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.TransactionChainIdentifier;
  17 import org.opendaylight.controller.cluster.datastore.identifiers.TransactionIdentifier;
  18 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  19 import org.opendaylight.controller.cluster.datastore.messages.PrimaryShardInfo;
  20 import org.opendaylight.controller.md.sal.common.api.data.TransactionChainClosedException;
  21 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
  22 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
  23 import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransactionChain;
  24 import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
  25 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
  26 import org.slf4j.Logger;
  27 import org.slf4j.LoggerFactory;
  28 import scala.concurrent.Future;
  29 import scala.concurrent.Promise;
  30
  31 /**
  32  * A chain of {@link TransactionProxy}s. It allows a single open transaction to be open
  33  * at a time. For remote transactions, it also tracks the outstanding readiness requests
  34  * towards the shard and unblocks operations only after all have completed.
  35  */
  36 final class TransactionChainProxy extends AbstractTransactionContextFactory<LocalTransactionChain> implements DOMStoreTransactionChain {
  37     private static abstract class State {
  38         /**
  39          * Check if it is okay to allocate a new transaction.
  40          * @throws IllegalStateException if a transaction may not be allocated.
  41          */
  42         abstract void checkReady();
  43
  44         /**
  45          * Return the future which needs to be waited for before shard information
  46          * is returned (which unblocks remote transactions).
  47          * @return Future to wait for, or null of no wait is necessary
  48          */
  49         abstract Future<?> previousFuture();
  50     }
  51
  52     private static abstract class Pending extends State {
  53         private final TransactionIdentifier transaction;
  54         private final Future<?> previousFuture;
  55
  56         Pending(final TransactionIdentifier transaction, final Future<?> previousFuture) {
  57             this.previousFuture = previousFuture;
  58             this.transaction = Preconditions.checkNotNull(transaction);
  59         }
  60
  61         @Override
  62         final Future<?> previousFuture() {
  63             return previousFuture;
  64         }
  65
  66         final TransactionIdentifier getIdentifier() {
  67             return transaction;
  68         }
  69     }
  70
  71     private static final class Allocated extends Pending {
  72         Allocated(final TransactionIdentifier transaction, final Future<?> previousFuture) {
  73             super(transaction, previousFuture);
  74         }
  75
  76         @Override
  77         void checkReady() {
  78             throw new IllegalStateException(String.format("Previous transaction %s is not ready yet", getIdentifier()));
  79         }
  80     }
  81
  82     private static final class Submitted extends Pending {
  83         Submitted(final TransactionIdentifier transaction, final Future<?> previousFuture) {
  84             super(transaction, previousFuture);
  85         }
  86
  87         @Override
  88         void checkReady() {
  89             // Okay to allocate
  90         }
  91     }
  92
  93     private static abstract class DefaultState extends State {
  94         @Override
  95         final Future<?> previousFuture() {
  96             return null;
  97         }
  98     }
  99
 100     private static final State IDLE_STATE = new DefaultState() {
 101         @Override
 102         void checkReady() {
 103             // Okay to allocate
 104         }
 105     };
 106
 107     private static final State CLOSED_STATE = new DefaultState() {
 108         @Override
 109         void checkReady() {
 110             throw new TransactionChainClosedException("Transaction chain has been closed");
 111         }
 112     };
 113
 114     private static final Logger LOG = LoggerFactory.getLogger(TransactionChainProxy.class);
 115     private static final AtomicInteger CHAIN_COUNTER = new AtomicInteger();
 116     private static final AtomicReferenceFieldUpdater<TransactionChainProxy, State> STATE_UPDATER =
 117             AtomicReferenceFieldUpdater.newUpdater(TransactionChainProxy.class, State.class, "currentState");
 118
 119     private final TransactionChainIdentifier transactionChainId;
 120     private final TransactionContextFactory parent;
 121     private volatile State currentState = IDLE_STATE;
 122
 123     TransactionChainProxy(final TransactionContextFactory parent) {
 124         super(parent.getActorContext());
 125
 126         transactionChainId = new TransactionChainIdentifier(parent.getActorContext().getCurrentMemberName(), CHAIN_COUNTER.incrementAndGet());
 127         this.parent = parent;
 128     }
 129
 130     public String getTransactionChainId() {
 131         return transactionChainId.toString();
 132     }
 133
 134     @Override
 135     public DOMStoreReadTransaction newReadOnlyTransaction() {
 136         currentState.checkReady();
 137         return new TransactionProxy(this, TransactionType.READ_ONLY);
 138     }
 139
 140     @Override
 141     public DOMStoreReadWriteTransaction newReadWriteTransaction() {
 142         getActorContext().acquireTxCreationPermit();
 143         return allocateWriteTransaction(TransactionType.READ_WRITE);
 144     }
 145
 146     @Override
 147     public DOMStoreWriteTransaction newWriteOnlyTransaction() {
 148         getActorContext().acquireTxCreationPermit();
 149         return allocateWriteTransaction(TransactionType.WRITE_ONLY);
 150     }
 151
 152     @Override
 153     public void close() {
 154         currentState = CLOSED_STATE;
 155
 156         // Send a close transaction chain request to each and every shard
 157         getActorContext().broadcast(new CloseTransactionChain(transactionChainId.toString()).toSerializable());
 158     }
 159
 160     private TransactionProxy allocateWriteTransaction(final TransactionType type) {
 161         State localState = currentState;
 162         localState.checkReady();
 163
 164         final TransactionProxy ret = new TransactionProxy(this, type);
 165         currentState = new Allocated(ret.getIdentifier(), localState.previousFuture());
 166         return ret;
 167     }
 168
 169     @Override
 170     protected LocalTransactionChain factoryForShard(final String shardName, final ActorSelection shardLeader, final DataTree dataTree) {
 171         final LocalTransactionChain ret = new LocalTransactionChain(this, shardLeader, dataTree);
 172         LOG.debug("Allocated transaction chain {} for shard {} leader {}", ret, shardName, shardLeader);
 173         return ret;
 174     }
 175
 176     /**
 177      * This method is overridden to ensure the previous Tx's ready operations complete
 178      * before we initiate the next 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<PrimaryShardInfo> findPrimaryShard(final String shardName) {
 183         // Read current state atomically
 184         final State localState = currentState;
 185
 186         // There are no outstanding futures, shortcut
 187         final Future<?> previous = localState.previousFuture();
 188         if (previous == null) {
 189             return parent.findPrimaryShard(shardName);
 190         }
 191
 192         final String previousTransactionId;
 193
 194         if(localState instanceof Pending){
 195             previousTransactionId = ((Pending) localState).getIdentifier().toString();
 196             LOG.debug("Waiting for ready futures with pending Tx {}", previousTransactionId);
 197         } else {
 198             previousTransactionId = "";
 199             LOG.debug("Waiting for ready futures on chain {}", getTransactionChainId());
 200         }
 201
 202         // Add a callback for completion of the combined Futures.
 203         final Promise<PrimaryShardInfo> returnPromise = akka.dispatch.Futures.promise();
 204
 205         final OnComplete onComplete = new OnComplete() {
 206             @Override
 207             public void onComplete(final Throwable failure, final Object notUsed) {
 208                 if (failure != null) {
 209                     // A Ready Future failed so fail the returned Promise.
 210                     LOG.error("Ready future failed for Tx {}", previousTransactionId);
 211                     returnPromise.failure(failure);
 212                 } else {
 213                     LOG.debug("Previous Tx {} readied - proceeding to FindPrimaryShard",
 214                             previousTransactionId);
 215
 216                     // Send the FindPrimaryShard message and use the resulting Future to complete the
 217                     // returned Promise.
 218                     returnPromise.completeWith(parent.findPrimaryShard(shardName));
 219                 }
 220             }
 221         };
 222
 223         previous.onComplete(onComplete, getActorContext().getClientDispatcher());
 224         return returnPromise.future();
 225     }
 226
 227     @Override
 228     protected <T> void onTransactionReady(final TransactionIdentifier transaction, final Collection<Future<T>> cohortFutures) {
 229         final State localState = currentState;
 230         Preconditions.checkState(localState instanceof Allocated, "Readying transaction %s while state is %s", transaction, localState);
 231         final TransactionIdentifier currentTx = ((Allocated)localState).getIdentifier();
 232         Preconditions.checkState(transaction.equals(currentTx), "Readying transaction %s while %s is allocated", transaction, currentTx);
 233
 234         // Transaction ready and we are not waiting for futures -- go to idle
 235         if (cohortFutures.isEmpty()) {
 236             currentState = IDLE_STATE;
 237             return;
 238         }
 239
 240         // Combine the ready Futures into 1
 241         final Future<Iterable<T>> combined = akka.dispatch.Futures.sequence(
 242                 cohortFutures, getActorContext().getClientDispatcher());
 243
 244         // Record the we have outstanding futures
 245         final State newState = new Submitted(transaction, combined);
 246         currentState = newState;
 247
 248         // Attach a completion reset, but only if we do not allocate a transaction
 249         // in-between
 250         combined.onComplete(new OnComplete<Iterable<T>>() {
 251             @Override
 252             public void onComplete(final Throwable arg0, final Iterable<T> arg1) {
 253                 STATE_UPDATER.compareAndSet(TransactionChainProxy.this, newState, IDLE_STATE);
 254             }
 255         }, getActorContext().getClientDispatcher());
 256     }
 257
 258     @Override
 259     protected TransactionIdentifier nextIdentifier() {
 260         return transactionChainId.newTransactionIdentifier();
 261     }
 262 }