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package derms.replica2;
import java.io.IOException;
import java.io.Serializable;
import java.net.*;
import java.util.NoSuchElementException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.logging.Logger;
class ReturnResource {
public static final int port = 5559;
public static final int bufsize = 4096;
static class Client {
private CoordinatorID coordinatorID;
private ResourceID resourceID;
Client(CoordinatorID cid, ResourceID rid) {
this.coordinatorID = cid;
this.resourceID = rid;
}
Response sendRequest(InetAddress serverAddr) throws IOException {
Request request = new Request(coordinatorID, resourceID);
DatagramSocket sock;
try {
sock = new DatagramSocket();
} catch (Exception e) {
throw new IOException("Return Resource Client: failed to open socket: "+e.getMessage());
}
DatagramPacket requestPkt;
try {
requestPkt = ObjectPacket.create(request, new InetSocketAddress(serverAddr, port));
} catch (IOException e) {
sock.close();
throw new IOException("Return Resource Client: failed to create request: "+e.getMessage());
}
sock.send(requestPkt);
byte[] buf = new byte[bufsize];
DatagramPacket responsePkt = new DatagramPacket(buf, buf.length);
try {
sock.receive(responsePkt);
} catch (Exception e) {
sock.close();
throw new IOException("Return Resource Client: error receiving from server: "+e.getMessage());
}
try {
return ObjectPacket.deserialize(responsePkt, Response.class);
} catch (IOException e) {
throw new IOException("Return Resource Client: failed to deserialize response: "+e.getMessage());
} finally {
sock.close();
}
}
}
static class Server implements Runnable {
private InetAddress localAddr;
private Resources resources;
private ExecutorService pool;
private Logger log;
Server(InetAddress localAddr, Resources resources) throws IOException {
this.localAddr = localAddr;
this.resources = resources;
pool = Executors.newWorkStealingPool();
this.log = DermsLogger.getLogger(this.getClass());
}
@Override
public void run() {
DatagramSocket sock = null;
try {
sock = new DatagramSocket(port, localAddr);
} catch (Exception e) {
log.severe("Failed to bind socket to "+localAddr.toString()
+": "+e.getMessage());
return;
}
log.info("Listening on "+localAddr.toString()+":"+port);
DatagramPacket requestPkt = new DatagramPacket(new byte[bufsize], bufsize);
try {
for (;;) {
try {
sock.receive(requestPkt);
} catch (Exception e) {
log.warning("Error receiving from socket: "+e.getMessage());
continue;
}
log.fine("Got request");
Request request = null;
try {
request = ObjectPacket.deserialize(requestPkt, Request.class);
} catch (IOException e) {
log.warning("Failed to deserialize request: "+e.getMessage());
continue;
}
pool.execute(new RequestHandler(request, requestPkt.getSocketAddress(), resources));
}
} finally {
sock.close();
}
}
}
private static class Request implements Serializable {
private CoordinatorID coordinatorID;
private ResourceID resourceID;
private Request(CoordinatorID cid, ResourceID rid) {
this.coordinatorID = cid;
this.resourceID = rid;
}
}
private static class RequestHandler implements Runnable {
private Request request;
private SocketAddress client;
private Resources resources;
private RequestHandler(Request request, SocketAddress client, Resources resources) {
this.request = request;
this.client = client;
this.resources = resources;
}
@Override
public void run() {
Response response = returnResource();
DatagramSocket sock;
try {
sock= new DatagramSocket();
} catch (Exception e) {
System.err.println("Request Resource Server: failed to open socket: "+e.getMessage());
return;
}
DatagramPacket pkt;
try {
pkt = ObjectPacket.create(response, client);
} catch (IOException e) {
System.err.println("Request Resource Server: failed to create response packet: "+e.getMessage());
sock.close();
return;
}
try {
sock.send(pkt);
} catch (Exception e) {
System.err.println("Request Resource Server: failed to send response: "+e.getMessage());
}
sock.close();
}
private Response returnResource() {
try {
Resource resource = resources.getByID(request.resourceID);
synchronized (resource) {
if (!resource.isBorrowed || !resource.borrower.equals(request.coordinatorID)) {
return new Response(Response.Status.NOT_BORROWED,
request.resourceID+" is not borrowed by "+request.coordinatorID);
}
resource.isBorrowed = false;
resource.borrower = new CoordinatorID();
resource.borrowDuration = -1;
return new Response(Response.Status.SUCCESS, request.coordinatorID+" successfully returned "+resource.id);
}
} catch (NoSuchElementException e) {
return new Response(Response.Status.NO_SUCH_RESOURCE, "no such resource "+request.resourceID);
}
}
}
static class Response implements Serializable {
Status status;
String message;
private Response(Status status, String message) {
this.status = status;
this.message = message;
}
enum Status {
SUCCESS, NO_SUCH_RESOURCE, NOT_BORROWED
}
}
}
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