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+get命令本质是调用了lookupKeyRead这个底层方法， |
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+lookupKeyRead方法如下： |
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+ |
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{{plantuml}} |
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@startuml |
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start |
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-:GET Command; |
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-: lookupKeyRead(); |
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+: lookupKeyReadWithFlags; |
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end |
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@@ -11,15 +11,34 @@ |
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@enduml |
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{{/plantuml}} |
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+ |
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+lookupKeyReadWithFlags方法如下： |
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+ |
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{{plantuml}} |
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@startuml |
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start |
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-:lookupKeyRead(); |
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+if (调用expireIfNeeded方法判断key是否过期) then(1) |
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+if (当前环境为主节点) then（yes） |
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+:返回null； |
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+stop |
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+endif |
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-: lookupKeyReadWithFlags(); |
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+if (当前环境为从节点，并且命令为读的时候，那说明key过期是安全的) then(yes) |
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+:返回null; |
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+stop |
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+endif |
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+endif |
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+:调用lookupKey方法，查询value的值； |
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+if (返回值为空) then(yes) |
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+:缓存命中+1; |
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+else(no) |
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+:缓存非命中+1; |
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+endif |
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+:返回查询的结果; |
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+ |
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end |
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@enduml |
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{{/plantuml}} |