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TransactionC.java
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TransactionC.java
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package main;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.Lock;
class TransactionC extends Thread implements MVCC.Transaction {
private final MVCC mvcc;
private List<MVCC.Transaction> challengers;
private final List<MVCC.Read> readhandles;
private boolean aborted = true;
private volatile int timestamp;
public List<MVCC.Writehandle> writehandles;
private volatile boolean cancelled;
private boolean precommit;
private boolean restart;
private int attempts = 0;
private boolean success;
private boolean blessed;
private boolean defeated;
private ConcurrentHashMap<String, Lock> locks;
public TransactionC(MVCC mvcc) {
this.mvcc = mvcc;
this.writehandles = new ArrayList<>();
this.challengers = Collections.synchronizedList(new ArrayList<>());
this.readhandles = new ArrayList<>();
this.locks = new ConcurrentHashMap<>();
}
@Override
public void run() {
super.run();
try {
while (aborted) {
while (true) {
success = true;
attempts++;
int previous_timestamp = timestamp;
timestamp = mvcc.issue(this);
System.out.println(String.format("Was previously aborted. New timestamp is %d previous was %d", timestamp, previous_timestamp));
MVCC.Read A = mvcc.read(this, "A");
if (A == null) {
success = false;
break;
}
MVCC.Read B = mvcc.read(this, "B");
if (B == null) {
success = false;
break;
}
MVCC.Writehandle writeC = mvcc.intend_to_write(this, "A", A.value + 1, A.timestamp);
if (writeC == null) {
success = false;
break;
}
MVCC.Writehandle writeD = mvcc.intend_to_write(this, "B", B.value + 1, B.timestamp);
if (writeD == null) {
success = false;
break;
}
mvcc.commit(this);
mvcc.dump();
break;
}
}
} catch (Throwable exception) {
System.out.println(exception.getMessage());
exception.printStackTrace();
System.exit(1);
}
}
@Override
public List<MVCC.Writehandle> getWritehandles() {
return writehandles;
}
@Override
public int getTimestamp() {
return timestamp;
}
@Override
public void setAborted(boolean aborted) {
this.aborted = aborted;
}
@Override
public void clear(MVCC mvcc) {
writehandles.clear();
cancelled = false;
challengers.clear();
readhandles.clear();
precommit = false;
restart = false;
for (Map.Entry<String, Lock> entry : locks.entrySet()) {
entry.getValue().unlock();
}
locks.clear();
}
@Override
public void addWrite(MVCC.Writehandle writehandle) {
writehandles.add(writehandle);
}
@Override
public boolean getAborted() {
return aborted;
}
@Override
public void setTimestamp(int timestamp) {
this.timestamp = timestamp;
}
@Override
public void cancel() {
this.cancelled = true;
}
@Override
public boolean getCancelled() {
return cancelled;
}
@Override
public void addChallenger(MVCC.Transaction transaction) {
assert(transaction != null);
challengers.add(transaction);
}
@Override
public List<MVCC.Transaction> getChallengers() {
return challengers;
}
@Override
public void addRead(MVCC.Read readHandle) {
readhandles.add(readHandle);
}
@Override
public List<MVCC.Read> getReadHandles() {
return readhandles;
}
@Override
public boolean checkChallengers(MVCC mvcc, MVCC.Transaction transaction) {
synchronized (challengers) {
for (MVCC.Transaction challenger : challengers) {
assert (challenger != null);
if (mvcc.shouldRestart(transaction, challenger)) {
return true;
}
}
}
return false;
}
@Override
public void markPrecommit() {
precommit = true;
}
@Override
public boolean getPrecommit() {
return precommit;
}
@Override
public void markRestart(boolean restart) {
this.restart = restart;
}
@Override
public boolean getRestart() {
return restart;
}
public int getNumberOfAttempts() {
return attempts;
}
@Override
public void markSuccessful() {
success = true;
}
@Override
public boolean getSuccessful() {
return success;
}
@Override
public void addLock(String key, Lock lock) {
locks.put(key, lock);
}
@Override
public Lock getLock(String key) {
return locks.get(key);
}
}