docker: add a README

[nit.git] / lib / pthreads / threadpool.nit

diff --git a/lib/pthreads/threadpool.nit b/lib/pthreads/threadpool.nit
index 42931d3..02042ba 100644 (file)
--- 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