| /* |
| * 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.tephra.inmemory; |
| |
| import it.unimi.dsi.fastutil.longs.LongArrayList; |
| import org.apache.tephra.InvalidTruncateTimeException; |
| import org.apache.tephra.Transaction; |
| import org.apache.tephra.TransactionCouldNotTakeSnapshotException; |
| import org.apache.tephra.TransactionSystemClient; |
| import org.apache.tephra.TransactionType; |
| import org.apache.tephra.TxConstants; |
| |
| import java.io.InputStream; |
| import java.util.Collection; |
| import java.util.Set; |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| /** |
| * Implementation of the tx system client that doesn't talk to any global service and tries to do its best to meet the |
| * tx system requirements/expectations. In fact it implements enough logic to support running flows (when each flowlet |
| * uses its own detached tx system client, without talking to each other and sharing any state) with "process exactly |
| * once" guarantee if no failures happen. |
| * |
| * NOTE: Will NOT detect conflicts. May leave inconsistent state when process crashes. Does NOT provide even read |
| * isolation guarantees. |
| * |
| * Good for performance testing. For demoing high throughput. For use-cases with relaxed tx guarantees. |
| */ |
| public class DetachedTxSystemClient implements TransactionSystemClient { |
| // Dataset and queue logic relies on tx id to grow monotonically even after restart. Hence we need to start with |
| // value that is for sure bigger than the last one used before restart. |
| // NOTE: with code below we assume we don't do more than InMemoryTransactionManager.MAX_TX_PER_MS tx/ms |
| // by single client |
| private AtomicLong generator = new AtomicLong(System.currentTimeMillis() * TxConstants.MAX_TX_PER_MS); |
| |
| @Override |
| public Transaction startShort() { |
| long wp = getWritePointer(); |
| // NOTE: -1 here is because we have logic that uses (readpointer + 1) as a "exclusive stop key" in some datasets |
| return new Transaction( |
| Long.MAX_VALUE - 1, wp, new long[0], new long[0], |
| Transaction.NO_TX_IN_PROGRESS, TransactionType.SHORT); |
| } |
| |
| private long getWritePointer() { |
| long wp = generator.incrementAndGet(); |
| // NOTE: using InMemoryTransactionManager.MAX_TX_PER_MS to be at least close to real one |
| long now = System.currentTimeMillis(); |
| if (wp < now * TxConstants.MAX_TX_PER_MS) { |
| // trying to advance to align with timestamp, but only once: if failed, we'll just try again later with next tx |
| long advanced = now * TxConstants.MAX_TX_PER_MS; |
| if (generator.compareAndSet(wp, advanced)) { |
| wp = advanced; |
| } |
| } |
| return wp; |
| } |
| |
| @Override |
| public Transaction startShort(int timeout) { |
| return startShort(); |
| } |
| |
| @Override |
| public Transaction startLong() { |
| return startShort(); |
| } |
| |
| @Override |
| public boolean canCommit(Transaction tx, Collection<byte[]> changeIds) { |
| return true; |
| } |
| |
| @Override |
| public boolean canCommitOrThrow(Transaction tx, Collection<byte[]> changeIds) { |
| return true; |
| } |
| |
| @Override |
| public boolean commit(Transaction tx) { |
| return true; |
| } |
| |
| @Override |
| public void abort(Transaction tx) { |
| // do nothing |
| } |
| |
| @Override |
| public boolean invalidate(long tx) { |
| return true; |
| } |
| |
| @Override |
| public Transaction checkpoint(Transaction tx) { |
| long newWritePointer = getWritePointer(); |
| LongArrayList newCheckpointPointers = new LongArrayList(tx.getCheckpointWritePointers()); |
| newCheckpointPointers.add(newWritePointer); |
| return new Transaction(tx, newWritePointer, newCheckpointPointers.toLongArray()); |
| } |
| |
| @Override |
| public InputStream getSnapshotInputStream() throws TransactionCouldNotTakeSnapshotException { |
| throw new TransactionCouldNotTakeSnapshotException( |
| "Snapshot not implemented in detached transaction system client"); |
| } |
| |
| @Override |
| public String status() { |
| return TxConstants.STATUS_OK; |
| } |
| |
| @Override |
| public void resetState() { |
| // do nothing |
| } |
| |
| @Override |
| public boolean truncateInvalidTx(Set<Long> invalidTxIds) { |
| return true; |
| } |
| |
| @Override |
| public boolean truncateInvalidTxBefore(long time) throws InvalidTruncateTimeException { |
| return true; |
| } |
| |
| @Override |
| public int getInvalidSize() { |
| return 0; |
| } |
| |
| @Override |
| public void pruneNow() { |
| // do nothing |
| } |
| } |