sentinel源码分析第九篇一核心流程一lookProcessChain查找资源处理链

原创

ren5201313 2022-12-19 14:07:25 博主文章分类：sentinel源码分析 ©著作权

文章标签 sentinel ide 源码分析限流 文章分类 虚拟化云计算

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文章目录

源码分析一lookProcessChain
源码分析一SlotChainProvider构建slotChain
源码分析一slotChainBuilder.build
总结

源码分析一lookProcessChain

通过chainMap获取resource对应的chain
存在则直接返回
SLOT_CHAIN实例超过6000则返回null,不进行处理
通过SlotChainProvider构建chain
加入chainMap

ProcessorSlot<Object> lookProcessChain(ResourceWrapper resourceWrapper) {
    chainMap 缓存resourceWrapper对应的Slot
    ProcessorSlotChain chain = chainMap.get(resourceWrapper);
    if (chain == null) {
        synchronized (LOCK) {
            chain = chainMap.get(resourceWrapper);
            if (chain == null) {
                如果资源数过多则直接返回null不进行限流处理
                if (chainMap.size() >= Constants.MAX_SLOT_CHAIN_SIZE) {
                    return null;
                }
                创建新的ProcessorSlotChain
                chain = SlotChainProvider.newSlotChain();
                构建新的资源和处理器链池
                Map<ResourceWrapper, ProcessorSlotChain> newMap = new HashMap<ResourceWrapper, ProcessorSlotChain>(
                        chainMap.size() + 1);
                newMap.putAll(chainMap);
                newMap.put(resourceWrapper, chain);
                chainMap = newMap;
            }
        }
    }
    return chain;
}

源码分析一SlotChainProvider构建slotChain

通过spi获取建造者DefaultSlotChainBuilder

public final class SlotChainProvider {
    private static volatile SlotChainBuilder slotChainBuilder = null;

    public static ProcessorSlotChain newSlotChain() {
        step-1: slotChain建造者存在则构建
        if (slotChainBuilder != null) {
            return slotChainBuilder.build();
        }
        
        step-2: spi==spi和默认的都是:DefaultSlotChainBuilder
        slotChainBuilder = SpiLoader.loadFirstInstanceOrDefault(SlotChainBuilder.class, DefaultSlotChainBuilder.class);

        step-3: 默认策略
        if (slotChainBuilder == null) {
            slotChainBuilder = new DefaultSlotChainBuilder();
        } 
        return slotChainBuilder.build();
    }
}

源码分析一slotChainBuilder.build

通过spi加载slotchain

public class DefaultSlotChainBuilder implements SlotChainBuilder {

    @Override
    public ProcessorSlotChain build() {
        ProcessorSlotChain chain = new DefaultProcessorSlotChain();

        // Note: the instances of ProcessorSlot should be different, since they are not stateless.
        List<ProcessorSlot> sortedSlotList = SpiLoader.loadPrototypeInstanceListSorted(ProcessorSlot.class);


        /**
         *
         * 单向链表
         *    first                     end
         * DefaultProcessorSlotChain  -->  --> spi
         * spi结果:
         * 构建node树
         * com.alibaba.csp.sentinel.slots.nodeselector.NodeSelectorSlot
         * 构建clusterNode
         * com.alibaba.csp.sentinel.slots.clusterbuilder.ClusterBuilderSlot
         * 日志
         * com.alibaba.csp.sentinel.slots.logger.LogSlot
         * 统计
         * com.alibaba.csp.sentinel.slots.statistic.StatisticSlot
         * 授权 白名单 黑名单
         * com.alibaba.csp.sentinel.slots.block.authority.AuthoritySlot
         * 系统
         * com.alibaba.csp.sentinel.slots.system.SystemSlot
         * 限流
         * com.alibaba.csp.sentinel.slots.block.flow.FlowSlot
         * 降级
         * com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot
         */
        for (ProcessorSlot slot : sortedSlotList) {
            if (!(slot instanceof AbstractLinkedProcessorSlot)) {
                RecordLog.warn("The ProcessorSlot(" + slot.getClass().getCanonicalName() + ") is not an instance of AbstractLinkedProcessorSlot, can't be added into ProcessorSlotChain");
                continue;
            }

            chain.addLast((AbstractLinkedProcessorSlot<?>) slot);
        }

        return chain;
    }
}