opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/TransactionChainProxy.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8
   9 package org.opendaylight.controller.cluster.datastore;
  10
  11 import akka.actor.ActorSelection;
  12 import akka.dispatch.OnComplete;
  13 import com.google.common.base.Preconditions;
  14 import java.util.Collections;
  15 import java.util.List;
  16 import java.util.concurrent.atomic.AtomicInteger;
  17 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  18 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  19 import org.opendaylight.controller.md.sal.common.api.data.TransactionChainClosedException;
  20 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
  21 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
  22 import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransactionChain;
  23 import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
  24 import org.slf4j.Logger;
  25 import org.slf4j.LoggerFactory;
  26 import scala.concurrent.Future;
  27 import scala.concurrent.Promise;
  28
  29 /**
  30  * TransactionChainProxy acts as a proxy for a DOMStoreTransactionChain created on a remote shard
  31  */
  32 public class TransactionChainProxy implements DOMStoreTransactionChain {
  33
  34     private static final Logger LOG = LoggerFactory.getLogger(TransactionChainProxy.class);
  35
  36     private interface State {
  37         boolean isReady();
  38
  39         List<Future<ActorSelection>> getPreviousReadyFutures();
  40     }
  41
  42     private static class Allocated implements State {
  43         private final ChainedTransactionProxy transaction;
  44
  45         Allocated(ChainedTransactionProxy transaction) {
  46             this.transaction = transaction;
  47         }
  48
  49         @Override
  50         public boolean isReady() {
  51             return transaction.isReady();
  52         }
  53
  54         @Override
  55         public List<Future<ActorSelection>> getPreviousReadyFutures() {
  56             return transaction.getReadyFutures();
  57         }
  58     }
  59
  60     private static abstract class AbstractDefaultState implements State {
  61         @Override
  62         public List<Future<ActorSelection>> getPreviousReadyFutures() {
  63             return Collections.emptyList();
  64         }
  65     }
  66
  67     private static final State IDLE_STATE = new AbstractDefaultState() {
  68         @Override
  69         public boolean isReady() {
  70             return true;
  71         }
  72     };
  73
  74     private static final State CLOSED_STATE = new AbstractDefaultState() {
  75         @Override
  76         public boolean isReady() {
  77             throw new TransactionChainClosedException("Transaction chain has been closed");
  78         }
  79     };
  80
  81     private static final AtomicInteger counter = new AtomicInteger(0);
  82
  83     private final ActorContext actorContext;
  84     private final String transactionChainId;
  85     private volatile State currentState = IDLE_STATE;
  86
  87     public TransactionChainProxy(ActorContext actorContext) {
  88         this.actorContext = actorContext;
  89         transactionChainId = actorContext.getCurrentMemberName() + "-txn-chain-" + counter.incrementAndGet();
  90     }
  91
  92     public String getTransactionChainId() {
  93         return transactionChainId;
  94     }
  95
  96     @Override
  97     public DOMStoreReadTransaction newReadOnlyTransaction() {
  98         State localState = currentState;
  99         checkReadyState(localState);
 100
 101         return new ChainedTransactionProxy(actorContext, TransactionProxy.TransactionType.READ_ONLY,
 102                 transactionChainId, localState.getPreviousReadyFutures());
 103     }
 104
 105     @Override
 106     public DOMStoreReadWriteTransaction newReadWriteTransaction() {
 107         return allocateWriteTransaction(TransactionProxy.TransactionType.READ_WRITE);
 108     }
 109
 110     @Override
 111     public DOMStoreWriteTransaction newWriteOnlyTransaction() {
 112         return allocateWriteTransaction(TransactionProxy.TransactionType.WRITE_ONLY);
 113     }
 114
 115     @Override
 116     public void close() {
 117         currentState = CLOSED_STATE;
 118
 119         // Send a close transaction chain request to each and every shard
 120         actorContext.broadcast(new CloseTransactionChain(transactionChainId));
 121     }
 122
 123     private ChainedTransactionProxy allocateWriteTransaction(TransactionProxy.TransactionType type) {
 124         State localState = currentState;
 125
 126         checkReadyState(localState);
 127
 128         // Pass the ready Futures from the previous Tx.
 129         ChainedTransactionProxy txProxy = new ChainedTransactionProxy(actorContext, type,
 130                 transactionChainId, localState.getPreviousReadyFutures());
 131
 132         currentState = new Allocated(txProxy);
 133
 134         return txProxy;
 135     }
 136
 137     private void checkReadyState(State state) {
 138         Preconditions.checkState(state.isReady(), "Previous transaction is not ready yet");
 139     }
 140
 141     private static class ChainedTransactionProxy extends TransactionProxy {
 142
 143         /**
 144          * Stores the ready Futures from the previous Tx in the chain.
 145          */
 146         private final List<Future<ActorSelection>> previousReadyFutures;
 147
 148         /**
 149          * Stores the ready Futures from this transaction when it is readied.
 150          */
 151         private volatile List<Future<ActorSelection>> readyFutures;
 152
 153         private ChainedTransactionProxy(ActorContext actorContext, TransactionType transactionType,
 154                 String transactionChainId, List<Future<ActorSelection>> previousReadyFutures) {
 155             super(actorContext, transactionType, transactionChainId);
 156             this.previousReadyFutures = previousReadyFutures;
 157         }
 158
 159         List<Future<ActorSelection>> getReadyFutures() {
 160             return readyFutures;
 161         }
 162
 163         boolean isReady() {
 164             return readyFutures != null;
 165         }
 166
 167         @Override
 168         protected void onTransactionReady(List<Future<ActorSelection>> readyFutures) {
 169             LOG.debug("onTransactionReady {} pending readyFutures size {} chain {}", getIdentifier(),
 170                     readyFutures.size(), getTransactionChainId());
 171             this.readyFutures = readyFutures;
 172         }
 173
 174         /**
 175          * This method is overridden to ensure the previous Tx's ready operations complete
 176          * before we create the next shard Tx in the chain to avoid creation failures if the
 177          * previous Tx's ready operations haven't completed yet.
 178          */
 179         @Override
 180         protected Future<Object> sendCreateTransaction(final ActorSelection shard,
 181                 final Object serializedCreateMessage) {
 182
 183             // Check if there are any previous ready Futures, otherwise let the super class handle it.
 184             if(previousReadyFutures.isEmpty()) {
 185                 return super.sendCreateTransaction(shard, serializedCreateMessage);
 186             }
 187
 188             // Combine the ready Futures into 1.
 189             Future<Iterable<ActorSelection>> combinedFutures = akka.dispatch.Futures.sequence(
 190                     previousReadyFutures, getActorContext().getActorSystem().dispatcher());
 191
 192             // Add a callback for completion of the combined Futures.
 193             final Promise<Object> createTxPromise = akka.dispatch.Futures.promise();
 194             OnComplete<Iterable<ActorSelection>> onComplete = new OnComplete<Iterable<ActorSelection>>() {
 195                 @Override
 196                 public void onComplete(Throwable failure, Iterable<ActorSelection> notUsed) {
 197                     if(failure != null) {
 198                         // A Ready Future failed so fail the returned Promise.
 199                         createTxPromise.failure(failure);
 200                     } else {
 201                         LOG.debug("Previous Tx readied - sending CreateTransaction for {} on chain {}",
 202                                 getIdentifier(), getTransactionChainId());
 203
 204                         // Send the CreateTx message and use the resulting Future to complete the
 205                         // returned Promise.
 206                         createTxPromise.completeWith(getActorContext().executeOperationAsync(shard,
 207                                 serializedCreateMessage));
 208                     }
 209                 }
 210             };
 211
 212             combinedFutures.onComplete(onComplete, getActorContext().getActorSystem().dispatcher());
 213
 214             return createTxPromise.future();
 215         }
 216     }
 217 }