From: BlackMinou <romain.chanoir@viacesi.fr>
Date: Sat, 28 Nov 2015 20:21:24 +0000 (-0500)
Subject: Introduces JoinTask, joinabale tasks
X-Git-Tag: v0.8~54^2~1
X-Git-Url: http://nitlanguage.org?ds=sidebyside

Introduces JoinTask, joinabale tasks

Signed-off-by: BlackMinou <romain.chanoir@viacesi.fr>
---

diff --git a/lib/pthreads/concurrent_collections.nit b/lib/pthreads/concurrent_collections.nit
index 67e6765..d55bad0 100644
--- a/lib/pthreads/concurrent_collections.nit
+++ b/lib/pthreads/concurrent_collections.nit
@@ -499,4 +499,12 @@ class ConcurrentList[E]
 		real_collection.push(e)
 		mutex.unlock
 	end
+
+	redef fun shift
+	do
+		mutex.lock
+		var value = real_collection.shift
+		mutex.unlock
+		return value
+	end
 end
diff --git a/lib/pthreads/examples/threadpool_example.nit b/lib/pthreads/examples/threadpool_example.nit
index f7fafd7..fec1ae2 100644
--- a/lib/pthreads/examples/threadpool_example.nit
+++ b/lib/pthreads/examples/threadpool_example.nit
@@ -19,7 +19,7 @@ import threadpool
 
 # Task printing "hello world" on standard output
 class HWTask
-	super Task
+	super JoinTask
 
 	# Sleeping time
 	var sec: Int
diff --git a/lib/pthreads/threadpool.nit b/lib/pthreads/threadpool.nit
index 42931d3..02042ba 100644
--- a/lib/pthreads/threadpool.nit
+++ b/lib/pthreads/threadpool.nit
@@ -20,7 +20,7 @@ import concurrent_collections
 
 # A simple ThreadPool implemented with an array
 class ThreadPool
-	private var queue = new ConcurrentList[Task].wrap(new List[Task])
+	private var queue = new ConcurrentList[JoinTask].wrap(new List[JoinTask])
 	private var mutex = new Mutex
 	private var cond = new NativePthreadCond
 
@@ -37,7 +37,7 @@ class ThreadPool
 	private fun set_nb_threads(nb: nullable Int) is autoinit do nb_threads = nb or else 5
 
 	# Adds a Task into the queue
-	fun execute(task: Task) do
+	fun execute(task: JoinTask) do
 		queue.push(task)
 		cond.signal
 	end
@@ -47,20 +47,49 @@ end
 private class PoolThread
 	super Thread
 
-	var queue: ConcurrentList[Task]
+	var queue: ConcurrentList[JoinTask]
 	var mutex: Mutex
 	var cond : NativePthreadCond
 
 	redef fun main do
 		loop
-			var t: nullable Task = null
+			var t: nullable JoinTask = null
 			mutex.lock
 			if queue.is_empty then cond.wait(mutex.native.as(not null))
 			if not queue.is_empty then
-				t = queue.pop
+				t = queue.shift
 			end
 			mutex.unlock
-			if t != null then t.main
+			if t != null then
+				t.main
+				t.mutex.lock
+				t.is_done = true
+				var tcond = t.cond
+				if tcond != null then tcond.signal
+				t.mutex.unlock
+			end
+		end
+	end
+end
+
+# A Task which is joinable, meaning it can return a value and if the value is not set yet, it blocks the execution
+class JoinTask
+	super Task
+
+	# Is `self` done ?
+	var is_done = false
+
+	private var mutex = new Mutex
+	private var cond: nullable NativePthreadCond = null
+
+	# Return immediatly if the task terminated, or block waiting for `self` to terminate
+	fun join do
+		mutex.lock
+		if not is_done then
+			var cond = new NativePthreadCond
+			self.cond = cond
+			cond.wait(mutex.native.as(not null))
 		end
+		mutex.unlock
 	end
 end