irc: configure anti-looping system

Co-authored-by: dgw <dgw@technobabbl.es>

docs/source/configuration.rst

@@ -333,8 +333,8 @@ policy.
 
 .. versionadded:: 7.0
 
-    Additional configuration options: ``flood_burst_lines``, ``flood_empty_wait``,
-    and ``flood_refill_rate``.
+    Additional configuration options: ``flood_burst_lines``,
+    ``flood_empty_wait``, and ``flood_refill_rate``.
 
 .. versionadded:: 7.1
 
@@ -350,6 +350,79 @@ policy.
 
         *"It's some arcane magic from AT LEAST a decade ago."*
 
+Loop prevention
+---------------
+
+In order to prevent the bot from entering a loop (for example when there is
+another bot in the same channel, or if a user spams a command), it'll try to
+see if the next message to send is repeating too often in the last ten messages
+in the last few minutes. If that happens, the bot will send ``...`` a few times
+before remaining silent::
+
+    <bot> I repeat myself!
+    <bot> I repeat myself!
+    <bot> I repeat myself!
+    <bot> I repeat myself!
+    <bot> I repeat myself!
+    # wanted to say: "I repeat myself"
+    <bot> ...
+    # wanted to say: "I repeat myself"
+    <bot> ...
+    # wanted to say: "I repeat myself"
+    <bot> ...
+    # silence, wanted to say: "..." instead of "I repeat myself"
+
+This doesn't affect non-repeating messages, and if enough time has passed
+between now and the last message sent, the loop prevention won't be triggered.
+
+This behavior can be configured with:
+
+* :attr:`~CoreSection.antiloop_threshold`: the number of repeating messages
+  before triggering the loop prevention.
+* :attr:`~CoreSection.antiloop_silent_after`: how many times the bot will send
+  the repeat text until it remains silent.
+* :attr:`~CoreSection.antiloop_window`: how much time (in seconds) since the
+  last message must pass before ignoring the loop prevention.
+* :attr:`~CoreSection.antiloop_repeat_text`: the text used to replace repeating
+  messages (default to ``...``).
+
+For example this configuration::
+
+    [core]
+    antiloop_threshold = 2
+    antiloop_silent_after = 1
+    antiloop_window = 60
+    antiloop_repeat_text = Ditto.
+
+will activate the loop prevention feature if there is at least one message in
+the last 60s, from the last 10 messages, 2 are already the same. In that case
+the bot will send ``...``, but only *once*. After that, the bot will remain
+silent. This doesn't affect other messages, i.e. messages that don't repeat::
+
+    <bot> I repeat myself!
+    <bot> No I don't!
+    <bot> I can talk.
+    <bot> I repeat myself!
+    <bot> No I don't!
+    # wanted to say: "I repeat myself"
+    <bot> Ditto.
+    # silence, wanted to say: "Ditto." instead of "No I don't!"
+    <bot> This message is unique.
+
+You can **deactivate** the loop prevention by setting
+:attr:`~CoreSection.antiloop_threshold` to 0.
+
+.. versionadded:: 8.0
+
+    The loop prevention feature wasn't configurable before Sopel 8.0. The
+    new configuration options are: ``antiloop_threshold``,
+    ``antiloop_silent_after``, and ``antiloop_window``.
+
+.. note::
+
+    Since Sopel remembers only the last ten messages, it will use the minimum
+    value between ``antiloop_threshold`` and ten.
+
 Perform commands on connect
 ---------------------------
 

sopel/config/core_section.py

@@ -133,6 +133,92 @@ class CoreSection(StaticSection):
     :func:`~sopel.plugin.nickname_command`.
     """
 
+    antiloop_repeat_text = ValidatedAttribute(
+        'antiloop_repeat_text', default='...')
+    """The replacement text when detecting a repeating message.
+
+    :default: ``...``
+
+    This is equivalent to the default value:
+
+    .. code-block:: ini
+
+        antiloop_repeat_text = ...
+
+    .. seealso::
+
+        The :ref:`Loop Prevention` chapter to learn what each antiloop-related
+        setting does.
+
+    .. versionadded:: 8.0
+    """
+
+    antiloop_silent_after = ValidatedAttribute(
+        'antiloop_silent_after', int, default=3)
+    """How many times the anti-looping message will be sent before stopping.
+
+    :default: ``3``
+
+    This is equivalent to the default value:
+
+    .. code-block:: ini
+
+        antiloop_silent_after = 3
+
+    .. seealso::
+
+        The :ref:`Loop Prevention` chapter to learn what each antiloop-related
+        setting does.
+
+    .. versionadded:: 8.0
+    """
+
+    antiloop_threshold = ValidatedAttribute(
+        'antiloop_threshold', int, default=5)
+    """How many times a message can be repeated without anti-looping action.
+
+    :default: ``5``
+
+    This is equivalent to the default value:
+
+    .. code-block:: ini
+
+        antiloop_threshold = 5
+
+    You can deactivate the anti-looping feature (not recommended) by setting
+    this to ``0``:
+
+    .. code-block:: ini
+
+        antiloop_threshold = 0
+
+    .. seealso::
+
+        The :ref:`Loop Prevention` chapter to learn what each antiloop-related
+        setting does.
+
+    .. versionadded:: 8.0
+    """
+
+    antiloop_window = ValidatedAttribute('antiloop_window', int, default=120)
+    """The time window (in seconds) used to activate anti-looping.
+
+    :default: ``120``
+
+    This is equivalent to the default value:
+
+    .. code-block:: ini
+
+        antiloop_window = 120
+
+    .. seealso::
+
+        The :ref:`Loop Prevention` chapter to learn what each antiloop-related
+        setting does.
+
+    .. versionadded:: 8.0
+    """
+
     auth_method = ChoiceAttribute('auth_method', choices=[
         'nickserv', 'authserv', 'Q', 'sasl', 'server', 'userserv'])
     """Simple method to authenticate with the server.

sopel/irc/__init__.py

@@ -790,6 +790,11 @@ def say(
         flood_text_length = self.settings.core.flood_text_length
         flood_penalty_ratio = self.settings.core.flood_penalty_ratio
 
+        antiloop_threshold = min(10, self.settings.core.antiloop_threshold)
+        antiloop_window = self.settings.core.antiloop_window
+        antiloop_repeat_text = self.settings.core.antiloop_repeat_text
+        antiloop_silent_after = self.settings.core.antiloop_silent_after
+
         with self.sending:
             recipient_id = self.make_identifier(recipient)
             recipient_stack = self.stack.setdefault(recipient_id, {
@@ -840,18 +845,22 @@ def say(
                     time.sleep(sleep_time)
 
             # Loop detection
-            messages = [m[1] for m in recipient_stack['messages'][-8:]]
+            if antiloop_threshold > 0 and elapsed < antiloop_window:
+                messages = [m[1] for m in recipient_stack['messages'][-10:]]
 
-            # If what we're about to send repeated at least 5 times in the last
-            # two minutes, replace it with '...'
-            if messages.count(text) >= 5 and elapsed < 120:
-                text = '...'
-                if messages.count('...') >= 3:
-                    # If we've already said '...' 3 times, discard message
-                    return
+                # If what we're about to send repeated at least N times
+                # in the anti-looping window, replace it
+                if messages.count(text) >= antiloop_threshold:
+                    text = antiloop_repeat_text
+                    if messages.count(text) >= antiloop_silent_after:
+                        # If we've already said that N times, discard message
+                        return
 
             self.backend.send_privmsg(recipient, text)
-            recipient_stack['flood_left'] = max(0, recipient_stack['flood_left'] - 1)
+
+            # update recipient meta-data
+            flood_left = recipient_stack['flood_left'] - 1
+            recipient_stack['flood_left'] = max(0, flood_left)
             recipient_stack['messages'].append((time.time(), safe(text)))
             recipient_stack['messages'] = recipient_stack['messages'][-10:]
 

test/test_irc.py

@@ -353,7 +353,7 @@ def test_say_long_truncation_trailing(bot):
     )
 
 
-def test_say_no_repeat_protection(bot):
+def test_say_antiloop(bot):
     # five is fine
     bot.say('hello', '#sopel')
     bot.say('hello', '#sopel')
@@ -407,8 +407,73 @@ def test_say_no_repeat_protection(bot):
         'PRIVMSG #sopel :hello',
         'PRIVMSG #sopel :hello',
         'PRIVMSG #sopel :hello',
-        #  three time, then stop
+        #  three times, then stop
         'PRIVMSG #sopel :...',
         'PRIVMSG #sopel :...',
         'PRIVMSG #sopel :...',
     )
+
+
+def test_say_antiloop_configuration(bot):
+    bot.settings.core.antiloop_threshold = 3
+    bot.settings.core.antiloop_silent_after = 2
+    bot.settings.core.antiloop_repeat_text = '???'
+
+    # three is fine now
+    bot.say('hello', '#sopel')
+    bot.say('hello', '#sopel')
+    bot.say('hello', '#sopel')
+
+    assert bot.backend.message_sent == rawlist(
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+    )
+
+    # fourth: replaced by '???'
+    bot.say('hello', '#sopel')
+
+    assert bot.backend.message_sent == rawlist(
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+        # the extra hello is replaced by '???'
+        'PRIVMSG #sopel :???',
+    )
+
+    # this one will add one more '???'
+    bot.say('hello', '#sopel')
+
+    assert bot.backend.message_sent == rawlist(
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :???',
+        # the new one is also replaced by '???'
+        'PRIVMSG #sopel :???',
+    )
+
+    # but at some point it just stops talking
+    bot.say('hello', '#sopel')
+
+    assert bot.backend.message_sent == rawlist(
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+        'PRIVMSG #sopel :hello',
+        #  two times, then stop
+        'PRIVMSG #sopel :???',
+        'PRIVMSG #sopel :???',
+    )
+
+
+def test_say_antiloop_deactivated(bot):
+    bot.settings.core.antiloop_threshold = 0
+
+    # no more loop prevention
+    for _ in range(10):
+        bot.say('hello', '#sopel')
+
+    expected = ['PRIVMSG #sopel :hello'] * 10
+    assert bot.backend.message_sent == rawlist(*expected), (
+        'When antiloop is deactivated, messages must not be replaced.'
+    )