EventDispatcher

Dispatches event messages.

Attributes

Attribute	Type	Description
DISABLED_TRANSPORTS	set = {'sql'}	A set of transport driver types for which event dispatching is automatically disabled.
app	[Celery](../../app/base/celery.md?sid=celery_app_base_celery) = None	The Celery application instance associated with this dispatcher.
on_enabled	set = None	set of callbacks to be called when :meth:enabled.
on_disabled	set = None	set of callbacks to be called when :meth:disabled.
publisher	kombu.Producer	Alias for the internal producer instance used to publish messages to the broker.

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Constructor

Signature

def EventDispatcher(
    connection: kombu.Connection = None,
    hostname: str = None,
    enabled: bool = True,
    channel: kombu.Channel = None,
    buffer_while_offline: bool = True,
    app: [Celery](../../app/base/celery.md?sid=celery_app_base_celery) = None,
    serializer: str = None,
    groups: Sequence[str] = None,
    delivery_mode: int = 1,
    buffer_group: frozenset = None,
    buffer_limit: int = 24,
    on_send_buffered: Callable = None
)

Parameters

Name	Type	Description
connection	kombu.Connection = None	Connection to the broker.
hostname	str = None	Hostname to identify the dispatcher.
enabled	bool = True	Whether to actually publish events.
channel	kombu.Channel = None	Specific channel to use for sending events.
buffer_while_offline	bool = True	If true, events are buffered while the connection is down.
app	[Celery](../../app/base/celery.md?sid=celery_app_base_celery) = None	The Celery app instance.
serializer	str = None	The serialization method to use.
groups	Sequence[str] = None	List of event groups to send.
delivery_mode	int = 1	Transient (1) or Persistent (2) delivery.
buffer_group	frozenset = None	Groups that should be buffered.
buffer_limit	int = 24	Maximum number of events in a group buffer before flushing.
on_send_buffered	Callable = None	Callback for when an event is buffered.

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Methods

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enable()

@classmethod
def enable()

Initializes the message producer and triggers all registered on_enabled callbacks.

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disable()

@classmethod
def disable()

Deactivates the dispatcher, closes the producer, and triggers all registered on_disabled callbacks.

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publish()

@classmethod
def publish(
    type: str,
    fields: dict,
    producer: kombu.Producer,
    blind: bool,
    Event: Callable
) - > Any

Publish event using custom :class:~kombu.Producer.

Parameters

Name	Type	Description
type	str	Event type name, with group separated by dash (-).
fields	dict	Dictionary of event fields, must be json serializable.
producer	kombu.Producer	Producer instance to use: only the publish method will be called.
blind	bool	Don't set logical clock value (also don't forward the internal logical clock).
Event	Callable	Event type used to create event. Defaults to :func:Event.

Returns

Type	Description
Any	The result of the internal _publish call.

---

send()

@classmethod
def send(
    type: str,
    blind: bool,
    utcoffset: Callable,
    retry: bool,
    retry_policy: dict,
    Event: Callable,
    **fields: Any
) - > Any

Send event.

Parameters

Name	Type	Description
type	str	Event type name, with group separated by dash (-).
blind	bool	Don't set logical clock value (also don't forward the internal logical clock).
utcoffset	Callable	Function returning the current utc offset in hours.
retry	bool	Retry in the event of connection failure.
retry_policy	dict	Map of custom retry policy options.
Event	Callable	Event type used to create event, defaults to :func:Event.
**fields	Any	Event fields -- must be json serializable.

Returns

Type	Description
Any	Returns the result of the publication or None if the event is buffered or ignored.

---

flush()

@classmethod
def flush(
    errors: bool,
    groups: bool
)

Flush the outbound buffer.

Parameters

Name	Type	Description
errors	bool	If true, attempts to send events that were buffered due to previous connection errors.
groups	bool	If true, flushes events that were intentionally buffered by group.

---

extend_buffer()

@classmethod
def extend_buffer(
    other: [EventDispatcher](eventdispatcher.md?sid=celery_events_dispatcher_eventdispatcher)
)

Copy the outbound buffer of another instance.

Parameters

Name	Type	Description
other	[EventDispatcher](eventdispatcher.md?sid=celery_events_dispatcher_eventdispatcher)	The other dispatcher instance from which to copy buffered events.

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close()

@classmethod
def close()

Close the event dispatcher.

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