alluxio.client.file.dora

Class ConsistentHashProvider

java.lang.Object

alluxio.client.file.dora.ConsistentHashProvider

@ThreadSafe
public class ConsistentHashProvider
extends Object

A consistent hashing algorithm implementation. This implementation is thread safe in lazy init and in refreshing the worker list. See inline comments for thread safety guarantees and semantics.

Constructor Summary

Constructors

Constructor and Description
ConsistentHashProvider(int maxAttempts, long workerListTtlMs) Constructor.

Method Summary

Modifier and Type	Method and Description
List<BlockWorkerInfo>	getMultiple(String key, int count) Finds multiple workers from the hash ring.
void	refresh(List<BlockWorkerInfo> workerInfos, int numVirtualNodes) Initializes or refreshes the worker list using the given list of workers and number of virtual nodes.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ConsistentHashProvider

public ConsistentHashProvider(int maxAttempts,
                              long workerListTtlMs)

Constructor.

Parameters:

maxAttempts - max attempts to rehash

workerListTtlMs - interval between retries

Method Detail

getMultiple

public List<BlockWorkerInfo> getMultiple(String key,
                                         int count)

Finds multiple workers from the hash ring.

Parameters:

key - the key to hash on

count - the expected number of workers

Returns:

a list of workers following the hash ring

refresh

public void refresh(List<BlockWorkerInfo> workerInfos,
                    int numVirtualNodes)

Initializes or refreshes the worker list using the given list of workers and number of virtual nodes.
Thread safety: If called concurrently by two or more threads, only one of the callers will actually update the state of the hash provider using the worker list provided by that thread, and all others will not change the internal state of the hash provider.

Parameters:

workerInfos - the up-to-date worker list

numVirtualNodes - the number of virtual nodes used by consistent hashing