view contrib/debugcmdserver.py @ 26123:bdac264e5ed4

contrib: add showstack extension

This allows getting a Python stack trace at any time on Unix by
hitting Ctrl-\ (or Ctrl-T on BSDs). Useful for debugging mysterious
hangs on the fly. Sample output:

$ hg log -k nosuchmessage
^\
  File "/home/mpm/hg/mercurial/revset.py", line 3089, in _iterfilter
    if cond(x):
  File "/home/mpm/hg/mercurial/util.py", line 415, in f
    cache[arg] = func(arg)
  File "/home/mpm/hg/mercurial/revset.py", line 1215, in matches
    for t in c.files() + [c.user(), c.description()])
  File "/home/mpm/hg/mercurial/context.py", line 525, in files
    return self._changeset[3]
  File "/home/mpm/hg/mercurial/util.py", line 531, in __get__
    result = self.func(obj)
  File "/home/mpm/hg/mercurial/context.py", line 498, in _changeset
    return self._repo.changelog.read(self.rev())
  File "/home/mpm/hg/mercurial/changelog.py", line 338, in read
    text = self.revision(node)
  File "/home/mpm/hg/mercurial/revlog.py", line 1092, in revision
    bins = self._chunks(chain)
  File "/home/mpm/hg/mercurial/revlog.py", line 1013, in _chunks
    ladd(decompress(buffer(data, chunkstart - offset, chunklength)))
  File "/home/mpm/hg/mercurial/revlog.py", line 91, in decompress
    return _decompress(bin)
----

#!/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()