org.springframework.data.redis.cache.BatchStrategies Maven / Gradle / Ivy
/*
* Copyright 2021-2022 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.redis.cache;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Optional;
import org.springframework.data.redis.connection.RedisConnection;
import org.springframework.data.redis.core.Cursor;
import org.springframework.data.redis.core.ScanOptions;
import org.springframework.util.Assert;
/**
* A collection of predefined {@link BatchStrategy} implementations using {@code KEYS} or {@code SCAN} command.
*
* @author Mark Paluch
* @author Christoph Strobl
* @since 2.6
*/
public abstract class BatchStrategies {
private BatchStrategies() {
// can't touch this - oh-oh oh oh oh-oh-oh
}
/**
* A {@link BatchStrategy} using a single {@code KEYS} and {@code DEL} command to remove all matching keys.
* {@code KEYS} scans the entire keyspace of the Redis database and can block the Redis worker thread for a long time
* on large keyspaces.
*
* {@code KEYS} is supported for standalone and clustered (sharded) Redis operation modes.
*
* @return batching strategy using {@code KEYS}.
*/
public static BatchStrategy keys() {
return Keys.INSTANCE;
}
/**
* A {@link BatchStrategy} using a {@code SCAN} cursors and potentially multiple {@code DEL} commands to remove all
* matching keys. This strategy allows a configurable batch size to optimize for scan batching.
*
* Note that using the {@code SCAN} strategy might be not supported on all drivers and Redis operation modes.
*
* @return batching strategy using {@code SCAN}.
*/
public static BatchStrategy scan(int batchSize) {
Assert.isTrue(batchSize > 0, "Batch size must be greater than zero!");
return new Scan(batchSize);
}
/**
* {@link BatchStrategy} using {@code KEYS}.
*/
static class Keys implements BatchStrategy {
static Keys INSTANCE = new Keys();
@Override
public long cleanCache(RedisConnection connection, String name, byte[] pattern) {
byte[][] keys = Optional.ofNullable(connection.keys(pattern)).orElse(Collections.emptySet())
.toArray(new byte[0][]);
if (keys.length > 0) {
connection.del(keys);
}
return keys.length;
}
}
/**
* {@link BatchStrategy} using {@code SCAN}.
*/
static class Scan implements BatchStrategy {
private final int batchSize;
Scan(int batchSize) {
this.batchSize = batchSize;
}
@Override
public long cleanCache(RedisConnection connection, String name, byte[] pattern) {
Cursor cursor = connection.scan(ScanOptions.scanOptions().count(batchSize).match(pattern).build());
long count = 0;
PartitionIterator partitions = new PartitionIterator<>(cursor, batchSize);
while (partitions.hasNext()) {
List keys = partitions.next();
count += keys.size();
if (keys.size() > 0) {
connection.del(keys.toArray(new byte[0][]));
}
}
return count;
}
}
/**
* Utility to split and buffer outcome from a {@link Iterator} into {@link List lists} of {@code T} with a maximum
* chunks {@code size}.
*
* @param
*/
static class PartitionIterator implements Iterator> {
private final Iterator iterator;
private final int size;
PartitionIterator(Iterator iterator, int size) {
this.iterator = iterator;
this.size = size;
}
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public List next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
List list = new ArrayList<>(size);
while (list.size() < size && iterator.hasNext()) {
list.add(iterator.next());
}
return list;
}
}
}