view tests/test-dispatch.py @ 37212:f09a2eab11cf

server: add an error feedback mechanism for when the daemon fails to launch

There's a recurring problem on Windows where `hg serve -d` will randomly fail to
spawn a detached process.  The reason for the failure is completely hidden, and
it takes hours to get a single failure on my laptop.  All this does is redirect
stdout/stderr of the child to a file until the lock file is freed, and then the
parent dumps it out if it fails to spawn.

I chose to put the output into the lock file because that is always cleaned up.
There's no way to report errors after that anyway.  On Windows, killdaemons.py
is roughly `kill -9`, so this ensures that junk won't pile up.

This may end up being a case of EADDRINUSE.  At least that's what I saw spit out
a few times (among other odd errors and missing output on Windows).  But I also
managed to get the same thing on Fedora 26 by running test-hgwebdir.t with
--loop -j10 for several hours.  Running `netstat` immediately after killing that
run printed a wall of sockets in the TIME_WAIT state, which were gone a couple
seconds later.  I couldn't match up ports that failed, because --loop doesn't
print out the message about the port that was used.  So maybe the fix is to
rotate the use of HGPORT[12] in the tests.  But, let's collect some more data
first.

from __future__ import absolute_import, print_function
import os
from mercurial import (
    dispatch,
)

def testdispatch(cmd):
    """Simple wrapper around dispatch.dispatch()

    Prints command and result value, but does not handle quoting.
    """
    print(b"running: %s" % (cmd,))
    req = dispatch.request(cmd.split())
    result = dispatch.dispatch(req)
    print(b"result: %r" % (result,))

testdispatch(b"init test1")
os.chdir('test1')

# create file 'foo', add and commit
f = open('foo', 'wb')
f.write(b'foo\n')
f.close()
testdispatch(b"add foo")
testdispatch(b"commit -m commit1 -d 2000-01-01 foo")

# append to file 'foo' and commit
f = open('foo', 'ab')
f.write(b'bar\n')
f.close()
testdispatch(b"commit -m commit2 -d 2000-01-02 foo")

# check 88803a69b24 (fancyopts modified command table)
testdispatch(b"log -r 0")
testdispatch(b"log -r tip")