algorithm 参与度算法

潇洒

发布于 2023-10-23 14:40:52

1550

发布于 2023-10-23 14:40:52

文章被收录于专栏：石头岛

前言

参与度算法是用在计算多个节点之间的参与情况的算法，也就是说在多个已经确认的节点个数之间的一种算法。

说人话就是假设有10个节点，这10个节点都正常工作参与度就是100%，如果挂了一个节点，参与度就是：90%。是不是有点感觉了。

在分布式场景下，参与度是个重要的指标，尤其是各种分布式应用，那用的更是多。比如有一堆reids集群，挂了几个还可以工作，这就是一个参与度的阀值。在DPOS共识的区块链的场景下，这个值就可以起到一个参考指标的作用。

实现

package com.liukai.blockchain.labs;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.IntStream;

import static java.util.Arrays.fill;

/**
 * @author liukai
 * @since 2022/4/25.
 */
public class BlockFilledSlot {

  public static Map<String, Object> database = new HashMap<>();

  public static final int BLOCK_FILLED_SLOTS_NUMBER = 128;

  static {
    initFill();
    initBlockFilledSlotsIndex();
  }

  public static void initFill() {
    int[] blockFilledSlots = new int[getBlockFilledSlotsNumber()];
    fill(blockFilledSlots, 1);
    database.put("BLOCK_FILLED_SLOTS", blockFilledSlots);
    System.out.println("init param");
    System.out.println("SlotCount=" + IntStream.of(blockFilledSlots).sum());
    System.out.println("Percent=" + calculateFilledSlotsCount() + "%");
    System.out.println("===================");
  }

  public static void initBlockFilledSlotsIndex() {
    database.put("BLOCK_FILLED_SLOTS_INDEX", 0);
  }

  public static int getBlockFilledSlotsIndex() {
    return (int) database.get("BLOCK_FILLED_SLOTS_INDEX");
  }

  public static int getBlockFilledSlotsNumber() {
    return BLOCK_FILLED_SLOTS_NUMBER;
  }

  public static int[] getBlockFilledSlots() {
    return (int[]) database.get("BLOCK_FILLED_SLOTS");
  }

  // 每一次 true false 都会让 index 往前移动一步
  public static void applyBlock(boolean fillBlock) {
    int[] blockFilledSlots = getBlockFilledSlots();
    int blockFilledSlotsIndex = getBlockFilledSlotsIndex();
//    System.out.println("blockFilledSlotsIndex before: " + blockFilledSlotsIndex);
    blockFilledSlots[blockFilledSlotsIndex] = fillBlock ? 1 : 0;
    saveBlockFilledSlots(blockFilledSlots);
    saveBlockFilledSlotsIndex((blockFilledSlotsIndex + 1) % getBlockFilledSlotsNumber());
//    System.out.println("blockFilledSlotsIndex after: " + getBlockFilledSlotsIndex());
  }

  private static void saveBlockFilledSlots(int[] blockFilledSlots) {
//    System.out.println("array: " + Arrays.toString(blockFilledSlots));
    database.put("BLOCK_FILLED_SLOTS", blockFilledSlots);
  }

  private static void saveBlockFilledSlotsIndex(int i) {
    database.put("BLOCK_FILLED_SLOTS_INDEX", i);
  }

  public static int calculateFilledSlotsCount() {
    int[] blockFilledSlots = getBlockFilledSlots();
    int sum = IntStream.of(blockFilledSlots).sum();
//    System.out.println("calculateFilledSlotsCount: " + sum);
    return 100 * sum / getBlockFilledSlotsNumber();
  }

  public static void main(String[] args) {
    int slot = 64;
    // 实际中，slot 的个数是根据 witness 的产块与否来决定的
    for (int i = 0; i < slot; i++) {
      applyBlock(false);
      System.out.println("SlotsCount: " + IntStream.of(getBlockFilledSlots()).sum());
      System.out.println("Percent: " + calculateFilledSlotsCount() + " %");
    }
    System.out.println("-----------");
    for (int i = 0; i < 128; i++) {
      applyBlock(true);
      System.out.println("SlotsCount: " + IntStream.of(getBlockFilledSlots()).sum());
      System.out.println("Percent: " + calculateFilledSlotsCount() + " %");
    }
  }
}