verbo.sokka.task — ai.verbo/sokka 0.0.1-SNAPSHOT

Protocols and constants to implement a task queue.

LeaseSupervision clj protocol

Protocol for backends (usually stores that dont support db level locks) that require special supervision of leased tasks to prevent issues caused by clock skew.

list-leased-tasks clj

(list-leased-tasks this topic cursor)

List all running / snoozed tasks

task-allowed-status-transitions clj

List of possible task statuses mapped to statuses they can transition to

task-statuses clj

List of possible statuses for a task

TaskStore clj protocol

Protocol for a task store with functions to manage the life-cycle of a task.

create-task! clj

(create-task! this task)

Create and returns a new task.

fail! clj

(fail! this task-id pid error)

Updates the status of the task to :failed. An optional error-message can be passed.

terminate! clj

(terminate! this task-id pid)

Updates the status to :terminated. This means the task has been executed successfully.

task clj

(task this task-id)

Get task by task-id. Returns nil when no task is found.

revoke-lease! clj

(revoke-lease! this task-id record-ver)

Forcefully revoke the lease held for the specified task-id. The record-ver from the last time the task was read must be supplied. This is used to implement MVCC to ensure that the task wasn't updated by another process concurrently.

reserve-task! clj

(reserve-task! this topic pid)

Attempts to reserve the next available task for execution by obtaining a lease for configured amount of time (implementation specific). Returns nil when there is no task is available for reservation.

snooze! clj

(snooze! this task-id pid snooze-time)

Temporarily pause the task for snooze-time milliseconds. Updates the status to :snoozed.

tasks clj

(tasks this task-group-id)

Get tasks for a given task-group-id. Returns nil when no tasks are found for the supplied input.

list-tasks clj

(list-tasks this
            {:keys [from to sub-topic] :as filters}
            {:keys [limit] :as cursor})

List all tasks

extend-lease! clj

(extend-lease! this task-id pid)

Attempts to extend lease of the specified task. Throws the following exceptions: :no-task-found - Task not found. :already-done - Task terminated. :wrong-owner - Attempted to extend lease of a task owned by another process. :lease-expired - Attempted to extend lease of a task whose lease already expired.