[MERGE/RFC] Flush .bzr.log periodically

[Vincent Ladeuil]

>>>>> "jam" == John Arbash Meinel <john at arbash-meinel.com> writes:

<snip/>

    jam> I'm not settled that we need it, but it did make
    jam> following the log file on windows during a long running
    jam> process nicer.

Flushing every 2 seconds (if only a few chars have been written
since otherwise the flush should already occurs "naturally")
sounds very useful to me (I have a lot of bzr commands that run
for hours or even days recently :-/).

    jam> (I haven't broken it out into a mergable patch yet, but
    jam> the change is pretty small).

    jam> I know there is a comment that the tracefile is line
    jam> buffered, but I can guarantee that isn't the case on
    jam> Windows.

    jam> John
    jam> =:->

    jam> === modified file 'bzrlib/trace.py'
    jam> --- bzrlib/trace.py	2008-11-01 14:44:47 +0000
    jam> +++ bzrlib/trace.py	2009-01-07 21:59:52 +0000
    jam> @@ -129,9 +129,11 @@
    jam>  info = note
    jam>  log_error = _bzr_logger.error
    jam>  error =     _bzr_logger.error
    jam> +_last_mutter_flush_time = None


    jam>  def mutter(fmt, *args):
    jam> +    global _last_mutter_flush_time
    jam>      if _trace_file is None:
    jam>          return
    jam>      if (getattr(_trace_file, 'closed', None) is not None) and
    jam> _trace_file.closed:
    jam> @@ -152,11 +154,16 @@
    jam>          out = fmt % tuple(real_args)
    jam>      else:
    jam>          out = fmt
    jam> -    timestamp = '%0.3f  ' % (time.time() - _bzr_log_start_time,)
    jam> +    now = time.time()
    jam> +    timestamp = '%0.3f  ' % (now - _bzr_log_start_time,)
    jam>      out = timestamp + out + '\n'
    jam>      _trace_file.write(out)
    jam>      # no need to flush here, the trace file is now linebuffered when it's
    jam>      # opened.
    jam> +    if (_last_mutter_flush_time is None
    jam> +        or (now - _last_mutter_flush_time) > 2.0):
    jam> +        _trace_file.flush()
    jam> +        _last_mutter_flush_time = now

You should either delete the comment or not use flush() or some
people (including me in a couple of years and may be even you :)
will get confused.

BB:approve

     Vincent