| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.jena.sparql.core; |
| |
| import org.apache.jena.atlas.lib.Lib; |
| import org.apache.jena.query.ReadWrite ; |
| import org.apache.jena.query.TxnType; |
| import org.apache.jena.shared.Lock ; |
| import org.apache.jena.shared.LockMRPlusSW ; |
| import org.apache.jena.shared.LockMRSW ; |
| import org.apache.jena.shared.LockMutex ; |
| import org.apache.jena.sparql.JenaTransactionException ; |
| |
| /** An implementation of Transactional that provides MRSW locking but no abort. |
| * This is often the best you can do for a system that does not itself provide transactions. |
| * @apiNote |
| * To use with implementation inheritance, for when you don't inherit: |
| * <pre> |
| * private final Transactional txn = TransactionalLock.createMRSW() ; |
| * private final Transactional txn() { return txn; } |
| * {@literal @}Override public void begin(TxnType txnType) { txn().begin(txnType) ; } |
| * {@literal @}Override public void begin() { txn().begin(); } |
| * {@literal @}Override public void begin(TxnType txnType) { txn().begin(txnType); } |
| * {@literal @}Override public void begin(ReadWrite mode) { txn().begin(mode); } |
| * {@literal @}Override public boolean promote() { return txn().promote(); } |
| * {@literal @}Override public void commit() { txn().commit(); } |
| * {@literal @}Override public void abort() { txn().abort(); } |
| * {@literal @}Override public boolean isInTransaction() { return txn().isInTransaction(); } |
| * {@literal @}Override public void end() { txn().end(); } |
| * {@literal @}Override public ReadWrite transactionMode() { return txn().transactionMode(); } |
| * {@literal @}Override public TxnType transactionType() { return txn().transactionType(); } |
| * {@literal @}Override public boolean supportsTransactions() { return true; } |
| * {@literal @}Override public boolean supportsTransactionAbort() { return false; } |
| * </pre> |
| */ |
| public class TransactionalLock implements Transactional { |
| /* |
| private final Transactional txn = TransactionalLock.createMRSW() ; |
| private final Transactional txn() { return txn; } |
| @Override public void begin() { txn().begin(); } |
| @Override public void begin(TxnType txnType) { txn().begin(txnType); } |
| @Override public void begin(ReadWrite mode) { txn().begin(mode); } |
| @Override public void commit() { txn().commit(); } |
| @Override public void abort() { txn().abort(); } |
| @Override public boolean isInTransaction() { return txn().isInTransaction(); } |
| @Override public void end() { txn().end(); } |
| @Override public ReadWrite transactionMode() { return txn().transactionMode(); } |
| @Override public TxnType transactionType() { return txn().transactionType(); } |
| @Override public boolean supportsTransactions() { return true; } |
| @Override public boolean supportsTransactionAbort() { return false; } |
| */ |
| |
| private ThreadLocal<Boolean> inTransaction = ThreadLocal.withInitial(() -> Boolean.FALSE); |
| private ThreadLocal<TxnType> txnType = ThreadLocal.withInitial(() -> null); |
| private ThreadLocal<ReadWrite> txnMode = ThreadLocal.withInitial(() -> null); |
| private final Lock lock ; |
| |
| /** Create a Transactional using the given lock */ |
| public static TransactionalLock create(Lock lock) { |
| return new TransactionalLock(lock) ; |
| } |
| |
| /** Create a Transactional using a MR+SW (Multiple Reader AND a Single Writer) lock */ |
| public static TransactionalLock createMRPlusSW() { |
| return create(new LockMRPlusSW()) ; |
| } |
| |
| /** Create a Transactional using a MRSW (Multiple Reader OR a Single Writer) lock */ |
| public static TransactionalLock createMRSW() { |
| return create(new LockMRSW()) ; |
| } |
| |
| /** Create a Transactional using a mutex (exclusive - one at a time) lock */ |
| public static TransactionalLock createMutex() { |
| return create(new LockMutex()) ; |
| } |
| |
| protected TransactionalLock(Lock lock) { |
| this.lock = lock ; |
| } |
| |
| @Override |
| public void begin(ReadWrite readWrite) { |
| begin(TxnType.convert(readWrite)); |
| } |
| |
| @Override |
| public void begin(TxnType txnType) { |
| if ( isInTransaction() ) |
| error("Already in a transaction") ; |
| switch(txnType) { |
| case READ_PROMOTE: |
| case READ_COMMITTED_PROMOTE: |
| throw new UnsupportedOperationException("begin("+txnType+")"); |
| default: |
| } |
| ReadWrite readWrite = TxnType.convert(txnType); |
| boolean isRead = readWrite.equals(ReadWrite.READ) ; |
| lock.enterCriticalSection(isRead); |
| this.inTransaction.set(true); |
| this.txnMode.set(readWrite); |
| this.txnType.set(txnType); |
| } |
| |
| @Override public ReadWrite transactionMode() { |
| return Lib.readThreadLocal(txnMode) ; |
| } |
| |
| @Override public TxnType transactionType() { |
| return Lib.readThreadLocal(txnType) ; |
| } |
| |
| // Lock promotion required (Ok for mutex) |
| |
| @Override |
| public boolean promote(Promote txnType) { |
| return false; |
| } |
| |
| @Override |
| public void commit() { |
| endOnce() ; |
| } |
| |
| @Override |
| public void abort() { |
| // if ( isTransactionType(ReadWrite.WRITE) ) |
| // error("Transactional.abort()") ; |
| endOnce() ; |
| } |
| |
| @Override |
| public boolean isInTransaction() { |
| return inTransaction.get(); |
| } |
| |
| public boolean isTransactionMode(ReadWrite mode) { |
| if ( ! isInTransaction() ) |
| return false; |
| return Lib.readThreadLocal(txnMode) == mode; |
| } |
| |
| @Override |
| public void end() { |
| if ( isTransactionMode(ReadWrite.WRITE) ) |
| error("Write transaction - no commit or abort before end()") ; |
| endOnce() ; |
| } |
| |
| protected void endOnce() { |
| if ( isInTransaction() ) { |
| lock.leaveCriticalSection() ; |
| txnMode.set(null); |
| txnType.set(null); |
| inTransaction.set(false); |
| txnMode.remove(); |
| txnType.remove(); |
| inTransaction.remove(); |
| } |
| } |
| |
| protected void error(String msg) { |
| throw new JenaTransactionException(msg) ; |
| } |
| } |