| /** |
| * 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 storm.trident.topology.state; |
| |
| import backtype.storm.utils.Utils; |
| import org.apache.zookeeper.KeeperException; |
| |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.SortedMap; |
| import java.util.TreeMap; |
| |
| public class RotatingTransactionalState { |
| public static interface StateInitializer { |
| Object init(long txid, Object lastState); |
| } |
| |
| private TransactionalState _state; |
| private String _subdir; |
| |
| private TreeMap<Long, Object> _curr = new TreeMap<Long, Object>(); |
| |
| public RotatingTransactionalState(TransactionalState state, String subdir) { |
| _state = state; |
| _subdir = subdir; |
| state.mkdir(subdir); |
| sync(); |
| } |
| |
| |
| public Object getLastState() { |
| if(_curr.isEmpty()) return null; |
| else return _curr.lastEntry().getValue(); |
| } |
| |
| public void overrideState(long txid, Object state) { |
| _state.setData(txPath(txid), state); |
| _curr.put(txid, state); |
| } |
| |
| public void removeState(long txid) { |
| if(_curr.containsKey(txid)) { |
| _curr.remove(txid); |
| _state.delete(txPath(txid)); |
| } |
| } |
| |
| public Object getState(long txid) { |
| return _curr.get(txid); |
| } |
| |
| public Object getState(long txid, StateInitializer init) { |
| if(!_curr.containsKey(txid)) { |
| SortedMap<Long, Object> prevMap = _curr.headMap(txid); |
| SortedMap<Long, Object> afterMap = _curr.tailMap(txid); |
| |
| Long prev = null; |
| if(!prevMap.isEmpty()) prev = prevMap.lastKey(); |
| |
| Object data; |
| if(afterMap.isEmpty()) { |
| Object prevData; |
| if(prev!=null) { |
| prevData = _curr.get(prev); |
| } else { |
| prevData = null; |
| } |
| data = init.init(txid, prevData); |
| } else { |
| data = null; |
| } |
| _curr.put(txid, data); |
| _state.setData(txPath(txid), data); |
| } |
| return _curr.get(txid); |
| } |
| |
| public Object getPreviousState(long txid) { |
| SortedMap<Long, Object> prevMap = _curr.headMap(txid); |
| if(prevMap.isEmpty()) return null; |
| else return prevMap.get(prevMap.lastKey()); |
| } |
| |
| public boolean hasCache(long txid) { |
| return _curr.containsKey(txid); |
| } |
| |
| /** |
| * Returns null if it was created, the value otherwise. |
| */ |
| public Object getStateOrCreate(long txid, StateInitializer init) { |
| if(_curr.containsKey(txid)) { |
| return _curr.get(txid); |
| } else { |
| getState(txid, init); |
| return null; |
| } |
| } |
| |
| public void cleanupBefore(long txid) { |
| SortedMap<Long, Object> toDelete = _curr.headMap(txid); |
| for(long tx: new HashSet<Long>(toDelete.keySet())) { |
| _curr.remove(tx); |
| try { |
| _state.delete(txPath(tx)); |
| } catch(RuntimeException e) { |
| // Ignore NoNodeExists exceptions because when sync() it may populate _curr with stale data since |
| // zookeeper reads are eventually consistent. |
| if(!Utils.exceptionCauseIsInstanceOf(KeeperException.NoNodeException.class, e)) { |
| throw e; |
| } |
| } |
| } |
| } |
| |
| private void sync() { |
| List<String> txids = _state.list(_subdir); |
| for(String txid_s: txids) { |
| Object data = _state.getData(txPath(txid_s)); |
| _curr.put(Long.parseLong(txid_s), data); |
| } |
| } |
| |
| private String txPath(long tx) { |
| return txPath("" + tx); |
| } |
| |
| private String txPath(String tx) { |
| return _subdir + "/" + tx; |
| } |
| |
| } |