From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51514) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cjstH-0006gR-DV for qemu-devel@nongnu.org; Fri, 03 Mar 2017 14:29:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cjstE-0001xB-7g for qemu-devel@nongnu.org; Fri, 03 Mar 2017 14:29:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50982) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cjstD-0001wX-VT for qemu-devel@nongnu.org; Fri, 03 Mar 2017 14:29:20 -0500 References: <20170303185427.32681-1-jsnow@redhat.com> From: John Snow Message-ID: <5303cac4-a8d8-bf89-b525-3b0fb1b19127@redhat.com> Date: Fri, 3 Mar 2017 14:29:19 -0500 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] qmp-shell: add persistent command history List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Nir Soffer Cc: qemu-devel@nongnu.org, armbru@redhat.com On 03/03/2017 02:26 PM, Nir Soffer wrote: > On Fri, Mar 3, 2017 at 8:54 PM, John Snow 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 >> --- >> >> 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') >> >> 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. >> + 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 >