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package com.weibo.api.motan.cluster.loadbalance;
import com.weibo.api.motan.core.extension.SpiMeta;
import com.weibo.api.motan.rpc.Referer;
import com.weibo.api.motan.rpc.Request;
import com.weibo.api.motan.util.CollectionUtil;
import com.weibo.api.motan.util.LoggerUtil;
import com.weibo.api.motan.util.MathUtil;
import org.apache.commons.lang3.StringUtils;
import java.util.*;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicInteger;
@SpiMeta(name = "configurableWeight")
public class ConfigurableWeightLoadBalance<T> extends ActiveWeightLoadBalance<T> {
@SuppressWarnings("rawtypes")
private static final RefererListCacheHolder emptyHolder = new EmptyHolder();
@SuppressWarnings("unchecked")
private volatile RefererListCacheHolder<T> holder = emptyHolder;
private String weightString;
@SuppressWarnings("unchecked")
@Override
public void onRefresh(List<Referer<T>> referers) {
super.onRefresh(referers);
if (CollectionUtil.isEmpty(referers)) {
holder = emptyHolder;
} else if (StringUtils.isEmpty(weightString)) {
holder = new SingleGroupHolder<T>(referers);
} else {
holder = new MultiGroupHolder<T>(weightString, referers);
}
}
@Override
protected Referer<T> doSelect(Request request) {
if (holder == emptyHolder) {
return null;
}
RefererListCacheHolder<T> h = this.holder;
Referer<T> r = h.next();
if (!r.isAvailable()) {
int retryTimes = getReferers().size() - 1;
for (int i = 0; i < retryTimes; i++) {
r = h.next();
if (r.isAvailable()) {
break;
}
}
}
if (r.isAvailable()) {
return r;
} else {
noAvailableReferer();
return null;
}
}
@Override
protected void doSelectToHolder(Request request, List<Referer<T>> refersHolder) {
if (holder == emptyHolder) {
return;
}
RefererListCacheHolder<T> h = this.holder;
int i = 0, j = 0;
while (i++ < getReferers().size()) {
Referer<T> r = h.next();
if (r.isAvailable()) {
refersHolder.add(r);
if (++j == MAX_REFERER_COUNT) {
return;
}
}
}
if (refersHolder.isEmpty()) {
noAvailableReferer();
}
}
private void noAvailableReferer() {
LoggerUtil.error(this.getClass().getSimpleName() + " 当前没有可用连接, pool.size=" + getReferers().size());
}
@Override
public void setWeightString(String weightString) {
this.weightString = weightString;
}
static abstract class RefererListCacheHolder<T> {
abstract Referer<T> next();
}
static class EmptyHolder<T> extends RefererListCacheHolder<T> {
@Override
Referer<T> next() {
return null;
}
}
@SuppressWarnings("hiding")
class SingleGroupHolder<T> extends RefererListCacheHolder<T> {
private int size;
private List<Referer<T>> cache;
SingleGroupHolder(List<Referer<T>> list) {
cache = list;
size = list.size();
LoggerUtil.info("ConfigurableWeightLoadBalance build new SingleGroupHolder.");
}
@Override
Referer<T> next() {
return cache.get(ThreadLocalRandom.current().nextInt(size));
}
}
@SuppressWarnings("hiding")
class MultiGroupHolder<T> extends RefererListCacheHolder<T> {
private int randomKeySize = 0;
private List<String> randomKeyList = new ArrayList<String>();
private Map<String, AtomicInteger> cursors = new HashMap<String, AtomicInteger>();
private Map<String, List<Referer<T>>> groupReferers = new HashMap<String, List<Referer<T>>>();
MultiGroupHolder(String weights, List<Referer<T>> list) {
LoggerUtil.info("ConfigurableWeightLoadBalance build new MultiGroupHolder. weights:" + weights);
String[] groupsAndWeights = weights.split(",");
int[] weightsArr = new int[groupsAndWeights.length];
Map<String, Integer> weightsMap = new HashMap<String, Integer>(groupsAndWeights.length);
int i = 0;
for (String groupAndWeight : groupsAndWeights) {
String[] gw = groupAndWeight.split(":");
if (gw.length == 2) {
Integer w = Integer.valueOf(gw[1]);
weightsMap.put(gw[0], w);
groupReferers.put(gw[0], new ArrayList<Referer<T>>());
weightsArr[i++] = w;
}
}
int weightGcd = findGcd(weightsArr);
if (weightGcd != 1) {
for(Map.Entry<String,Integer> entry: weightsMap.entrySet()) {
weightsMap.put(entry.getKey(),entry.getValue()/weightGcd);
}
}
for (Map.Entry<String, Integer> entry : weightsMap.entrySet()) {
for (int j = 0; j < entry.getValue(); j++) {
randomKeyList.add(entry.getKey());
}
}
Collections.shuffle(randomKeyList);
randomKeySize = randomKeyList.size();
for (String key : weightsMap.keySet()) {
cursors.put(key, new AtomicInteger(0));
}
for (Referer<T> referer : list) {
groupReferers.get(referer.getServiceUrl().getGroup()).add(referer);
}
}
@Override
Referer<T> next() {
String group = randomKeyList.get(ThreadLocalRandom.current().nextInt(randomKeySize));
AtomicInteger ai = cursors.get(group);
List<Referer<T>> referers = groupReferers.get(group);
return referers.get(MathUtil.getNonNegative(ai.getAndIncrement()) % referers.size());
}
private int findGcd(int n, int m) {
return (n == 0 || m == 0) ? n + m : findGcd(m, n % m);
}
private int findGcd(int[] arr) {
int i = 0;
for (; i < arr.length - 1; i++) {
arr[i + 1] = findGcd(arr[i], arr[i + 1]);
}
return findGcd(arr[i], arr[i - 1]);
}
}
}
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