fix possible race-condition

Author: Psilo

pom.xml

@@ -11,7 +11,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>info.unterrainer.commons.udp-observer</groupId>
 	<artifactId>udp-observer</artifactId>
-	<version>0.1.3</version>
+	<version>0.1.4</version>
 	<name>UdpObserver</name>
 	<packaging>jar</packaging>
 

src/main/java/info/unterrainer/commons/udpobserver/Information.java

@@ -2,6 +2,6 @@
 
 public class Information {
 	public static final String name = "UDP-Observer";
-	public static final String buildTime = "2021-03-10T08:29:08Z";
-	public static final String pomVersion = "0.1.3";
+	public static final String buildTime = "2021-03-31T07:33:16Z";
+	public static final String pomVersion = "0.1.4";
 }

src/main/java/info/unterrainer/commons/udpobserver/UdpObserver.java

@@ -39,16 +39,18 @@ public void run() {
 					socket.receive(packet);
 					String received = new String(packet.getData(), 0, packet.getLength());
 					InetSocketAddress adr = (InetSocketAddress) packet.getSocketAddress();
-					outputs.add(UdpDatagram.builder()
-							.metaData(UdpDatagramMetaData.builder()
-									.hostString(adr.getHostString())
-									.sender(adr.getAddress())
-									.sendPort(adr.getPort())
-									.timestamp(LocalDateTime.now(ZoneOffset.UTC))
-									.build())
-							.content(received)
-							.bytes(Arrays.copyOf(packet.getData(), packet.getLength()))
-							.build());
+					synchronized (outputs) {
+						outputs.add(UdpDatagram.builder()
+								.metaData(UdpDatagramMetaData.builder()
+										.hostString(adr.getHostString())
+										.sender(adr.getAddress())
+										.sendPort(adr.getPort())
+										.timestamp(LocalDateTime.now(ZoneOffset.UTC))
+										.build())
+								.content(received)
+								.bytes(Arrays.copyOf(packet.getData(), packet.getLength()))
+								.build());
+					}
 				} catch (IOException e) {
 					// NOOP
 				}
@@ -61,9 +63,11 @@ public void run() {
 	}
 
 	public Collection<UdpDatagram> getReceivedDatagrams() {
-		List<UdpDatagram> result = outputs.stream().filter(Objects::nonNull).collect(Collectors.toList());
-		outputs.clear();
-		return result;
+		synchronized (outputs) {
+			List<UdpDatagram> result = outputs.stream().filter(Objects::nonNull).collect(Collectors.toList());
+			outputs.clear();
+			return result;
+		}
 	}
 
 	public void close() {