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