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1. When SlotPool starts, BlockedTaskManagerChecker will be passed in to check whether a task manager is blocked.
2. When receiving slot offers from blocked task managers (including task managers on blocked nodes), all offers should be rejected.
3. When a task manager is newly blocked, BlocklistContext will perform the following on SlotPool:
   1. If the action is MARK_BLOCKED, release all free(no task assigned) slots on the blocked task manager(it needs to introduce a new method: SlotPoolService#releaseFreeSlotsOnTaskManager).
   2. If the action is MARK_BLOCKED_AND_EVACUATE_TASKS, release all slots on the blocked task manager(it needs to introduce a new method: SlotPoolService#releaseSlotsOnTaskManager). Note that we should not unregister the TM directly, because in the case of batch jobs, there may be unconsumed result partitions on it.

4. When a slot state changes from reserved(task assigned) to free(no task assigned), it will check whether the corresponding task manager is blocked. If yes, release the slot.

We will introduce a new slot pool implementation: BlocklistSlotPool, which extends the DefaultDeclarativeSlotPool and overrides some methods to implement the blocklist-related functions described above, and the blocklist information will be passed in the constructor. This new implementation will be only used when the blocklist is enabled.

public interface SlotPoolService {

   /**
     * Releases all slots belonging to the owning TaskExecutor if it has been registered.
     *
     * @param taskManagerId identifying the TaskExecutor
     * @param cause cause for failing the slots
     */
    void releaseSlotsOnTaskManager(ResourceID taskManagerId, Exception cause);

    /**
     * Releases all free slots belonging to the owning TaskExecutor if it has been registered.
     *
     * @param taskManagerId identifying the TaskExecutor
     * @param cause cause for failing the slots
     */
    void releaseFreeSlotsOnTaskManager(ResourceID taskManagerId, Exception cause);

    //...
}

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public class BlocklistSlotPool extends DefaultDeclarativeSlotPool {
    // ...
}

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