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Transaction.java
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Transaction.java
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import java.net.*;
import java.util.ArrayList;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.io.*;
public class Transaction extends Thread {
private Socket clientSocket = null;
private PushbackInputStream pbis = null;
private DataInputStream in = null;
private PrintWriter out = null;
private ByteArrayOutputStream os = null;
private static final int IGNORE = -1;
private static final Object mutex = new Object();
private static Lock commitQueue = new ReentrantLock(true);
public Transaction (Socket clientSocket) {
//System.out.println("New client connection");
this.clientSocket = clientSocket;
try {
this.clientSocket.setTcpNoDelay(true);
this.clientSocket.setReuseAddress(true);
//this.clientSocket.setSoTimeout(FileServer.getTimeout());
pbis = new PushbackInputStream(this.clientSocket.getInputStream(), 1);
in = new DataInputStream(pbis);
out = new PrintWriter(this.clientSocket.getOutputStream(),true);
} catch (SocketException e) {
System.err.println ("SocketException: " + e.getMessage());
} catch (IOException e) {
System.err.println ("IOException: " + e.getMessage());
}
}
/* Called to send COMMIT requests to the backup for replication */
public static void backupSYNC (LogRecord transactionRecord) {
commitQueue.lock();
try {
if (transactionRecord.hasReceivedBackupACK()) return;
int timeout = 600;
FileServer.commitPort = FileServer.findFreePort(); // port primary will use to send COMMIT requests to the backup (and receive the corresponding ACK's)
FileServer.updatePrimary(FileServer.bindAddr, FileServer.port, FileServer.primaryFile);
InetSocketAddress peerAddress = FileServer.getPeerAddress();
System.out.println(String.format("Try to send COMMIT for (TID:%d, CLSN:%d) to backup", transactionRecord.getTransactionID(), transactionRecord.getCommitLSN()));
Socket socket = null;
ObjectOutputStream os;
ObjectInputStream inputStream;
ServerMessage response;
try {
socket = new Socket();
socket.bind(new InetSocketAddress(FileServer.bindAddr, FileServer.commitPort));
//socket = new Socket(peerAddress.getAddress(), peerAddress.getPort());
//FileServer.commitSocket = new Socket();
socket.connect(new InetSocketAddress(peerAddress.getAddress(), peerAddress.getPort()));
socket.setTcpNoDelay(true);
socket.setReuseAddress(true);
socket.setSoTimeout(timeout);
os = new ObjectOutputStream(socket.getOutputStream());
os.writeObject(transactionRecord);
os.flush();
inputStream = new ObjectInputStream(socket.getInputStream());
while (true) {
response = (ServerMessage) inputStream.readObject();
switch (response.getResponseMethod()) {
case ACK:
if (response.getCommitLSN() == transactionRecord.getCommitLSN()) {
System.out.println(String.format("Received ACK for (TID:%d, CLSN:%d) from backup", transactionRecord.getTransactionID(), response.getCommitLSN()));
transactionRecord.setBackupACK(true);
return;
}
break;
case ASK_RESEND:
int expectedLSN = response.getCommitLSN();
LogRecord toSend = FileServer.getRecordByCommitLSN(expectedLSN);
System.out.println("Received ASK_RESEND request for CLSN: " + expectedLSN);
os.writeObject(toSend);
os.flush();
break;
default:
break;
}
}
} catch (SocketTimeoutException e) {
//System.err.println("No response received from backup after " + timeout + "ms , timing out.");
return;
} catch (IOException e) {
// System.err.println(e.getMessage());
// System.err.println("Unable to connect to backup, continue...");
return;
} catch (ClassNotFoundException e) {
// this should never happen
} finally {
if (socket != null) {
try {
socket.close();
} catch (IOException e) {
}
}
}
} finally {
commitQueue.unlock();
}
}
@Override
public void run () {
// if you are the backup, listen for COMMIT requests from the primary
if (!FileServer.isPrimary()) {
ServerMessage message = null;
ObjectOutputStream oos = null;
ObjectInputStream inputStream = null;
try {
inputStream = new ObjectInputStream(clientSocket.getInputStream());
oos = new ObjectOutputStream(clientSocket.getOutputStream());
LogRecord logRecord = (LogRecord) inputStream.readObject();
System.out.println("Received CLSN: " + logRecord.getCommitLSN());
// ensures that commit records are received and applied in proper order
int expectedLSN = LogRecord.getCurrentLSN()+1;
int receivedLSN = logRecord.getCommitLSN();
while (expectedLSN != receivedLSN) {
System.out.println("Sending ASK_RESEND for LSN: " + expectedLSN);
message = new ServerMessage(ServerMessage.ResponseMethod.ASK_RESEND, expectedLSN);
oos.writeObject(message);
oos.flush();
logRecord = (LogRecord) inputStream.readObject();
receivedLSN = logRecord.getCommitLSN();
System.out.println("Waiting for commitLSN: " + expectedLSN + " to arrive, received: " + logRecord.getCommitLSN());
// try {
// Thread.currentThread().sleep(10);
// } catch (InterruptedException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// }
}
FileServer.manageFile(logRecord.getFileName());
LogRecord.setLSN(logRecord.getCommitLSN());
LogRecord newRecord = new LogRecord (
RequestMessage.RequestMethod.COMMIT,
logRecord.getTransactionID(),
logRecord.getSequenceNumber(),
null,
null);
FileServer.transactionDB.put(logRecord.getTransactionID(), logRecord);
FileServer.commitDB.put(logRecord.getCommitLSN(), logRecord);
FileServer.addCommit(logRecord.getTransactionID());
FileServer.processCommits();
//FileServer.addLog(newRecord);
message = new ServerMessage(ServerMessage.ResponseMethod.ACK, logRecord.getCommitLSN());
oos.writeObject(message);
oos.flush();
logRecord.setBackupACK(true);
return;
} catch (IOException e) {
// TODO Auto-generated catch block
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
} finally {
try {
clientSocket.close();
} catch (IOException e) {
}
}
}
// check if request message is from the backup - assuming you are currently the primary server
// && clientSocket.getPort() == FileServer.getPeerAddress().getPort()
if (FileServer.isPrimary() && (clientSocket.getInetAddress().equals(FileServer.getPeerAddress().getAddress()) && clientSocket.getPort() == FileServer.getPeerAddress().getPort())) {
try {
ServerMessage message = null;
ObjectOutputStream oos = null;
ObjectInputStream inputStream = null;
clientSocket.setSoTimeout(1200);
try {
inputStream = new ObjectInputStream(clientSocket.getInputStream());
oos = new ObjectOutputStream(clientSocket.getOutputStream());
message = (ServerMessage) inputStream.readObject();
} catch (IOException e) {
return;
} catch (ClassNotFoundException e) {
return;
}
switch (message.getRequestMethod()) {
case SYNC:
int backupLSN = message.getCommitLSN()+1;
LogRecord record;
ArrayList<LogRecord> missingTransactions = new ArrayList<LogRecord>();
for (int i = backupLSN; i <= LogRecord.getCurrentLSN(); i++) {
record = FileServer.getRecordByCommitLSN (i);
missingTransactions.add(record);
}
try {
oos.reset();
oos.writeObject(missingTransactions);
oos.flush();
} catch (IOException e) {
e.printStackTrace();
return;
}
break;
default:
break;
}
return;
} catch (SocketException e1) {
// TODO Auto-generated catch block
} finally {
if (clientSocket != null) {
try {
clientSocket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
}
}
}
}
LogRecord log;
LogRecord newRecord;
try {
int singleByte;
while ((singleByte = pbis.read()) != -1) {
//this.clientSocket.setSoTimeout(FileServer.getTimeout());
pbis.unread(singleByte);
RequestMessage request = ClientServerProtocol.parseMessage(in);
int transactionID = request.getTransactionID();
switch (request.getMethod()) {
case ABORT:
{
log = FileServer.getLog(transactionID);
if (log.hasCommitted()) {
throw new ServerException(String.format("TID: %d has committed, you cannot ABORT a commited transaction.", transactionID), ClientServerProtocol.Error.INVALID_OPERATION);
}
newRecord = new LogRecord (
request.getMethod(),
transactionID,
IGNORE,
null,
null);
log.setAborted(true);
log.addLog(newRecord);
String response = ClientServerProtocol.buildResponse(
ClientServerProtocol.ResponseMethod.ACK,
transactionID, // return the generated transaction ID to the client
IGNORE,
ClientServerProtocol.Error.NONE,
0,
null);
out.print(response);
out.flush();
}
break;
case COMMIT:
{
// the sequence number for a COMMIT request represents that of the LAST write request for this transaction
log = FileServer.getLog(transactionID);
if (log.hasCommitted() && request.getSequenceNumber() != log.getSequenceNumber()) {
FileServer.removeCommit(log.getTransactionID());
throw new ServerException(String.format("TID:%d has already commited with a different sequence number (%d)", transactionID, log.getSequenceNumber()), ClientServerProtocol.Error.INVALID_OPERATION);
}
if (log.hasAborted()) {
FileServer.removeCommit(log.getTransactionID());
throw new ServerException(String.format("TID:%d has aborted, you cannot commit an aborted transaction.", transactionID), ClientServerProtocol.Error.INVALID_OPERATION);
}
if (!log.hasReceivedCommitRequest()) {
// officially sets the sequence number the server will use to commit this transaction (anything else will be an error)
log.setSequenceNumber(request.getSequenceNumber());
log.setReceivedCommitRequest(true);
}
if (!log.hasCommitted() && log.hasReceivedCommitRequest() && (request.getSequenceNumber() != log.getSequenceNumber())) {
//FileServer.removeCommit(log.getTransactionID());
throw new ServerException(String.format("TID:%d has already been requested to commit with a different sequence number (%d)", transactionID, log.getSequenceNumber()), ClientServerProtocol.Error.INVALID_OPERATION);
}
ArrayList<Integer> missingSequenceNumbers = log.getMissingSequenceNumbers(log.getSequenceNumber());
if (!missingSequenceNumbers.isEmpty()) {
for (Integer missingNumber : missingSequenceNumbers) {
String response = ClientServerProtocol.buildResponse(
ClientServerProtocol.ResponseMethod.ASK_RESEND,
transactionID, // return the generated transaction ID to the client
missingNumber,
ClientServerProtocol.Error.NONE,
0,
null);
//FileServer.removeCommit(log.getTransactionID());
out.print(response);
out.flush();
}
} else {
if (request.getSequenceNumber() != log.getSequenceNumber()) {
FileServer.removeCommit(log.getTransactionID());
throw new ServerException(String.format("The server is expecting sequence number %d in order to commit as this number had been requested in an earlier request", log.getLargestSequenceNumber()), ClientServerProtocol.Error.INVALID_OPERATION);
}
if (!log.hasCommitted()) {
newRecord = new LogRecord (
request.getMethod(),
transactionID,
request.getSequenceNumber(),
null,
null);
log.setCommited(true);
log.setSequenceNumber(request.getSequenceNumber());
log.setCommitLSN();
//log.setSequenceNumber(request.getSequenceNumber());
//log.addLog(newRecord);
//FileServer.addLog (newRecord); // since the sequence number has already been used, we just add straight to log and flush to disk
FileServer.processCommits();
} else {
FileServer.removeCommit(transactionID);
}
String response = ClientServerProtocol.buildResponse(
ClientServerProtocol.ResponseMethod.ACK,
transactionID, // return the generated transaction ID to the client
IGNORE,
ClientServerProtocol.Error.NONE,
0,
null);
// if you are the primary server, do not send ACK to client until you have received ACK from backup
// perhaps put this in a loop until backup has responded
if (FileServer.isPrimary() && !log.hasReceivedBackupACK()) {
backupSYNC(log);
}
// out.print(response);
// out.flush();
// } else {
// out.print(response);
// out.flush();
// }
out.print(response);
out.flush();
}
}
break;
case NEW_TXN: /* create a new log record for the new transaction, generate a new ID and add it to the active transactions table */
{
transactionID = FileServer.generateID();
String filename = request.getData();
newRecord = new LogRecord (
request.getMethod(),
transactionID,
0,
filename,
filename);
log = FileServer.getLog(transactionID);
log.setFilename(filename);
FileServer.manageFile(filename);
log.addLog(newRecord);
String response = ClientServerProtocol.buildResponse(
ClientServerProtocol.ResponseMethod.ACK,
transactionID, // return the generated transaction ID to the client
request.getSequenceNumber(),
ClientServerProtocol.Error.NONE,
0,
null);
out.print(response);
out.flush();
}
break;
case READ:
{
String data = FileServer.readFile (request.getData());
int contentLength = data.getBytes().length;
String response = ClientServerProtocol.buildResponse(
ClientServerProtocol.ResponseMethod.ACK,
IGNORE,
IGNORE,
ClientServerProtocol.Error.NONE,
contentLength,
data);
out.print(response);
out.flush();
}
break;
case WRITE:
{
log = FileServer.getLog(transactionID); // does necessary checks for a valid TID
if (log.hasCommitted() || log.hasAborted()) {
throw new ServerException(String.format("TID: %d has already committed/aborted.", transactionID), ClientServerProtocol.Error.INVALID_OPERATION);
}
newRecord = new LogRecord ( // does necessary check for duplicate sequence numbers
request.getMethod(),
transactionID,
request.getSequenceNumber(),
null,
request.getData());
log.addLog(newRecord);
// check to see if you can commit:
// server has previously received a commit request and was unable to commit due to missing sequence numbers,
// the server can commit if this write has satisfied all of the servers ASK_RESEND requests
if (log.hasReceivedCommitRequest() && log.getMissingSequenceNumbers(log.getSequenceNumber()).isEmpty()) {
// newRecord = new LogRecord (
// RequestMessage.RequestMethod.COMMIT,
// transactionID,
// log.getSequenceNumber(),
// null,
// null);
String response = ClientServerProtocol.buildResponse(
ClientServerProtocol.ResponseMethod.ACK,
transactionID, // return the generated transaction ID to the client
IGNORE,
ClientServerProtocol.Error.NONE,
0,
null);
log.setCommited(true);
log.setCommitLSN();
log.setSequenceNumber(log.getLargestSequenceNumber());
FileServer.processCommits();
if (FileServer.isPrimary() && !log.hasReceivedBackupACK()) {
backupSYNC(log);
}
//FileServer.addCommit(log.getTransactionID());
//FileServer.addLog (newRecord); // since the sequence number has already been used, we just add straight to log and flush to disk
out.print(response);
out.flush();
}
}
break;
default:
break;
}
}
} catch (ServerException e) {
String response = ClientServerProtocol.buildResponse(
ClientServerProtocol.ResponseMethod.ERROR,
IGNORE,
IGNORE,
e.getError(),
(e.getMessage().length() + e.getError().toString().length() + 2),
e.getError().toString() + ": " + e.getMessage());
out.print(response);
out.flush();
}
catch (SocketTimeoutException e) {
System.err.println("No more data coming from client, server timed out after " + FileServer.getTimeout() + "ms : " + e.getMessage());
}
catch (IOException e) {
e.printStackTrace();
System.out.print("IOException: " + e.getMessage());
}
}
}