spring-data-redis ClusterSlotHashUtil 源码

spring-data-redis ClusterSlotHashUtil 代码

文件路径：/src/main/java/org/springframework/data/redis/connection/ClusterSlotHashUtil.java

/*
 * Copyright 2015-2022 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.connection;

import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Collection;

import org.springframework.data.redis.util.ByteUtils;
import org.springframework.util.Assert;

/**
 * @author Christoph Strobl
 * @since 1.7
 */
public final class ClusterSlotHashUtil {

	private static final int SLOT_COUNT = 16384;

	private static final byte SUBKEY_START = '{';
	private static final byte SUBKEY_END = '}';

	private static final int[] LOOKUP_TABLE = { 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7, 0x8108,
			0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF, 0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7,
			0x62D6, 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE, 0x2462, 0x3443, 0x0420, 0x1401, 0x64E6,
			0x74C7, 0x44A4, 0x5485, 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D, 0x3653, 0x2672, 0x1611,
			0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4, 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC, 0x48C4,
			0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823, 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A,
			0xB92B, 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12, 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79,
			0x8B58, 0xBB3B, 0xAB1A, 0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41, 0xEDAE, 0xFD8F, 0xCDEC,
			0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49, 0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70, 0xFF9F,
			0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78, 0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E,
			0xE16F, 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067, 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D,
			0xD31C, 0xE37F, 0xF35E, 0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256, 0xB5EA, 0xA5CB, 0x95A8,
			0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D, 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xA7DB,
			0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C, 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615,
			0x5634, 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB, 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0,
			0x08E1, 0x3882, 0x28A3, 0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A, 0x4A75, 0x5A54, 0x6A37,
			0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92, 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9, 0x7C26,
			0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1, 0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9,
			0x9FF8, 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0 };

	private ClusterSlotHashUtil() {

	}

	/**
	 * @param keys must not be {@literal null}.
	 * @return
	 * @since 2.0
	 */
	public static boolean isSameSlotForAllKeys(Collection<ByteBuffer> keys) {

		Assert.notNull(keys, "Keys must not be null");

		if (keys.size() <= 1) {
			return true;
		}

		return isSameSlotForAllKeys((byte[][]) keys.stream() //
				.map(ByteBuffer::duplicate) //
				.map(ByteUtils::getBytes) //
				.toArray(byte[][]::new));
	}

	/**
	 * @param keys must not be {@literal null}.
	 * @return
	 * @since 2.0
	 */
	public static boolean isSameSlotForAllKeys(ByteBuffer... keys) {

		Assert.notNull(keys, "Keys must not be null");
		return isSameSlotForAllKeys(Arrays.asList(keys));
	}

	/**
	 * @param keys must not be {@literal null}.
	 * @return
	 */
	public static boolean isSameSlotForAllKeys(byte[]... keys) {

		Assert.notNull(keys, "Keys must not be null");

		if (keys.length <= 1) {
			return true;
		}

		int slot = calculateSlot(keys[0]);
		for (int i = 1; i < keys.length; i++) {
			if (slot != calculateSlot(keys[i])) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Calculate the slot from the given key.
	 *
	 * @param key must not be {@literal null} or empty.
	 * @return
	 */
	public static int calculateSlot(String key) {

		Assert.hasText(key, "Key must not be null or empty");
		return calculateSlot(key.getBytes());
	}

	/**
	 * Calculate the slot from the given key.
	 *
	 * @param key must not be {@literal null}.
	 * @return
	 */
	public static int calculateSlot(byte[] key) {

		Assert.notNull(key, "Key must not be null");

		byte[] finalKey = key;
		int start = indexOf(key, SUBKEY_START);
		if (start != -1) {
			int end = indexOf(key, start + 1, SUBKEY_END);
			if (end != -1 && end != start + 1) {

				finalKey = new byte[end - (start + 1)];
				System.arraycopy(key, start + 1, finalKey, 0, finalKey.length);
			}
		}
		return crc16(finalKey) % SLOT_COUNT;
	}

	private static int indexOf(byte[] haystack, byte needle) {
		return indexOf(haystack, 0, needle);
	}

	private static int indexOf(byte[] haystack, int start, byte needle) {

		for (int i = start; i < haystack.length; i++) {

			if (haystack[i] == needle) {
				return i;
			}
		}

		return -1;
	}

	private static int crc16(byte[] bytes) {

		int crc = 0x0000;

		for (byte b : bytes) {
			crc = ((crc << 8) ^ LOOKUP_TABLE[((crc >>> 8) ^ (b & 0xFF)) & 0xFF]);
		}
		return crc & 0xFFFF;
	}
}

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