BitcoinSerializer: store packetMagic in instance field

Author: msgilligan

core/src/main/java/org/bitcoinj/core/BitcoinSerializer.java

@@ -50,6 +50,7 @@ public class BitcoinSerializer extends MessageSerializer {
     private static final int COMMAND_LEN = 12;
 
     private final NetworkParameters params;
+    private final int packetMagic;
     private final int protocolVersion;
 
     private static final Map<Class<? extends Message>, String> names = new HashMap<>();
@@ -96,6 +97,7 @@ public BitcoinSerializer(NetworkParameters params) {
      */
     public BitcoinSerializer(NetworkParameters params, int protocolVersion) {
         this.params = params;
+        this.packetMagic = params.getPacketMagic();
         this.protocolVersion = protocolVersion;
     }
 
@@ -116,7 +118,7 @@ public int getProtocolVersion() {
     @Override
     public void serialize(String name, byte[] message, OutputStream out) throws IOException {
         byte[] header = new byte[4 + COMMAND_LEN + 4 + 4 /* checksum */];
-        ByteUtils.writeInt32BE(params.getPacketMagic(), header, 0);
+        ByteUtils.writeInt32BE(packetMagic, header, 0);
 
         // The header array is initialized to zero by Java so we don't have to worry about
         // NULL terminating the string here.
@@ -344,7 +346,7 @@ public void seekPastMagicBytes(ByteBuffer in) throws BufferUnderflowException {
             byte b = in.get();
             // We're looking for a run of bytes that is the same as the packet magic but we want to ignore partial
             // magics that aren't complete. So we keep track of where we're up to with magicCursor.
-            byte expectedByte = (byte)(0xFF & params.getPacketMagic() >>> (magicCursor * 8));
+            byte expectedByte = (byte)(0xFF & packetMagic >>> (magicCursor * 8));
             if (b == expectedByte) {
                 magicCursor--;
                 if (magicCursor < 0) {