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Dispatcher

zenml.dispatcher

Process-wide event dispatch contracts.

Attributes

__all__ = ['Event', 'EventDispatcher', 'EventHandler', 'PipelineRunStatusUpdate'] module-attribute

Classes

Event

Bases: BaseModel

Base class for immutable dispatcher event envelopes.

EventDispatcher()

Process-wide broadcaster of event envelopes.

Initialize the dispatcher with an empty handler list.

Source code in src/zenml/dispatcher/dispatcher.py 
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def __init__(self) -> None:
    """Initialize the dispatcher with an empty handler list."""
    self._event_handlers: List[EventHandler] = []
    self._handlers_lock = threading.Lock()
Methods:
dispatch_event(event: Event) -> None

Dispatch an event to all registered handlers.

Parameters:

Name Type Description Default
event Event

The event envelope to dispatch.

 required
Source code in src/zenml/dispatcher/dispatcher.py 
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def dispatch_event(self, event: Event) -> None:
    """Dispatch an event to all registered handlers.

    Args:
        event: The event envelope to dispatch.
    """
    with self._handlers_lock:
        handlers = list(self._event_handlers)

    for event_handler in handlers:
        try:
            logger.debug(
                "Event handler %s received %s",
                event_handler.__class__.__name__,
                event.__class__.__name__,
            )
            event_handler.handle_event(event)
        except Exception as exc:
            logger.exception(
                "%s failed to handle %s",
                event_handler.__class__.__name__,
                event.__class__.__name__,
                exc_info=exc,
            )
has_handlers() -> bool

Return True if any handlers are registered.

Returns:

Type Description
bool

Whether the dispatcher would fan out to at least one handler.
Source code in src/zenml/dispatcher/dispatcher.py 
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def has_handlers(self) -> bool:
    """Return True if any handlers are registered.

    Returns:
        Whether the dispatcher would fan out to at least one handler.
    """
    with self._handlers_lock:
        return bool(self._event_handlers)
register_event_handler(event_handler: EventHandler) -> None

Register an event handler.

Parameters:

Name Type Description Default
event_handler EventHandler

An event handler to register.

 required
Source code in src/zenml/dispatcher/dispatcher.py 
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def register_event_handler(self, event_handler: EventHandler) -> None:
    """Register an event handler.

    Args:
        event_handler: An event handler to register.
    """
    with self._handlers_lock:
        self._event_handlers.append(event_handler)
unregister_event_handler(event_handler: EventHandler) -> None

Unregister a previously-registered event handler.

No-op if the handler isn't registered.

Parameters:

Name Type Description Default
event_handler EventHandler

The event handler instance to remove.

 required
Source code in src/zenml/dispatcher/dispatcher.py 
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def unregister_event_handler(self, event_handler: EventHandler) -> None:
    """Unregister a previously-registered event handler.

    No-op if the handler isn't registered.

    Args:
        event_handler: The event handler instance to remove.
    """
    with self._handlers_lock:
        try:
            self._event_handlers.remove(event_handler)
        except ValueError:
            pass

EventHandler

Bases: ABC

Abstract base for handlers registered with EventDispatcher.

Methods:
create() -> EventHandler async classmethod

Factory used by the source loader.

Needs to be implemented if a handler is specified via server_config.event_handler_sources.

Raises:

Type Description
NotImplementedError

Always.

Returns:

Type Description
EventHandler

Handler instance.
Source code in src/zenml/dispatcher/handler.py 
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@classmethod
async def create(cls) -> "EventHandler":
    """Factory used by the source loader.

    Needs to be implemented if a handler is specified via
    `server_config.event_handler_sources`.

    Raises:
        NotImplementedError: Always.

    Returns:
        Handler instance.
    """
    raise NotImplementedError(
        f"{cls.__name__}.create() is not implemented."
    )
handle_event(event: Event) -> None abstractmethod

Handle or ignore one dispatched event.

Parameters:

Name Type Description Default
event Event

The event envelope.

 required
Source code in src/zenml/dispatcher/handler.py 
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@abstractmethod
def handle_event(self, event: Event) -> None:
    """Handle or ignore one dispatched event.

    Args:
        event: The event envelope.
    """

PipelineRunStatusUpdate

Bases: Event

A pipeline run status transition.

Modules

dispatcher

Process-wide event dispatcher.

Classes
EventDispatcher()

Process-wide broadcaster of event envelopes.

Initialize the dispatcher with an empty handler list.

Source code in src/zenml/dispatcher/dispatcher.py 
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def __init__(self) -> None:
    """Initialize the dispatcher with an empty handler list."""
    self._event_handlers: List[EventHandler] = []
    self._handlers_lock = threading.Lock()
Methods:
dispatch_event(event: Event) -> None

Dispatch an event to all registered handlers.

Parameters:

Name Type Description Default
event Event

The event envelope to dispatch.

 required
Source code in src/zenml/dispatcher/dispatcher.py 
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def dispatch_event(self, event: Event) -> None:
    """Dispatch an event to all registered handlers.

    Args:
        event: The event envelope to dispatch.
    """
    with self._handlers_lock:
        handlers = list(self._event_handlers)

    for event_handler in handlers:
        try:
            logger.debug(
                "Event handler %s received %s",
                event_handler.__class__.__name__,
                event.__class__.__name__,
            )
            event_handler.handle_event(event)
        except Exception as exc:
            logger.exception(
                "%s failed to handle %s",
                event_handler.__class__.__name__,
                event.__class__.__name__,
                exc_info=exc,
            )
has_handlers() -> bool

Return True if any handlers are registered.

Returns:

Type Description
bool

Whether the dispatcher would fan out to at least one handler.
Source code in src/zenml/dispatcher/dispatcher.py 
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def has_handlers(self) -> bool:
    """Return True if any handlers are registered.

    Returns:
        Whether the dispatcher would fan out to at least one handler.
    """
    with self._handlers_lock:
        return bool(self._event_handlers)
register_event_handler(event_handler: EventHandler) -> None

Register an event handler.

Parameters:

Name Type Description Default
event_handler EventHandler

An event handler to register.

 required
Source code in src/zenml/dispatcher/dispatcher.py 
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def register_event_handler(self, event_handler: EventHandler) -> None:
    """Register an event handler.

    Args:
        event_handler: An event handler to register.
    """
    with self._handlers_lock:
        self._event_handlers.append(event_handler)
unregister_event_handler(event_handler: EventHandler) -> None

Unregister a previously-registered event handler.

No-op if the handler isn't registered.

Parameters:

Name Type Description Default
event_handler EventHandler

The event handler instance to remove.

 required
Source code in src/zenml/dispatcher/dispatcher.py 
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def unregister_event_handler(self, event_handler: EventHandler) -> None:
    """Unregister a previously-registered event handler.

    No-op if the handler isn't registered.

    Args:
        event_handler: The event handler instance to remove.
    """
    with self._handlers_lock:
        try:
            self._event_handlers.remove(event_handler)
        except ValueError:
            pass
Functions:

events

Event envelopes dispatched to process-wide event handlers.

Classes
Event

Bases: BaseModel

Base class for immutable dispatcher event envelopes.

PipelineRunStatusUpdate

Bases: Event

A pipeline run status transition.

handler

Base class for event handlers registered with the dispatcher.

Classes
EventHandler

Bases: ABC

Abstract base for handlers registered with EventDispatcher.

Methods:
create() -> EventHandler async classmethod

Factory used by the source loader.

Needs to be implemented if a handler is specified via server_config.event_handler_sources.

Raises:

Type Description
NotImplementedError

Always.

Returns:

Type Description
EventHandler

Handler instance.
Source code in src/zenml/dispatcher/handler.py 
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@classmethod
async def create(cls) -> "EventHandler":
    """Factory used by the source loader.

    Needs to be implemented if a handler is specified via
    `server_config.event_handler_sources`.

    Raises:
        NotImplementedError: Always.

    Returns:
        Handler instance.
    """
    raise NotImplementedError(
        f"{cls.__name__}.create() is not implemented."
    )
handle_event(event: Event) -> None abstractmethod

Handle or ignore one dispatched event.

Parameters:

Name Type Description Default
event Event

The event envelope.

 required
Source code in src/zenml/dispatcher/handler.py 
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@abstractmethod
def handle_event(self, event: Event) -> None:
    """Handle or ignore one dispatched event.

    Args:
        event: The event envelope.
    """