storm操作zookeeper源码分析-cluster.clj
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storm操作zookeeper的主要函数都定义在命名空间backtype.storm.cluster中(即cluster.clj文件中)。backtype.storm.cluster定义了两个重要protocol:ClusterState和StormClusterState。clojure中的protocol可以看成java中的接口,封装了一组方法。ClusterState协议中封装了一组与zookeeper进行交互的基础函数,如获取子节点函数,获取子节点数据函数等,ClusterState协议定义如下:
ClusterState协议
(set-ephemeral-node[thispath data])
(delete-node[thispath])
(create-sequential[thispath data])
;; if node does not exist, create persistent with this data
(set-data[thispath data])
(get-data[thispath watch?])
(get-version[thispath watch?])
(get-data-with-version[thispath watch?])
(get-children[thispath watch?])
(mkdirs[thispath])
(close[this])
(register[thiscallback])
(unregister[thisid]))
StormClusterState协议封装了一组storm与zookeeper进行交互的函数,可以将StormClusterState协议中的函数看成ClusterState协议中函数的"组合"。StormClusterState协议定义如下:
StormClusterState协议
(assignments[thiscallback])
(assignment-info[thisstorm-idcallback])
(assignment-info-with-version[thisstorm-idcallback])
(assignment-version[thisstorm-idcallback])
(active-storms[this])
(storm-base[thisstorm-idcallback])
(get-worker-heartbeat[thisstorm-idnode port])
(executor-beats[thisstorm-idexecutor->node+port])
(supervisors[thiscallback])
(supervisor-info[thissupervisor-id]);; returns nil if doesn‘t exist
(setup-heartbeats![thisstorm-id])
(teardown-heartbeats![thisstorm-id])
(teardown-topology-errors![thisstorm-id])
(heartbeat-storms[this])
(error-topologies[this])
(worker-heartbeat![thisstorm-idnode portinfo])
(remove-worker-heartbeat![thisstorm-idnode port])
(supervisor-heartbeat![thissupervisor-idinfo])
(activate-storm![thisstorm-idstorm-base])
(update-storm![thisstorm-idnew-elems])
(remove-storm-base![thisstorm-id])
(set-assignment![thisstorm-idinfo])
(remove-storm![thisstorm-id])
(report-error[thisstorm-idtask-idnode porterror])
(errors[thisstorm-idtask-id])
(disconnect[this]))
命名空间backtype.storm.cluster除了定义ClusterState和StormClusterState这两个重要协议外,还定义了两个重要函数:mk-distributed-cluster-state和mk-storm-cluster-state。
mk-distributed-cluster-state函数如下:
该函数返回一个实现了ClusterState协议的对象,通过这个对象就可以与zookeeper进行交互了。
mk-distributed-cluster-state函数
;; conf绑定了storm.yaml中的配置信息,是一个map对象
[conf]
;; zk绑定一个zk client,Storm使用CuratorFramework与Zookeeper进行交互
(let [zk (zk/mk-clientconf (confSTORM-ZOOKEEPER-SERVERS) (confSTORM-ZOOKEEPER-PORT) :auth-confconf)]
;; 创建storm集群在zookeeper上的根目录,默认值为/storm
(zk/mkdirszk (confSTORM-ZOOKEEPER-ROOT))
(.closezk))
;; callbacks绑定回调函数集合,是一个map对象
(let [callbacks (atom{})
;; active标示zookeeper集群状态
active (atomtrue)
;; zk重新绑定新的zk client,该zk client设置了watcher,这样当zookeeper集群的状态发生变化时,zk server会给zk client发送相应的event,zk client设置的watcher会调用callbacks中相应回调函数来处理event
;; 启动nimbus时,callbacks是一个空集合,所以nimbus端收到event后不会调用任何回调函数;但是启动supervisor时,callbacks中注册了回调函数,所以当supervisor收到zk server发送的event后,会调用相应的回调函数
;; mk-client函数定义在zookeeper.clj文件中,请参见其定义部分
zk (zk/mk-clientconf
(confSTORM-ZOOKEEPER-SERVERS)
(confSTORM-ZOOKEEPER-PORT)
:auth-confconf
:root (confSTORM-ZOOKEEPER-ROOT)
;; :watcher绑定一个函数,指定zk client的默认watcher函数,state标示当前zk client的状态;type标示事件类型;path标示zookeeper上产生该事件的znode
;; 该watcher函数主要功能就是执行callbacks集合中的函数,callbacks集合中的函数是在mk-storm-cluster-state函数中通过调用ClusterState的register函数添加的
:watcher (fn [statetypepath]
(when @active
(when-not (= :connectedstate)
(log-warn"Received event "state":"type":"path " with disconnected Zookeeper."))
(when-not (= :nonetype)
(doseq [callback (vals @callbacks)]
(callbacktypepath))))))]
;; reify相当于java中的implements,这里表示实现一个协议
(reify
ClusterState
;; register函数用于将回调函数加入callbacks中,key是一个32位的标识
(register
[thiscallback]
(let [id (uuid)]
(swap!callbacksassoc idcallback)
id))
;; unregister函数用于将指定key的回调函数从callbacks中删除
(unregister
[thisid]
(swap!callbacksdissoc id))
;; 在zookeeper上添加一个临时节点
(set-ephemeral-node
[thispath data]
(zk/mkdirszk (parent-pathpath))
(if (zk/existszkpath false)
(try-cause
(zk/set-datazkpath data) ; should verify that it‘s ephemeral
(catchKeeperException$NoNodeExceptione
(log-warn-errore"Ephemeral node disappeared between checking for existing and setting data")
(zk/create-nodezkpath data:ephemeral)
))
(zk/create-nodezkpath data:ephemeral)))
;; 在zookeeper上添加一个顺序节点
(create-sequential
[thispath data]
(zk/create-nodezkpath data:sequential))
;; 修改某个节点数据
(set-data
[thispath data]
;; note: this does not turn off any existing watches
(if (zk/existszkpath false)
(zk/set-datazkpath data)
(do
(zk/mkdirszk (parent-pathpath))
(zk/create-nodezkpath data:persistent))))
;; 删除指定节点
(delete-node
[thispath]
(zk/delete-recursivezkpath))
;; 获取指定节点数据。path标示节点路径;watch?是一个布尔类型值,表示是否需要对该节点进行"观察",如果watch?=true,当调用set-data函数修改该节点数据后,
;; 会给zk client发送一个事件,zk client接收事件后,会调用创建zk client时指定的默认watcher函数(即:watcher绑定的函数)
(get-data
[thispath watch?]
(zk/get-datazkpath watch?))
;; 与get-data函数的区别就是获取指定节点数据的同时,获取节点数据的version,version表示节点数据修改的次数
(get-data-with-version
[thispath watch?]
(zk/get-data-with-versionzkpath watch?))
;; 获取指定节点的version,watch?的含义与get-data函数中的watch?相同
(get-version
[thispath watch?]
(zk/get-versionzkpath watch?))
;; 获取指定节点的子节点列表,watch?的含义与get-data函数中的watch?相同
(get-children
[thispath watch?]
(zk/get-childrenzkpath watch?))
;; 在zookeeper上创建一个节点
(mkdirs
[thispath]
(zk/mkdirszkpath))
;; 关闭zk client
(close
[this]
(reset!activefalse)
(.closezk)))))
mk-storm-cluster-state函数定义如下:
mk-storm-cluster-state函数非常重要,该函数返回一个实现了StormClusterState协议的实例,通过该实例storm就可以更加方便与zookeeper进行交互在启动nimbus和supervisor的函数中均调用了
mk-storm-cluster-state函数。关于nimbus和supervisor的启动将在之后的文章中介绍。
mk-storm-cluster-state函数
[cluster-state-spec]
;; satisfies?谓词相当于java中的instanceof,判断cluster-state-spec是不是ClusterState实例
(let [[solo?cluster-state] (if (satisfies?ClusterStatecluster-state-spec)
[falsecluster-state-spec]
[true (mk-distributed-cluster-statecluster-state-spec)])
;; 绑定topology id->回调函数的map,当/assignments/{topology id}数据发生变化时,zk client执行assignment-info-callback中topology id所对应的回调函数
assignment-info-callback (atom{})
;; assignment-info-with-version-callback与assignment-info-callback类似
assignment-info-with-version-callback (atom{})
;; assignment-version-callback与assignments-callback类似
assignment-version-callback (atom{})
;; 当/supervisors标示的znode的子节点发生变化时,zk client执行supervisors-callback指向的函数
supervisors-callback (atomnil)
;; 当/assignments标示的znode的子节点发生变化时,zk client执行assignments-callback指向的函数
assignments-callback (atomnil)
;; 当/storms/{topology id}标示的znode的数据发生变化时,zk client执行storm-base-callback中topology id所对应的回调函数
storm-base-callback (atom{})
;; register函数将"回调函数(fn ...)"添加到cluster-state的callbacks集合中,并返回标示该回调函数的uuid
state-id (register
cluster-state
;; 定义"回调函数",type标示事件类型,path标示znode
(fn [typepath]
;; subtree绑定路径前缀如"assignments"、"storms"、"supervisors"等,args存放topology id
(let [[subtree&args] (tokenize-pathpath)]
;; condp相当于java中的switch
(condp= subtree
;; 当subtree="assignments"时,如果args为空,说明是/assignments的子节点发生变化,执行assignments-callback指向的回调函数,否则
;; 说明/assignments/{topology id}标示的节点数据发生变化,执行assignment-info-callback指向的回调函数
ASSIGNMENTS-ROOT (if (empty?args)
(issue-callback!assignments-callback)
(issue-map-callback!assignment-info-callback (first args)))
;; 当subtree="supervisors"时,说明是/supervisors的子节点发生变化,执行supervisors-callback指向的回调函数
SUPERVISORS-ROOT (issue-callback!supervisors-callback)
;; 当subtree="storms"时,说明是/storms/{topology id}标示的节点数据发生变化,执行storm-base-callback指向的回调函数
STORMS-ROOT (issue-map-callback!storm-base-callback (first args))
;; this should never happen
(exit-process!30"Unknown callback for subtree "subtreeargs)))))]
;; 在zookeeper上创建storm运行topology所必需的znode
(doseq [p [ASSIGNMENTS-SUBTREESTORMS-SUBTREESUPERVISORS-SUBTREEWORKERBEATS-SUBTREEERRORS-SUBTREE]]
(mkdirscluster-state p))
;; 返回一个实现StormClusterState协议的实例
(reify
StormClusterState
;; 获取/assignments的子节点列表,如果callback不为空,将其赋值给assignments-callback,并对/assignments添加"节点观察"
(assignments
[thiscallback]
(when callback
(reset!assignments-callbackcallback))
(get-childrencluster-stateASSIGNMENTS-SUBTREE (not-nil?callback)))
;; 获取/assignments/{storm-id}节点数据,即storm-id的分配信息,如果callback不为空,将其添加到assignment-info-callback中,并对/assignments/{storm-id}添加"数据观察"
(assignment-info
[thisstorm-idcallback]
(when callback
(swap!assignment-info-callbackassoc storm-idcallback))
(maybe-deserialize (get-datacluster-state (assignment-pathstorm-id) (not-nil?callback))))
;; 获取/assignments/{storm-id}节点数据包括version信息,如果callback不为空,将其添加到assignment-info-with-version-callback中,并对/assignments/{storm-id}添加"数据观察"
(assignment-info-with-version
[thisstorm-idcallback]
(when callback
(swap!assignment-info-with-version-callbackassoc storm-idcallback))
(let [{data:dataversion:version}
(get-data-with-versioncluster-state (assignment-pathstorm-id) (not-nil?callback))]
{:data (maybe-deserializedata)
:versionversion}))
;; 获取/assignments/{storm-id}节点数据的version信息,如果callback不为空,将其添加到assignment-version-callback中,并对/assignments/{storm-id}添加"数据观察"
(assignment-version
[thisstorm-idcallback]
(when callback
(swap!assignment-version-callbackassoc storm-idcallback))
(get-versioncluster-state (assignment-pathstorm-id) (not-nil?callback)))
;; 获取storm集群中正在运行的topology id即/storms的子节点列表
(active-storms
[this]
(get-childrencluster-stateSTORMS-SUBTREEfalse))
;; 获取storm集群中所有有心跳的topology id即/workerbeats的子节点列表
(heartbeat-storms
[this]
(get-childrencluster-stateWORKERBEATS-SUBTREEfalse))
;; 获取所有有错误的topology id即/errors的子节点列表
(error-topologies
[this]
(get-childrencluster-stateERRORS-SUBTREEfalse))
;; 获取指定storm-id进程的心跳信息,即/workerbeats/{storm-id}/{node-port}节点数据
(get-worker-heartbeat
[thisstorm-idnode port]
(-> cluster-state
(get-data (workerbeat-pathstorm-idnode port) false)
maybe-deserialize))
;; 获取指定进程中所有线程的心跳信息
(executor-beats
[thisstorm-idexecutor->node+port]
;; need to take executor->node+port in explicitly so that we don‘t run into a situation where a
;; long dead worker with a skewed clock overrides all the timestamps. By only checking heartbeats
;; with an assigned node+port, and only reading executors from that heartbeat that are actually assigned,
;; we avoid situations like that
(let [node+port->executors (reverse-mapexecutor->node+port)
all-heartbeats (for [[[node port]executors]node+port->executors]
(->> (get-worker-heartbeatthisstorm-idnode port)
(convert-executor-beatsexecutors)
))]
(apply merge all-heartbeats)))
;; 获取/supervisors的子节点列表,如果callback不为空,将其赋值给supervisors-callback,并对/supervisors添加"节点观察"
(supervisors
[thiscallback]
(when callback
(reset!supervisors-callbackcallback))
(get-childrencluster-stateSUPERVISORS-SUBTREE (not-nil?callback)))
;; 获取/supervisors/{supervisor-id}节点数据,即supervisor的心跳信息
(supervisor-info
[thissupervisor-id]
(maybe-deserialize (get-datacluster-state (supervisor-pathsupervisor-id) false)))
;; 设置进程心跳信息
(worker-heartbeat!
[thisstorm-idnode portinfo]
(set-datacluster-state (workerbeat-pathstorm-idnode port) (Utils/serializeinfo)))
;; 删除进程心跳信息
(remove-worker-heartbeat!
[thisstorm-idnode port]
(delete-nodecluster-state (workerbeat-pathstorm-idnode port)))
;; 创建指定storm-id的topology的用于存放心跳信息的节点
(setup-heartbeats!
[thisstorm-id]
(mkdirscluster-state (workerbeat-storm-rootstorm-id)))
;; 删除指定storm-id的topology的心跳信息节点
(teardown-heartbeats!
[thisstorm-id]
(try-cause
(delete-nodecluster-state (workerbeat-storm-rootstorm-id))
(catchKeeperExceptione
(log-warn-errore"Could not teardown heartbeats for "storm-id))))
;; 删除指定storm-id的topology的错误信息节点
(teardown-topology-errors!
[thisstorm-id]
(try-cause
(delete-nodecluster-state (error-storm-rootstorm-id))
(catchKeeperExceptione
(log-warn-errore"Could not teardown errors for "storm-id))))
;; 创建临时节点存放supervisor的心跳信息
(supervisor-heartbeat!
[thissupervisor-idinfo]
(set-ephemeral-nodecluster-state (supervisor-pathsupervisor-id) (Utils/serializeinfo)))
;; 创建/storms/{storm-id}节点
(activate-storm!
[thisstorm-idstorm-base]
(set-datacluster-state (storm-pathstorm-id) (Utils/serializestorm-base)))
;; 更新topology对应的StormBase对象,即更新/storm/{storm-id}节点
(update-storm!
[thisstorm-idnew-elems]
;; base绑定storm-id在zookeeper上的StormBase对象
(let [base (storm-basethisstorm-idnil)
;; executors绑定component名称->组件并行度的map
executors (:component->executorsbase)
;; new-elems绑定合并后的组件并行度map,update函数将组件新并行度map合并到旧map中
new-elems (updatenew-elems:component->executors (partial merge executors))]
;; 更新StormBase对象中的组件并行度map,并写入zookeeper的/storms/{storm-id}节点
(set-datacluster-state (storm-pathstorm-id)
(-> base
(merge new-elems)
Utils/serialize))))
;; 获取storm-id的StormBase对象,即读取/storms/{storm-id}节点数据,如果callback不为空,将其赋值给storm-base-callback,并为/storms/{storm-id}节点添加"数据观察"
(storm-base
[thisstorm-idcallback]
(when callback
(swap!storm-base-callbackassoc storm-idcallback))
(maybe-deserialize (get-datacluster-state (storm-pathstorm-id) (not-nil?callback))))
;; 删除storm-id的StormBase对象,即删除/storms/{storm-id}节点
(remove-storm-base!
[thisstorm-id]
(delete-nodecluster-state (storm-pathstorm-id)))
;; 更新storm-id的分配信息,即更新/assignments/{storm-id}节点数据
(set-assignment!
[thisstorm-idinfo]
(set-datacluster-state (assignment-pathstorm-id) (Utils/serializeinfo)))
;; 删除storm-id的分配信息,同时删除其StormBase信息,即删除/assignments/{storm-id}节点和/storms/{storm-id}节点
(remove-storm!
[thisstorm-id]
(delete-nodecluster-state (assignment-pathstorm-id))
(remove-storm-base!thisstorm-id))
;; 将组件异常信息写入zookeeper
(report-error
[thisstorm-idcomponent-idnode porterror]
;; path绑定"/errors/{storm-id}/{component-id}"
(let [path (error-pathstorm-idcomponent-id)
;; data绑定异常信息,包括异常时间、异常堆栈信息、主机和端口
data{:time-secs (current-time-secs) :error (stringify-errorerror) :hostnode :portport}
;; 创建/errors/{storm-id}/{component-id}节点
_ (mkdirscluster-statepath)
;; 创建/errors/{storm-id}/{component-id}的子顺序节点,并写入异常信息
_ (create-sequentialcluster-state (str path "/e") (Utils/serializedata))
;; to-kill绑定除去顺序节点编号最大的前10个节点的剩余节点的集合
to-kill (->> (get-childrencluster-statepath false)
(sort-by parse-error-path)
reverse
(drop 10))]
;; 删除to-kill中包含的节点
(doseq [kto-kill]
(delete-nodecluster-state (str path "/"k)))))
;; 得到给定的storm-id component-id下的异常信息
(errors
[thisstorm-idcomponent-id]
(let [path (error-pathstorm-idcomponent-id)
_ (mkdirscluster-statepath)
children (get-childrencluster-statepath false)
errors (dofor[cchildren]
(let [data (-> (get-datacluster-state (str path "/"c) false)
maybe-deserialize)]
(when data
(struct TaskError (:errordata) (:time-secsdata) (:hostdata) (:portdata))
)))
]
(->> (filter not-nil?errors)
(sort-by (comp - :time-secs)))))
;; 关闭连接,在关闭连接前,将回调函数从cluster-state的callbacks中删除
(disconnect
[this]
(unregistercluster-statestate-id)
(when solo?
(closecluster-state))))))
zookeeper.clj中mk-client函数定义如下:
mk-client函数创建一个CuratorFramework实例,为该实例注册了CuratorListener,当一个后台操作完成或者指定的watch被触发时将会执行CuratorListener中的eventReceived()。eventReceived中调用的wacher函数就是mk-distributed-cluster-state中:watcher绑定的函数。
mk-client函数
[confserversport
:root""
:watcherdefault-watcher
:auth-confnil]
(let [fk (Utils/newCuratorconfserversportroot (when auth-conf (ZookeeperAuthInfo.auth-conf)))]
(.. fk
(getCuratorListenable)
(addListener
(reifyCuratorListener
(^voideventReceived[this^CuratorFramework_fk^CuratorEvente]
(when (= (.getTypee) CuratorEventType/WATCHED)
(let [^WatchedEventevent (.getWatchedEvente)]
(watcher (zk-keeper-states (.getStateevent))
(zk-event-types (.getTypeevent))
(.getPathevent))))))))
(.startfk)
fk))
以上就是storm与zookeeper进行交互的源码分析,我觉得最重要的部分就是如何给zk client添加"wacher",storm的很多功能都是通过zookeeper的wacher机制实现的,如"分配信息领取"。添加"wacher"大概分为以下几个步骤:
-
mk-distributed-cluster-state函数创建了一个zk client,并通过:watcher给该zk client指定了"wacher"函数,这个"wacher"函数只是简单调用ClusterState的callbacks集合中的函数,这样这个"wacher"函数执行哪些函数将由ClusterState实例决定
- ClusterState实例提供register函数来更新callbacks集合,ClusterState实例被传递给了mk-storm-cluster-state函数,在mk-storm-cluster-state中调用register添加了一个函数(fn [type path] ... ),这个函数实现了"watcher"函数的全部逻辑
-
mk-storm-cluster-state中注册的函数执行的具体内容由StormClusterState实例决定,对zookeeper节点添加"观察"也是通过StormClusterState实例实现的,这样我们就可以通过StormClusterState实例对我们感兴趣的节点添加"观察"和"回调函数",当节点或节点数据发生变化后,zk server就会给zk client发送"通知",zk client中的"wather"函数将被调用,进而我们注册的"回到函数"将被执行。
这部分源码与zookeeper联系十分紧密,涉及了很多zookeeper中的概念和特性,如"数据观察"和"节点观察"等,有关zookeeper的wacher机制请参考
http://www.cnblogs.com/ggjucheng/p/3369946.html
http://www.cnblogs.com/zhangchaoyang/articles/3813217.html
storm并没有直接使用zookeeper的api,而是使用Curator框架,Curator框架简化了访问zookeeper的操作。关于Curator框架请参考
http://f.dataguru.cn/thread-120125-1-1.html
原文:http://www.cnblogs.com/ierbar0604/p/3948257.html
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