Propagate cancellation of quickly cancelled async executions

Author: jhalterman

src/main/java/net/jodah/failsafe/FailsafeFuture.java

@@ -38,6 +38,7 @@ public class FailsafeFuture<T> extends CompletableFuture<T> {
   private Future<?> dependentStageFuture;
   private Runnable cancelFn;
   private List<Future<T>> timeoutFutures;
+  private boolean cancelWithInterrupt;
 
   FailsafeFuture(FailsafeExecutor<T> executor) {
     this.executor = executor;
@@ -68,6 +69,7 @@ public synchronized boolean cancel(boolean mayInterruptIfRunning) {
     if (isDone())
       return false;
 
+    this.cancelWithInterrupt = mayInterruptIfRunning;
     execution.cancelledIndex = Integer.MAX_VALUE;
     boolean cancelResult = super.cancel(mayInterruptIfRunning);
     cancelResult = cancelDependencies(mayInterruptIfRunning, cancelResult);
@@ -140,7 +142,11 @@ synchronized void injectPolicy(Future<?> policyExecFuture) {
    * Injects a {@code dependentStageFuture} to be cancelled when this future is cancelled.
    */
   synchronized void injectStage(Future<?> dependentStageFuture) {
-    this.dependentStageFuture = dependentStageFuture;
+    // If outer future has already been cancelled, propagate the cancellation
+    if (isCancelled())
+      dependentStageFuture.cancel(cancelWithInterrupt);
+    else
+      this.dependentStageFuture = dependentStageFuture;
   }
 
   /**

src/main/java/net/jodah/failsafe/Functions.java

@@ -153,7 +153,7 @@ static <T> Supplier<CompletableFuture<ExecutionResult>> getPromiseOfStage(
         execution.preExecute();
         CompletionStage<? extends T> stage = supplier.get(execution);
         if (stage instanceof Future)
-          execution.future.injectPolicy((Future) stage);
+          execution.future.injectStage((Future) stage);
         stage.whenComplete((result, failure) -> {
           if (failure instanceof CompletionException)
             failure = failure.getCause();