ConditionVariable#wait needs to check both for Thread#{wakeup,run} and after a safepoint

Author: eregon

src/main/java/org/truffleruby/core/mutex/ConditionVariableNodes.java

@@ -91,6 +91,10 @@ private void waitInternal(DynamicObject conditionVariable, ReentrantLock mutexLo
                 endNanoTime = 0;
             }
 
+            // Clear the wakeUp flag, following Ruby semantics:
+            // it should only be considered if we are inside Mutex#sleep when Thread#{run,wakeup} is called.
+            Layouts.THREAD.getWakeUp(thread).set(false);
+
             // condLock must be locked before unlocking mutexLock, to avoid losing potential signals
             getContext().getThreadManager().runUntilResult(this, () -> {
                 condLock.lockInterruptibly();
@@ -167,6 +171,17 @@ private void awaitSignal(DynamicObject self, DynamicObject thread, long duration
                     } finally {
                         condLock.lock();
                     }
+
+                    // Thread#{wakeup,run} might have woken us. In that a case, no signal is consumed.
+                    if (Layouts.THREAD.getWakeUp(thread).getAndSet(false)) {
+                        return;
+                    }
+
+                    // Check if a signal are available now, since another thread might have used
+                    // ConditionVariable#signal while we released condLock to check for safepoints.
+                    if (consumeSignal(self)) {
+                        return;
+                    }
                 }
             }
         }