clojure.lang.LazySeq 不能转换为 clojure.lang.IFn

Question

我是 Riemann 和 Clojure 的新手。我想要做的就是在某些服务的 TTL 到期时向三个电子邮件组发送电子邮件通知。
我创建了某种配置文件，用于存储电子邮件列表:

{
  :email_group_1 (
                  "first@example.com"
                  "second@example.ru"
                 )
  :email_group_2 (
                  "third@example.com"
                 )
}

我的 riemann 配置如下所示:

(logging/init {:console true})
(import org.apache.log4j.Level)
(logging/set-level Level/DEBUG)

(require '[clojure.java.io :as io])
(import '[java.io PushbackReader])

(let [host "0.0.0.0"]
  (tcp-server {:host host :port 60001})
  (udp-server {:host host})
  (ws-server  {:host host :port 60003}))
(repl-server  {:host "127.0.0.1"})

(def cwd (System/getProperty "user.dir"))

(def emails
  (with-open [r (io/reader (str cwd "/etc/emails.clj"))]
             (read (PushbackReader. r))))

(periodically-expire 5)

(def email (mailer))

(defn notify [& egroups]
  (for [egroup egroups]
    (rollup 1 60 (apply email (emails egroup)))))

(let [index (index)]
  (streams
    (default :ttl 60
      index

      (expired
          (where (service "service_connect_active")
                    #(info "expired" %)
                    (notify :email_group_1 :email_group_2))))))

代码看起来不错(对我来说)，但是当此服务过期时，我收到以下错误:

09:45:39 riemann.1      | INFO [2015-05-08 10:45:39,313] Thread-5 - riemann.config - expired {:ttl 60, :time 357766884827/250, :state expired, :service service_connect_active, :host ava.local}
09:45:39 riemann.1      | WARN [2015-05-08 10:45:39,319] Thread-5 - riemann.config - clojure.lang.LazySeq@841649b8 threw
09:45:39 riemann.1      | java.lang.ClassCastException: clojure.lang.LazySeq cannot be cast to clojure.lang.IFn
09:45:39 riemann.1      |   at riemann.config$eval66$stream__70$fn__75.invoke(riemann.development.config:34)
09:45:39 riemann.1      |   at riemann.config$eval66$stream__70.invoke(riemann.development.config:45)
09:45:39 riemann.1      |   at riemann.streams$match$stream__3514$fn__3525.invoke(streams.clj:1209)
09:45:39 riemann.1      |   at riemann.streams$match$stream__3514.invoke(streams.clj:1209)
09:45:39 riemann.1      |   at riemann.streams$default$stream__3731$fn__3742.invoke(streams.clj:1328)
09:45:39 riemann.1      |   at riemann.streams$default$stream__3731.invoke(streams.clj:1328)
09:45:39 riemann.1      |   at riemann.core$stream_BANG_$fn__4415.invoke(core.clj:19)
09:45:39 riemann.1      |   at riemann.core$stream_BANG_.invoke(core.clj:18)
09:45:39 riemann.1      |   at riemann.core$reaper$worker__4529$fn__4539.invoke(core.clj:303)
09:45:39 riemann.1      |   at riemann.core$reaper$worker__4529.invoke(core.clj:297)
09:45:39 riemann.1      |   at riemann.service.ThreadService$thread_service_runner__1973$fn__1974.invoke(service.clj:71)
09:45:39 riemann.1      |   at riemann.service.ThreadService$thread_service_runner__1973.invoke(service.clj:70)
09:45:39 riemann.1      |   at clojure.lang.AFn.run(AFn.java:22)
09:45:39 riemann.1      |   at java.lang.Thread.run(Thread.java:745)

有人可以帮我吗？谢谢。

Answer 1

“cannot to be cast to clojure.lang.IFn”错误总是指向一些期望函数被赋予一些不能被视为这样的东西......

(defn notify [& egroups]
  (for [egroup egroups]
    (rollup 1 60 (apply email (emails egroup)))))

这将返回一个 for-generated LazySeq 的汇总流，而不是实际的流(在 Riemann 中，流是一个 IFn)。因此，当 Riemann 尝试将流作为 IFn 调用时，您的错误就会发生......

怎么样:

(defn notify [& egroups]
  (rollup 1 60 (apply email (mapcat emails egroups))))

在这里，我们只是预先将群组列表转换为电子邮件列表，然后继续我们的生活。

或者，如果您确实想要多个流(例如，避免共享 To: 行)，则将它们应用于汇总。

(defn notify [& egroups]
  (apply rollup 1 60 (map email (map emails groups))))

希望这会有所帮助，我显然没有复制您的整个配置。