selectors now work

 - list query to dstore throws nullexception

src/ftp/Controller.java

@@ -27,7 +27,6 @@ public class Controller extends Server {
         this.timeout = timeout;
         this.rbPeriod = rbPeriod;
 
-
         openSelector();
     }
 
@@ -53,17 +52,7 @@ public class Controller extends Server {
         switch(args[0]) {
             case "JOIN":
                 key.attach(new DstoreConnection(new Index(), Integer.parseInt(args[1])));
-
-                SocketChannel toDstore = null;
-                try {
-                     toDstore = SocketChannel.open(new InetSocketAddress(Integer.parseInt(args[1])));
-                     toDstore.register(selector, SelectionKey.OP_WRITE);
-                } catch (IOException e) {
-                    e.printStackTrace();
-                }
-
-                sendMessage("test",toDstore,buffer);
-
+                sendMessage("LIST",key,buffer);
                 break;
         }
     }

src/ftp/Server.java

@@ -2,8 +2,10 @@ package ftp;
 
 import java.io.IOException;
 import java.net.InetSocketAddress;
+import java.net.Socket;
 import java.nio.ByteBuffer;
 import java.nio.channels.*;
+import java.util.Arrays;
 import java.util.Iterator;
 import java.util.Set;
 
@@ -15,9 +17,19 @@ public abstract class Server {
     protected Selector selector;
 
 
+    /**
+     * @desc abstract method which handles server requests based on implmentation
+     * @param request request to be handled
+     * @param key corresponding key
+     * @param buffer buffer to be used for r/w
+     */
     protected abstract void handleRequest(String request, SelectionKey key, ByteBuffer buffer);
 
 
+    /**
+     * @desc starts the selector and begins the server loop
+     * @throws IOException
+     */
     protected void openSelector() throws IOException {
         selector = Selector.open();
         ServerSocketChannel serverSocket = ServerSocketChannel.open();
@@ -26,6 +38,59 @@ public abstract class Server {
         serverSocket.register(selector, SelectionKey.OP_ACCEPT);
         ByteBuffer buffer = ByteBuffer.allocate(256);               //buffer to read/write
 
+        System.out.println("Selector Started");
+
+        while (true) {
+            selector.select();
+            Set<SelectionKey> selectedKeys = selector.selectedKeys();
+            Iterator<SelectionKey> iter = selectedKeys.iterator();
+            while (iter.hasNext()) {
+
+                SelectionKey key = iter.next();
+
+                if (key.isAcceptable()) {
+                    System.out.println("Server socket ready to accept connection");
+                    register(selector, serverSocket);
+                }
+
+                if (key.isConnectable()) {
+                    System.out.println("Channel is ready to connect to the server");
+                }
+
+                if (key.isReadable()) {
+                    System.out.println("Channel has data to be read");
+                    String request = takeRequest(buffer, key);
+                    handleRequest(request, key, buffer);
+                }
+
+                iter.remove();
+            }
+        }
+    }
+
+
+    /**
+     * @desc starts the selector and begins the server loop, registers given initial channels
+     * @param channels initial channels to be registered with the selector
+     * @throws IOException
+     */
+    protected void openSelector(SocketChannel[] channels) throws IOException{
+        selector = Selector.open();
+        ServerSocketChannel serverSocket = ServerSocketChannel.open();
+        serverSocket.bind(new InetSocketAddress(port));
+        serverSocket.configureBlocking(false);
+
+        serverSocket.register(selector, SelectionKey.OP_ACCEPT);
+        Iterator<SocketChannel> sockIt = Arrays.stream(channels).iterator();
+        while (sockIt.hasNext()) {
+            SocketChannel channel = sockIt.next();
+            channel.register(selector, SelectionKey.OP_READ | SelectionKey.OP_WRITE);
+        }
+
+        ByteBuffer buffer = ByteBuffer.allocate(256);               //buffer to read/write
+
+        System.out.println("Selector Started");
+
         while (true) {
             selector.select();
             Set<SelectionKey> selectedKeys = selector.selectedKeys();
@@ -35,10 +100,16 @@ public abstract class Server {
                 SelectionKey key = iter.next();
 
                 if (key.isAcceptable()) {
+                    System.out.println("Server socket ready to accept connection");
                     register(selector, serverSocket);
                 }
 
+                if (key.isConnectable()) {
+                    System.out.println("Channel is ready to connect to the server");
+                }
+
                 if (key.isReadable()) {
+                    System.out.println("Channel has data to be read");
                     String request = takeRequest(buffer, key);
                     handleRequest(request, key, buffer);
                 }
@@ -49,13 +120,27 @@ public abstract class Server {
     }
 
 
+    /**
+     * @desc registers a newly accepted channel with the selector
+     * @param selector selector to be registered with
+     * @param serverSocket server socket which accepts the connection
+     * @throws IOException
+     */
     protected void register(Selector selector, ServerSocketChannel serverSocket) throws IOException {
         SocketChannel client = serverSocket.accept();
+        System.out.println("Channel accepted");
         client.configureBlocking(false);
         client.register(selector, SelectionKey.OP_READ);
     }
 
 
+    /**
+     * @desc reads request from buffer
+     * @param buffer buffer to read request from
+     * @param key key linking to the channel
+     * @return returns the request
+     * @throws IOException
+     */
     protected String takeRequest(ByteBuffer buffer, SelectionKey key) throws IOException {
         SocketChannel client = (SocketChannel) key.channel();
         client.read(buffer);
@@ -65,42 +150,100 @@ public abstract class Server {
     }
 
 
-    protected String sendMessage(String msg, SelectionKey key, ByteBuffer buffer) {
-        buffer.clear();
+    /**
+     * @desc sends a message using a given key and waits for a response
+     * @param msg message to be sent
+     * @param key key of corresponding channel to send message through
+     * @param buffer buffer to r/w messages
+     * @return
+     */
+    protected String sendMessageResponse(String msg, SelectionKey key, ByteBuffer buffer) {
         buffer = ByteBuffer.wrap(msg.getBytes());
-System.out.println(msg);
+
         SocketChannel channel = (SocketChannel) key.channel();
 
         String response = null;
         try {
             channel.write(buffer);
             buffer.clear();
+            System.out.println("Sent message: " + msg);
+
             channel.read(buffer);
             response = new String(buffer.array()).trim();
-            buffer.clear();
         } catch (IOException e) {
             e.printStackTrace();
         }
+
         return response;
     }
 
 
-    protected String sendMessage(String msg, SocketChannel channel, ByteBuffer buffer) {
-        buffer.clear();
+    /**
+     * @desc sends a message using a given channel and waits for a response
+     * @param msg message to be sent
+     * @param channel channel to send message through
+     * @param buffer buffer to r/w messages
+     * @return
+     */
+    protected String sendMessageResponse(String msg, SocketChannel channel, ByteBuffer buffer) {
         buffer = ByteBuffer.wrap(msg.getBytes());
 
         String response = null;
         try {
             channel.write(buffer);
             buffer.clear();
+            System.out.println("Sent message: " + msg);
+
             channel.read(buffer);
             response = new String(buffer.array()).trim();
-            buffer.clear();
         } catch (IOException e) {
             e.printStackTrace();
         }
+
         return response;
     }
 
 
+    /**
+     * @desc sends a message using a given key, does not wait for a response
+     * @param msg message to be sent
+     * @param key key of corresponding channel to send message through
+     * @param buffer buffer to r/w messages
+     * @return
+     */
+    protected void sendMessage(String msg, SelectionKey key, ByteBuffer buffer) {
+        buffer = ByteBuffer.wrap(msg.getBytes());
+
+        SocketChannel channel = (SocketChannel) key.channel();
+
+        try {
+            channel.write(buffer);
+            buffer.clear();
+            System.out.println("Sent message: " + msg);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+
+    /**
+     * @desc sends a message using a given channel, does not wait for a response
+     * @param msg message to be sent
+     * @param channel channel to send message through
+     * @param buffer buffer to r/w messages
+     * @return
+     */
+    protected void sendMessage(String msg, SocketChannel channel, ByteBuffer buffer) {
+        buffer = ByteBuffer.wrap(msg.getBytes());
+
+        try {
+            channel.write(buffer);
+            buffer.clear();
+            System.out.println("Sent message: " + msg);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+
 }

src/ftp/dstore1/Dstore.java

@@ -7,6 +7,7 @@ import ftp.Server;
 import java.io.File;
 import java.io.IOException;
 import java.net.InetSocketAddress;
+import java.net.SocketException;
 import java.nio.ByteBuffer;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.SocketChannel;
@@ -37,37 +38,24 @@ public class Dstore extends Server {
         this.file_folder = file_folder;
 
 
+        ByteBuffer buffer = ByteBuffer.allocate(256);
+
+
         // opening connection to controller
         // open(addr) acts as convenience method for open() and connect()
         // in blocking mode, so will wait for response before progressing
         //
         try {
             toController = SocketChannel.open(new InetSocketAddress(cport));
+            toController.configureBlocking(false);
         } catch (IOException e) {
             e.printStackTrace();
         }
 
-        ByteBuffer buffer = ByteBuffer.allocate(256);
 
         sendMessage("JOIN " + port, toController, buffer);
 
-
-        openSelector();
-
-
-        /*
-        // creating server socket to receive files
-        //
-        ServerSocketChannel serverSocket = ServerSocketChannel.open();
-        serverSocket.bind(new InetSocketAddress(port));
-        while (true) {
-            SocketChannel client = serverSocket.accept();
-
-            new Thread( () -> {
-
-            } ).start();
-        }
-         */
+        openSelector(new SocketChannel[] {toController});
     }
 
 
@@ -93,10 +81,14 @@ public class Dstore extends Server {
     }
 
 
-    private File[] list() {
-        File folder = new File("./storage");
-        return folder.listFiles();
-    }
+//    /**
+//     * @desc lists the files of the datastore
+//     * @return
+//     */
+//    private File[] list() {
+//        File folder = new File("./storage");
+//        return folder.listFiles();
+//    }
 
 
     @Override
@@ -105,9 +97,14 @@ public class Dstore extends Server {
 
         switch(args[0]) {
             case "LIST":
-                String fileNames = Arrays.stream(list())
-                        .map(File::getName)
+                File folder = new File("./storage");
+                String[] files = folder.list();
+//                String fileNames = Arrays.stream(list())
+//                        .map(File::getName)
+//                        .reduce("", (file1, file2) -> file1 + " " + file2);
+                String fileNames = Arrays.stream(files)
                         .reduce("", (file1, file2) -> file1 + " " + file2);
+                System.out.println(fileNames);
 
                 sendMessage(fileNames, key, buffer);
                 break;