public void acquire(Transaction transaction, String tableName, LockType lockType)
            throws IllegalArgumentException {
        if (!transaction.getStatus().equals(Transaction.Status.Running)) {
            throw new IllegalArgumentException();
        }

        TableLock tLock = tableToTableLock.get(tableName);
        if (tLock == null || tLock.lockOwners.isEmpty()) {
            tLock = new TableLock(lockType);
            tLock.lockOwners.add(transaction);
            tableToTableLock.put(tableName, tLock);
            return;
        }

        boolean granted = true;
        boolean promote = false;
        for (Request r : tLock.requestersQueue) {
            if (r.transaction.equals(transaction)) {
                if (r.lockType.equals(LockType.Exclusive) || r.lockType.equals(lockType))
                    throw new IllegalArgumentException();
                else {
                    if (tLock.requestersQueue.size() == 1) {
                        // promotion granted
                        tLock.lockType = LockType.Exclusive;
                        tableToTableLock.put(tableName, tLock);
                        return;
                    } else {
                        promote = true;
                    }
                }
            } else if (r.lockType.equals(LockType.Exclusive) && tLock.lockOwners.contains(r.transaction)) {
                transaction.sleep();
                granted = false;
                break;
            } else if (r.lockType.equals(LockType.Shared) && tLock.lockOwners.contains(r.transaction) && lockType.equals(LockType.Exclusive)) {
                transaction.sleep();
                granted = false;
                break;
            }
        }

        if (granted) {
            tLock.lockType = lockType;
            tLock.lockOwners.add(transaction);
        } else {
            // TODO check lockType waitDie woundWait
            if (promote)
                tLock.requestersQueue.addFirst(new Request(transaction, lockType));
            else
                tLock.requestersQueue.add(new Request(transaction, lockType));
        }

    }