Merge a1d7243 into 322da75

changelog/4830.feature.rst

@@ -0,0 +1,25 @@
+Added conversation sessions to trackers.
+
+A conversation session represents the dialog between the assistant and a user.
+Conversation sessions can begin in three ways: 1. the user begins the conversation
+with the assistant, 2. the user sends their first message after a configurable period
+of inactivity, or 3. a manual session start is triggered with the ``/session_start``
+intent message. The period of inactivity after which a new conversation session is
+triggered is defined in the domain using the ``session_expiration_time`` key in the
+``session_config`` section. The introduction of conversation sessions comprises the
+following changes:
+
+- Added a new event ``SessionStarted`` that marks the beginning of a new conversation
+  session.
+- Added a new default action ``ActionSessionStart``. This action takes all
+  ``SlotSet`` events from the previous session and applies it to the next session.
+- Added a new default intent ``session_start`` which triggers the start of a new
+  conversation session.
+- ``SQLTrackerStore`` and ``MongoTrackerStore`` only retrieve
+  events from the last session from the database.
+
+
+.. note::
+
+  The session behaviour is disabled for existing projects, i.e. existing domains
+  without session config section.

data/test_domains/duplicate_intents.yml

@@ -26,3 +26,7 @@ actions:
   - utter_default
   - utter_greet
   - utter_goodbye
+
+session_config:
+  session_expiration_time: 60
+  carry_over_slots_to_new_session: true

docs/api/events.rst

@@ -271,3 +271,25 @@ Log an executed action
     .. literalinclude:: ../../rasa/core/events/__init__.py
       :dedent: 4
       :pyobject: ActionExecuted.apply_to
+
+Start a new conversation session
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+:Short: Marks the beginning of a new conversation session. Resets the tracker and
+        triggers an ``ActionSessionStart`` which by default applies the existing
+        ``SlotSet`` events to the new session.
+
+:JSON:
+    .. literalinclude:: ../../tests/core/test_events.py
+      :start-after: # DOCS MARKER ActionExecuted
+      :dedent: 4
+      :end-before: # DOCS END
+:Class:
+    .. autoclass:: rasa.core.events.SessionStarted
+
+:Effect:
+    When added to a tracker, this is the code used to update the tracker:
+
+    .. literalinclude:: ../../rasa/core/events/__init__.py
+      :dedent: 4
+      :pyobject: SessionStarted.apply_to

docs/core/actions.rst

@@ -222,6 +222,16 @@ There are eight default actions:
 |                                   | if the :ref:`mapping-policy` is included in    |
 |                                   | the policy configuration.                      |
 +-----------------------------------+------------------------------------------------+
+| ``action_session_start``          | Start a new conversation session. Take all set |
+|                                   | slots, mark the beginning of a new conversation|
+|                                   | session and re-apply the existing ``SlotSet``  |
+|                                   | events. This action is triggered automatically |
+|                                   | after an inactivity period defined by the      |
+|                                   | ``session_expiration_time`` parameter in the   |
+|                                   | domain's session config. Can be triggered      |
+|                                   | manually during a conversation by entering     |
+|                                   | ``/session_start``.                            |
++-----------------------------------+------------------------------------------------+
 | ``action_default_fallback``       | Undo the last user message (as if the user did |
 |                                   | not send it and the bot did not react) and     |
 |                                   | utter a message that the bot did not           |

rasa/cli/initial_project/domain.yml

@@ -34,3 +34,7 @@ templates:
 
   utter_iamabot:
   - text: "I am a bot, powered by Rasa."
+
+session_config:
+  session_expiration_time: 60
+  carry_over_slots_to_new_session: true

rasa/cli/x.py

@@ -2,12 +2,11 @@
 import asyncio
 import importlib.util
 import logging
-import warnings
 import os
 import signal
 import traceback
 from multiprocessing import get_context
-from typing import List, Text, Optional, Tuple, Union, Iterable
+from typing import List, Text, Optional, Tuple, Iterable
 
 import aiohttp
 import ruamel.yaml as yaml
@@ -328,7 +327,7 @@ def rasa_x(args: argparse.Namespace):
 async def _pull_runtime_config_from_server(
     config_endpoint: Optional[Text],
     attempts: int = 60,
-    wait_time_between_pulls: Union[int, float] = 5,
+    wait_time_between_pulls: float = 5,
     keys: Iterable[Text] = ("endpoints", "credentials"),
 ) -> Optional[List[Text]]:
     """Pull runtime config from `config_endpoint`.

rasa/constants.py

@@ -46,3 +46,6 @@
 DEFAULT_SANIC_WORKERS = 1
 ENV_SANIC_WORKERS = "SANIC_WORKERS"
 ENV_SANIC_BACKLOG = "SANIC_BACKLOG"
+
+DEFAULT_SESSION_EXPIRATION_TIME_IN_MINUTES = 60
+DEFAULT_CARRY_OVER_SLOTS_TO_NEW_SESSION = True

rasa/core/actions/action.py

@@ -2,7 +2,7 @@
 import json
 import logging
 import typing
-from typing import List, Text, Optional, Dict, Any
+from typing import List, Text, Optional, Dict, Any, Generator
 
 import aiohttp
 
@@ -37,13 +37,16 @@
     from rasa.core.domain import Domain
     from rasa.core.nlg import NaturalLanguageGenerator
     from rasa.core.channels.channel import OutputChannel
+    from rasa.core.events import SlotSet
 
 logger = logging.getLogger(__name__)
 
 ACTION_LISTEN_NAME = "action_listen"
 
 ACTION_RESTART_NAME = "action_restart"
 
+ACTION_SESSION_START_NAME = "action_session_start"
+
 ACTION_DEFAULT_FALLBACK_NAME = "action_default_fallback"
 
 ACTION_DEACTIVATE_FORM_NAME = "action_deactivate_form"
@@ -62,6 +65,7 @@ def default_actions() -> List["Action"]:
     return [
         ActionListen(),
         ActionRestart(),
+        ActionSessionStart(),
         ActionDefaultFallback(),
         ActionDeactivateForm(),
         ActionRevertFallbackEvents(),
@@ -331,6 +335,49 @@ async def run(
         return evts + [Restarted()]
 
 
+class ActionSessionStart(Action):
+    """Applies a conversation session start.
+
+    Takes all `SlotSet` events from the previous session and applies them to the new
+    session.
+    """
+
+    def name(self) -> Text:
+        return ACTION_SESSION_START_NAME
+
+    @staticmethod
+    def _slot_set_events_from_tracker(
+        tracker: "DialogueStateTracker",
+    ) -> List["SlotSet"]:
+        """Fetch SlotSet events from tracker and carry over key, value and metadata."""
+
+        from rasa.core.events import SlotSet
+
+        return [
+            SlotSet(key=event.key, value=event.value, metadata=event.metadata)
+            for event in tracker.applied_events()
+            if isinstance(event, SlotSet)
+        ]
+
+    async def run(
+        self,
+        output_channel: "OutputChannel",
+        nlg: "NaturalLanguageGenerator",
+        tracker: "DialogueStateTracker",
+        domain: "Domain",
+    ) -> List[Event]:
+        from rasa.core.events import SessionStarted
+
+        _events = [SessionStarted()]
+
+        if domain.session_config.carry_over_slots:
+            _events.extend(self._slot_set_events_from_tracker(tracker))
+
+        _events.append(ActionExecuted(ACTION_LISTEN_NAME))
+
+        return _events
+
+
 class ActionDefaultFallback(ActionUtterTemplate):
     """Executes the fallback action and goes back to the previous state
     of the dialogue"""

rasa/core/agent.py

@@ -486,11 +486,13 @@ def noop(_):
             return await processor.handle_message(message)
 
     # noinspection PyUnusedLocal
-    def predict_next(self, sender_id: Text, **kwargs: Any) -> Optional[Dict[Text, Any]]:
+    async def predict_next(
+        self, sender_id: Text, **kwargs: Any
+    ) -> Optional[Dict[Text, Any]]:
         """Handle a single message."""
 
         processor = self.create_processor()
-        return processor.predict_next(sender_id)
+        return await processor.predict_next(sender_id)
 
     # noinspection PyUnusedLocal
     async def log_message(

rasa/core/brokers/pika.py

@@ -29,7 +29,7 @@ def initialise_pika_connection(
     password: Text,
     port: Union[Text, int] = 5672,
     connection_attempts: int = 20,
-    retry_delay_in_seconds: Union[int, float] = 5,
+    retry_delay_in_seconds: float = 5,
 ) -> "BlockingConnection":
     """Create a Pika `BlockingConnection`.
 
@@ -60,7 +60,7 @@ def _get_pika_parameters(
     password: Text,
     port: Union[Text, int] = 5672,
     connection_attempts: int = 20,
-    retry_delay_in_seconds: Union[int, float] = 5,
+    retry_delay_in_seconds: float = 5,
 ) -> "Parameters":
     """Create Pika `Parameters`.
 
@@ -135,7 +135,7 @@ def initialise_pika_channel(
     password: Text,
     port: Union[Text, int] = 5672,
     connection_attempts: int = 20,
-    retry_delay_in_seconds: Union[int, float] = 5,
+    retry_delay_in_seconds: float = 5,
 ) -> "BlockingChannel":
     """Initialise a Pika channel with a durable queue.
 

rasa/core/constants.py

@@ -27,6 +27,8 @@
 
 USER_INTENT_RESTART = "restart"
 
+USER_INTENT_SESSION_START = "session_start"
+
 USER_INTENT_BACK = "back"
 
 USER_INTENT_OUT_OF_SCOPE = "out_of_scope"

rasa/core/domain.py

@@ -5,13 +5,17 @@
 import os
 import typing
 from pathlib import Path
-from typing import Any, Dict, List, Optional, Text, Tuple, Union, Set
+from typing import Any, Dict, List, Optional, Text, Tuple, Union, Set, NamedTuple
 
 import rasa.core.constants
 import rasa.utils.common as common_utils
 import rasa.utils.io
 from rasa.cli.utils import bcolors
-from rasa.constants import DOMAIN_SCHEMA_FILE
+from rasa.constants import (
+    DOMAIN_SCHEMA_FILE,
+    DEFAULT_SESSION_EXPIRATION_TIME_IN_MINUTES,
+    DEFAULT_CARRY_OVER_SLOTS_TO_NEW_SESSION,
+)
 from rasa.core import utils
 from rasa.core.actions import action  # pytype: disable=pyi-error
 from rasa.core.actions.action import Action  # pytype: disable=pyi-error
@@ -32,6 +36,10 @@
 PREV_PREFIX = "prev_"
 ACTIVE_FORM_PREFIX = "active_form_"
 
+CARRY_OVER_SLOTS_KEY = "carry_over_slots_to_new_session"
+SESSION_EXPIRATION_TIME_KEY = "session_expiration_time"
+SESSION_CONFIG_KEY = "session_config"
+
 if typing.TYPE_CHECKING:
     from rasa.core.trackers import DialogueStateTracker
 
@@ -47,6 +55,19 @@ def __str__(self):
         return bcolors.FAIL + self.message + bcolors.ENDC
 
 
+class SessionConfig(NamedTuple):
+    session_expiration_time: float  # in minutes
+    carry_over_slots: bool
+
+    @staticmethod
+    def default() -> "SessionConfig":
+        # TODO: 2.0, reconsider how to apply sessions to old projects
+        return SessionConfig(0, DEFAULT_CARRY_OVER_SLOTS_TO_NEW_SESSION)
+
+    def are_sessions_enabled(self) -> bool:
+        return self.session_expiration_time > 0
+
+
 class Domain:
     """The domain specifies the universe in which the bot's policy acts.
 
@@ -109,6 +130,7 @@ def from_dict(cls, data: Dict) -> "Domain":
         utter_templates = cls.collect_templates(data.get("templates", {}))
         slots = cls.collect_slots(data.get("slots", {}))
         additional_arguments = data.get("config", {})
+        session_config = cls._get_session_config(data.get(SESSION_CONFIG_KEY, {}))
         intents = data.get("intents", {})
 
         return cls(
@@ -118,9 +140,31 @@ def from_dict(cls, data: Dict) -> "Domain":
             utter_templates,
             data.get("actions", []),
             data.get("forms", []),
+            session_config=session_config,
             **additional_arguments,
         )
 
+    @staticmethod
+    def _get_session_config(session_config: Dict) -> SessionConfig:
+        session_expiration_time = session_config.get(SESSION_EXPIRATION_TIME_KEY)
+
+        # TODO: 2.0 reconsider how to apply sessions to old projects and legacy trackers
+        if session_expiration_time is None:
+            warnings.warn(
+                "No tracker session configuration was found in the loaded domain. "
+                "Domains without a session config will automatically receive a "
+                "session expiration time of 60 minutes in Rasa version 2.0 if not "
+                "configured otherwise.",
+                FutureWarning,
+            )
+            session_expiration_time = 0
+
+        carry_over_slots = session_config.get(
+            CARRY_OVER_SLOTS_KEY, DEFAULT_CARRY_OVER_SLOTS_TO_NEW_SESSION
+        )
+
+        return SessionConfig(session_expiration_time, carry_over_slots)
+
     @classmethod
     def from_directory(cls, path: Text) -> "Domain":
         """Loads and merges multiple domain files recursively from a directory tree."""
@@ -278,13 +322,15 @@ def __init__(
         action_names: List[Text],
         form_names: List[Text],
         store_entities_as_slots: bool = True,
+        session_config: SessionConfig = SessionConfig.default(),
     ) -> None:
 
         self.intent_properties = self.collect_intent_properties(intents)
         self.entities = entities
         self.form_names = form_names
         self.slots = slots
         self.templates = templates
+        self.session_config = session_config
 
         # only includes custom actions and utterance actions
         self.user_actions = action_names
@@ -651,10 +697,13 @@ def _slot_definitions(self) -> Dict[Any, Dict[str, Any]]:
         return {slot.name: slot.persistence_info() for slot in self.slots}
 
     def as_dict(self) -> Dict[Text, Any]:
-        additional_config = {"store_entities_as_slots": self.store_entities_as_slots}
 
         return {
-            "config": additional_config,
+            "config": {"store_entities_as_slots": self.store_entities_as_slots},
+            SESSION_CONFIG_KEY: {
+                SESSION_EXPIRATION_TIME_KEY: self.session_config.session_expiration_time,
+                CARRY_OVER_SLOTS_KEY: self.session_config.carry_over_slots,
+            },
             "intents": [{k: v} for k, v in self.intent_properties.items()],
             "entities": self.entities,
             "slots": self._slot_definitions(),