dom/mdsal-dom-broker/src/main/java/org/opendaylight/mdsal/dom/broker/ShardedDOMDataTreeProducer.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.mdsal.dom.broker;
   9
  10 import static java.util.Objects.requireNonNull;
  11
  12 import com.google.common.base.Preconditions;
  13 import com.google.common.base.Verify;
  14 import com.google.common.collect.ImmutableSet;
  15 import java.util.Collection;
  16 import java.util.Map;
  17 import java.util.Set;
  18 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
  19 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  20 import org.checkerframework.checker.lock.qual.GuardedBy;
  21 import org.checkerframework.checker.lock.qual.Holding;
  22 import org.opendaylight.mdsal.common.api.CommitInfo;
  23 import org.opendaylight.mdsal.dom.api.DOMDataTreeCursorAwareTransaction;
  24 import org.opendaylight.mdsal.dom.api.DOMDataTreeIdentifier;
  25 import org.opendaylight.mdsal.dom.api.DOMDataTreeListener;
  26 import org.opendaylight.mdsal.dom.api.DOMDataTreeProducer;
  27 import org.opendaylight.mdsal.dom.api.DOMDataTreeProducerBusyException;
  28 import org.opendaylight.mdsal.dom.api.DOMDataTreeProducerException;
  29 import org.opendaylight.mdsal.dom.api.DOMDataTreeShard;
  30 import org.slf4j.Logger;
  31 import org.slf4j.LoggerFactory;
  32
  33 class ShardedDOMDataTreeProducer implements DOMDataTreeProducer {
  34     private static final Logger LOG = LoggerFactory.getLogger(ShardedDOMDataTreeProducer.class);
  35
  36     private final Set<DOMDataTreeIdentifier> subtrees;
  37     private final ShardedDOMDataTree dataTree;
  38
  39     private static final AtomicReferenceFieldUpdater<ShardedDOMDataTreeProducer, ShardedDOMDataTreeWriteTransaction>
  40         CURRENT_UPDATER = AtomicReferenceFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class,
  41             ShardedDOMDataTreeWriteTransaction.class, "currentTx");
  42     private volatile ShardedDOMDataTreeWriteTransaction currentTx;
  43
  44     private static final AtomicReferenceFieldUpdater<ShardedDOMDataTreeProducer, ShardedDOMDataTreeWriteTransaction>
  45         OPEN_UPDATER = AtomicReferenceFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class,
  46             ShardedDOMDataTreeWriteTransaction.class, "openTx");
  47     private volatile ShardedDOMDataTreeWriteTransaction openTx;
  48
  49     private static final AtomicReferenceFieldUpdater<ShardedDOMDataTreeProducer, ShardedDOMDataTreeWriteTransaction>
  50         LAST_UPDATER = AtomicReferenceFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class,
  51             ShardedDOMDataTreeWriteTransaction.class, "lastTx");
  52     private volatile ShardedDOMDataTreeWriteTransaction lastTx;
  53
  54     private static final AtomicIntegerFieldUpdater<ShardedDOMDataTreeProducer> CLOSED_UPDATER =
  55             AtomicIntegerFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class, "closed");
  56     private volatile int closed;
  57
  58     private volatile DOMDataTreeListener attachedListener;
  59     private volatile ProducerLayout layout;
  60
  61     ShardedDOMDataTreeProducer(final ShardedDOMDataTree dataTree,
  62                                final Collection<DOMDataTreeIdentifier> subtrees,
  63                                final Map<DOMDataTreeIdentifier, DOMDataTreeShard> shardMap) {
  64         this.dataTree = requireNonNull(dataTree);
  65         this.subtrees = ImmutableSet.copyOf(subtrees);
  66         this.layout = ProducerLayout.create(shardMap);
  67     }
  68
  69     static DOMDataTreeProducer create(final ShardedDOMDataTree dataTree,
  70                                       final Collection<DOMDataTreeIdentifier> subtrees,
  71                                       final Map<DOMDataTreeIdentifier, DOMDataTreeShard> shardMap) {
  72         return new ShardedDOMDataTreeProducer(dataTree, subtrees, shardMap);
  73     }
  74
  75     private void checkNotClosed() {
  76         Preconditions.checkState(closed == 0, "Producer is already closed");
  77     }
  78
  79     private void checkIdle() {
  80         Preconditions.checkState(openTx == null, "Transaction %s is still open", openTx);
  81     }
  82
  83     void subshardAdded(final Map<DOMDataTreeIdentifier, DOMDataTreeShard> shardMap) {
  84         checkIdle();
  85         layout = layout.reshard(shardMap);
  86     }
  87
  88     @Override
  89     public DOMDataTreeCursorAwareTransaction createTransaction(final boolean isolated) {
  90         checkNotClosed();
  91         checkIdle();
  92
  93         LOG.debug("Creating transaction from producer {}", this);
  94
  95         final ShardedDOMDataTreeWriteTransaction current = CURRENT_UPDATER.getAndSet(this, null);
  96         final ShardedDOMDataTreeWriteTransaction ret;
  97         if (isolated) {
  98             ret = createIsolatedTransaction(layout, current);
  99         } else {
 100             ret = createReusedTransaction(layout, current);
 101         }
 102
 103         final boolean success = OPEN_UPDATER.compareAndSet(this, null, ret);
 104         Preconditions.checkState(success, "Illegal concurrent access to producer %s detected", this);
 105         return ret;
 106     }
 107
 108     // This may look weird, but this has side-effects on local's producers, hence it needs to be properly synchronized
 109     // so that it happens-after submitTransaction() which may have been stolen by a callback.
 110     @GuardedBy("this")
 111     private ShardedDOMDataTreeWriteTransaction createTransaction(final ProducerLayout local) {
 112         return new ShardedDOMDataTreeWriteTransaction(this, local.createTransactions(), local);
 113
 114     }
 115
 116     // Isolated case. If we have a previous transaction, submit it before returning this one.
 117     private synchronized ShardedDOMDataTreeWriteTransaction createIsolatedTransaction(
 118             final ProducerLayout local, final ShardedDOMDataTreeWriteTransaction current) {
 119         if (current != null) {
 120             submitTransaction(current);
 121         }
 122
 123         return createTransaction(local);
 124     }
 125
 126     private ShardedDOMDataTreeWriteTransaction createReusedTransaction(final ProducerLayout local,
 127             final ShardedDOMDataTreeWriteTransaction current) {
 128         if (current != null) {
 129             // Lock-free fast path
 130             if (local.equals(current.getLayout())) {
 131                 LOG.debug("Reusing previous transaction {} since there is still a transaction inflight",
 132                     current.getIdentifier());
 133                 return current;
 134             }
 135
 136             synchronized (this) {
 137                 submitTransaction(current);
 138                 return createTransaction(local);
 139             }
 140         }
 141
 142         // Null indicates we have not seen a previous transaction -- which does not mean it is ready, as it may have
 143         // been stolen and in is process of being submitted.
 144         synchronized (this) {
 145             return createTransaction(local);
 146         }
 147     }
 148
 149     @Holding("this")
 150     private void submitTransaction(final ShardedDOMDataTreeWriteTransaction tx) {
 151         lastTx = tx;
 152         tx.doSubmit(this::transactionSuccessful, this::transactionFailed);
 153     }
 154
 155     @Override
 156     @SuppressWarnings("checkstyle:hiddenField")
 157     public DOMDataTreeProducer createProducer(final Collection<DOMDataTreeIdentifier> subtrees) {
 158         checkNotClosed();
 159         checkIdle();
 160
 161         final ProducerLayout local = layout;
 162
 163         for (final DOMDataTreeIdentifier s : subtrees) {
 164             // Check if the subtree was visible at any time
 165             Preconditions.checkArgument(local.haveSubtree(s), "Subtree %s was never available in producer %s", s, this);
 166             // Check if the subtree has not been delegated to a child
 167             final DOMDataTreeProducer child = local.lookupChild(s);
 168             Preconditions.checkArgument(child == null, "Subtree %s is delegated to child producer %s", s, child);
 169
 170             // Check if part of the requested subtree is not delegated to a child.
 171             for (final DOMDataTreeIdentifier c : local.getChildTrees()) {
 172                 Preconditions.checkArgument(!s.contains(c),
 173                     "Subtree %s cannot be delegated as it is a superset of already-delegated %s", s, c);
 174             }
 175         }
 176
 177
 178         final DOMDataTreeProducer ret;
 179         synchronized (this) {
 180             ret = dataTree.createProducer(this, subtrees);
 181         }
 182
 183         layout = local.addChild(ret, subtrees);
 184         return ret;
 185     }
 186
 187     boolean isDelegatedToChild(final DOMDataTreeIdentifier path) {
 188         return layout.lookupChild(path) != null;
 189     }
 190
 191     @Override
 192     public void close() throws DOMDataTreeProducerException {
 193         if (openTx != null) {
 194             throw new DOMDataTreeProducerBusyException(String.format("Transaction %s is still open", openTx));
 195         }
 196
 197         if (CLOSED_UPDATER.compareAndSet(this, 0, 1)) {
 198             synchronized (this) {
 199                 dataTree.destroyProducer(this);
 200                 layout.close();
 201             }
 202         }
 203     }
 204
 205     protected Set<DOMDataTreeIdentifier> getSubtrees() {
 206         return subtrees;
 207     }
 208
 209     void cancelTransaction(final ShardedDOMDataTreeWriteTransaction transaction) {
 210         final boolean success = OPEN_UPDATER.compareAndSet(this, transaction, null);
 211         if (success) {
 212             LOG.debug("Transaction {} cancelled", transaction);
 213         } else {
 214             LOG.warn("Transaction {} is not open in producer {}", transaction, this);
 215         }
 216     }
 217
 218     // Called when the user submits a transaction
 219     void transactionSubmitted(final ShardedDOMDataTreeWriteTransaction transaction) {
 220         final boolean wasOpen = OPEN_UPDATER.compareAndSet(this, transaction, null);
 221         Preconditions.checkState(wasOpen, "Attempted to submit non-open transaction %s", transaction);
 222
 223         if (lastTx == null) {
 224             // No transaction outstanding, we need to submit it now
 225             synchronized (this) {
 226                 submitTransaction(transaction);
 227             }
 228
 229             return;
 230         }
 231
 232         // There is a potentially-racing submitted transaction. Publish the new one, which may end up being
 233         // picked up by processNextTransaction.
 234         final boolean success = CURRENT_UPDATER.compareAndSet(this, null, transaction);
 235         Verify.verify(success);
 236
 237         // Now a quick check: if the racing transaction completed in between, it may have missed the current
 238         // transaction, hence we need to re-check
 239         if (lastTx == null) {
 240             submitCurrentTransaction();
 241         }
 242     }
 243
 244     private void submitCurrentTransaction() {
 245         final ShardedDOMDataTreeWriteTransaction current = currentTx;
 246         if (current != null) {
 247             synchronized (this) {
 248                 if (CURRENT_UPDATER.compareAndSet(this, current, null)) {
 249                     submitTransaction(current);
 250                 }
 251             }
 252         }
 253     }
 254
 255     private void transactionSuccessful(final ShardedDOMDataTreeWriteTransaction tx) {
 256         LOG.debug("Transaction {} completed successfully", tx.getIdentifier());
 257
 258         tx.onTransactionSuccess(CommitInfo.empty());
 259         transactionCompleted(tx);
 260     }
 261
 262     private void transactionFailed(final ShardedDOMDataTreeWriteTransaction tx, final Throwable throwable) {
 263         LOG.debug("Transaction {} failed", tx.getIdentifier(), throwable);
 264
 265         tx.onTransactionFailure(throwable);
 266         // FIXME: transaction failure should result in a hard error
 267         transactionCompleted(tx);
 268     }
 269
 270     private void transactionCompleted(final ShardedDOMDataTreeWriteTransaction tx) {
 271         final boolean wasLast = LAST_UPDATER.compareAndSet(this, tx, null);
 272         if (wasLast) {
 273             submitCurrentTransaction();
 274         }
 275     }
 276
 277     void bindToListener(final DOMDataTreeListener listener) {
 278         final DOMDataTreeListener local = attachedListener;
 279         Preconditions.checkState(local == null, "Producer %s is already attached to listener %s", this, local);
 280         this.attachedListener = requireNonNull(listener);
 281     }
 282 }