opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/TransactionProxy.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 package org.opendaylight.controller.cluster.datastore;
   9
  10 import akka.actor.ActorSelection;
  11 import com.google.common.annotations.VisibleForTesting;
  12 import com.google.common.base.Function;
  13 import com.google.common.base.Optional;
  14 import com.google.common.base.Preconditions;
  15 import com.google.common.base.Supplier;
  16 import com.google.common.collect.Iterables;
  17 import com.google.common.util.concurrent.CheckedFuture;
  18 import com.google.common.util.concurrent.Futures;
  19 import com.google.common.util.concurrent.ListenableFuture;
  20 import com.google.common.util.concurrent.MoreExecutors;
  21 import com.google.common.util.concurrent.SettableFuture;
  22 import java.util.ArrayList;
  23 import java.util.Collection;
  24 import java.util.List;
  25 import java.util.Map;
  26 import java.util.Map.Entry;
  27 import java.util.Set;
  28 import java.util.TreeMap;
  29 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  30 import org.opendaylight.controller.cluster.datastore.messages.AbstractRead;
  31 import org.opendaylight.controller.cluster.datastore.messages.DataExists;
  32 import org.opendaylight.controller.cluster.datastore.messages.ReadData;
  33 import org.opendaylight.controller.cluster.datastore.modification.AbstractModification;
  34 import org.opendaylight.controller.cluster.datastore.modification.DeleteModification;
  35 import org.opendaylight.controller.cluster.datastore.modification.MergeModification;
  36 import org.opendaylight.controller.cluster.datastore.modification.WriteModification;
  37 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  38 import org.opendaylight.controller.cluster.datastore.utils.NormalizedNodeAggregator;
  39 import org.opendaylight.mdsal.common.api.MappingCheckedFuture;
  40 import org.opendaylight.mdsal.common.api.ReadFailedException;
  41 import org.opendaylight.mdsal.dom.spi.store.AbstractDOMStoreTransaction;
  42 import org.opendaylight.mdsal.dom.spi.store.DOMStoreReadWriteTransaction;
  43 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  44 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  45 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
  46 import org.slf4j.Logger;
  47 import org.slf4j.LoggerFactory;
  48 import scala.concurrent.Future;
  49 import scala.concurrent.Promise;
  50
  51 /**
  52  * A transaction potentially spanning multiple backend shards.
  53  */
  54 public class TransactionProxy extends AbstractDOMStoreTransaction<TransactionIdentifier>
  55         implements DOMStoreReadWriteTransaction {
  56     private enum TransactionState {
  57         OPEN,
  58         READY,
  59         CLOSED,
  60     }
  61
  62     private static final Logger LOG = LoggerFactory.getLogger(TransactionProxy.class);
  63
  64     // Global lock used for transactions spanning multiple shards - synchronizes sending of the ready messages
  65     // for atomicity to avoid potential deadlock with concurrent transactions spanning the same shards as outlined
  66     // in the following scenario:
  67     //
  68     //  - Tx1 sends ready message to shard A
  69     //  - Tx2 sends ready message to shard A
  70     //  - Tx2 sends ready message to shard B
  71     //  - Tx1 sends ready message to shard B
  72     //
  73     // This scenario results in deadlock: after Tx1 canCommits to shard A, it can't proceed with shard B until Tx2
  74     // completes as Tx2 was readied first on shard B. However Tx2 cannot make progress because it's waiting to canCommit
  75     // on shard A which is blocked by Tx1.
  76     //
  77     // The global lock avoids this as it forces the ready messages to be sent in a predictable order:
  78     //
  79     //  - Tx1 sends ready message to shard A
  80     //  - Tx1 sends ready message to shard B
  81     //  - Tx2 sends ready message to shard A
  82     //  - Tx2 sends ready message to shard B
  83     //
  84     private static final Object GLOBAL_TX_READY_LOCK = new Object();
  85
  86     private final Map<String, TransactionContextWrapper> txContextWrappers = new TreeMap<>();
  87     private final AbstractTransactionContextFactory<?> txContextFactory;
  88     private final TransactionType type;
  89     private TransactionState state = TransactionState.OPEN;
  90
  91     @VisibleForTesting
  92     public TransactionProxy(final AbstractTransactionContextFactory<?> txContextFactory, final TransactionType type) {
  93         super(txContextFactory.nextIdentifier(), txContextFactory.getActorContext().getDatastoreContext()
  94                 .isTransactionDebugContextEnabled());
  95         this.txContextFactory = txContextFactory;
  96         this.type = Preconditions.checkNotNull(type);
  97
  98         LOG.debug("New {} Tx - {}", type, getIdentifier());
  99     }
 100
 101     @Override
 102     public CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
 103         return executeRead(shardNameFromIdentifier(path), new DataExists(path, DataStoreVersions.CURRENT_VERSION));
 104     }
 105
 106     private <T> CheckedFuture<T, ReadFailedException> executeRead(final String shardName,
 107             final AbstractRead<T> readCmd) {
 108         Preconditions.checkState(type != TransactionType.WRITE_ONLY,
 109                 "Reads from write-only transactions are not allowed");
 110
 111         LOG.trace("Tx {} {} {}", getIdentifier(), readCmd.getClass().getSimpleName(), readCmd.getPath());
 112
 113         final SettableFuture<T> proxyFuture = SettableFuture.create();
 114         TransactionContextWrapper contextWrapper = getContextWrapper(shardName);
 115         contextWrapper.maybeExecuteTransactionOperation(new TransactionOperation() {
 116             @Override
 117             public void invoke(final TransactionContext transactionContext, final Boolean havePermit) {
 118                 transactionContext.executeRead(readCmd, proxyFuture, havePermit);
 119             }
 120         });
 121
 122         return MappingCheckedFuture.create(proxyFuture, ReadFailedException.MAPPER);
 123     }
 124
 125     @Override
 126     public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
 127         Preconditions.checkState(type != TransactionType.WRITE_ONLY,
 128                 "Reads from write-only transactions are not allowed");
 129         Preconditions.checkNotNull(path, "path should not be null");
 130
 131         LOG.trace("Tx {} read {}", getIdentifier(), path);
 132         return path.isEmpty() ? readAllData() :  singleShardRead(shardNameFromIdentifier(path), path);
 133     }
 134
 135     private CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> singleShardRead(
 136             final String shardName, final YangInstanceIdentifier path) {
 137         return executeRead(shardName, new ReadData(path, DataStoreVersions.CURRENT_VERSION));
 138     }
 139
 140     private CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readAllData() {
 141         final Set<String> allShardNames = txContextFactory.getActorContext().getConfiguration().getAllShardNames();
 142         final Collection<CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException>> futures =
 143                 new ArrayList<>(allShardNames.size());
 144
 145         for (String shardName : allShardNames) {
 146             futures.add(singleShardRead(shardName, YangInstanceIdentifier.EMPTY));
 147         }
 148
 149         final ListenableFuture<List<Optional<NormalizedNode<?, ?>>>> listFuture = Futures.allAsList(futures);
 150         final ListenableFuture<Optional<NormalizedNode<?, ?>>> aggregateFuture;
 151
 152         aggregateFuture = Futures.transform(listFuture,
 153             (Function<List<Optional<NormalizedNode<?, ?>>>, Optional<NormalizedNode<?, ?>>>) input -> {
 154                 try {
 155                     return NormalizedNodeAggregator.aggregate(YangInstanceIdentifier.EMPTY, input,
 156                             txContextFactory.getActorContext().getSchemaContext(),
 157                             txContextFactory.getActorContext().getDatastoreContext().getLogicalStoreType());
 158                 } catch (DataValidationFailedException e) {
 159                     throw new IllegalArgumentException("Failed to aggregate", e);
 160                 }
 161             }, MoreExecutors.directExecutor());
 162
 163         return MappingCheckedFuture.create(aggregateFuture, ReadFailedException.MAPPER);
 164     }
 165
 166     @Override
 167     public void delete(final YangInstanceIdentifier path) {
 168         executeModification(new DeleteModification(path));
 169     }
 170
 171     @Override
 172     public void merge(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
 173         executeModification(new MergeModification(path, data));
 174     }
 175
 176     @Override
 177     public void write(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
 178         executeModification(new WriteModification(path, data));
 179     }
 180
 181     private void executeModification(final AbstractModification modification) {
 182         checkModificationState();
 183
 184         LOG.trace("Tx {} executeModification {} {}", getIdentifier(), modification.getClass().getSimpleName(),
 185                 modification.getPath());
 186
 187         TransactionContextWrapper contextWrapper = getContextWrapper(modification.getPath());
 188         contextWrapper.maybeExecuteTransactionOperation(new TransactionOperation() {
 189             @Override
 190             protected void invoke(final TransactionContext transactionContext, final Boolean havePermit) {
 191                 transactionContext.executeModification(modification, havePermit);
 192             }
 193         });
 194     }
 195
 196     private void checkModificationState() {
 197         Preconditions.checkState(type != TransactionType.READ_ONLY,
 198                 "Modification operation on read-only transaction is not allowed");
 199         Preconditions.checkState(state == TransactionState.OPEN,
 200                 "Transaction is sealed - further modifications are not allowed");
 201     }
 202
 203     private boolean seal(final TransactionState newState) {
 204         if (state == TransactionState.OPEN) {
 205             state = newState;
 206             return true;
 207         } else {
 208             return false;
 209         }
 210     }
 211
 212     @Override
 213     public final void close() {
 214         if (!seal(TransactionState.CLOSED)) {
 215             Preconditions.checkState(state == TransactionState.CLOSED, "Transaction %s is ready, it cannot be closed",
 216                 getIdentifier());
 217             // Idempotent no-op as per AutoCloseable recommendation
 218             return;
 219         }
 220
 221         for (TransactionContextWrapper contextWrapper : txContextWrappers.values()) {
 222             contextWrapper.maybeExecuteTransactionOperation(new TransactionOperation() {
 223                 @Override
 224                 public void invoke(final TransactionContext transactionContext, final Boolean havePermit) {
 225                     transactionContext.closeTransaction();
 226                 }
 227             });
 228         }
 229
 230
 231         txContextWrappers.clear();
 232     }
 233
 234     @Override
 235     public final AbstractThreePhaseCommitCohort<?> ready() {
 236         Preconditions.checkState(type != TransactionType.READ_ONLY, "Read-only transactions cannot be readied");
 237
 238         final boolean success = seal(TransactionState.READY);
 239         Preconditions.checkState(success, "Transaction %s is %s, it cannot be readied", getIdentifier(), state);
 240
 241         LOG.debug("Tx {} Readying {} components for commit", getIdentifier(), txContextWrappers.size());
 242
 243         final AbstractThreePhaseCommitCohort<?> ret;
 244         switch (txContextWrappers.size()) {
 245             case 0:
 246                 ret = NoOpDOMStoreThreePhaseCommitCohort.INSTANCE;
 247                 break;
 248             case 1:
 249                 final Entry<String, TransactionContextWrapper> e = Iterables.getOnlyElement(
 250                         txContextWrappers.entrySet());
 251                 ret = createSingleCommitCohort(e.getKey(), e.getValue());
 252                 break;
 253             default:
 254                 ret = createMultiCommitCohort(txContextWrappers.entrySet());
 255         }
 256
 257         txContextFactory.onTransactionReady(getIdentifier(), ret.getCohortFutures());
 258
 259         final Throwable debugContext = getDebugContext();
 260         return debugContext == null ? ret : new DebugThreePhaseCommitCohort(getIdentifier(), ret, debugContext);
 261     }
 262
 263     @SuppressWarnings({ "rawtypes", "unchecked" })
 264     private AbstractThreePhaseCommitCohort<?> createSingleCommitCohort(final String shardName,
 265             final TransactionContextWrapper contextWrapper) {
 266
 267         LOG.debug("Tx {} Readying transaction for shard {}", getIdentifier(), shardName);
 268
 269         final OperationCallback.Reference operationCallbackRef =
 270                 new OperationCallback.Reference(OperationCallback.NO_OP_CALLBACK);
 271
 272         final TransactionContext transactionContext = contextWrapper.getTransactionContext();
 273         final Future future;
 274         if (transactionContext == null) {
 275             final Promise promise = akka.dispatch.Futures.promise();
 276             contextWrapper.maybeExecuteTransactionOperation(new TransactionOperation() {
 277                 @Override
 278                 public void invoke(final TransactionContext newTransactionContext, final Boolean havePermit) {
 279                     promise.completeWith(getDirectCommitFuture(newTransactionContext, operationCallbackRef,
 280                         havePermit));
 281                 }
 282             });
 283             future = promise.future();
 284         } else {
 285             // avoid the creation of a promise and a TransactionOperation
 286             future = getDirectCommitFuture(transactionContext, operationCallbackRef, null);
 287         }
 288
 289         return new SingleCommitCohortProxy(txContextFactory.getActorContext(), future, getIdentifier(),
 290             operationCallbackRef);
 291     }
 292
 293     private Future<?> getDirectCommitFuture(final TransactionContext transactionContext,
 294             final OperationCallback.Reference operationCallbackRef, final Boolean havePermit) {
 295         TransactionRateLimitingCallback rateLimitingCallback = new TransactionRateLimitingCallback(
 296                 txContextFactory.getActorContext());
 297         operationCallbackRef.set(rateLimitingCallback);
 298         rateLimitingCallback.run();
 299         return transactionContext.directCommit(havePermit);
 300     }
 301
 302     private AbstractThreePhaseCommitCohort<ActorSelection> createMultiCommitCohort(
 303             final Set<Entry<String, TransactionContextWrapper>> txContextWrapperEntries) {
 304
 305         final List<ThreePhaseCommitCohortProxy.CohortInfo> cohorts = new ArrayList<>(txContextWrapperEntries.size());
 306
 307         synchronized (GLOBAL_TX_READY_LOCK) {
 308             for (Entry<String, TransactionContextWrapper> e : txContextWrapperEntries) {
 309                 LOG.debug("Tx {} Readying transaction for shard {}", getIdentifier(), e.getKey());
 310
 311                 final TransactionContextWrapper wrapper = e.getValue();
 312
 313                 // The remote tx version is obtained the via TransactionContext which may not be available yet so
 314                 // we pass a Supplier to dynamically obtain it. Once the ready Future is resolved the
 315                 // TransactionContext is available.
 316                 Supplier<Short> txVersionSupplier = () -> wrapper.getTransactionContext().getTransactionVersion();
 317
 318                 cohorts.add(new ThreePhaseCommitCohortProxy.CohortInfo(wrapper.readyTransaction(), txVersionSupplier));
 319             }
 320         }
 321
 322         return new ThreePhaseCommitCohortProxy(txContextFactory.getActorContext(), cohorts, getIdentifier());
 323     }
 324
 325     private String shardNameFromIdentifier(final YangInstanceIdentifier path) {
 326         return txContextFactory.getActorContext().getShardStrategyFactory().getStrategy(path).findShard(path);
 327     }
 328
 329     private TransactionContextWrapper getContextWrapper(final YangInstanceIdentifier path) {
 330         return getContextWrapper(shardNameFromIdentifier(path));
 331     }
 332
 333     private TransactionContextWrapper getContextWrapper(final String shardName) {
 334         final TransactionContextWrapper existing = txContextWrappers.get(shardName);
 335         if (existing != null) {
 336             return existing;
 337         }
 338
 339         final TransactionContextWrapper fresh = txContextFactory.newTransactionContextWrapper(this, shardName);
 340         txContextWrappers.put(shardName, fresh);
 341         return fresh;
 342     }
 343
 344     TransactionType getType() {
 345         return type;
 346     }
 347
 348     boolean isReady() {
 349         return state != TransactionState.OPEN;
 350     }
 351
 352     ActorContext getActorContext() {
 353         return txContextFactory.getActorContext();
 354     }
 355 }