PeerDiscovery: Change getPeers() return type from array to list.

This gets rid of a lot of array/list conversions.

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

@@ -930,7 +930,7 @@ public class PeerGroup implements TransactionBroadcaster {
         final Stopwatch watch = Stopwatch.createStarted();
         final List<PeerAddress> addressList = new LinkedList<>();
         for (PeerDiscovery peerDiscovery : peerDiscoverers /* COW */) {
-            InetSocketAddress[] addresses;
+            List<InetSocketAddress> addresses;
             try {
                 addresses = peerDiscovery.getPeers(requiredServices, peerDiscoveryTimeoutMillis, TimeUnit.MILLISECONDS);
             } catch (PeerDiscoveryException e) {

core/src/main/java/org/bitcoinj/net/discovery/DnsDiscovery.java

@@ -84,14 +84,14 @@ public class DnsDiscovery extends MultiplexingDiscovery {
         }
 
         @Override
-        public InetSocketAddress[] getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException {
+        public List<InetSocketAddress> getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException {
             if (services != 0)
                 throw new PeerDiscoveryException("DNS seeds cannot filter by services: " + services);
             try {
                 InetAddress[] response = InetAddress.getAllByName(hostname);
-                InetSocketAddress[] result = new InetSocketAddress[response.length];
+                List<InetSocketAddress> result = new ArrayList<>(response.length);
-                for (int i = 0; i < response.length; i++)
+                for (InetAddress r : response)
-                    result[i] = new InetSocketAddress(response[i], params.getPort());
+                    result.add(new InetSocketAddress(r, params.getPort()));
                 return result;
             } catch (UnknownHostException e) {
                 throw new PeerDiscoveryException(e);

core/src/main/java/org/bitcoinj/net/discovery/HttpDiscovery.java

@@ -84,7 +84,7 @@ public class HttpDiscovery implements PeerDiscovery {
     }
 
     @Override
-    public InetSocketAddress[] getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException {
+    public List<InetSocketAddress> getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException {
         try {
             HttpUrl.Builder url = HttpUrl.get(details.uri).newBuilder();
             if (services != 0)
@@ -114,7 +114,7 @@ public class HttpDiscovery implements PeerDiscovery {
     }
 
     @VisibleForTesting
-    public InetSocketAddress[] protoToAddrs(PeerSeedProtos.SignedPeerSeeds proto) throws PeerDiscoveryException,
+    public List<InetSocketAddress> protoToAddrs(PeerSeedProtos.SignedPeerSeeds proto) throws PeerDiscoveryException,
             InvalidProtocolBufferException, SignatureDecodeException, SignatureException {
         if (details.pubkey != null) {
             if (!Arrays.equals(proto.getPubkey().toByteArray(), details.pubkey.getPubKey()))
@@ -127,10 +127,9 @@ public class HttpDiscovery implements PeerDiscovery {
             throw new PeerDiscoveryException("Seed data is more than one day old: replay attack?");
         if (!seeds.getNet().equals(params.getPaymentProtocolId()))
             throw new PeerDiscoveryException("Network mismatch");
-        InetSocketAddress[] results = new InetSocketAddress[seeds.getSeedCount()];
+        List<InetSocketAddress> results = new ArrayList<>(seeds.getSeedCount());
-        int i = 0;
         for (PeerSeedProtos.PeerSeedData data : seeds.getSeedList())
-            results[i++] = new InetSocketAddress(data.getIpAddress(), data.getPort());
+            results.add(new InetSocketAddress(data.getIpAddress(), data.getPort()));
         return results;
     }
 

core/src/main/java/org/bitcoinj/net/discovery/MultiplexingDiscovery.java

@@ -26,7 +26,6 @@ import org.slf4j.LoggerFactory;
 
 import java.net.InetSocketAddress;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
@@ -104,46 +103,46 @@ public class MultiplexingDiscovery implements PeerDiscovery {
     }
 
     @Override
-    public InetSocketAddress[] getPeers(final long services, final long timeoutValue, final TimeUnit timeoutUnit) throws PeerDiscoveryException {
+    public List<InetSocketAddress> getPeers(final long services, final long timeoutValue, final TimeUnit timeoutUnit) throws PeerDiscoveryException {
         vThreadPool = createExecutor();
         try {
-            List<Callable<InetSocketAddress[]>> tasks = new ArrayList<>();
+            List<Callable<List<InetSocketAddress>>> tasks = new ArrayList<>();
             if (parallelQueries) {
                 for (final PeerDiscovery seed : seeds) {
-                    tasks.add(new Callable<InetSocketAddress[]>() {
+                    tasks.add(new Callable<List<InetSocketAddress>>() {
                         @Override
-                        public InetSocketAddress[] call() throws Exception {
+                        public List<InetSocketAddress> call() throws Exception {
                             return seed.getPeers(services, timeoutValue, timeoutUnit);
                         }
                     });
                 }
             } else {
-                tasks.add(new Callable<InetSocketAddress[]>() {
+                tasks.add(new Callable<List<InetSocketAddress>>() {
                     @Override
-                    public InetSocketAddress[] call() throws Exception {
+                    public List<InetSocketAddress> call() throws Exception {
                         List<InetSocketAddress> peers = new LinkedList<>();
                         for (final PeerDiscovery seed : seeds)
-                            peers.addAll(Arrays.asList(seed.getPeers(services, timeoutValue, timeoutUnit)));
+                            peers.addAll(seed.getPeers(services, timeoutValue, timeoutUnit));
-                        return peers.toArray(new InetSocketAddress[peers.size()]);
+                        return peers;
                     }
                 });
             }
-            final List<Future<InetSocketAddress[]>> futures = vThreadPool.invokeAll(tasks, timeoutValue, timeoutUnit);
+            final List<Future<List<InetSocketAddress>>> futures = vThreadPool.invokeAll(tasks, timeoutValue, timeoutUnit);
-            ArrayList<InetSocketAddress> addrs = new ArrayList<>();
+            List<InetSocketAddress> addrs = new ArrayList<>();
             for (int i = 0; i < futures.size(); i++) {
-                Future<InetSocketAddress[]> future = futures.get(i);
+                Future<List<InetSocketAddress>> future = futures.get(i);
                 if (future.isCancelled()) {
                     log.warn("Seed {}: timed out", parallelQueries ? seeds.get(i) : "any");
                     continue;  // Timed out.
                 }
-                final InetSocketAddress[] inetAddresses;
+                final List<InetSocketAddress> inetAddresses;
                 try {
                     inetAddresses = future.get();
                 } catch (ExecutionException e) {
                     log.warn("Seed {}: failed to look up: {}", parallelQueries ? seeds.get(i) : "any", e.getMessage());
                     continue;
                 }
-                Collections.addAll(addrs, inetAddresses);
+                addrs.addAll(inetAddresses);
             }
             if (addrs.size() == 0)
                 throw new PeerDiscoveryException("No peer discovery returned any results in "
@@ -151,7 +150,7 @@ public class MultiplexingDiscovery implements PeerDiscovery {
             if (shufflePeers)
                 Collections.shuffle(addrs);
             vThreadPool.shutdownNow();
-            return addrs.toArray(new InetSocketAddress[addrs.size()]);
+            return addrs;
         } catch (InterruptedException e) {
             throw new PeerDiscoveryException(e);
         } finally {

core/src/main/java/org/bitcoinj/net/discovery/PeerDiscovery.java

@@ -18,6 +18,7 @@
 package org.bitcoinj.net.discovery;
 
 import java.net.InetSocketAddress;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 import org.bitcoinj.core.VersionMessage;
@@ -30,10 +31,10 @@ public interface PeerDiscovery {
     // TODO: Flesh out this interface a lot more.
 
     /**
-     * Returns an array of addresses. This method may block.
+     * Queries the addresses. This method may block.
      * @param services Required services as a bitmask, e.g. {@link VersionMessage#NODE_NETWORK}.
      */
-    InetSocketAddress[] getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException;
+    List<InetSocketAddress> getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException;
 
     /** Stops any discovery in progress when we want to shut down quickly. */
     void shutdown();

core/src/main/java/org/bitcoinj/net/discovery/SeedPeers.java

@@ -23,6 +23,8 @@ import javax.annotation.Nullable;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.UnknownHostException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -82,10 +84,10 @@ public class SeedPeers implements PeerDiscovery {
     }
 
     /**
-     * Returns an array containing all the Bitcoin nodes within the list.
+     * Returns all the Bitcoin nodes within the list.
      */
     @Override
-    public InetSocketAddress[] getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException {
+    public List<InetSocketAddress> getPeers(long services, long timeoutValue, TimeUnit timeoutUnit) throws PeerDiscoveryException {
         if (services != 0)
             throw new PeerDiscoveryException("Pre-determined peers cannot be filtered by services: " + services);
         try {
@@ -95,10 +97,10 @@ public class SeedPeers implements PeerDiscovery {
         }
     }
 
-    private InetSocketAddress[] allPeers() throws UnknownHostException {
+    private List<InetSocketAddress> allPeers() throws UnknownHostException {
-        InetSocketAddress[] addresses = new InetSocketAddress[seedAddrs.length];
+        List<InetSocketAddress> addresses = new ArrayList<>(seedAddrs.length);
-        for (int i = 0; i < seedAddrs.length; ++i) {
+        for (int seedAddr : seedAddrs) {
-            addresses[i] = new InetSocketAddress(convertAddress(seedAddrs[i]), params.getPort());
+            addresses.add(new InetSocketAddress(convertAddress(seedAddr), params.getPort()));
         }
         return addresses;
     }

core/src/test/java/org/bitcoinj/core/PeerGroupTest.java

@@ -141,14 +141,14 @@ public class PeerGroupTest extends TestWithPeerGroup {
         final AtomicBoolean result = new AtomicBoolean();
         peerGroup.addPeerDiscovery(new PeerDiscovery() {
             @Override
-            public InetSocketAddress[] getPeers(long services, long unused, TimeUnit unused2) throws PeerDiscoveryException {
+            public List<InetSocketAddress> getPeers(long services, long unused, TimeUnit unused2) throws PeerDiscoveryException {
                 if (!result.getAndSet(true)) {
                     // Pretend we are not connected to the internet.
                     throw new PeerDiscoveryException("test failure");
                 } else {
                     // Return a bogus address.
                     latch.countDown();
-                    return new InetSocketAddress[]{new InetSocketAddress("localhost", 1)};
+                    return Arrays.asList(new InetSocketAddress("localhost", 1));
                 }
             }
 
@@ -165,13 +165,13 @@ public class PeerGroupTest extends TestWithPeerGroup {
 
     // Utility method to create a PeerDiscovery with a certain number of addresses.
     private PeerDiscovery createPeerDiscovery(int nrOfAddressesWanted, int port) {
-        final InetSocketAddress[] addresses = new InetSocketAddress[nrOfAddressesWanted];
+        final List<InetSocketAddress> addresses = new ArrayList<>(nrOfAddressesWanted);
         for (int addressNr = 0; addressNr < nrOfAddressesWanted; addressNr++) {
             // make each address unique by using the counter to increment the port.
-            addresses[addressNr] = new InetSocketAddress("localhost", port + addressNr);
+            addresses.add(new InetSocketAddress("localhost", port + addressNr));
         }
         return new PeerDiscovery() {
-            public InetSocketAddress[] getPeers(long services, long unused, TimeUnit unused2) throws PeerDiscoveryException {
+            public List<InetSocketAddress> getPeers(long services, long unused, TimeUnit unused2) throws PeerDiscoveryException {
                 return addresses;
             }
             public void shutdown() {
@@ -557,8 +557,8 @@ public class PeerGroupTest extends TestWithPeerGroup {
         peerGroup.addPreMessageReceivedEventListener(preMessageReceivedListener);
         peerGroup.addPeerDiscovery(new PeerDiscovery() {
             @Override
-            public InetSocketAddress[] getPeers(long services, long unused, TimeUnit unused2) throws PeerDiscoveryException {
+            public List<InetSocketAddress> getPeers(long services, long unused, TimeUnit unused2) throws PeerDiscoveryException {
-                return addresses.toArray(new InetSocketAddress[addresses.size()]);
+                return addresses;
             }
 
             @Override

core/src/test/java/org/bitcoinj/net/discovery/DnsDiscoveryTest.java

@@ -20,6 +20,7 @@ import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertTrue;
 
 import java.net.InetSocketAddress;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 import org.bitcoinj.params.MainNetParams;
@@ -33,7 +34,7 @@ public class DnsDiscoveryTest {
         DnsDiscovery dnsDiscovery = new DnsDiscovery(seeds, MainNetParams.get());
         assertTrue(dnsDiscovery.seeds.size() == 2);
         for (PeerDiscovery peerDiscovery : dnsDiscovery.seeds) {
-            assertTrue(peerDiscovery.getPeers(0, 100, TimeUnit.MILLISECONDS).length > 0);
+            assertTrue(peerDiscovery.getPeers(0, 100, TimeUnit.MILLISECONDS).size() > 0);
         }
     }
 
@@ -47,8 +48,8 @@ public class DnsDiscoveryTest {
     public void testGetPeersReturnsNotEmptyListOfSocketAddresses() throws PeerDiscoveryException {
         DnsDiscovery.DnsSeedDiscovery dnsSeedDiscovery = new DnsDiscovery.DnsSeedDiscovery(MainNetParams.get(),
                 "localhost");
-        InetSocketAddress[] inetSocketAddresses = dnsSeedDiscovery.getPeers(0, 100, TimeUnit.MILLISECONDS);
+        List<InetSocketAddress> inetSocketAddresses = dnsSeedDiscovery.getPeers(0, 100, TimeUnit.MILLISECONDS);
-        assertNotEquals(0, inetSocketAddresses.length);
+        assertNotEquals(0, inetSocketAddresses.size());
     }
 
     @Test(expected = PeerDiscoveryException.class)

core/src/test/java/org/bitcoinj/net/discovery/SeedPeersTest.java

@@ -22,6 +22,7 @@ import org.bitcoinj.params.MainNetParams;
 import org.junit.Test;
 
 import java.net.InetSocketAddress;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 import static org.hamcrest.CoreMatchers.equalTo;
@@ -49,7 +50,7 @@ public class SeedPeersTest {
     @Test
     public void getPeers_length() throws Exception{
         SeedPeers seedPeers = new SeedPeers(MAINNET);
-        InetSocketAddress[] addresses = seedPeers.getPeers(0, 0, TimeUnit.SECONDS);
+        List<InetSocketAddress> addresses = seedPeers.getPeers(0, 0, TimeUnit.SECONDS);
-        assertThat(addresses.length, equalTo(MAINNET.getAddrSeeds().length));
+        assertThat(addresses.size(), equalTo(MAINNET.getAddrSeeds().length));
     }
 }

examples/src/main/java/org/bitcoinj/examples/PrintPeers.java

@@ -41,14 +41,14 @@ import java.util.concurrent.TimeUnit;
  * Prints a list of IP addresses obtained from DNS.
  */
 public class PrintPeers {
-    private static InetSocketAddress[] dnsPeers;
+    private static List<InetSocketAddress> dnsPeers;
 
     private static void printElapsed(long start) {
         long now = System.currentTimeMillis();
         System.out.println(String.format("Took %.2f seconds", (now - start) / 1000.0));
     }
 
-    private static void printPeers(InetSocketAddress[] addresses) {
+    private static void printPeers(List<InetSocketAddress> addresses) {
         for (InetSocketAddress address : addresses) {
             String hostAddress = address.getAddress().getHostAddress();
             System.out.println(String.format("%s:%d", hostAddress, address.getPort()));