Nir Soffer <nir...@gmail.com> writes: > On Fri, Mar 3, 2017 at 9:29 PM, John Snow <js...@redhat.com> wrote: >> >> >> On 03/03/2017 02:26 PM, Nir Soffer wrote: >>> On Fri, Mar 3, 2017 at 8:54 PM, John Snow <js...@redhat.com> wrote: >>>> Use the existing readline history function we are utilizing >>>> to provide persistent command history across instances of qmp-shell. >>>> >>>> This assists entering debug commands across sessions that may be >>>> interrupted by QEMU sessions terminating, where the qmp-shell has >>>> to be relaunched. >>>> >>>> Signed-off-by: John Snow <js...@redhat.com> >>>> --- >>>> >>>> v2: Adjusted the errors to whine about non-ENOENT errors, but still >>>> intercept all errors as non-fatal. >>>> Save history atexit() to match bash standard behavior >>>> >>>> scripts/qmp/qmp-shell | 19 +++++++++++++++++++ >>>> 1 file changed, 19 insertions(+) >>>> >>>> diff --git a/scripts/qmp/qmp-shell b/scripts/qmp/qmp-shell >>>> index 0373b24..55a8285 100755 >>>> --- a/scripts/qmp/qmp-shell >>>> +++ b/scripts/qmp/qmp-shell >>>> @@ -70,6 +70,9 @@ import json >>>> import ast >>>> import readline >>>> import sys >>>> +import os >>>> +import errno >>>> +import atexit >>>> >>>> class QMPCompleter(list): >>>> def complete(self, text, state): >>>> @@ -109,6 +112,7 @@ class QMPShell(qmp.QEMUMonitorProtocol): >>>> self._pretty = pretty >>>> self._transmode = False >>>> self._actions = list() >>>> + self._histfile = os.path.join(os.path.expanduser('~'), >>>> '.qmp_history')
I selfishly object to this filename, because I'm using it with $ socat UNIX:/work/armbru/images/test-qmp READLINE,history=$HOME/.qmp_history,prompt='QMP> ' Just kidding. But seriously, shouldn't this be named after the *application* (qmp-shell) rather than the protocol (qmp)? >>>> >>>> def __get_address(self, arg): >>>> """ >>>> @@ -137,6 +141,21 @@ class QMPShell(qmp.QEMUMonitorProtocol): >>>> # XXX: default delimiters conflict with some command names (eg. >>>> query-), >>>> # clearing everything as it doesn't seem to matter >>>> readline.set_completer_delims('') >>>> + try: >>>> + readline.read_history_file(self._histfile) >>>> + except Exception as e: >>>> + if isinstance(e, IOError) and e.errno == errno.ENOENT: >>>> + # File not found. No problem. >>>> + pass >>>> + else: >>>> + print "Failed to read history '%s'; %s" % >>>> (self._histfile, e) >>> >>> I would handle only IOError, since any other error means a bug in this code >>> or in the underlying readline library, and the best way to handle this is to >>> let it fail loudly. >>> >> >> Disagree. No reason to stop the shell from working because a QOL feature >> didn't initialize correctly. >> >> The warning will be enough to solicit reports and fixes if necessary. > > I agree, the current solution is good tradeoff. For what it's worth, bash seems to silently ignore a history file it can't read. Tested by running "HISTFILE=xxx bash", then chmod 0 xxx, da capo. > One thing missing, is a call to readline.set_history_length, without > it the history > will grow without limit, see: > https://docs.python.org/2/library/readline.html#readline.set_history_length Should this be addressed for 2.9? >>>> + atexit.register(self.__save_history) >>>> + >>>> + def __save_history(self): >>>> + try: >>>> + readline.write_history_file(self._histfile) >>>> + except Exception as e: >>>> + print "Failed to save history file '%s'; %s" % >>>> (self._histfile, e) >>>> >>>> def __parse_value(self, val): >>>> try: >>> >>> But I think this is good enough and useful as is. >>> >>> Reviewed-by: Nir Soffer <nir...@gmail.com> >>>