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         actorContext.acquireTxCreationPermit();
 108         return allocateWriteTransaction(TransactionProxy.TransactionType.READ_WRITE);
 109     }
 110
 111     @Override
 112     public DOMStoreWriteTransaction newWriteOnlyTransaction() {
 113         actorContext.acquireTxCreationPermit();
 114         return allocateWriteTransaction(TransactionProxy.TransactionType.WRITE_ONLY);
 115     }
 116
 117     @Override
 118     public void close() {
 119         currentState = CLOSED_STATE;
 120
 121         // Send a close transaction chain request to each and every shard
 122         actorContext.broadcast(new CloseTransactionChain(transactionChainId));
 123     }
 124
 125     private ChainedTransactionProxy allocateWriteTransaction(TransactionProxy.TransactionType type) {
 126         State localState = currentState;
 127
 128         checkReadyState(localState);
 129
 130         // Pass the ready Futures from the previous Tx.
 131         ChainedTransactionProxy txProxy = new ChainedTransactionProxy(actorContext, type,
 132                 transactionChainId, localState.getPreviousReadyFutures());
 133
 134         currentState = new Allocated(txProxy);
 135
 136         return txProxy;
 137     }
 138
 139     private void checkReadyState(State state) {
 140         Preconditions.checkState(state.isReady(), "Previous transaction is not ready yet");
 141     }
 142
 143     private static class ChainedTransactionProxy extends TransactionProxy {
 144
 145         /**
 146          * Stores the ready Futures from the previous Tx in the chain.
 147          */
 148         private final List<Future<ActorSelection>> previousReadyFutures;
 149
 150         /**
 151          * Stores the ready Futures from this transaction when it is readied.
 152          */
 153         private volatile List<Future<ActorSelection>> readyFutures;
 154
 155         private ChainedTransactionProxy(ActorContext actorContext, TransactionType transactionType,
 156                 String transactionChainId, List<Future<ActorSelection>> previousReadyFutures) {
 157             super(actorContext, transactionType, transactionChainId);
 158             this.previousReadyFutures = previousReadyFutures;
 159         }
 160
 161         List<Future<ActorSelection>> getReadyFutures() {
 162             return readyFutures;
 163         }
 164
 165         boolean isReady() {
 166             return readyFutures != null;
 167         }
 168
 169         @Override
 170         protected void onTransactionReady(List<Future<ActorSelection>> readyFutures) {
 171             LOG.debug("onTransactionReady {} pending readyFutures size {} chain {}", getIdentifier(),
 172                     readyFutures.size(), getTransactionChainId());
 173             this.readyFutures = readyFutures;
 174         }
 175
 176         /**
 177          * This method is overridden to ensure the previous Tx's ready operations complete
 178          * before we create the next shard Tx in the chain to avoid creation failures if the
 179          * previous Tx's ready operations haven't completed yet.
 180          */
 181         @Override
 182         protected Future<Object> sendCreateTransaction(final ActorSelection shard,
 183                 final Object serializedCreateMessage) {
 184
 185             // Check if there are any previous ready Futures, otherwise let the super class handle it.
 186             if(previousReadyFutures.isEmpty()) {
 187                 return super.sendCreateTransaction(shard, serializedCreateMessage);
 188             }
 189
 190             // Combine the ready Futures into 1.
 191             Future<Iterable<ActorSelection>> combinedFutures = akka.dispatch.Futures.sequence(
 192                     previousReadyFutures, getActorContext().getActorSystem().dispatcher());
 193
 194             // Add a callback for completion of the combined Futures.
 195             final Promise<Object> createTxPromise = akka.dispatch.Futures.promise();
 196             OnComplete<Iterable<ActorSelection>> onComplete = new OnComplete<Iterable<ActorSelection>>() {
 197                 @Override
 198                 public void onComplete(Throwable failure, Iterable<ActorSelection> notUsed) {
 199                     if(failure != null) {
 200                         // A Ready Future failed so fail the returned Promise.
 201                         createTxPromise.failure(failure);
 202                     } else {
 203                         LOG.debug("Previous Tx readied - sending CreateTransaction for {} on chain {}",
 204                                 getIdentifier(), getTransactionChainId());
 205
 206                         // Send the CreateTx message and use the resulting Future to complete the
 207                         // returned Promise.
 208                         createTxPromise.completeWith(getActorContext().executeOperationAsync(shard,
 209                                 serializedCreateMessage));
 210                     }
 211                 }
 212             };
 213
 214             combinedFutures.onComplete(onComplete, getActorContext().getActorSystem().dispatcher());
 215
 216             return createTxPromise.future();
 217         }
 218     }
 219 }