@Override
public void beforeReadAccess(Object obj, long field) {
if (vr) {
readHash = LockTable.hash(obj, field);
// Lock entry in read mode (might throw an exception)
readLock = LockTable.lock(this, readHash, id, false);
if (readLock >= 0) {
synchronized (writeSet) {
// Mutual exclusion on write set to allow other transaction to drop locks
if ((status.get() & STATUS_MASK) != TX_ACTIVE) {
// We have been killed: drop lock we just acquired (not in write set)
LockTable.setAndReleaseLock(readHash, readLock);
// Abort
throw KILLED_EXCEPTION;
}
// Add to write set (for being able to drop lock later)
writeSet.addRead(readHash, obj, field, readLock);
}
}
} else {
readHash = LockTable.hash(obj, field);
// Check if the field is locked (may throw an exception)
readLock = LockTable.checkLock(this, readHash, id);
}
}
@Override
public void beforeReadAccess(Object obj, long field, int advice) {
ReadFieldAccess next = readSet.getNext();
currentReadFieldAccess = next;
next.init(obj, field, advice);
// Check the read is still valid
lastReadLock = LockTable.checkLock(next.hashCode(), localClock);
}
private boolean onReadAccess(Object obj, long field, Type type) {
if (vr) {
// Visible read
if (readLock == LockTable.LOCKED_WRITE) {
// We already own that lock in write mode
WriteFieldAccess w = writeSet.get(readHash, obj, field);
if (w == null) return false;
readValue = w.getValue();
return true;
} else {
// We already own that lock in read mode
return false;
}
} else {
// Invisible read
if ((status.get() & STATUS_MASK) != TX_ACTIVE) {
// We have been killed: abort
throw KILLED_EXCEPTION;
}
if (readLock == LockTable.LOCKED_WRITE) {
// We already own that lock in write mode
WriteFieldAccess w = writeSet.get(readHash, obj, field);
if (w == null) return false;
readValue = w.getValue();
return true;
} else if (readLock == LockTable.LOCKED_READ) {
// We already own that lock in read mode
return false;
}
boolean b = false;
while (true) {
while (readLock <= endTime) {
// Re-read timestamp (check for race)
long lock = LockTable.checkLock(this, readHash, id);
if (lock != readLock) {
readLock = lock;
readValue = Field.getValue(obj, field, type);
b = true;
continue;
}
// We have read a valid value (in snapshot)
if (readWriteHint) {
// Save to read set
readSet.add(obj, field, readHash, lock);
}
return b;
}
// Try to extend snapshot
if (!(readWriteHint && extend())) {
throw EXTEND_FAILURE_EXCEPTION;
}
}
}
}
private WriteFieldAccess onReadAccess0(Object obj, long field, int advice) {
ReadFieldAccess current = currentReadFieldAccess;
int hash = current.hashCode();
// Check the read is still valid
LockTable.checkLock(hash, localClock, lastReadLock);
// Check if it is already included in the write set
return writeSet.contains(current);
}
