Update ThreadParallel.kt

src/net/torvald/terrarum/concurrent/ThreadParallel.kt

@@ -1,14 +1,19 @@
 package net.torvald.terrarum.concurrent
 
 import net.torvald.terrarum.Terrarum
+import kotlin.collections.ArrayList
+
+typealias RunnableFun = () -> Unit
+/** Int: index of the processing core */
+typealias ThreadableFun = (Int) -> Unit
 
 /**
  * Created by minjaesong on 2016-05-25.
  */
 object ThreadParallel {
-    val threads = Terrarum.THREADS // modify this to your taste
+    val threadCount = Terrarum.THREADS // modify this to your taste
 
-    private val pool: Array<Thread?> = Array(threads, { null })
+    private val pool: Array<Thread?> = Array(threadCount, { null })
 
     /**
      * Map Runnable object to certain index of the thread pool.
@@ -23,7 +28,7 @@ object ThreadParallel {
     /**
      * @param runFunc A function that takes an int input (the index), and returns nothing
      */
-    fun map(index: Int, prefix: String, runFunc: (Int) -> Unit) {
+    fun map(index: Int, prefix: String, runFunc: ThreadableFun) {
         val runnable = object : Runnable {
             override fun run() {
                 runFunc(index)
@@ -57,10 +62,60 @@ object ThreadParallel {
     }
 }
 
+/**
+ * A thread pool that will hold the execution until all the tasks are completed.
+ *
+ * Tasks are not guaranteed to be done orderly; but the first task in the list will be executed first.
+ */
+object BlockingThreadPool {
+    val threadCount = Terrarum.THREADS // modify this to your taste
+    private val pool: Array<Thread?> = Array(threadCount, { null })
+    private var tasks: List<RunnableFun> = ArrayList<RunnableFun>()
+    private var allTasksDone = false
+    private var dispatchedTasks = 0
+    private var threadPrefix = ""
+
+    fun map(prefix: String, tasks: List<RunnableFun>) = setTasks(tasks, prefix)
+    fun setTasks(tasks: List<RunnableFun>, prefix: String) {
+        this.tasks = tasks
+        dispatchedTasks = 0
+        threadPrefix = prefix
+    }
+
+    fun dequeueTask(): RunnableFun {
+        dispatchedTasks += 1
+        return tasks[dispatchedTasks - 1]
+    }
+
+    fun startAllWaitForDie() {
+        while (!allTasksDone) {
+            // marble rolling down the slanted channel-track of threads, if a channel is empty (a task assigned
+            //     to the thread is dead) the marble will roll into the channel, and the marble is a task  #MarbleMachineX
+            for (i in 0 until threadCount) {
+                // but unlike the marble machine, marble don't actually roll down, we can just pick up any number
+                // of marbles and put it into an empty channel whenever we encounter one
+
+                // SO WHAT WE DO is first fill any empty channels:
+                if (pool[i] == null || pool[i]!!.state == Thread.State.TERMINATED) {
+                    pool[i] = Thread(dequeueTask().makeRunnable(), "$threadPrefix-$dispatchedTasks") // thread name index is one-based
+                    pool[i]!!.start()
+                }
+
+                // then, sleep this very thread, wake if any of the thread in the pool is terminated,
+                // and GOTO loop_start; if we don't sleep, this function will be busy-waiting
+
+
+            }
+        }
+    }
+
+    private fun RunnableFun.makeRunnable() = Runnable { this.invoke() }
+}
+
 object ParallelUtils {
     fun <T, R> Iterable<T>.parallelMap(transform: (T) -> R): List<R> {
-        val tasks = this.sliceEvenly(ThreadParallel.threads)
-        val destination = Array(ThreadParallel.threads) { ArrayList<R>() }
+        val tasks = this.sliceEvenly(ThreadParallel.threadCount)
+        val destination = Array(ThreadParallel.threadCount) { ArrayList<R>() }
         tasks.forEachIndexed { index, list ->
             ThreadParallel.map(index, "ParallelUtils.parallelMap@${this.javaClass.canonicalName}") {
                 for (item in list)