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

   1 /*
   2  * Copyright (c) 2015 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 package org.opendaylight.controller.cluster.datastore;
   9
  10 import akka.actor.ActorSelection;
  11 import akka.dispatch.OnComplete;
  12 import com.google.common.base.Preconditions;
  13 import java.util.Collection;
  14 import java.util.concurrent.atomic.AtomicInteger;
  15 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  16 import org.opendaylight.controller.cluster.datastore.identifiers.TransactionIdentifier;
  17 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  18 import org.opendaylight.controller.cluster.datastore.messages.PrimaryShardInfo;
  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.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
  25 import org.slf4j.Logger;
  26 import org.slf4j.LoggerFactory;
  27 import scala.concurrent.Future;
  28 import scala.concurrent.Promise;
  29
  30 /**
  31  * A chain of {@link TransactionProxy}s. It allows a single open transaction to be open
  32  * at a time. For remote transactions, it also tracks the outstanding readiness requests
  33  * towards the shard and unblocks operations only after all have completed.
  34  */
  35 final class TransactionChainProxy extends AbstractTransactionContextFactory<LocalTransactionChain> implements DOMStoreTransactionChain {
  36     private static abstract class State {
  37         /**
  38          * Check if it is okay to allocate a new transaction.
  39          * @throws IllegalStateException if a transaction may not be allocated.
  40          */
  41         abstract void checkReady();
  42
  43         /**
  44          * Return the future which needs to be waited for before shard information
  45          * is returned (which unblocks remote transactions).
  46          * @return Future to wait for, or null of no wait is necessary
  47          */
  48         abstract Future<?> previousFuture();
  49     }
  50
  51     private static abstract class Pending extends State {
  52         private final TransactionIdentifier transaction;
  53         private final Future<?> previousFuture;
  54
  55         Pending(final TransactionIdentifier transaction, final Future<?> previousFuture) {
  56             this.previousFuture = previousFuture;
  57             this.transaction = Preconditions.checkNotNull(transaction);
  58         }
  59
  60         @Override
  61         final Future<?> previousFuture() {
  62             return previousFuture;
  63         }
  64
  65         final TransactionIdentifier getIdentifier() {
  66             return transaction;
  67         }
  68     }
  69
  70     private static final class Allocated extends Pending {
  71         Allocated(final TransactionIdentifier transaction, final Future<?> previousFuture) {
  72             super(transaction, previousFuture);
  73         }
  74
  75         @Override
  76         void checkReady() {
  77             throw new IllegalStateException(String.format("Previous transaction %s is not ready yet", getIdentifier()));
  78         }
  79     }
  80
  81     private static final class Submitted extends Pending {
  82         Submitted(final TransactionIdentifier transaction, final Future<?> previousFuture) {
  83             super(transaction, previousFuture);
  84         }
  85
  86         @Override
  87         void checkReady() {
  88             // Okay to allocate
  89         }
  90     }
  91
  92     private static abstract class DefaultState extends State {
  93         @Override
  94         final Future<?> previousFuture() {
  95             return null;
  96         }
  97     }
  98
  99     private static final State IDLE_STATE = new DefaultState() {
 100         @Override
 101         void checkReady() {
 102             // Okay to allocate
 103         }
 104     };
 105
 106     private static final State CLOSED_STATE = new DefaultState() {
 107         @Override
 108         void checkReady() {
 109             throw new TransactionChainClosedException("Transaction chain has been closed");
 110         }
 111     };
 112
 113     private static final Logger LOG = LoggerFactory.getLogger(TransactionChainProxy.class);
 114     private static final AtomicInteger CHAIN_COUNTER = new AtomicInteger();
 115     private static final AtomicReferenceFieldUpdater<TransactionChainProxy, State> STATE_UPDATER =
 116             AtomicReferenceFieldUpdater.newUpdater(TransactionChainProxy.class, State.class, "currentState");
 117
 118     private final String transactionChainId;
 119     private final TransactionContextFactory parent;
 120     private volatile State currentState = IDLE_STATE;
 121
 122     TransactionChainProxy(final TransactionContextFactory parent) {
 123         super(parent.getActorContext());
 124         transactionChainId = parent.getActorContext().getCurrentMemberName() + "-txn-chain-" + CHAIN_COUNTER.incrementAndGet();
 125         this.parent = parent;
 126     }
 127
 128     public String getTransactionChainId() {
 129         return transactionChainId;
 130     }
 131
 132     @Override
 133     public DOMStoreReadTransaction newReadOnlyTransaction() {
 134         currentState.checkReady();
 135         return new TransactionProxy(this, TransactionType.READ_ONLY);
 136     }
 137
 138     @Override
 139     public DOMStoreReadWriteTransaction newReadWriteTransaction() {
 140         getActorContext().acquireTxCreationPermit();
 141         return allocateWriteTransaction(TransactionType.READ_WRITE);
 142     }
 143
 144     @Override
 145     public DOMStoreWriteTransaction newWriteOnlyTransaction() {
 146         getActorContext().acquireTxCreationPermit();
 147         return allocateWriteTransaction(TransactionType.WRITE_ONLY);
 148     }
 149
 150     @Override
 151     public void close() {
 152         currentState = CLOSED_STATE;
 153
 154         // Send a close transaction chain request to each and every shard
 155         getActorContext().broadcast(new CloseTransactionChain(transactionChainId).toSerializable());
 156     }
 157
 158     private TransactionProxy allocateWriteTransaction(final TransactionType type) {
 159         State localState = currentState;
 160         localState.checkReady();
 161
 162         final TransactionProxy ret = new TransactionProxy(this, type);
 163         currentState = new Allocated(ret.getIdentifier(), localState.previousFuture());
 164         return ret;
 165     }
 166
 167     @Override
 168     protected LocalTransactionChain factoryForShard(final String shardName, final ActorSelection shardLeader, final DataTree dataTree) {
 169         final LocalTransactionChain ret = new LocalTransactionChain(this, shardLeader, dataTree);
 170         LOG.debug("Allocated transaction chain {} for shard {} leader {}", ret, shardName, shardLeader);
 171         return ret;
 172     }
 173
 174     /**
 175      * This method is overridden to ensure the previous Tx's ready operations complete
 176      * before we initiate the next 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<PrimaryShardInfo> findPrimaryShard(final String shardName) {
 181         // Read current state atomically
 182         final State localState = currentState;
 183
 184         // There are no outstanding futures, shortcut
 185         final Future<?> previous = localState.previousFuture();
 186         if (previous == null) {
 187             return parent.findPrimaryShard(shardName);
 188         }
 189
 190         LOG.debug("Waiting for ready futures for on chain {}", getTransactionChainId());
 191
 192         // Add a callback for completion of the combined Futures.
 193         final Promise<PrimaryShardInfo> returnPromise = akka.dispatch.Futures.promise();
 194
 195         final OnComplete onComplete = new OnComplete() {
 196             @Override
 197             public void onComplete(final Throwable failure, final Object notUsed) {
 198                 if (failure != null) {
 199                     // A Ready Future failed so fail the returned Promise.
 200                     returnPromise.failure(failure);
 201                 } else {
 202                     LOG.debug("Previous Tx readied - proceeding to FindPrimaryShard on chain {}",
 203                             getTransactionChainId());
 204
 205                     // Send the FindPrimaryShard message and use the resulting Future to complete the
 206                     // returned Promise.
 207                     returnPromise.completeWith(parent.findPrimaryShard(shardName));
 208                 }
 209             }
 210         };
 211
 212         previous.onComplete(onComplete, getActorContext().getClientDispatcher());
 213         return returnPromise.future();
 214     }
 215
 216     @Override
 217     protected <T> void onTransactionReady(final TransactionIdentifier transaction, final Collection<Future<T>> cohortFutures) {
 218         final State localState = currentState;
 219         Preconditions.checkState(localState instanceof Allocated, "Readying transaction %s while state is %s", transaction, localState);
 220         final TransactionIdentifier currentTx = ((Allocated)localState).getIdentifier();
 221         Preconditions.checkState(transaction.equals(currentTx), "Readying transaction %s while %s is allocated", transaction, currentTx);
 222
 223         // Transaction ready and we are not waiting for futures -- go to idle
 224         if (cohortFutures.isEmpty()) {
 225             currentState = IDLE_STATE;
 226             return;
 227         }
 228
 229         // Combine the ready Futures into 1
 230         final Future<Iterable<T>> combined = akka.dispatch.Futures.sequence(
 231                 cohortFutures, getActorContext().getClientDispatcher());
 232
 233         // Record the we have outstanding futures
 234         final State newState = new Submitted(transaction, combined);
 235         currentState = newState;
 236
 237         // Attach a completion reset, but only if we do not allocate a transaction
 238         // in-between
 239         combined.onComplete(new OnComplete<Iterable<T>>() {
 240             @Override
 241             public void onComplete(final Throwable arg0, final Iterable<T> arg1) {
 242                 STATE_UPDATER.compareAndSet(TransactionChainProxy.this, newState, IDLE_STATE);
 243             }
 244         }, getActorContext().getClientDispatcher());
 245     }
 246
 247     @Override
 248     protected TransactionIdentifier nextIdentifier() {
 249         return TransactionIdentifier.create(getMemberName(), TX_COUNTER.getAndIncrement(), transactionChainId);
 250     }
 251 }