基于百分比的路由算法 [英] Percentage based routing algorithm
问题描述
浏览基于百分比的路由,偶然发现了这个主题.
根据以下提议的算法:
对于给定的模型如下:
public class Host {
private String name;
private int percentageLoad;
private int percentageAccum;
}
百分比Accum 的初始值是百分比负载的值.
The initial value for percentageAccum is the value of percentageLoad.
收到请求时:
- 选择Accum百分比最大的主机
- 从所选主机的百分比中减去 100
- 将所有主机(包括所选主机)的百分比负载添加到百分比数据
下面是我的实现
@Builder
@Data
@AllArgsConstructor
@NoArgsConstructor
public class HostWeightage{
private String hostId;
private int weightage;
private int accumulatedWeightageSoFar;
}
示例 Java 执行程序
Sample Java executor
public String getRoutedHost(List<HostWeightage> hostWeightageList) {
// assume 0th index as default
HostWeightage hostWithMaxAccWeight = hostWeightageList.get(0);
// choose the host with the largest percentageAccum
for (int i = 1; i < hostWeightageList.size(); i++) {
if (hostWeightageList.get(i).getAccumulatedWeightageSoFar() >= hostWithMaxAccWeight.getAccumulatedWeightageSoFar()){
hostWithMaxAccWeight = hostWeightageList.get(i);
}
}
// subtract 100 from the percentageAccum for the chosen host
int inverseAccWeight = hostWithMaxAccWeight.getAccumulatedWeightageSoFar() - 100;
hostWithMaxAccWeight.setAccumulatedWeightageSoFar(inverseAccWeight);
// add percentageLoad to percentageAccum for all hosts, including the chosen host
int weight = hostWithMaxAccWeight.getWeightage();
for (HostWeightage wightedHost : hostWeightageList) {
int accWeight = wightedHost.getAccumulatedWeightageSoFar();
wightedHost.setAccumulatedWeightageSoFar(weight + accWeight);
}
return hostWithMaxAccWeight.getHostId();
}
这是我每次运行 10 次调用的示例
here is my sample runs for 10 calls each
INFO: initial config
HostWeightage(hostId=redirect_host_1, weightage=10, accumulatedWeightageSoFar=10),
HostWeightage(hostId=redirect_host_2, weightage=40, accumulatedWeightageSoFar=40),
HostWeightage(hostId=redirect_host_3, weightage=50, accumulatedWeightageSoFar=50)
final distribution of 10 calls:
INFO: host1 3 ( should have been 1)
INFO: host2 3 ( should have been 4)
INFO: host3 4 ( should have been 5)
-------------------------
INFO: initial config
HostWeightage(hostId=redirect_host_1, weightage=30, accumulatedWeightageSoFar=30),
HostWeightage(hostId=redirect_host_2, weightage=30, accumulatedWeightageSoFar=30),
HostWeightage(hostId=redirect_host_3, weightage=40, accumulatedWeightageSoFar=40)
final distribution of 10 calls:
INFO: host1 3 ( correct output )
INFO: host2 3 ( correct output )
INFO: host3 4 ( correct output )
-------------------------
INFO: initial config
HostWeightage(hostId=redirect_host_1, weightage=10, accumulatedWeightageSoFar=10),
HostWeightage(hostId=redirect_host_2, weightage=20, accumulatedWeightageSoFar=20),
HostWeightage(hostId=redirect_host_3, weightage=70, accumulatedWeightageSoFar=70)
final distribution of 10 calls:
INFO: host1 3 ( should have been 1 )
INFO: host2 3 ( should have been 2 )
INFO: host3 4 ( should have been 7 )
感谢任何指出算法实现错误的指针!!
any pointers to what is wrong in algo implementation is appreciated!!
推荐答案
问题出在代码末尾的循环中.由于以下行,它对所有主机使用相同的权重:
The problem is in the loop at the end of the code. It's using the same weight for all of the hosts, due to the line:
int weight = hostWithMaxAccWeight.getWeightage();
添加到每个主机的累加器的权重需要是该主机的权重,而不是所选主机的权重.所以循环应该是:
The weight that's added to each host's accumulator needs to be that host's weight, not the weight of the host that was chosen. So the loop should be:
for (HostWeightage weightedHost : hostWeightageList) {
int weight = weightedHost.getWeightage();
int accWeight = weightedHost.getAccumulatedWeightageSoFar();
weightedHost.setAccumulatedWeightageSoFar(weight + accWeight);
}
使用权重的算法运行示例 A:10 B:80 C:10
如下所示:
A sample run of the algorithm using weights A:10 B:80 C:10
looks like this:
accumulators
A B C
10 80 10 choose B
20 60 20 choose B
30 40 30 choose B
40 20 40 choose A
-50 100 50 choose B
-40 80 60 choose B
-30 60 70 choose C
-20 140 -20 choose B
-10 120 -10 choose B
0 100 0 choose B
10 80 10 back to start
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