view contrib/debugcmdserver.py @ 23732:c51d6c043bb1

rebase: clarify comment about merge ancestor when rebasing merges

The code for picking a merge ancestor when rebasing merges had a long and
incorrect comment.

The comment would perhaps have been fine as commit message but does
not make the code more readable or maintainable and is a bad
substitute for correct and readable code.

The correct essense of the comment is quite trivial: a merge of an ancestor of
the rebase destination and an 'outside' revision can be rebased as if it was a
linear change, using 'destination ancestor parent' as base and pretty much
ignoring the 'outside' revision.

The code path where the comment is placed is however also used for other kinds
of merge rebases. The comment is thus not really correct and not helpful. I
think it would be better to drop the comment and rewrite the code.

#!/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'

import sys, struct

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()