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Documentation Index

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prefect.server.utilities.messaging.memory

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Functions

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log_metrics_periodically 

log_metrics_periodically(interval: float = 2.0) -> None

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update_metric 

update_metric(topic: str, key: str, amount: int = 1) -> None

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break_topic 

break_topic()

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ephemeral_subscription 

ephemeral_subscription(topic: str) -> AsyncGenerator[Mapping[str, Any], None]

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Classes

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MemoryMessage

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Subscription

A subscription to a topic. Messages are delivered to the subscription’s queue and retried up to a maximum number of times. If a message cannot be delivered after the maximum number of retries it is moved to the dead letter queue. The dead letter queue is a directory of JSON files containing the serialized message. Messages remain in the dead letter queue until they are removed manually. Attributes:
  • topic: The topic that the subscription receives messages from.
  • max_retries: The maximum number of times a message will be retried for this subscription.
  • dead_letter_queue_path: The path to the dead letter queue folder.
Methods:

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deliver 

deliver(self, message: MemoryMessage) -> None
Deliver a message to the subscription’s queue. Args:
  • message: The message to deliver.

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get 

get(self) -> MemoryMessage
Get a message from the subscription’s queue.

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retry 

retry(self, message: MemoryMessage) -> None
Place a message back on the retry queue. If the message has retried more than the maximum number of times it is moved to the dead letter queue. Args:
  • message: The message to retry.

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send_to_dead_letter_queue 

send_to_dead_letter_queue(self, message: MemoryMessage) -> None
Send a message to the dead letter queue. The dead letter queue is a directory of JSON files containing the serialized messages. Args:
  • message: The message to send to the dead letter queue.

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Topic

Methods:

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by_name 

by_name(cls, name: str) -> 'Topic'

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clear 

clear(self) -> None

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clear_all 

clear_all(cls) -> None

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publish 

publish(self, message: MemoryMessage) -> None

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subscribe 

subscribe(self, **subscription_kwargs: Any) -> Subscription

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unsubscribe 

unsubscribe(self, subscription: Subscription) -> None

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Cache

Methods:

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clear_recently_seen_messages 

clear_recently_seen_messages(self) -> None

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forget_duplicates 

forget_duplicates(self, attribute: str, messages: Iterable[M]) -> None

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without_duplicates 

without_duplicates(self, attribute: str, messages: Iterable[M]) -> list[M]

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Publisher

Methods:

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publish_data 

publish_data(self, data: bytes, attributes: Mapping[str, str]) -> None

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Consumer

Methods:

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cleanup 

cleanup(self) -> None
Cleanup resources by unsubscribing from the topic. This should be called when the consumer is no longer needed to prevent memory leaks from orphaned subscriptions.

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run 

run(self, handler: MessageHandler) -> None