Function _wait

redo/jobserver.py:286–338

Wait for a subproc to die or, if want_token, tokenfd to be readable. Does not actually read tokenfd once it's readable (so someone else might read it before us). This function returns after max_delay seconds or when at least one subproc dies or (if want_token) for tokenfd to be rea

(want_token, max_delay)

def _wait(want_token, max_delay):
    """Wait for a subproc to die or, if want_token, tokenfd to be readable.

    Does not actually read tokenfd once it's readable (so someone else might
    read it before us).  This function returns after max_delay seconds or
    when at least one subproc dies or (if want_token) for tokenfd to be
    readable.

    Args:
      want_token: true if we should return when tokenfd is readable.
      max_delay: max seconds to wait, or None to wait forever.
    Returns:
      None
    """
    rfds = _waitfds.keys()
    if want_token:
        rfds.append(_tokenfds[0])
    assert rfds
    assert state.is_flushed()
    _debug('_tokenfds=%r; jfds=%r\n' % (_tokenfds, _waitfds))
    r, w, x = select.select(rfds, [], [], max_delay)
    _debug('readable: %r\n' % (r,))
    for fd in r:
        if fd == _tokenfds[0]:
            pass
        else:
            pd = _waitfds[fd]
            _debug("done: %r\n" % pd.name)
            # redo subprocesses are expected to die without releasing their
            # tokens, so things are less likely to get confused if they
            # die abnormally.  Since a child has died, that means a token has
            # 'disappeared' and we now need to recreate it.
            b = _try_read(_cheatfds[0], 1)
            if b:
                # someone exited with _cheats > 0, so we need to compensate
                # by *not* re-creating a token now.
                _debug('EAT cheatfd %r\n' % b)
            else:
                _create_tokens(1)
                if has_token():
                    _release_except_mine()
            os.close(fd)
            del _waitfds[fd]
            rv = os.waitpid(pd.pid, 0)
            assert rv[0] == pd.pid
            _debug("done1: rv=%r\n" % (rv,))
            rv = rv[1]
            if os.WIFEXITED(rv):
                pd.rv = os.WEXITSTATUS(rv)
            else:
                pd.rv = -os.WTERMSIG(rv)
            _debug("done2: rv=%d\n" % pd.rv)
            pd.donefunc(pd.name, pd.rv)


def has_token():