", action="store",
help="check if file is newer (or same)")
parser.add_option("-r", "--recurse", action="store_true",
help="recurse into directories")
parser.add_option("-S", "--sha1", action="store_true",
help="show sha1 hash of the content")
parser.add_option("", "--sha256", action="store_true",
help="show sha256 hash of the content")
parser.add_option("-M", "--md5", action="store_true",
help="show md5 hash of the content")
parser.add_option("-D", "--dump", action="store_true",
help="dump file content")
parser.add_option("-H", "--hexdump", action="store_true",
help="hexdump file content")
parser.add_option("-B", "--bytes", type="int",
help="number of characters to dump")
parser.add_option("-L", "--lines", type="int",
help="number of lines to dump")
parser.add_option("-q", "--quiet", action="store_true",
help="no default output")
(opts, filenames) = parser.parse_args(sys.argv[1:])
if not filenames:
filenames = ['-']
visit(opts, filenames, getattr(sys.stdout, 'buffer', sys.stdout))