runtime-core: Guard from multiple invocations, fix #708

runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/internal/component/StatisticsReporterSchedulerComponentImpl.java

@@ -24,18 +24,25 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 /**
  *
  * @author Per Minborg
  */
 public class StatisticsReporterSchedulerComponentImpl implements StatisticsReporterSchedulerComponent {
 
+    private final AtomicBoolean outstanding;
+
     @Config(name = "statistics.scheduler.enabled", value = "true")
     private boolean enabled;
 
     private ScheduledExecutorService scheduler;
 
+    public StatisticsReporterSchedulerComponentImpl() {
+        outstanding = new AtomicBoolean();
+    }
+
     @ExecuteBefore(State.INITIALIZED)
     public void init() {
         if (enabled) {
@@ -51,7 +58,7 @@ public void init() {
     public void start(StatisticsReporterComponent src) {
         if (enabled) {
             scheduler.submit(src::reportStarted);
-            scheduler.scheduleAtFixedRate(src::alive, 1, 1, TimeUnit.HOURS);
+            scheduler.scheduleAtFixedRate(() -> guardedCall(src::alive), 1, 1, TimeUnit.HOURS);
         }
     }
 
@@ -70,4 +77,19 @@ public void stop(StatisticsReporterComponent src) {
         }
     }
 
+    /**
+     * Method to guard from multiple invocations. Used to fix #708
+     * @param r runnable
+     */
+    void guardedCall(Runnable r) {
+        if (outstanding.compareAndSet(false,true)) {
+            try {
+                r.run();
+            } finally {
+                outstanding.set(false);
+            }
+
+        }
+    }
+
 }

runtime-parent/runtime-core/src/test/java/com/speedment/runtime/core/internal/component/StatisticsReporterSchedulerComponentImplTest.java

@@ -0,0 +1,50 @@
+package com.speedment.runtime.core.internal.component;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class StatisticsReporterSchedulerComponentImplTest {
+
+    @Test
+    void guardedCallStalled() {
+
+        final AtomicBoolean called = new AtomicBoolean();
+        final StatisticsReporterSchedulerComponentImpl instance = new StatisticsReporterSchedulerComponentImpl();
+
+        final Thread t0 = new Thread(() -> { instance.guardedCall(() -> dly(1000)); });
+        final Thread t1 = new Thread(() -> { called.set(true); });
+
+        t0.start();
+        dly(100);
+        t1.start();
+
+        assertFalse(called.get());
+    }
+
+
+    @Test
+    void guardedCallClean() {
+
+        final AtomicBoolean called = new AtomicBoolean();
+        final StatisticsReporterSchedulerComponentImpl instance = new StatisticsReporterSchedulerComponentImpl();
+
+        instance.guardedCall(() -> {});
+        instance.guardedCall(() -> called.set(true));
+
+        assertTrue(called.get());
+    }
+
+
+
+    private void dly(long ms) {
+        try {
+            Thread.sleep(ms);
+        } catch (InterruptedException ignored) {
+
+        }
+    }
+
+}