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