Fix NPE if thread.interrupt is called but not started. (#91)

core/src/main/kotlin/org/pastalab/fray/core/RunContext.kt

@@ -172,7 +172,9 @@ class RunContext(val config: Configuration) {
     val context = registeredThreads[t.id]!!
     mainExiting = true
     while (registeredThreads.any {
-      it.value.state != ThreadState.Completed && it.value != context
+      it.value.state != ThreadState.Completed &&
+          it.value.state != ThreadState.Created &&
+          it.value != context
     }) {
       try {
         context.state = ThreadState.Enabled
@@ -230,14 +232,17 @@ class RunContext(val config: Configuration) {
     executor.shutdown()
   }
 
-  fun threadStart(t: Thread) {
+  fun threadCreateDone(t: Thread) {
     val originalHanlder = t.uncaughtExceptionHandler
     val handler = UncaughtExceptionHandler { t, e ->
       onReportError(e)
       originalHanlder?.uncaughtException(t, e)
     }
     t.setUncaughtExceptionHandler(handler)
-    registeredThreads[t.id] = ThreadContext(t, registeredThreads.size, this)
+    registeredThreads[t.threadId()] = ThreadContext(t, registeredThreads.size, this)
+  }
+
+  fun threadStart(t: Thread) {
     syncManager.createWait(t, 1)
   }
 
@@ -246,10 +251,6 @@ class RunContext(val config: Configuration) {
     syncManager.wait(t)
   }
 
-  fun monitorEnterDone(lock: Any) {
-    syncManager.wait(lock)
-  }
-
   fun threadPark() {
     val t = Thread.currentThread()
     val context = registeredThreads[t.id]!!

core/src/main/kotlin/org/pastalab/fray/core/RuntimeDelegate.kt

@@ -47,6 +47,12 @@ class RuntimeDelegate(val context: RunContext) : org.pastalab.fray.runtime.Deleg
     entered.set(false)
   }
 
+  override fun onThreadCreateDone(t: Thread) {
+    if (checkEntered()) return
+    context.threadCreateDone(t)
+    entered.set(false)
+  }
+
   override fun onThreadStart(t: Thread) {
     if (checkEntered()) {
       onSkipMethod("thread.start")

core/src/main/kotlin/org/pastalab/fray/core/ThreadContext.kt

@@ -9,7 +9,7 @@ import org.pastalab.fray.rmi.ThreadState
 
 class ThreadContext(val thread: Thread, val index: Int, context: RunContext) {
   val localRandomProbe = context.config.randomnessProvider.nextInt()
-  var state = ThreadState.Paused
+  var state = ThreadState.Created
   var unparkSignaled = false
   var interruptSignaled = false
   var isExiting = false

instrumentation/base/src/main/kotlin/org/pastalab/fray/instrumentation/base/visitors/ThreadInstrumenter.kt

@@ -16,6 +16,19 @@ class ThreadInstrumenter(cv: ClassVisitor) : ClassVisitorBase(cv, Thread::class.
       signature: String?,
       exceptions: Array<out String>?
   ): MethodVisitor {
+    if (name == "<init>" &&
+        descriptor ==
+            "(Ljava/lang/ThreadGroup;Ljava/lang/String;ILjava/lang/Runnable;JLjava/security/AccessControlContext;)V") {
+      return MethodExitVisitor(
+          mv,
+          org.pastalab.fray.runtime.Runtime::onThreadCreateDone,
+          access,
+          name,
+          descriptor,
+          true,
+          false,
+          false)
+    }
     if (name == "start") {
       val eMv =
           MethodExitVisitor(

integration-test/src/main/java/org/pastalab/fray/test/success/thread/ThreadInterruptionWithoutStart.java

@@ -0,0 +1,9 @@
+package org.pastalab.fray.test.success.thread;
+
+public class ThreadInterruptionWithoutStart {
+
+    public static void main(String[] args) {
+        Thread t = new Thread();
+        t.interrupt();
+    }
+}

integration-test/src/test/java/org/pastalab/fray/test/FrayTestCase.java

@@ -17,6 +17,7 @@
 import org.pastalab.fray.test.success.rwlock.ReentrantReadWriteLockDowngradingNoDeadlock;
 import org.pastalab.fray.test.success.rwlock.ReentrantReadWriteLockNoDeadlock;
 import org.pastalab.fray.test.success.stampedlock.StampedLockTryLockNoDeadlock;
+import org.pastalab.fray.test.success.thread.ThreadInterruptionWithoutStart;
 
 import java.util.*;
 
@@ -69,8 +70,9 @@ public void testOne() throws Throwable {
                     new ExecutionInfo(
                             new LambdaExecutor(() -> {
                                 try {
-                                    ReentrantReadWriteLockDowngradingNoDeadlock.main(new String[]{});
+                                    ThreadInterruptionWithoutStart.main(new String[]{});
                                 } catch (Exception e) {
+                                    throw new RuntimeException(e);
                                 }
                                 return null;
                             }),

rmi/src/main/kotlin/org/pastalab/fray/rmi/RemoteScheduler.kt

@@ -10,6 +10,7 @@ enum class ThreadState {
   Running,
   Paused,
   Completed,
+  Created,
 }
 
 data class ThreadInfo(

runtime/src/main/java/org/pastalab/fray/runtime/Delegate.java

@@ -10,6 +10,9 @@
 
 public class Delegate {
 
+    public void onThreadCreateDone(Thread t) {
+    }
+
     public void onThreadStart(Thread t) {
     }
 

runtime/src/main/java/org/pastalab/fray/runtime/Runtime.java

@@ -15,6 +15,10 @@
 public class Runtime {
     public static Delegate DELEGATE = new Delegate();
 
+    public static void onThreadCreateDone(Thread t) {
+        DELEGATE.onThreadCreateDone(t);
+    }
+
     public static void onThreadStart(Thread t) {
         DELEGATE.onThreadStart(t);
     }