From 38111c6204cbbdc1f784fdedb03170fe33d000af Mon Sep 17 00:00:00 2001
From: Matthias Jaros <jarlucmat@mailbox.org>
Date: Thu, 20 Aug 2026 11:07:12 +0200
Subject: Get rid of RejectedExecutionException when cancelling a scan

---
 src/main/java/com/it_jaros/jns/scan/Scanner.java | 32 +++++++++++++++++-------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/src/main/java/com/it_jaros/jns/scan/Scanner.java b/src/main/java/com/it_jaros/jns/scan/Scanner.java
index 00cd937..9a62d52 100644
--- a/src/main/java/com/it_jaros/jns/scan/Scanner.java
+++ b/src/main/java/com/it_jaros/jns/scan/Scanner.java
@@ -4,6 +4,7 @@ import com.it_jaros.jns.scan.domain.ScanResult;
 import com.it_jaros.jns.scan.engine.*;
 
 import java.time.Duration;
+import java.util.Optional;
 import java.util.concurrent.*;
 import java.util.function.Consumer;
 
@@ -56,15 +57,7 @@ public class Scanner implements AutoCloseable {
                 if (poll instanceof PollState.Success<ScanResult>(ScanResult value)) {
                     consumer.accept(value);
                 } else if (poll instanceof PollState.Failure<ScanResult>(Throwable error)) {
-                    if (error instanceof RejectedExecutionException) {
-                        // happens when strg-c is pressed
-                        continue;
-                    }
-                    if (error instanceof ScanHostException e) {
-                        consumer.accept(ScanResult.from(e));
-                    } else {
-                        consumer.accept(ScanResult.from(error));
-                    }
+                    mapToScanResult(error).ifPresent(consumer);
                 }
             } catch (InterruptedException e) {
                 Thread.currentThread().interrupt();
@@ -73,6 +66,27 @@ public class Scanner implements AutoCloseable {
         scan.stop();
     }
 
+    private Optional<ScanResult> mapToScanResult(Throwable error) {
+        if (error instanceof RejectedExecutionException) {
+            // happens when Ctrl-C is pressed
+            // we don't want to tell the user that
+            // the host had an error because it did
+            // not get executed. Actually it is not
+            // even an error
+            return Optional.empty();
+        }
+
+        if (error instanceof ScanHostException e) {
+            if (e.getCause() instanceof RejectedExecutionException) {
+                // see comment above
+                return Optional.empty();
+            }
+            return Optional.of(ScanResult.from(e));
+        }
+
+        return Optional.of(ScanResult.from(error));
+    }
+
     private PollState<ScanResult> getHostResult(ProducerState<ScanResult> state) throws InterruptedException {
         Future<ScanResult> finishedHost = state.completionService().poll(ProducerThread.pollInterval.toMillis(), TimeUnit.MILLISECONDS);
         if (finishedHost == null) {
-- 
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