Added close support

Author: bbakerman

src/main/java/org/dataloader/registries/ScheduledDataLoaderRegistry.java

@@ -25,17 +25,27 @@
  * call {@link #rescheduleNow()}.
  */
 @PublicApi
-public class ScheduledDataLoaderRegistry extends DataLoaderRegistry {
+public class ScheduledDataLoaderRegistry extends DataLoaderRegistry implements AutoCloseable {
 
     private final ScheduledExecutorService scheduledExecutorService;
     private final DispatchPredicate dispatchPredicate;
     private final Duration schedule;
+    private volatile boolean closed;
 
     private ScheduledDataLoaderRegistry(Builder builder) {
         this.dataLoaders.putAll(builder.dataLoaders);
         this.scheduledExecutorService = builder.scheduledExecutorService;
         this.dispatchPredicate = builder.dispatchPredicate;
         this.schedule = builder.schedule;
+        this.closed = false;
+    }
+
+    /**
+     * Once closed this registry will never again reschedule checks
+     */
+    @Override
+    public void close() {
+        closed = true;
     }
 
     /**
@@ -92,8 +102,10 @@ public void rescheduleNow() {
     }
 
     private void reschedule(String key, DataLoader<?, ?> dataLoader) {
-        Runnable runThis = () -> dispatchOrReschedule(key, dataLoader);
-        scheduledExecutorService.schedule(runThis, schedule.toMillis(), TimeUnit.MILLISECONDS);
+        if (!closed) {
+            Runnable runThis = () -> dispatchOrReschedule(key, dataLoader);
+            scheduledExecutorService.schedule(runThis, schedule.toMillis(), TimeUnit.MILLISECONDS);
+        }
     }
 
     private void dispatchOrReschedule(String key, DataLoader<?, ?> dataLoader) {

src/test/java/org/dataloader/registries/ScheduledDataLoaderRegistryTest.java

@@ -212,7 +212,49 @@ public void test_it_will_take_out_the_schedule_once_it_dispatches() {
         snooze(2000);
 
         assertThat(calls, equalTo(asList(asList("K1", "K2"), asList("K3", "K4"))));
+    }
+
+    public void test_close_is_a_one_way_door() {
+        AtomicInteger counter = new AtomicInteger();
+        DispatchPredicate countingPredicate = (dataLoaderKey, dataLoader) -> {
+            counter.incrementAndGet();
+            return false;
+        };
+
+        DataLoader<String, String> dlA = TestKit.idLoader();
+        dlA.load("K1");
+        dlA.load("K2");
+
+        ScheduledDataLoaderRegistry registry = ScheduledDataLoaderRegistry.newScheduledRegistry()
+                .register("a", dlA)
+                .dispatchPredicate(countingPredicate)
+                .schedule(Duration.ofMillis(10))
+                .build();
+
+        registry.rescheduleNow();
 
+        snooze(200);
+
+        assertTrue(counter.get() > 0);
+
+        registry.close();
+
+        snooze(100);
+        int countThen = counter.get();
+
+        registry.rescheduleNow();
+        snooze(200);
+        assertEquals(counter.get(), countThen);
 
+        registry.rescheduleNow();
+        snooze(200);
+        assertEquals(counter.get(), countThen);
+
+        registry.dispatchAll();
+        snooze(200);
+        assertEquals(counter.get(), countThen + 1); // will have re-entered
+
+        snooze(200);
+        assertEquals(counter.get(), countThen + 1);
     }
 }