stm

I'm writing a stateful server in Clojure backed by Neo4j that can serve socket requests, like HTTP. Which means, of course, that I need to be able to start and stop socket servers from within this server. Design-wise, I would want to be able to declare a "service" within this server and start and stop it. What I'm trying to wrap my mind around in Clojure is how to ensure that starting and stopping these services is thread-safe. This server I'm writing will have NREPL embedded inside it and process incoming requests in a parallel way. Some of these requests will be administrative: start service

@Scheduled(cron = " 0 00 00 1 4,7,10,1 ?")//每个季度的第一天零点进行统计此注解是每个季度结束后的下一天执行(因为Spring不识别字母（L---每月最后一天）)所以只能采用下个月的第一天以下代码针对时间进行处理 Calendar cal = Calendar.getInstance();//当前时间int month = cal.get(Calendar.MONTH) + 1;//当前月份int year = cal.get(Calendar.YEAR);//当前年int quarter=0;//当前季度int stm = 1;//季度的起始月份int etm = 3;//季度的结束月份switch (month){ case 1: stm = 10; etm=12; quarter=3; year=year-1; break;//因为一月份进入方法是统计上一年第四季度的信息，所以处理年份信息 case 10: stm = 7; etm=9; quarter=2; break;//本年 case 7: stm = 4; etm=6; quarter=1; break;//本年 case 4: stm = 1; etm=3; quarter=0; break;//本年}最终得到 year---年份　　　　 quarter--季度　　　　

I have a TChan as input for a thread which should behave like this: If sombody writes to the TChan within a specific time, the content should be retrieved. If there is nothing written within the specified time, it should unblock and continue with Nothing . My attempt on this was to use the timeout function from System.Timeout like this: timeout 1000000 $ atomically $ readTChan pktChannel This seemed to work but now I discovered, that I am sometimes loosing packets (they are written to the channel, but not read on the other side. In the log I get this: 2014.063.11.53.43.588365 Pushing Recorded

Is there any way to poll whether Clojure's STM transactions are being retried, and at what rate? You can observe the history count of a ref which will indicate that there is contention on it: user=> (def my-ref (ref 0 :min-history 1)) #'user/my-ref user=> (ref-history-count my-ref) 0 user=> (dosync (alter my-ref inc)) 1 user=> (ref-history-count my-ref) 1 The history count does not directly represent contention. Instead it represents the number of past values that have been maintained in order to service concurrent reads. The size of the history is limited by min and max values. By default

What is the difference between Clojure STM (dosync) approach and Java synchronize Block? I'm reading the code below from "The sleeping barber" problem. ( http://www.bestinclass.dk/index.clj/2009/09/scala-vs-clojure-round-2-concurrency.html ) (defn the-shop [a] (print "[k] entering shop" a) (dosync (if (< (count @queue) seats) (alter queue conj a) (print "[s] turning away customer" a)))) To avoid race conditions, dosync is used, so i ask myself "What is the difference (STM) from Java synchronize block" ? Will it block this critical code ? Thanks in advance ! Dantas dosync and synchronized give