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