Remove redundant copies of PortRange BitSet. Instead use one copy with

diffferent counters for each port scan

4 files changed, 9 insertions, 6 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 c388ef3..05231d2 100644
--- a/src/main/java/com/it_jaros/jns/scan/Scanner.java
+++ b/src/main/java/com/it_jaros/jns/scan/Scanner.java
@@ -1,5 +1,6 @@
 package com.it_jaros.jns.scan;
 
+import com.it_jaros.jns.scan.domain.PortRange;
 import com.it_jaros.jns.scan.domain.ScanResult;
 import com.it_jaros.jns.scan.engine.*;
 
@@ -35,7 +36,8 @@ public class Scanner implements AutoCloseable {
                 executor,
                 socketLimit,
                 cancelledToken,
-                scan
+                scan,
+                new PortRange(scan.getPorts()) // parsed once for the whole scan
         );
 
         scan.start();
diff --git a/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java b/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java
index e67b362..8996b34 100644
--- a/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java
+++ b/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java
@@ -4,16 +4,15 @@ import java.util.BitSet;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
-import static com.it_jaros.jns.scan.domain.PortRange.MAX_PORT;
 import static com.it_jaros.jns.scan.domain.PortRange.MIN_PORT;
 
 public class PortRangeIterator implements Iterator<Integer> {
 
     private int nextPort; // cached next-set-bit, only ever advances
-    private final BitSet availablePorts = new BitSet(MAX_PORT);
+    private final BitSet availablePorts; // shared from the scan, read-only via a monotonically advancing cursor
 
     public PortRangeIterator(BitSet specifiedPorts) {
-        availablePorts.or(specifiedPorts);
+        this.availablePorts = specifiedPorts;
         nextPort = availablePorts.nextSetBit(MIN_PORT);
     }
 
diff --git a/src/main/java/com/it_jaros/jns/scan/engine/ScanExecutionContext.java b/src/main/java/com/it_jaros/jns/scan/engine/ScanExecutionContext.java
index 96924c8..0c5f00b 100644
--- a/src/main/java/com/it_jaros/jns/scan/engine/ScanExecutionContext.java
+++ b/src/main/java/com/it_jaros/jns/scan/engine/ScanExecutionContext.java
@@ -2,6 +2,7 @@ package com.it_jaros.jns.scan.engine;
 
 import com.it_jaros.jns.scan.Scan;
 import com.it_jaros.jns.scan.ScanOptions;
+import com.it_jaros.jns.scan.domain.PortRange;
 
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Semaphore;
@@ -11,5 +12,6 @@ public record ScanExecutionContext(
         ExecutorService executorService,
         Semaphore socketLimit,
         CancelledToken cancelledToken,
-        Scan scan
+        Scan scan,
+        PortRange portRange // parsed once per scan, shared read-only by all host tasks
 ) {}
diff --git a/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java b/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java
index 9a4d6db..d2ce647 100644
--- a/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java
+++ b/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java
@@ -64,7 +64,7 @@ public class ScanHostTask implements Callable<ScanResult> {
             }
         }
 
-        final PortRange portRange = new PortRange(scan.getPorts());
+        final PortRange portRange = context.portRange(); // parsed once per scan, shared read-only
         Function<Integer, Callable<PortResult>> scanFactory = this.context.scanOptions().useUdp()
                 ? port -> new ScanUdpPortTask(port, context, hostContext)
                 : port -> new ScanPortTask(port, context, hostContext);