Bnorm at 04:45, 30 July 2021

2021-07-30T04:45:39Z

Bnorm: Base robot which uses Kotlin coroutines

2021-07-30T04:03:55Z

Base robot which uses Kotlin coroutines

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== CoroutineRobot ==

Using [https://kotlinlang.org/ Kotlin] and [https://github.com/Kotlin/kotlinx.coroutines coroutines], safe and fair multithreading for a Robot can be implemented in Robocode. This can be achieved with [https://kotlinlang.org/docs/coroutines-basics.html structured concurrency] and a custom thread dispatcher.

<syntaxhighlight lang="Kotlin">
import kotlinx.coroutines.CoroutineDispatcher
import kotlinx.coroutines.runBlocking
import robocode.AdvancedRobot
import java.util.concurrent.LinkedBlockingQueue
import kotlin.concurrent.thread
import kotlin.coroutines.CoroutineContext

abstract class CoroutineRobot : AdvancedRobot() {
private val _computation = QueueCoroutineDispatcher(4)
val Computation: CoroutineDispatcher get() = _computation

private lateinit var _main: CoroutineDispatcher
val Main: CoroutineDispatcher get() = _main

final override fun run() {
try {
runBlocking {
_main = coroutineContext[CoroutineDispatcher]!!
coroutineRun()
}
} finally {
_computation.shutdown()
}
}

abstract suspend fun coroutineRun()

private class QueueCoroutineDispatcher(threadCount: Int) : CoroutineDispatcher() {
private val queue = LinkedBlockingQueue<Runnable?>()
private val threads = List(threadCount) {
thread(name = "Computation $it") {
try {
while (true) {
val task = queue.take() ?: break
task.run()
}
} catch (ignore: InterruptedException) {
// ignore
}
}
}

override fun dispatch(context: CoroutineContext, block: Runnable) {
queue.put(block)
}

fun shutdown() {
repeat(threads.size) {
// poison the queue once for each thread
queue.put(null)
}
}
}
}
</syntaxhighlight>

== Multithreading ==

With the above base class multithreading can be achieved using [https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/coroutine-scope.html coroutineScope], [https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/launch.html launch], and [https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/with-context.html withContext] builder functions.

<syntaxhighlight lang="Kotlin">
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext

class SampleRobot : CoroutineRobot() {
override suspend fun coroutineRun() {
while (true) {
coroutineScope { // Starts a logic container for asynchronous work
launch(Computation) { // Launch asynchronous work on 1 of the 4 computation threads

// Do radar logic

withContext(Main) { // Switch back to run thread
setTurnRadarRightRadians(radarTurn)
}
}
launch(Computation) { // Launch asynchronous work on 1 of the 4 computation threads

// Do firing logic

withContext(Main) { // Switch back to run thread
setTurnGunRightRadians(gunTurn)
setFire(bulletPower)
}
}
launch(Computation) { // Launch asynchronous work on 1 of the 4 computation threads

// Do movement logic

withContext(Main) { // Switch back to run thread
setTurnRightRadians(tankTurn)
setAhead(tankMove)
}
}
}

execute()
}
}
}
</syntaxhighlight>

@@ Line 32: / Line 32: @@
      private class QueueCoroutineDispatcher(threadCount: Int) : CoroutineDispatcher() {
-         private val queue = LinkedBlockingQueue<Runnable?>()
+        companion object {
          private val threads = List(threadCount) {
              thread(name = "Computation $it") {
                  try {
                      while (true) {
-                         val task = queue.take() ?: break
+                         val task = queue.take()
                          task.run()
+                     }
@@ Line 53: / Line 58: @@
              repeat(threads.size) {
                  // poison the queue once for each thread
-                 queue.put(null)
+                 queue.put(POISON)
+             }
+         }

User:Bnorm/CoroutineRobot - Revision history

Bnorm at 04:45, 30 July 2021

Bnorm: Base robot which uses Kotlin coroutines