From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50546) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cjsqQ-0005Ce-7H for qemu-devel@nongnu.org; Fri, 03 Mar 2017 14:26:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cjsqP-0000xD-D2 for qemu-devel@nongnu.org; Fri, 03 Mar 2017 14:26:26 -0500 Received: from mail-ot0-x244.google.com ([2607:f8b0:4003:c0f::244]:33302) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cjsqP-0000wz-86 for qemu-devel@nongnu.org; Fri, 03 Mar 2017 14:26:25 -0500 Received: by mail-ot0-x244.google.com with SMTP id 19so1393532oti.0 for ; Fri, 03 Mar 2017 11:26:23 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20170303185427.32681-1-jsnow@redhat.com> References: <20170303185427.32681-1-jsnow@redhat.com> From: Nir Soffer Date: Fri, 3 Mar 2017 21:26:22 +0200 Message-ID: Content-Type: text/plain; charset=UTF-8 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: John Snow Cc: qemu-devel@nongnu.org, armbru@redhat.com 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. > + 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