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package derms.replica.replica1;
import java.io.IOException;
import java.io.Serializable;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.logging.Logger;
import java.util.NoSuchElementException;
public class RequestResource {
public static final int port = 5557;
public static final int bufsize = 4096;
public static class Client {
private CoordinatorID coordinatorID;
private ResourceID resourceID;
private int duration;
public Client(CoordinatorID coordinatorID, ResourceID resourceID, int duration) {
this.coordinatorID = coordinatorID;
this.resourceID = resourceID;
this.duration = duration;
}
public Response sendRequest(InetAddress serverAddr) throws IOException {
Request request = new Request(coordinatorID, resourceID, duration);
DatagramSocket sock;
try {
sock = new DatagramSocket();
} catch (Exception e) {
throw new IOException("Request 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("Request 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("Request Resource Client: error receiving from server: "+e.getMessage());
}
try {
return ObjectPacket.deserialize(responsePkt, Response.class);
} catch (IOException e) {
throw new IOException("Request Resource Client: failed to deserialize response: "+e.getMessage());
} finally {
sock.close();
}
}
}
public static class Server implements Runnable {
private InetAddress localAddr;
private Resources resources;
private ExecutorService pool;
private Logger log;
public 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.info("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, log));
}
} finally {
sock.close();
}
}
}
private static class Request implements Serializable {
private CoordinatorID coordinatorID;
private ResourceID resourceID;
private int duration;
private Request(CoordinatorID cid, ResourceID rid, int duration) {
this.coordinatorID = cid;
this.resourceID = rid;
this.duration = duration;
}
}
private static class RequestHandler implements Runnable {
private Request request;
private SocketAddress client;
private Resources resources;
private Logger log;
private RequestHandler(Request request, SocketAddress client, Resources resources, Logger log) {
this.request = request;
this.client = client;
this.resources = resources;
this.log = log;
}
@Override
public void run() {
Response response = borrow();
DatagramSocket sock;
try {
sock = new DatagramSocket();
} catch (Exception e) {
log.severe("Failed to open socket: "+e.getMessage());
return;
}
DatagramPacket pkt;
try {
pkt = ObjectPacket.create(response, client);
} catch (IOException e) {
log.severe("Failed to create response packet: "+e.getMessage());
sock.close();
return;
}
try {
sock.send(pkt);
} catch (Exception e) {
log.severe("Failed to send response: "+e.getMessage());
}
sock.close();
}
private Response borrow() {
try {
Resource resource = resources.getByID(request.resourceID);
synchronized (resource) {
if (resource.isBorrowed && !request.coordinatorID.equals(resource.borrower)) {
return new Response(Response.Status.ALREADY_BORROWED,
request.coordinatorID+" cannot borrow "+request.resourceID
+"; already borrowed by "+resource.borrower);
} else if (request.duration <= 0) {
return new Response(Response.Status.INVALID_DURATION,
"duration "+request.duration+" less than 1");
} else if (request.duration > resource.duration) {
return new Response(Response.Status.INVALID_DURATION,
"cannot borrow "+resource.id+" for duration of "+request.duration
+"; only "+resource.duration+" remaining");
}
if (resource.borrower.equals(request.coordinatorID)) {
// Resource is already borrowed. Add to existing duration.
resource.borrowDuration += request.duration;
} else {
resource.borrowDuration = request.duration;
}
resource.borrower = request.coordinatorID;
resource.isBorrowed = true;
resource.duration -= request.duration;
return new Response(Response.Status.SUCCESS, request.coordinatorID
+" successfully borrowed "+request.resourceID);
}
} catch (NoSuchElementException e) {
return new Response(Response.Status.NO_SUCH_RESOURCE, "no such resource "+request.resourceID);
}
}
}
public static class Response implements Serializable {
public Status status;
public String message;
private Response(Status status, String message) {
this.status = status;
this.message = message;
}
private Response() {
this(Status.SUCCESS, "");
}
public enum Status {
SUCCESS, NO_SUCH_RESOURCE, ALREADY_BORROWED, INVALID_DURATION
}
}
}
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