源码阅读之storm操作zookeeper-cluster.clj

(defprotocol ClusterState  (set-ephemeral-node [this path data])  (delete-node [this path])  (create-sequential [this path data])  ;; if node does not exist, create persistent with this data  (set-data [this path data])  (get-data [this path watch?])  (get-version [this path watch?])  (get-data-with-version [this path watch?])  (get-children [this path watch?])  (mkdirs [this path])  (close [this])  (register [this callback])  (unregister [this id]))

(defprotocol StormClusterState (assignments [this callback]) (assignment-info [this storm-id callback]) (assignment-info-with-version [this storm-id callback]) (assignment-version [this storm-id callback]) (active-storms [this]) (storm-base [this storm-id callback]) (get-worker-heartbeat [this storm-id node port]) (executor-beats [this storm-id executor->node+port]) (supervisors [this callback]) (supervisor-info [this supervisor-id]) ;; returns nil if doesn't exist (setup-heartbeats! [this storm-id]) (teardown-heartbeats! [this storm-id]) (teardown-topology-errors! [this storm-id]) (heartbeat-storms [this]) (error-topologies [this]) (worker-heartbeat! [this storm-id node port info]) (remove-worker-heartbeat! [this storm-id node port]) (supervisor-heartbeat! [this supervisor-id info]) (activate-storm! [this storm-id storm-base]) (update-storm! [this storm-id new-elems]) (remove-storm-base! [this storm-id]) (set-assignment! [this storm-id info]) (remove-storm! [this storm-id]) (report-error [this storm-id task-id node port error]) (errors [this storm-id task-id]) (disconnect [this]))

(defn mk-distributed-cluster-state;; 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-client conf (conf STORM-ZOOKEEPER-SERVERS) (conf STORM-ZOOKEEPER-PORT)            :auth-conf conf)]  ;; 创建storm集群在zookeeper上的根目录，默认值为/storm  (zk/mkdirs zk (conf STORM-ZOOKEEPER-ROOT))  (.close zk));; 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 (atom true)  ;; 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-client conf           (conf STORM-ZOOKEEPER-SERVERS)           (conf STORM-ZOOKEEPER-PORT)           :auth-conf conf           :root (conf STORM-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 [state type path]                (when @active                 (when-not (= :connected state)                  (log-warn "Received event " state ":" type ":" path " with disconnected Zookeeper."))                 (when-not (= :none type)                  (doseq [callback (vals @callbacks)]                   (callback type path))))))];; 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  [this callback]  (let [id (uuid)]   (swap! callbacks assoc id callback)   id)) ;; unregister函数用于将指定key的回调函数从callbacks中删除 (unregister  [this id]  (swap! callbacks dissoc id)) ;; 在zookeeper上添加一个临时节点 (set-ephemeral-node  [this path data]  (zk/mkdirs zk (parent-path path))  (if (zk/exists zk path false)   (try-cause    (zk/set-data zk path data) ; should verify that it's ephemeral    (catch KeeperException$NoNodeException e     (log-warn-error e "Ephemeral node disappeared between checking for existing and setting data")     (zk/create-node zk path data :ephemeral)     ))   (zk/create-node zk path data :ephemeral))) ;; 在zookeeper上添加一个顺序节点 (create-sequential  [this path data]  (zk/create-node zk path data :sequential)) ;; 修改某个节点数据 (set-data  [this path data]  ;; note: this does not turn off any existing watches  (if (zk/exists zk path false)   (zk/set-data zk path data)   (do    (zk/mkdirs zk (parent-path path))    (zk/create-node zk path data :persistent)))) ;; 删除指定节点 (delete-node  [this path]  (zk/delete-recursive zk path)) ;; 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  [this path watch?]  (zk/get-data zk path 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  [this path watch?]  (zk/get-data-with-version zk path 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   [this path watch?]  (zk/get-version zk path 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  [this path watch?]  (zk/get-children zk path watch?)) ;; 在zookeeper上创建一个节点 (mkdirs  [this path]  (zk/mkdirs zk path)) ;; 关闭zk client (close  [this]  (reset! active false)  (.close zk)))))

(defn mk-storm-cluster-state [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? ClusterState cluster-state-spec)              [false cluster-state-spec]              [true (mk-distributed-cluster-state cluster-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 (atom nil)  ;; 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 (atom nil)  ;; 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 [type path]         ;; subtree绑定路径前缀如"assignments"、"storms"、"supervisors"等，args存放topology id         (let [[subtree & args] (tokenize-path path)]          ;; 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 " subtree args)))))];; 在zookeeper上创建storm运行topology所必需的znode(doseq [p [ASSIGNMENTS-SUBTREE STORMS-SUBTREE SUPERVISORS-SUBTREE WORKERBEATS-SUBTREE ERRORS-SUBTREE]] (mkdirs cluster-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  [this callback]  (when callback   (reset! assignments-callback callback))  (get-children cluster-state ASSIGNMENTS-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  [this storm-id callback]  (when callback   (swap! assignment-info-callback assoc storm-id callback))  (maybe-deserialize (get-data cluster-state (assignment-path storm-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   [this storm-id callback]  (when callback   (swap! assignment-info-with-version-callback assoc storm-id callback))  (let [{data :data version :version}      (get-data-with-version cluster-state (assignment-path storm-id) (not-nil? callback))]  {:data (maybe-deserialize data)   :version version})) ;; 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   [this storm-id callback]  (when callback   (swap! assignment-version-callback assoc storm-id callback))  (get-version cluster-state (assignment-path storm-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-children cluster-state STORMS-SUBTREE false)) ;; 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-children cluster-state WORKERBEATS-SUBTREE false)) ;; 获取所有有错误的topology id即/errors的子节点列表 (error-topologies  [this]  (get-children cluster-state ERRORS-SUBTREE false)) ;; 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  [this storm-id node port]  (-> cluster-state    (get-data (workerbeat-path storm-id node port) false)    maybe-deserialize)) ;; 获取指定进程中所有线程的心跳信息 (executor-beats  [this storm-id executor->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-map executor->node+port)     all-heartbeats (for [[[node port] executors] node+port->executors]              (->> (get-worker-heartbeat this storm-id node port)                (convert-executor-beats executors)                ))]   (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  [this callback]  (when callback   (reset! supervisors-callback callback))  (get-children cluster-state SUPERVISORS-SUBTREE (not-nil? callback))) ;; 获取/supervisors/{supervisor-id}节点数据，即supervisor的心跳信息 (supervisor-info  [this supervisor-id]  (maybe-deserialize (get-data cluster-state (supervisor-path supervisor-id) false))) ;; 设置进程心跳信息 (worker-heartbeat!  [this storm-id node port info]  (set-data cluster-state (workerbeat-path storm-id node port) (Utils/serialize info))) ;; 删除进程心跳信息 (remove-worker-heartbeat!  [this storm-id node port]  (delete-node cluster-state (workerbeat-path storm-id node port))) ;; 创建指定storm-id的topology的用于存放心跳信息的节点 (setup-heartbeats!  [this storm-id]  (mkdirs cluster-state (workerbeat-storm-root storm-id))) ;; 删除指定storm-id的topology的心跳信息节点 (teardown-heartbeats!  [this storm-id]  (try-cause   (delete-node cluster-state (workerbeat-storm-root storm-id))   (catch KeeperException e    (log-warn-error e "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!  [this storm-id]  (try-cause   (delete-node cluster-state (error-storm-root storm-id))   (catch KeeperException e    (log-warn-error e "Could not teardown errors for " storm-id)))) ;; 创建临时节点存放supervisor的心跳信息 (supervisor-heartbeat!  [this supervisor-id info]  (set-ephemeral-node cluster-state (supervisor-path supervisor-id) (Utils/serialize info))) ;; 创建/storms/{storm-id}节点 (activate-storm!  [this storm-id storm-base]  (set-data cluster-state (storm-path storm-id) (Utils/serialize storm-base))) ;; 更新topology对应的StormBase对象，即更新/storm/{storm-id}节点 (update-storm!  [this storm-id new-elems]  ;; base绑定storm-id在zookeeper上的StormBase对象  (let [base (storm-base this storm-id nil)     ;; executors绑定component名称->组件并行度的map     executors (:component->executors base)     ;; 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 (update new-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-data cluster-state (storm-path storm-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  [this storm-id callback]  (when callback   (swap! storm-base-callback assoc storm-id callback))  (maybe-deserialize (get-data cluster-state (storm-path storm-id) (not-nil? callback)))) ;; 删除storm-id的StormBase对象，即删除/storms/{storm-id}节点 (remove-storm-base!  [this storm-id]  (delete-node cluster-state (storm-path storm-id))) ;; 更新storm-id的分配信息，即更新/assignments/{storm-id}节点数据 (set-assignment!  [this storm-id info]  (set-data cluster-state (assignment-path storm-id) (Utils/serialize info))) ;; 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!  [this storm-id]  (delete-node cluster-state (assignment-path storm-id))  (remove-storm-base! this storm-id)) ;; 将组件异常信息写入zookeeper (report-error  [this storm-id component-id node port error]  ;; path绑定"/errors/{storm-id}/{component-id}"  (let [path (error-path storm-id component-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-error error) :host node :port port}     ;; 创建/errors/{storm-id}/{component-id}节点     _ (mkdirs cluster-state path)     ;; 创建/errors/{storm-id}/{component-id}的子顺序节点，并写入异常信息     _ (create-sequential cluster-state (str path "/e") (Utils/serialize data))     ;; 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-children cluster-state path false)            (sort-by parse-error-path)            reverse            (drop 10))]   ;; 删除to-kill中包含的节点   (doseq [k to-kill]    (delete-node cluster-state (str path "/" k))))) ;; 得到给定的storm-id component-id下的异常信息 (errors  [this storm-id component-id]  (let [path (error-path storm-id component-id)     _ (mkdirs cluster-state path)     children (get-children cluster-state path false)     errors (dofor [c children]            (let [data (-> (get-data cluster-state (str path "/" c) false)                    maybe-deserialize)]             (when data              (struct TaskError (:error data) (:time-secs data) (:host data) (:port data))              )))     ]   (->> (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]  (unregister cluster-state state-id)  (when solo?   (close cluster-state))))))

(defnk mk-client [conf servers port  :root ""  :watcher default-watcher  :auth-conf nil] (let [fk (Utils/newCurator conf servers port root (when auth-conf (ZookeeperAuthInfo. auth-conf)))]  (.. fk    (getCuratorListenable)    (addListener     (reify CuratorListener      (^void eventReceived [this ^CuratorFramework _fk ^CuratorEvent e]        (when (= (.getType e) CuratorEventType/WATCHED)         (let [^WatchedEvent event (.getWatchedEvent e)]          (watcher (zk-keeper-states (.getState event))              (zk-event-types (.getType event))              (.getPath event))))))))  (.start fk)  fk))