Execution spinner for unified and improved spinning

src/main/kotlin/ru/dbotthepony/kstarbound/util/ExecutionSpinner.kt

@@ -0,0 +1,74 @@
+package ru.dbotthepony.kstarbound.util
+
+import ru.dbotthepony.kommons.util.MailboxExecutorService
+import ru.dbotthepony.kstarbound.Starbound
+import java.util.concurrent.locks.LockSupport
+import java.util.function.BooleanSupplier
+
+class ExecutionSpinner(private val executor: MailboxExecutorService, private val spinner: BooleanSupplier, private val timeBetweenFrames: Long) : Runnable {
+	private var lastRender = System.nanoTime()
+	private var frameRenderTime = 0L
+	private val frameRenderTimes = LongArray(60) { 1L }
+	private var frameRenderIndex = 0
+	private val renderWaitTimes = LongArray(60) { 1L }
+	private var renderWaitIndex = 0
+
+	val averageRenderWait: Double get() {
+		var sum = 0.0
+
+		for (value in renderWaitTimes)
+			sum += value
+
+		if (sum == 0.0)
+			return 0.0
+
+		sum /= 1_000_000_000.0
+		return sum / renderWaitTimes.size
+	}
+
+	val averageRenderTime: Double get() {
+		var sum = 0.0
+
+		for (value in frameRenderTimes)
+			sum += value
+
+		if (sum == 0.0)
+			return 0.0
+
+		sum /= 1_000_000_000.0
+		return sum / frameRenderTimes.size
+	}
+
+	private fun timeUntilNextFrame(): Long {
+		return Starbound.TICK_TIME_ADVANCE_NANOS - (System.nanoTime() - lastRender) - frameRenderTime
+	}
+
+	fun spin(): Boolean {
+		var diff = timeUntilNextFrame()
+
+		while (diff > 1_000_000L) {
+			executor.executeQueuedTasks()
+			diff = timeUntilNextFrame()
+			if (diff > 1_000_000L) LockSupport.parkNanos(diff - 400_000L)
+		}
+
+		while (diff > 0L) {
+			executor.executeQueuedTasks()
+			diff = timeUntilNextFrame()
+			if (diff > 0L) Thread.yield()
+		}
+
+		val mark = System.nanoTime()
+		val result = spinner.asBoolean
+		frameRenderTime = System.nanoTime() - mark
+		frameRenderTimes[++frameRenderIndex % frameRenderTimes.size] = frameRenderTime
+		renderWaitTimes[++renderWaitIndex % renderWaitTimes.size] = System.nanoTime() - lastRender
+		lastRender = System.nanoTime()
+
+		return result
+	}
+
+	override fun run() {
+		while (spin()) {}
+	}
+}