--- a/src/core/constants.py	Sat Aug 15 22:13:27 2015 +0200
+++ b/src/core/constants.py	Sat Aug 15 22:13:27 2015 +0200
@@ -201,6 +201,7 @@
     SAVEFILE_DATABASE = APP_NAME_FILE + ".db"
     IQ_SET = '/iq[@type="set"]'
     ENV_PREFIX = 'SAT_' # Prefix used for environment variables
+    IGNORE = 'ignore'
 
 
     ## ANSI escape sequences ##

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/tools/sat_defer.py	Sat Aug 15 22:13:27 2015 +0200
@@ -0,0 +1,200 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# SàT: a XMPP client
+# Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014, 2015 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""tools related to deferred"""
+
+from sat.core.log import getLogger
+log = getLogger(__name__)
+from sat.core import exceptions
+from twisted.internet import defer
+from twisted.python import failure
+from sat.core.constants import Const as C
+from sat.memory import memory
+
+KEY_DEFERREDS = 'deferreds'
+KEY_NEXT = 'next_defer'
+
+
+class RTDeferredSessions(memory.Sessions):
+    """Real Time Deferred Sessions"""
+
+
+    def __init__(self, timeout=120):
+        """Manage list of Deferreds in real-time, allowing to get intermediate results
+
+        @param timeout (int): nb of seconds before deferreds cancellation
+        """
+        super(RTDeferredSessions, self).__init__(timeout=timeout, resettable_timeout=False)
+
+    def newSession(self, deferreds, profile):
+        """Launch a new session with a list of deferreds
+
+        @param deferreds(list[defer.Deferred]): list of deferred to call
+        @param profile: %(doc_profile)s
+        @param return (tupe[str, defer.Deferred]): tuple with session id and a deferred wich fire *WITHOUT RESULT* when all results are received
+        """
+        data = {KEY_NEXT: defer.Deferred()}
+        session_id, session_data = super(RTDeferredSessions, self).newSession(data, profile=profile)
+        if isinstance(deferreds, dict):
+            session_data[KEY_DEFERREDS] = deferreds.values()
+            iterator = deferreds.iteritems()
+        else:
+            session_data[KEY_DEFERREDS] = deferreds
+            iterator = enumerate(deferreds)
+
+        for idx, d in iterator:
+            d._RTDeferred_index = idx
+            d._RTDeferred_return = None
+            d.addCallback(self._callback, d, session_id, profile)
+            d.addErrback(self._errback, d, session_id, profile)
+        return session_id
+
+    def _purgeSession(self, session_id, reason=u"timeout", no_warning=False, got_result=False):
+        """Purge the session
+
+        @param session_id(str): id of the session to purge
+        @param reason (unicode): human readable reason why the session is purged
+        @param no_warning(bool): if True, no warning will be put in logs
+        @param got_result(bool): True if the session is purged after normal ending (i.e.: all the results have been gotten).
+            reason and no_warning are ignored if got_result is True.
+        @raise KeyError: session doesn't exists (anymore ?)
+        """
+        if not got_result:
+            try:
+                timer, session_data, profile = self._sessions[session_id]
+            except ValueError:
+                raise exceptions.InternalError(u'was expecting timer, session_data and profile; is profile set ?')
+
+            # next_defer must be called before deferreds,
+            # else its callback will be called by _gotResult
+            next_defer = session_data[KEY_NEXT]
+            if not next_defer.called:
+                next_defer.errback(failure.Failure(defer.CancelledError(reason)))
+
+            deferreds = session_data[KEY_DEFERREDS]
+            for d in deferreds:
+                d.cancel()
+
+            if not no_warning:
+                log.warning(u"RTDeferredList cancelled: {} (profile {})".format(reason, profile))
+
+        super(RTDeferredSessions, self)._purgeSession(session_id)
+
+    def _gotResult(self, session_id, profile):
+        """Method called after each callback or errback
+
+        manage the next_defer deferred
+        """
+        session_data = self.profileGet(session_id, profile)
+        defer_next = session_data[KEY_NEXT]
+        if not defer_next.called:
+            defer_next.callback(None)
+
+    def _callback(self, result, deferred, session_id, profile):
+        deferred._RTDeferred_return = (True, result)
+        self._gotResult(session_id, profile)
+
+    def _errback(self, failure, deferred, session_id, profile):
+        deferred._RTDeferred_return = (False, failure)
+        self._gotResult(session_id, profile)
+
+    def cancel(self, session_id, reason=u"timeout", no_log=False):
+        """Stop this RTDeferredList
+
+        Cancel all remaining deferred, and call self.final_defer.errback
+        @param reason (unicode): reason of the cancellation
+        @param no_log(bool): if True, don't log the cancellation
+        """
+        self._purgeSession(session_id, reason=reason, no_warning=no_log)
+
+    def getResults(self, session_id, on_success=None, on_error=None, profile=C.PROF_KEY_NONE):
+        """Get current results of a real-time deferred session
+
+        result already gotten are deleted
+        @param session_id(str): session id
+        @param on_success: can be:
+            - None: add success normaly to results
+            - callable: replace result by the return value of on_success(result) (may be deferred)
+        @param on_error: can be:
+            - None: add error normaly to results
+            - C.IGNORE: don't put errors in results
+            - callable: replace failure by the return value of on_error(failure) (may be deferred)
+        @param profile=%(doc_profile)s
+        @param result(tuple): tuple(remaining, results) where:
+            - remaining[int] is the number of remaining deferred
+                (deferreds from which we don't have result yet)
+            - results is a dict where:
+                - key is the index of the deferred if deferred is a list, or its key if it's a dict
+                - value = (success, result) where:
+                    - success is True if the deferred was successful
+                    - result is the result in case of success, else the failure
+            If remaining == 0, the session is ended
+        @raise KeyError: the session is already finished or doesn't exists at all
+        """
+        if profile == C.PROF_KEY_NONE:
+            raise exceptions.ProfileNotSetError
+        session_data = self.profileGet(session_id, profile)
+
+        @defer.inlineCallbacks
+        def next_cb(dummy):
+            # we got one or several results
+            results = {}
+            filtered_data = [] # used to keep deferreds without results
+            deferreds = session_data[KEY_DEFERREDS]
+
+            for d in deferreds:
+                if d._RTDeferred_return: # we don't use d.called as called is True before the full callbacks chain has been called
+                    # we have a result
+                    idx = d._RTDeferred_index
+                    success, result = d._RTDeferred_return
+                    if success:
+                        if on_success is not None:
+                            if callable(on_success):
+                                result = yield on_success(result)
+                            else:
+                                raise exceptions.InternalError('Unknown value of on_success: {}'.format(on_success))
+
+                    else:
+                        if on_error is not None:
+                            if on_error == C.IGNORE:
+                                continue
+                            elif callable(on_error):
+                                result = yield on_error(result)
+                            else:
+                                raise exceptions.InternalError('Unknown value of on_error: {}'.format(on_error))
+                    results[idx] = (success, result)
+                else:
+                    filtered_data.append(d)
+
+            # we change the deferred with the filtered list
+            # in other terms, we don't want anymore deferred from which we have got the result
+            session_data[KEY_DEFERREDS] = filtered_data
+
+            if filtered_data:
+                # we create a new next_defer only if we are still waiting for results
+                session_data[KEY_NEXT] = defer.Deferred()
+            else:
+                # no more data to get, the result have been gotten,
+                # we can cleanly finish the session
+                self._purgeSession(session_id, got_result=True)
+
+            defer.returnValue((len(filtered_data), results))
+
+        # we wait for a result
+        return session_data[KEY_NEXT].addCallback(next_cb)