Coverage Summary for Class: LinkListener (it.unibo.tuprolog.argumentation.parallel.federation)

 package it.unibo.tuprolog.argumentation.parallel.federation
 
 /**
  * A connection between two sites, over any transport (memory, the threads of a process, a socket): the frames sent on
  * it arrive in the order they were sent, until it is closed
  */
 interface Link {
     /** Sends [frame] to the site at the other end, if the link is still open */
     fun send(frame: String)
 
     /** Whether this site opened the link: a site requiring a code (see [Site.requiresCode]) checks the links it did not */
     val outgoing: Boolean get() = false
 
     /** The code this site presents on a link it opened, to a site requiring one: none by default */
     val code: String? get() = null
 
     /** The address of the other end, if known: the wrong codes of an address are refused for a while, after a few */
     val address: String? get() = null
 
     /** Closes the link: both ends are told (see [LinkListener.closed]) */
     fun close()
 }
 
 /** A site, as the transports see it: told of its links as they open, of the frames on them and of their closing */
 interface LinkListener {
     fun opened(link: Link)
 
     fun received(
         link: Link,
         frame: String,
     )
 
     fun closed(link: Link)
 }
 
 /** Links between sites of the same process, for tests and for sites sharing a machine without a network between them */
 object MemoryLinks {
     /**
      * A link between [first] and [second], each told of its end: the frames are delivered by [via] if given, on the
      * thread of the sender otherwise
      */
     fun connect(
         first: LinkListener,
         second: LinkListener,
         via: TaskQueue? = null,
     ) = link(first, second, via) { one, _ -> first.opened(one) }
 
     /** A link between [site] and [delegate], a delegate of it (see [Site.delegate]), as [connect] makes it */
     fun delegate(
         site: Site,
         delegate: LinkListener,
         via: TaskQueue? = null,
     ) = link(site, delegate, via) { one, _ -> site.delegate(one) }
 
     private fun link(
         first: LinkListener,
         second: LinkListener,
         via: TaskQueue?,
         open: (Link, Link) -> Unit,
     ) {
         val one = End(first, via)
         val other = End(second, via)
         one.other = other
         other.other = one
         open(one, other)
         second.opened(other)
     }
 
     private class End(
         private val listener: LinkListener,
         private val via: TaskQueue?,
     ) : Link {
         lateinit var other: End
 
         @kotlin.concurrent.Volatile
         private var open = true
 
         override fun send(frame: String) {
             if (open) run { other.listener.received(other, frame) }
         }
 
         override fun close() {
             if (!open) return
             open = false
             other.open = false
             run {
                 listener.closed(this)
                 other.listener.closed(other)
             }
         }
 
         private fun run(task: () -> Unit) = via?.post(task) ?: task()
     }
 }