Support negative delays in ScheduledFutures executed by the Determini…

jmock/src/main/java/org/jmock/lib/concurrent/DeterministicScheduler.java

@@ -27,7 +27,8 @@
  */
 public class DeterministicScheduler implements ScheduledExecutorService {
     private final DeltaQueue<ScheduledTask<?>> deltaQueue = new DeltaQueue<ScheduledTask<?>>();
-
+    private long passedTicks = 0;
+
     /**
      * Runs time forwards by a given duration, executing any commands scheduled for
      * execution during that time period, and any background tasks spawned by the 
@@ -39,12 +40,15 @@ public class DeterministicScheduler implements ScheduledExecutorService {
      */
     public void tick(long duration, TimeUnit timeUnit) {
         long remaining = toTicks(duration, timeUnit);
+        long total = remaining;
 
         do {
             remaining = deltaQueue.tick(remaining);
+            passedTicks += (total - remaining);
             runUntilIdle();
-
         } while (deltaQueue.isNotEmpty() && remaining > 0);
+
+        passedTicks += remaining;
     }
 
     /**
@@ -185,6 +189,7 @@ private final class ScheduledTask<T> implements ScheduledFuture<T>, Runnable {
         private boolean isDone = false;
         private T futureResult;
         private Exception failure = null;
+        private long ranAtTicks;
 
         public ScheduledTask(Callable<T> command) {
             this.repeatDelay = -1;
@@ -210,7 +215,11 @@ public boolean repeats() {
         }
 
         public long getDelay(TimeUnit unit) {
-            return unit.convert(deltaQueue.delay(this), TimeUnit.MILLISECONDS);
+            Long delay = deltaQueue.delay(this);
+            if (delay == null) {
+                delay = ranAtTicks - passedTicks;
+            }
+            return unit.convert(delay, TimeUnit.MILLISECONDS);
         }
 
         public int compareTo(Delayed o) {
@@ -248,6 +257,7 @@ public boolean isDone() {
         }
 
         public void run() {
+            ranAtTicks = passedTicks;
             try {
                 futureResult = command.call();
             }

jmock/src/main/java/org/jmock/lib/concurrent/internal/DeltaQueue.java

@@ -30,8 +30,8 @@ public T next() {
     public long delay() {
         return head.delay;
     }
-    
-    public long delay(T element) {
+
+    public Long delay(T element) {
         long ret = 0;
         Node<T> next = head;
         while (next != null) {
@@ -42,7 +42,7 @@ public long delay(T element) {
             next = next.next;
         }
         if (next == null) {
-            return -1;
+            return null;
         }
         return ret;
     }

jmock/src/test/java/org/jmock/test/unit/lib/concurrent/DeterministicSchedulerTests.java

@@ -308,7 +308,21 @@ public void testCannotBlockWaitingForFutureResultOfScheduledCallable() throws Ex
         }
         catch (UnsupportedSynchronousOperationException expected) {}
     }
-
+
+    public void testCanGetDelayAfterExecution() {
+        ScheduledFuture<?> task1 = scheduler.schedule(commandA, 1, TimeUnit.SECONDS);
+
+        checking(new Expectations() {{
+            oneOf (commandA).run();
+        }});
+
+        scheduler.tick(10, TimeUnit.SECONDS);
+
+        // Per getDelay documentation it returns: the remaining delay; zero or
+        // negative values indicate that the delay has already elapsed
+        assertEquals(-9, task1.getDelay(TimeUnit.SECONDS));
+    }
+
     private Action schedule(final Runnable command) {
         return ScheduleOnExecutorAction.schedule(scheduler, command);
     }

jmock/src/test/java/org/jmock/test/unit/lib/concurrent/internal/DeltaQueueTests.java

@@ -168,10 +168,10 @@ public void testReturnsFalseIfElementAlreadyRemoved() {
         assertFalse(deltaQueue.remove(elementC));
     }
 
-    public void testDelayIsMinusOneWhenElementIsAlreadyRemoved() {
+    public void testDelayIsNullWhenElementIsAlreadyRemoved() {
         deltaQueue.add(1L, elementA);
         deltaQueue.remove(elementA);
 
-        assertEquals("delay", -1, deltaQueue.delay(elementA));
+        assertNull("delay", deltaQueue.delay(elementA));
     }
 }