Support of externally created threads

src/jvmMain/kotlin/ru/landgrafhomyak/multitasking_0/threads/DrivenPlatformThread.kt

@@ -11,15 +11,9 @@ internal class DrivenPlatformThread : Thread {
 
 	override val _nativeThread: jThread
 
-	private val _sync: ReentrantLock
-	private var _uncaughtException: Throwable?
-	private var _isExplicitlyDestroyed: Boolean
 	private val _threadFinishedWaiter: CountDownLatch
 
 	internal constructor(name: String, isDaemon: Boolean, routine: ThreadRoutine) : super() {
-		this._sync = ReentrantLock()
-		this._uncaughtException = null
-		this._isExplicitlyDestroyed = false
 		this._threadFinishedWaiter = CountDownLatch(1)
 
 		this._nativeThread = jThread.ofPlatform().name(name).daemon(isDaemon).unstarted(this.Kernel(routine))
@@ -28,6 +22,7 @@ internal class DrivenPlatformThread : Thread {
 	private inner class Kernel(private val _routine: ThreadRoutine) : Runnable {
 		override fun run() {
 			try {
+				Thread._tl_currentThread.set(this@DrivenPlatformThread)
 				this._routine.runThread(this@DrivenPlatformThread)
 			} catch (t: Throwable) {
 				this@DrivenPlatformThread._sync.withLock {
@@ -39,84 +34,13 @@ internal class DrivenPlatformThread : Thread {
 		}
 	}
 
-	override val state: State
-		get() {
-			this._sync.withLock {
-				if (this._isExplicitlyDestroyed)
-					return State.DESTROYED
-
-				when (this._nativeThread.state) {
-					jThread.State.NEW -> return State.NEW
-					jThread.State.RUNNABLE -> return State.NOT_FINISHED
-					jThread.State.BLOCKED -> return State.NOT_FINISHED
-					jThread.State.WAITING -> return State.NOT_FINISHED
-					jThread.State.TIMED_WAITING -> return State.NOT_FINISHED
-					jThread.State.TERMINATED -> {
-						if (this._uncaughtException == null)
-							return State.FINISHED_SUCCESSFULLY
-						else
-							return State.FINISHED_WITH_ERROR
-					}
-				}
-			}
-		}
-
-	override val uncaughtException: Throwable
-		get() {
-			this._sync.withLock {
-				val e = this._uncaughtException
-				if (e != null)
-					return e
-
-				when (this._nativeThread.state) {
-					jThread.State.NEW, jThread.State.RUNNABLE, jThread.State.BLOCKED, jThread.State.WAITING, jThread.State.TIMED_WAITING ->
-						throw IllegalStateException("Thread not finished yet")
-
-					jThread.State.TERMINATED -> throw IllegalStateException("Thread finished without uncaught exceptions")
-				}
-			}
-		}
-
-	override fun start() {
-		this._sync.withLock {
-			if (this._isExplicitlyDestroyed)
-				throw IllegalStateException("Thread already was started, finished and destroyed")
-			// stdlib's errors aren't verbose
-			when (this._nativeThread.state) {
-				jThread.State.NEW -> {}
-				jThread.State.TERMINATED -> throw IllegalStateException("Thread already was started and finished")
-				jThread.State.RUNNABLE, jThread.State.BLOCKED, jThread.State.WAITING, jThread.State.TIMED_WAITING ->
-					throw IllegalStateException("Thread already was started")
-			}
-
-			this._nativeThread.start()
-		}
-	}
-
 	override fun join() {
 		this._sync.withLock {
-			if (this._isExplicitlyDestroyed)
-				throw IllegalStateException("Can't join on destroyed thread")
-			if (this._nativeThread.state == jThread.State.NEW)
-				throw IllegalStateException("Can't join on thread that isn't started")
+			this._assertJoinAllowed()
 		}
 
 		// stdlib's join uses Object.wait which may block caller virtual thread, so let wait in way virtual threads support
 		this._threadFinishedWaiter.await()
 		this._nativeThread.join()
 	}
-
-	override fun releaseResources() {
-		this._sync.withLock {
-			if (this._isExplicitlyDestroyed)
-				throw IllegalStateException("Thread already destroyed")
-			when (this._nativeThread.state) {
-				jThread.State.NEW -> {}
-				jThread.State.TERMINATED -> {}
-				jThread.State.RUNNABLE, jThread.State.BLOCKED, jThread.State.WAITING, jThread.State.TIMED_WAITING ->
-					throw IllegalStateException("Thread already was started")
-			}
-			this._isExplicitlyDestroyed = true
-		}
-	}
 }

src/jvmMain/kotlin/ru/landgrafhomyak/multitasking_0/threads/ExternalThread.kt

@@ -0,0 +1,34 @@
+package ru.landgrafhomyak.multitasking_0.threads
+
+import java.lang.Thread as jThread
+import kotlin.concurrent.withLock
+
+internal class ExternalThread : Thread {
+	override fun toString(): String = TODO()
+
+	override val _nativeThread: jThread
+
+	internal constructor(nativeThread: jThread) : super() {
+		this._nativeThread = nativeThread
+		nativeThread.uncaughtExceptionHandler = this.UncaughtExceptionHandlerImpl(nativeThread.uncaughtExceptionHandler)
+		if (nativeThread.state == jThread.State.TERMINATED)
+			this._isExplicitlyDestroyed = true
+	}
+
+	private inner class UncaughtExceptionHandlerImpl(
+		private val _next: jThread.UncaughtExceptionHandler?,
+	) : jThread.UncaughtExceptionHandler {
+		override fun uncaughtException(t: jThread?, e: Throwable?) {
+			this@ExternalThread._uncaughtException = e
+			this._next?.uncaughtException(t, e)
+		}
+	}
+
+	override fun join() {
+		this._sync.withLock {
+			this._assertJoinAllowed()
+		}
+
+		this._nativeThread.join()
+	}
+}

src/jvmMain/kotlin/ru/landgrafhomyak/multitasking_0/threads/Thread.kt

@@ -1,25 +1,108 @@
 package ru.landgrafhomyak.multitasking_0.threads
 
+import java.util.concurrent.locks.ReentrantLock
+import kotlin.concurrent.withLock
 import java.lang.Thread as jThread
 import ru.landgrafhomyak.multitasking_0.Fiber
 
 @Suppress("AMBIGUOUS_EXPECTS", "ACTUAL_WITHOUT_EXPECT")
 public actual sealed class Thread {
-	actual abstract override fun toString(): String
 	public actual var runningFiber: Fiber? = null
 
 	protected abstract val _nativeThread: jThread
+	protected val _sync: ReentrantLock = ReentrantLock()
+	protected var _isExplicitlyDestroyed: Boolean = false
+	protected var _uncaughtException: Throwable? = null
 
-	public actual val name: String get() = this._nativeThread.name
-	public actual val isDaemon: Boolean get() = this._nativeThread.isDaemon
-	public actual abstract val state: State
-	public actual abstract val uncaughtException: Throwable
-	public actual abstract fun releaseResources()
+	actual abstract override fun toString(): String
 
-	public actual abstract fun start()
+	public actual val name: String
+		get() = this._nativeThread.name
+
+	public actual val isDaemon: Boolean
+		get() = this._nativeThread.isDaemon
+
+	public actual val state: State
+		get() {
+			this._sync.withLock {
+				if (this._isExplicitlyDestroyed)
+					return State.DESTROYED
+
+				when (this._nativeThread.state) {
+					jThread.State.NEW -> return State.NEW
+					jThread.State.RUNNABLE -> return State.NOT_FINISHED
+					jThread.State.BLOCKED -> return State.NOT_FINISHED
+					jThread.State.WAITING -> return State.NOT_FINISHED
+					jThread.State.TIMED_WAITING -> return State.NOT_FINISHED
+					jThread.State.TERMINATED -> {
+						if (this._uncaughtException == null)
+							return State.FINISHED_SUCCESSFULLY
+						else
+							return State.FINISHED_WITH_ERROR
+					}
+				}
+			}
+		}
+
+	public actual val uncaughtException: Throwable
+		get() {
+			this._sync.withLock {
+				val e = this._uncaughtException
+				if (e != null)
+					return e
+
+				when (this._nativeThread.state) {
+					jThread.State.NEW, jThread.State.RUNNABLE, jThread.State.BLOCKED, jThread.State.WAITING, jThread.State.TIMED_WAITING ->
+						throw IllegalStateException("Thread not finished yet")
+
+					jThread.State.TERMINATED -> throw IllegalStateException("Thread finished without uncaught exceptions")
+				}
+			}
+		}
+
+
+	public actual fun start() {
+		this._sync.withLock {
+			if (this._isExplicitlyDestroyed)
+				throw IllegalStateException("Thread already was started, finished and destroyed")
+			// stdlib's errors aren't verbose
+			when (this._nativeThread.state) {
+				jThread.State.NEW -> {}
+				jThread.State.TERMINATED -> throw IllegalStateException("Thread already was started and finished")
+				jThread.State.RUNNABLE, jThread.State.BLOCKED, jThread.State.WAITING, jThread.State.TIMED_WAITING ->
+					throw IllegalStateException("Thread already was started")
+			}
+
+			this._nativeThread.start()
+		}
+	}
+
+	/**
+	 * Requires explicit synchronization
+	 */
+	protected fun _assertJoinAllowed() {
+		if (this._isExplicitlyDestroyed)
+			throw IllegalStateException("Can't join on destroyed thread")
+		if (this._nativeThread.state == jThread.State.NEW)
+			throw IllegalStateException("Can't join on thread that isn't started")
+	}
 
 	public actual abstract fun join()
 
+	public actual fun releaseResources() {
+		this._sync.withLock {
+			if (this._isExplicitlyDestroyed)
+				throw IllegalStateException("Thread already destroyed")
+			when (this._nativeThread.state) {
+				jThread.State.NEW -> {}
+				jThread.State.TERMINATED -> {}
+				jThread.State.RUNNABLE, jThread.State.BLOCKED, jThread.State.WAITING, jThread.State.TIMED_WAITING ->
+					throw IllegalStateException("Thread already was started")
+			}
+			this._isExplicitlyDestroyed = true
+		}
+	}
+
 	public actual enum class State {
 		NEW,
 		NOT_FINISHED,
@@ -28,15 +111,22 @@ public actual sealed class Thread {
 		DESTROYED
 	}
 
-	public actual companion object {
-		@JvmStatic
-		public actual fun create(name: String, isDaemon: Boolean, routine: ThreadRoutine): Thread {
-			TODO()
+	private object CurrentThreadVariable : ThreadLocal<Thread?>() {
+		override fun initialValue(): Thread? {
+			return ExternalThread(jThread.currentThread())
+		}
 	}
 
+	public actual companion object {
 		@JvmStatic
-		public actual fun currentThread(): Thread {
-			TODO()
-		}
+		internal val _tl_currentThread: ThreadLocal<Thread?> get() = CurrentThreadVariable
+
+		@JvmStatic
+		public actual fun create(name: String, isDaemon: Boolean, routine: ThreadRoutine): Thread =
+			DrivenPlatformThread(name, isDaemon, routine)
+
+		@JvmStatic
+		public actual fun currentThread(): Thread =
+			this._tl_currentThread.get() ?: throw RuntimeException("This java thread can't be wrapped")
 	}
 }

src/jvmMain/kotlin/ru/landgrafhomyak/multitasking_0/threads/impl/java_virtual_threads/JavaVirtualThreadFiber.kt

@@ -0,0 +1,126 @@
+package ru.landgrafhomyak.multitasking_0.threads.impl.java_virtual_threads
+
+import java.lang.Thread as jThread
+import java.util.concurrent.locks.Condition
+import java.util.concurrent.locks.ReentrantLock
+import kotlin.concurrent.withLock
+import ru.landgrafhomyak.multitasking_0.ExecutionState
+import ru.landgrafhomyak.multitasking_0.Fiber
+import ru.landgrafhomyak.multitasking_0.FiberRoutine
+import ru.landgrafhomyak.multitasking_0.threads.Thread as wThread
+
+public class JavaVirtualThreadFiber : Fiber {
+	private val _thisVThread: jThread
+	private val _syncLock: ReentrantLock
+	private val _syncCond: Condition
+	private var _state: ExecutionState
+	private var _uncaughtException: Throwable?
+	override val name: String
+	private var _resumedOnThread: wThread?
+	private var _resumedOnFiber: Fiber?
+
+	public constructor(name: String, routine: FiberRoutine) {
+		this.name = name
+		this._syncLock = ReentrantLock()
+		this._syncCond = this._syncLock.newCondition()
+		this._state = ExecutionState.CREATED
+		this._uncaughtException = null
+		this._resumedOnThread = null
+		this._resumedOnFiber = null
+
+		this._syncLock.withLock {
+			this._thisVThread = jThread.ofVirtual().name("fiber: $name").start(this.Kernel(routine))
+			this._syncCond.await()
+		}
+	}
+
+	private inner class Kernel(private val _routine: FiberRoutine) : Runnable {
+		override fun run() {
+			try {
+				this@JavaVirtualThreadFiber._syncLock.withLock {
+					this@JavaVirtualThreadFiber._syncCond.signal()
+					this@JavaVirtualThreadFiber._syncCond.await()
+					wThread._tl_currentThread.set(this@JavaVirtualThreadFiber._resumedOnThread!!)
+				}
+				this._routine.runFiber(this@JavaVirtualThreadFiber)
+				this@JavaVirtualThreadFiber._syncLock.withLock {
+					this@JavaVirtualThreadFiber._state = ExecutionState.FINISHED_SUCCESSFULLY
+					this@JavaVirtualThreadFiber._syncCond.signal()
+				}
+			} catch (t: Throwable) {
+				this@JavaVirtualThreadFiber._syncLock.withLock {
+					this@JavaVirtualThreadFiber._uncaughtException = t
+					this@JavaVirtualThreadFiber._state = ExecutionState.FINISHED_WITH_ERROR
+					this@JavaVirtualThreadFiber._syncCond.signal()
+				}
+			}
+		}
+	}
+
+	override val ownerThread: ru.landgrafhomyak.multitasking_0.threads.Thread? get() = null
+	override val state: ExecutionState get() = this._syncLock.withLock { this._state }
+	override val resumedOnThread: ru.landgrafhomyak.multitasking_0.threads.Thread? get() = this._syncLock.withLock { this._resumedOnThread }
+	override val resumedOnFiber: Fiber? get() = this._syncLock.withLock { this._resumedOnFiber }
+
+	override fun yield() {
+		if (jThread.currentThread() !== this._thisVThread)
+			TODO("err")
+
+		this._syncLock.withLock {
+			when (this._state) {
+				ExecutionState.RUNNING -> this._state = ExecutionState.MANUALLY_SUSPENDED
+				ExecutionState.CREATED, ExecutionState.MANUALLY_SUSPENDED ->
+					throw IllegalStateException(".yield() called inside fiber while it is suspended")
+
+				ExecutionState.FINISHED_SUCCESSFULLY, ExecutionState.FINISHED_WITH_ERROR ->
+					throw IllegalStateException(".yield() called inside fiber after it's marked as finished")
+			}
+
+
+			wThread._tl_currentThread.set(null)
+			this._syncCond.signal()
+			this._syncCond.await()
+			wThread._tl_currentThread.set(this._resumedOnThread!!)
+		}
+	}
+
+	override fun resume() {
+		this._syncLock.withLock {
+			when (this._state) {
+				ExecutionState.CREATED, ExecutionState.MANUALLY_SUSPENDED ->
+					this._state = ExecutionState.RUNNING
+
+				ExecutionState.RUNNING -> {
+					if (jThread.currentThread() == this._thisVThread) {
+						throw IllegalStateException("Recursive fiber execution")
+					} else {
+						throw IllegalStateException("Fiber already running")
+					}
+				}
+
+				ExecutionState.FINISHED_SUCCESSFULLY, ExecutionState.FINISHED_WITH_ERROR -> throw IllegalStateException("Fiber already finished")
+			}
+
+			val currentThread = wThread.currentThread()
+			this._resumedOnThread = currentThread
+			this._resumedOnFiber = currentThread.runningFiber
+			currentThread.runningFiber = this
+
+			this._syncCond.signal()
+			this._syncCond.await()
+
+			currentThread.runningFiber = this._resumedOnFiber
+			this._resumedOnThread = null
+			this._resumedOnFiber = null
+		}
+	}
+
+	override val uncaughtException: Throwable
+		get() = this._uncaughtException ?: when (this._syncLock.withLock { this._state }) {
+			ExecutionState.CREATED, ExecutionState.RUNNING, ExecutionState.MANUALLY_SUSPENDED ->
+				throw IllegalStateException("Fiber not finished yet")
+
+			ExecutionState.FINISHED_SUCCESSFULLY -> throw IllegalStateException("Fiber finished without exception")
+			ExecutionState.FINISHED_WITH_ERROR -> throw IllegalStateException("Finished with exception but it wasn't saved")
+		}
+}