@azure/event-hubs
Version:
Azure Event Hubs SDK for JS.
40 lines • 1.91 kB
JavaScript
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
import { listAvailablePartitions } from "./loadBalancingStrategy.js";
/**
* The BalancedLoadBalancerStrategy is meant to be used when the user
* wants to reach a load balanced state with less partition 'thrashing'.
*
* Partition thrashing - where a partition changes owners - is minimized
* by only returning a single partition to claim at a time.
* This minimizes the number of times a partition should need to be stolen.
* @internal
*/
export class BalancedLoadBalancingStrategy {
_partitionOwnershipExpirationIntervalInMs;
/**
* Creates an instance of BalancedLoadBalancingStrategy.
*
* @param _partitionOwnershipExpirationIntervalInMs - The length of time a partition claim is valid.
*/
constructor(_partitionOwnershipExpirationIntervalInMs) {
this._partitionOwnershipExpirationIntervalInMs = _partitionOwnershipExpirationIntervalInMs;
}
/**
* Implements load balancing by taking into account current ownership and
* the full set of partitions in the Event Hub.
* @param ourOwnerId - The id we should assume is _our_ id when checking for ownership.
* @param claimedPartitionOwnershipMap - The current claimed ownerships for partitions.
* @param partitionIds - Partitions to assign owners to.
* @returns Partition ids to claim.
*/
getPartitionsToClaim(ourOwnerId, claimedPartitionOwnershipMap, partitionIds) {
const claimablePartitions = listAvailablePartitions(ourOwnerId, claimedPartitionOwnershipMap, partitionIds, this._partitionOwnershipExpirationIntervalInMs);
if (!claimablePartitions.length) {
return [];
}
const randomIndex = Math.floor(Math.random() * claimablePartitions.length);
return [claimablePartitions[randomIndex]];
}
}
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