04storm 源码阅读 storm的进程间消息通信实现clojure端 生成带netty能力的线程

;; Licensed to the Apache Software Foundation (ASF) under one;; or more contributor license agreements.  See the NOTICE file;; distributed with this work for additional information;; regarding copyright ownership.  The ASF licenses this file;; to you under the Apache License, Version 2.0 (the;; "License"); you may not use this file except in compliance;; with the License.  You may obtain a copy of the License at;;;; http://www.apache.org/licenses/LICENSE-2.0;;;; Unless required by applicable law or agreed to in writing, software;; distributed under the License is distributed on an "AS IS" BASIS,;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.;; See the License for the specific language governing permissions and;; limitations under the License.;;主要负责加载持有netty功能的线程，对外暴露两个函数，mk-local-context，获取netty的Context对象。launch-receive-thread!，初始化持有netty能力的处理线程(ns backtype.storm.messaging.loader  (:use [backtype.storm util log])  (:import [java.util ArrayList Iterator])  (:import [backtype.storm.messaging IContext IConnection TaskMessage])  (:import [backtype.storm.utils DisruptorQueue MutableObject])  (:require [backtype.storm.messaging [local :as local]])  (:require [backtype.storm [disruptor :as disruptor]]));;这里拿到了local.clj对外暴露的接口IContext，相对于获取了netty的消息传递能力，这个是在外面单独被调用的，回头会被放入lauch方法(defn mk-local-context []  (local/mk-context)) ;;开启消息接受线程，持有netty，context（参数列表的socket），用于做流失计算。(defn- mk-receive-thread [context storm-id port transfer-local-fn  daemon kill-fn priority socket max-buffer-size thread-id]    (async-loop      ;;定义匿名fn []，函数。       (fn []         (log-message "Starting receive-thread: [stormId: " storm-id ", port: " port ", thread-id: " thread-id  " ]")         (fn []           (let [batched (ArrayList.)                 ^Iterator iter (.recv ^IConnection socket 0 thread-id)                 closed (atom false)]             (when iter               (while (and (not @closed) (.hasNext iter))                   (let [packet (.next iter)                        task (if packet (.task ^TaskMessage packet))                        message (if packet (.message ^TaskMessage packet))]                      (if (= task -1)                         (do (log-message "Receiving-thread:[" storm-id ", " port "] received shutdown notice")                           (.close socket)                           (reset! closed  true))                         (when packet (.add batched [task message]))))))                          (when (not @closed)               (do                 (if (> (.size batched) 0)                   (transfer-local-fn batched))                 0)))))      ;;定义匿名fn []，函数。      ;;序列map结构，给mk-receive-thread的参数列表传进来的几个参数，放在返回值内。key类型的以后好用         :factory? true         :daemon daemon         :kill-fn kill-fn         :priority priority         :thread-name (str "worker-receiver-thread-" thread-id)));;调用mk-receive-thread。根据thread-count参数，启动了对应的现场数量(defn- mk-receive-threads [context storm-id port transfer-local-fn  daemon kill-fn priority socket max-buffer-size thread-count]  (into [] (for [thread-id (range thread-count)]              (mk-receive-thread context storm-id port transfer-local-fn  daemon kill-fn priority socket max-buffer-size thread-id))));;参数列表的几个key类型给下面的提供引用，以后好用(defnk launch-receive-thread!  [context storm-id receiver-thread-count port transfer-local-fn max-buffer-size   :daemon true   :kill-fn (fn [t] (System/exit 1))   :priority Thread/NORM_PRIORITY]  (let [max-buffer-size (int max-buffer-size)        socket (.bind ^IContext context storm-id port)        ;;线程数默认值给1，根据这个receiver-thread-count定。        thread-count (if receiver-thread-count receiver-thread-count 1)        vthreads (mk-receive-threads context storm-id port transfer-local-fn daemon kill-fn priority socket max-buffer-size thread-count)]    ;;匿名函数fn []，执行加载逻辑    (fn []      (let [kill-socket (.connect ^IContext context storm-id "localhost" port)]        (log-message "Shutting down receiving-thread: [" storm-id ", " port "]")        (.send ^IConnection kill-socket                  -1 (byte-array []))                (.close ^IConnection kill-socket)                (log-message "Waiting for receiving-thread:[" storm-id ", " port "] to die")                (for [thread-id (range thread-count)]              (.join (vthreads thread-id)))                (log-message "Shutdown receiving-thread: [" storm-id ", " port "]")        ))))