/* * Copyright 2012-2015 org.opencloudb. * * 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 * * http://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.opencloudb.route.util; /** * 数据分区工具单独版本,请使用singleton的模式调用。 * * @author mycat */ public final class PartitionForSingle { // 分区长度:数据段分布定义,其中取模的数一定要是2^n, 因为这里使用x % 2^n == x & (2^n - 1)等式,来优化性能。 private static final int PARTITION_LENGTH = 1024; private static final int DEFAULT_HASH_LENGTH = 8; // %转换为&操作的换算数值 private static final long AND_VALUE = PARTITION_LENGTH - 1; // 分区线段 private final int[] segment = new int[PARTITION_LENGTH]; /** * @param count * 表示定义的分区数 * @param length * 表示对应每个分区的取值长度 * <p> * 注意:其中count,length两个数组的长度必须是一致的。 * </p> */ public PartitionForSingle(int[] count, int[] length) { if (count == null || length == null || (count.length != length.length)) { throw new RuntimeException("error,check your scope & scopeLength definition."); } int segmentLength = 0; for (int i = 0; i < count.length; i++) { segmentLength += count[i]; } int[] scopeSegment = new int[segmentLength + 1]; int index = 0; for (int i = 0; i < count.length; i++) { for (int j = 0; j < count[i]; j++) { scopeSegment[++index] = scopeSegment[index - 1] + length[i]; } } if (scopeSegment[scopeSegment.length - 1] != PARTITION_LENGTH) { throw new RuntimeException("error,check your partitionScope definition."); } // 数据映射操作 for (int i = 1; i < scopeSegment.length; i++) { for (int j = scopeSegment[i - 1]; j < scopeSegment[i]; j++) { segment[j] = (i - 1); } } } public int partition(long h) { return segment[(int) (h & AND_VALUE)]; } public int partition(String key) { return segment[(int) (hash(key) & AND_VALUE)]; } private static long hash(String s) { long h = 0; int len = s.length(); for (int i = 0; (i < DEFAULT_HASH_LENGTH && i < len); i++) { h = (h << 5) - h + s.charAt(i); } return h; } // for test public static void main(String[] args) { // 拆分为16份,每份长度均为:64。 // Scope scope = new Scope(new int[] { 16 }, new int[] { 64 }); // // 拆分为23份,前8份长度为:8,后15份长度为:64。 // Scope scope = new Scope(new int[] { 8, 15 }, new int[] { 8, 64 }); // // 拆分为128份,每份长度均为:8。 // Scope scope = new Scope(new int[] { 128 }, new int[] { 8 }); PartitionForSingle p = new PartitionForSingle(new int[] { 8, 15 }, new int[] { 8, 64 }); String memberId = "xianmao.hexm"; int value = 0; long st = System.currentTimeMillis(); for (int i = 0; i < 10000000; i++) { value = p.partition(memberId); } long et = System.currentTimeMillis(); System.out.println("value:" + value + ",take time:" + (et - st) + " ms."); } }