view contrib/debugcmdserver.py @ 32750:b698921ee137

dirstate: add identity information to detect simultaneous changing in storage

This identity is used to examine whether dirstate is simultaneously
changed in storage after previous caching (see issue5584 for detail).

util.cachestat can't be used for this purpose, because it has no
valuable information on Windows.

On the other hand, util.filestat can detect changing dirstate in
storage certainly, regardless of platforms.

    https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan

Strictly speaking, if underlying filesystem doesn't support
ctime/mtime, util.filestat can't detect simultaneous changing in
storage as expected. But simultaneous changing on such (very rare)
platform can't be detected regardless of this patch series.

Therefore, util.filestat should be reasonable identity for almost all
usecases.

#!/usr/bin/env python
#
# Dumps output generated by Mercurial's command server in a formatted style to a
# given file or stderr if '-' is specified. Output is also written in its raw
# format to stdout.
#
# $ ./hg serve --cmds pipe | ./contrib/debugcmdserver.py -
# o, 52   -> 'capabilities: getencoding runcommand\nencoding: UTF-8'

from __future__ import absolute_import, print_function
import struct
import sys

if len(sys.argv) != 2:
    print('usage: debugcmdserver.py FILE')
    sys.exit(1)

outputfmt = '>cI'
outputfmtsize = struct.calcsize(outputfmt)

if sys.argv[1] == '-':
    log = sys.stderr
else:
    log = open(sys.argv[1], 'a')

def read(size):
    data = sys.stdin.read(size)
    if not data:
        raise EOFError
    sys.stdout.write(data)
    sys.stdout.flush()
    return data

try:
    while True:
        header = read(outputfmtsize)
        channel, length = struct.unpack(outputfmt, header)
        log.write('%s, %-4d' % (channel, length))
        if channel in 'IL':
            log.write(' -> waiting for input\n')
        else:
            data = read(length)
            log.write(' -> %r\n' % data)
        log.flush()
except EOFError:
    pass
finally:
    if log != sys.stderr:
        log.close()