smarter network code, fixed various issues

- deciding on the stream at creation time is just silly - it should be done based on the identities (this part is TODO)
- changed NodeRegistry so it doesn't store nodes - this should help to connect faster
- inventory items shouldn't be advertised to nodes that are already aware of them (issue #13)
- objects shouldn't be requested more than once (issue #9)

domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java

@@ -267,7 +267,6 @@ public class BitmessageContext {
         AddressRepository addressRepo;
         MessageRepository messageRepo;
         ProofOfWorkEngine proofOfWorkEngine;
-        TreeSet<Long> streams;
 
         public Builder() {
         }
@@ -307,28 +306,12 @@ public class BitmessageContext {
             return this;
         }
 
-        public Builder streams(Collection<Long> streams) {
-            this.streams = new TreeSet<>(streams);
-            return this;
-        }
-
-        public Builder streams(long... streams) {
-            this.streams = new TreeSet<>();
-            for (long stream : streams) {
-                this.streams.add(stream);
-            }
-            return this;
-        }
-
         public BitmessageContext build() {
             nonNull("inventory", inventory);
             nonNull("nodeRegistry", nodeRegistry);
             nonNull("networkHandler", networkHandler);
             nonNull("addressRepo", addressRepo);
             nonNull("messageRepo", messageRepo);
-            if (streams == null) {
-                streams(1);
-            }
             if (proofOfWorkEngine == null) {
                 proofOfWorkEngine = new MultiThreadedPOWEngine();
             }

domain/src/main/java/ch/dissem/bitmessage/InternalContext.java

@@ -49,7 +49,7 @@ public class InternalContext {
     private final MessageRepository messageRepository;
     private final ProofOfWorkEngine proofOfWorkEngine;
 
-    private final TreeSet<Long> streams;
+    private final TreeSet<Long> streams = new TreeSet<>();
     private final int port;
     private long networkNonceTrialsPerByte = 1000;
     private long networkExtraBytes = 1000;
@@ -65,7 +65,7 @@ public class InternalContext {
         this.clientNonce = Security.randomNonce();
 
         port = builder.port;
-        streams = builder.streams;
+        streams.add(1L); // FIXME
 
         init(inventory, nodeRegistry, networkHandler, addressRepository, messageRepository, proofOfWorkEngine);
     }

domain/src/main/java/ch/dissem/bitmessage/ports/NetworkHandler.java

@@ -16,14 +16,11 @@
 
 package ch.dissem.bitmessage.ports;
 
-import ch.dissem.bitmessage.BitmessageContext;
 import ch.dissem.bitmessage.entity.ObjectMessage;
-import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.utils.Property;
 
 import java.io.IOException;
-import java.util.Map;
 
 /**
  * Handles incoming messages

domain/src/main/java/ch/dissem/bitmessage/utils/Collections.java

@@ -57,4 +57,15 @@ public class Collections {
         }
         return result;
     }
+
+    public static <T> T selectRandom(Collection<T> collection) {
+        int index = RANDOM.nextInt(collection.size());
+        for (T item : collection) {
+            if (index == 0) {
+                return item;
+            }
+            index--;
+        }
+        throw new IllegalArgumentException("Empty collection? Size: " + collection.size());
+    }
 }

domain/src/main/java/ch/dissem/bitmessage/utils/UnixTime.java

@@ -20,10 +20,14 @@ package ch.dissem.bitmessage.utils;
  * A simple utility class that simplifies using the second based time used in Bitmessage.
  */
 public class UnixTime {
+    /**
+     * Length of a minute in seconds, intended for use with {@link #now(long)}.
+     */
+    public static final int MINUTE = 60;
     /**
      * Length of an hour in seconds, intended for use with {@link #now(long)}.
      */
-    public static final long HOUR = 60 * 60;
+    public static final long HOUR = 60 * MINUTE;
     /**
      * Length of a day in seconds, intended for use with {@link #now(long)}.
      */