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.common.api.CommitInfo;
  20 import org.opendaylight.mdsal.dom.api.DOMDataTreeCursorAwareTransaction;
  21 import org.opendaylight.mdsal.dom.api.DOMDataTreeIdentifier;
  22 import org.opendaylight.mdsal.dom.api.DOMDataTreeListener;
  23 import org.opendaylight.mdsal.dom.api.DOMDataTreeProducer;
  24 import org.opendaylight.mdsal.dom.api.DOMDataTreeProducerBusyException;
  25 import org.opendaylight.mdsal.dom.api.DOMDataTreeProducerException;
  26 import org.opendaylight.mdsal.dom.api.DOMDataTreeShard;
  27 import org.slf4j.Logger;
  28 import org.slf4j.LoggerFactory;
  29
  30 class ShardedDOMDataTreeProducer implements DOMDataTreeProducer {
  31     private static final Logger LOG = LoggerFactory.getLogger(ShardedDOMDataTreeProducer.class);
  32
  33     private final Set<DOMDataTreeIdentifier> subtrees;
  34     private final ShardedDOMDataTree dataTree;
  35
  36     private static final AtomicReferenceFieldUpdater<ShardedDOMDataTreeProducer, ShardedDOMDataTreeWriteTransaction>
  37         CURRENT_UPDATER = AtomicReferenceFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class,
  38             ShardedDOMDataTreeWriteTransaction.class, "currentTx");
  39     private volatile ShardedDOMDataTreeWriteTransaction currentTx;
  40
  41     private static final AtomicReferenceFieldUpdater<ShardedDOMDataTreeProducer, ShardedDOMDataTreeWriteTransaction>
  42         OPEN_UPDATER = AtomicReferenceFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class,
  43             ShardedDOMDataTreeWriteTransaction.class, "openTx");
  44     private volatile ShardedDOMDataTreeWriteTransaction openTx;
  45
  46     private static final AtomicReferenceFieldUpdater<ShardedDOMDataTreeProducer, ShardedDOMDataTreeWriteTransaction>
  47         LAST_UPDATER = AtomicReferenceFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class,
  48             ShardedDOMDataTreeWriteTransaction.class, "lastTx");
  49     private volatile ShardedDOMDataTreeWriteTransaction lastTx;
  50
  51     private static final AtomicIntegerFieldUpdater<ShardedDOMDataTreeProducer> CLOSED_UPDATER =
  52             AtomicIntegerFieldUpdater.newUpdater(ShardedDOMDataTreeProducer.class, "closed");
  53     private volatile int closed;
  54
  55     private volatile DOMDataTreeListener attachedListener;
  56     private volatile ProducerLayout layout;
  57
  58     ShardedDOMDataTreeProducer(final ShardedDOMDataTree dataTree,
  59                                final Collection<DOMDataTreeIdentifier> subtrees,
  60                                final Map<DOMDataTreeIdentifier, DOMDataTreeShard> shardMap) {
  61         this.dataTree = Preconditions.checkNotNull(dataTree);
  62         this.subtrees = ImmutableSet.copyOf(subtrees);
  63         this.layout = ProducerLayout.create(shardMap);
  64     }
  65
  66     static DOMDataTreeProducer create(final ShardedDOMDataTree dataTree,
  67                                       final Collection<DOMDataTreeIdentifier> subtrees,
  68                                       final Map<DOMDataTreeIdentifier, DOMDataTreeShard> shardMap) {
  69         return new ShardedDOMDataTreeProducer(dataTree, subtrees, shardMap);
  70     }
  71
  72     private void checkNotClosed() {
  73         Preconditions.checkState(closed == 0, "Producer is already closed");
  74     }
  75
  76     private void checkIdle() {
  77         Preconditions.checkState(openTx == null, "Transaction %s is still open", openTx);
  78     }
  79
  80     void subshardAdded(final Map<DOMDataTreeIdentifier, DOMDataTreeShard> shardMap) {
  81         checkIdle();
  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     @SuppressWarnings("checkstyle:hiddenField")
 154     public DOMDataTreeProducer createProducer(final Collection<DOMDataTreeIdentifier> subtrees) {
 155         checkNotClosed();
 156         checkIdle();
 157
 158         final ProducerLayout local = layout;
 159
 160         for (final DOMDataTreeIdentifier s : subtrees) {
 161             // Check if the subtree was visible at any time
 162             Preconditions.checkArgument(local.haveSubtree(s), "Subtree %s was never available in producer %s", s, this);
 163             // Check if the subtree has not been delegated to a child
 164             final DOMDataTreeProducer child = local.lookupChild(s);
 165             Preconditions.checkArgument(child == null, "Subtree %s is delegated to child producer %s", s, child);
 166
 167             // Check if part of the requested subtree is not delegated to a child.
 168             for (final DOMDataTreeIdentifier c : local.getChildTrees()) {
 169                 Preconditions.checkArgument(!s.contains(c),
 170                     "Subtree %s cannot be delegated as it is a superset of already-delegated %s", s, c);
 171             }
 172         }
 173
 174
 175         final DOMDataTreeProducer ret;
 176         synchronized (this) {
 177             ret = dataTree.createProducer(this, subtrees);
 178         }
 179
 180         layout = local.addChild(ret, subtrees);
 181         return ret;
 182     }
 183
 184     boolean isDelegatedToChild(final DOMDataTreeIdentifier path) {
 185         return layout.lookupChild(path) != null;
 186     }
 187
 188     @Override
 189     public void close() throws DOMDataTreeProducerException {
 190         if (openTx != null) {
 191             throw new DOMDataTreeProducerBusyException(String.format("Transaction %s is still open", openTx));
 192         }
 193
 194         if (CLOSED_UPDATER.compareAndSet(this, 0, 1)) {
 195             synchronized (this) {
 196                 dataTree.destroyProducer(this);
 197                 layout.close();
 198             }
 199         }
 200     }
 201
 202     protected Set<DOMDataTreeIdentifier> getSubtrees() {
 203         return subtrees;
 204     }
 205
 206     void cancelTransaction(final ShardedDOMDataTreeWriteTransaction transaction) {
 207         final boolean success = OPEN_UPDATER.compareAndSet(this, transaction, null);
 208         if (success) {
 209             LOG.debug("Transaction {} cancelled", transaction);
 210         } else {
 211             LOG.warn("Transaction {} is not open in producer {}", transaction, this);
 212         }
 213     }
 214
 215     // Called when the user submits a transaction
 216     void transactionSubmitted(final ShardedDOMDataTreeWriteTransaction transaction) {
 217         final boolean wasOpen = OPEN_UPDATER.compareAndSet(this, transaction, null);
 218         Preconditions.checkState(wasOpen, "Attempted to submit non-open transaction %s", transaction);
 219
 220         if (lastTx == null) {
 221             // No transaction outstanding, we need to submit it now
 222             synchronized (this) {
 223                 submitTransaction(transaction);
 224             }
 225
 226             return;
 227         }
 228
 229         // There is a potentially-racing submitted transaction. Publish the new one, which may end up being
 230         // picked up by processNextTransaction.
 231         final boolean success = CURRENT_UPDATER.compareAndSet(this, null, transaction);
 232         Verify.verify(success);
 233
 234         // Now a quick check: if the racing transaction completed in between, it may have missed the current
 235         // transaction, hence we need to re-check
 236         if (lastTx == null) {
 237             submitCurrentTransaction();
 238         }
 239     }
 240
 241     private void submitCurrentTransaction() {
 242         final ShardedDOMDataTreeWriteTransaction current = currentTx;
 243         if (current != null) {
 244             synchronized (this) {
 245                 if (CURRENT_UPDATER.compareAndSet(this, current, null)) {
 246                     submitTransaction(current);
 247                 }
 248             }
 249         }
 250     }
 251
 252     private void transactionSuccessful(final ShardedDOMDataTreeWriteTransaction tx) {
 253         LOG.debug("Transaction {} completed successfully", tx.getIdentifier());
 254
 255         tx.onTransactionSuccess(CommitInfo.empty());
 256         transactionCompleted(tx);
 257     }
 258
 259     private void transactionFailed(final ShardedDOMDataTreeWriteTransaction tx, final Throwable throwable) {
 260         LOG.debug("Transaction {} failed", tx.getIdentifier(), throwable);
 261
 262         tx.onTransactionFailure(throwable);
 263         // FIXME: transaction failure should result in a hard error
 264         transactionCompleted(tx);
 265     }
 266
 267     private void transactionCompleted(final ShardedDOMDataTreeWriteTransaction tx) {
 268         final boolean wasLast = LAST_UPDATER.compareAndSet(this, tx, null);
 269         if (wasLast) {
 270             submitCurrentTransaction();
 271         }
 272     }
 273
 274     void bindToListener(final DOMDataTreeListener listener) {
 275         final DOMDataTreeListener local = attachedListener;
 276         Preconditions.checkState(local == null, "Producer %s is already attached to listener %s", this, local);
 277         this.attachedListener = Preconditions.checkNotNull(listener);
 278     }
 279 }