From 7db412df69ded4f035cfa21c5a49451d31877d23 Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jodersky@gmail.com>
Date: Mon, 25 May 2015 11:41:03 +0200
Subject: add deathwatch to watchers

---
 .../github/jodersky/flow/internal/Watcher.scala    | 38 ++++++++++++++++++----
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/flow-main/src/main/scala/com/github/jodersky/flow/internal/Watcher.scala b/flow-main/src/main/scala/com/github/jodersky/flow/internal/Watcher.scala
index c8ca374..8d89fb4 100644
--- a/flow-main/src/main/scala/com/github/jodersky/flow/internal/Watcher.scala
+++ b/flow-main/src/main/scala/com/github/jodersky/flow/internal/Watcher.scala
@@ -1,8 +1,8 @@
 package com.github.jodersky.flow
 package internal
 
-import akka.actor.{ Actor, ActorRef, Props }
-import java.nio.file.{ ClosedWatchServiceException, Files, FileSystems, Path, Paths, WatchEvent, WatchKey }
+import akka.actor.{ Actor, ActorRef, Props, Terminated }
+import java.nio.file.{ ClosedWatchServiceException, FileSystems, Files, Path, Paths, WatchEvent, WatchKey }
 import java.nio.file.StandardWatchEventKinds._
 import scala.collection.JavaConversions._
 import scala.collection.mutable.{ HashMap, Map, MultiMap, Set }
@@ -18,6 +18,25 @@ class Watcher(from: Option[ActorRef]) extends Actor {
   //directory -> watchkey
   private val keys: Map[String, WatchKey] = Map.empty
 
+  def subscribe(directory: String, client: ActorRef): WatchKey = {
+    val normal = Paths.get(directory).toAbsolutePath
+    val index = normal.toString
+    val key = keys.getOrElseUpdate(index, watcher.register(normal))
+    clients addBinding (index, client)
+    key
+  }
+
+  def unsubscribe(directory: String, client: ActorRef): Unit = {
+    val index = Paths.get(directory).toAbsolutePath.toString
+
+    clients removeBinding (index, sender)
+
+    if (clients.get(index).isEmpty && keys.get(index).isDefined) {
+      keys(index).cancel()
+      keys -= index
+    }
+  }
+
   def reply(msg: Any, sender: ActorRef) = {
     val origin = from match {
       case Some(ref) => ref
@@ -39,11 +58,11 @@ class Watcher(from: Option[ActorRef]) extends Actor {
       val normal = normalPath.toString
 
       Try {
-        keys.getOrElseUpdate(normal, watcher.watch(normalPath))
+        subscribe(directory, sender)
       } match {
         case Failure(err) => reply(Serial.CommandFailed(w, err), sender)
         case Success(key) =>
-          clients addBinding (normal, sender)
+          context watch sender
           if (!skipInitial) {
             Files.newDirectoryStream(normalPath) foreach { path =>
               if (!Files.isDirectory(path)) {
@@ -63,11 +82,16 @@ class Watcher(from: Option[ActorRef]) extends Actor {
         keys -= normal
       }
 
+    case Terminated(client) =>
+      for ((directory, c) <- clients if c == client) {
+        unsubscribe(directory, client)
+      }
+
     case Watcher.NewFile(directory, file) =>
       val normal = directory.toAbsolutePath
       val absFile = normal resolve file
-      clients.getOrElse(normal.toString, Set.empty) foreach { ref =>
-        reply(Serial.Connected(absFile.toString), ref)
+      clients.getOrElse(normal.toString, Set.empty) foreach { client =>
+        reply(Serial.Connected(absFile.toString), client)
       }
 
     case ThreadDied(`watcher`, err) => throw err //go down with watcher thread
@@ -87,7 +111,7 @@ object Watcher {
 
     private val service = FileSystems.getDefault().newWatchService()
 
-    def watch(directory: Path) = directory.register(service, ENTRY_CREATE)
+    def register(directory: Path) = directory.register(service, ENTRY_CREATE)
 
     override def run(): Unit = {
       var stop = false
-- 
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