dom/mdsal-dom-inmemory-datastore/src/main/java/org/opendaylight/mdsal/dom/store/inmemory/InMemoryDOMDataTreeShardProducer.java

   1 /*
   2  * Copyright (c) 2016 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.store.inmemory;
   9
  10 import static com.google.common.base.Preconditions.checkState;
  11 import static java.util.Objects.requireNonNull;
  12
  13 import com.google.common.collect.ImmutableSet;
  14 import java.util.Collection;
  15 import java.util.concurrent.atomic.AtomicLong;
  16 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  17 import org.opendaylight.mdsal.dom.api.DOMDataTreeIdentifier;
  18 import org.opendaylight.mdsal.dom.spi.shard.DOMDataTreeShardProducer;
  19 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
  20 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
  21 import org.slf4j.Logger;
  22 import org.slf4j.LoggerFactory;
  23
  24 class InMemoryDOMDataTreeShardProducer implements DOMDataTreeShardProducer {
  25
  26     private abstract static class State {
  27         /**
  28          * Allocate a new snapshot.
  29          *
  30          * @return A new snapshot
  31          */
  32         protected abstract DataTreeSnapshot getSnapshot(Object transactionId);
  33     }
  34
  35     private static final class Idle extends State {
  36         private final InMemoryDOMDataTreeShardProducer producer;
  37
  38         Idle(final InMemoryDOMDataTreeShardProducer producer) {
  39             this.producer = requireNonNull(producer);
  40         }
  41
  42         @Override
  43         protected DataTreeSnapshot getSnapshot(final Object transactionId) {
  44             return producer.takeSnapshot();
  45         }
  46     }
  47
  48     /**
  49      * We have a transaction out there.
  50      */
  51     private static final class Allocated extends State {
  52         private static final AtomicReferenceFieldUpdater<Allocated, DataTreeSnapshot> SNAPSHOT_UPDATER =
  53                 AtomicReferenceFieldUpdater.newUpdater(Allocated.class, DataTreeSnapshot.class, "snapshot");
  54         private final InmemoryDOMDataTreeShardWriteTransaction transaction;
  55         private volatile DataTreeSnapshot snapshot;
  56
  57         Allocated(final InmemoryDOMDataTreeShardWriteTransaction transaction) {
  58             this.transaction = requireNonNull(transaction);
  59         }
  60
  61         InmemoryDOMDataTreeShardWriteTransaction getTransaction() {
  62             return transaction;
  63         }
  64
  65         @Override
  66         protected DataTreeSnapshot getSnapshot(final Object transactionId) {
  67             final DataTreeSnapshot ret = snapshot;
  68             checkState(ret != null,
  69                     "Could not get snapshot for transaction %s - previous transaction %s is not ready yet",
  70                     transactionId, transaction.getIdentifier());
  71             return ret;
  72         }
  73
  74         void setSnapshot(final DataTreeSnapshot snapshot) {
  75             final boolean success = SNAPSHOT_UPDATER.compareAndSet(this, null, snapshot);
  76             checkState(success, "Transaction %s has already been marked as ready",
  77                     transaction.getIdentifier());
  78         }
  79     }
  80
  81     /**
  82      * Producer is logically shut down, no further allocation allowed.
  83      */
  84     private static final class Shutdown extends State {
  85         private final String message;
  86
  87         Shutdown(final String message) {
  88             this.message = requireNonNull(message);
  89         }
  90
  91         @Override
  92         protected DataTreeSnapshot getSnapshot(final Object transactionId) {
  93             throw new IllegalStateException(message);
  94         }
  95     }
  96
  97     private static final Logger LOG = LoggerFactory.getLogger(InMemoryDOMDataTreeShardProducer.class);
  98     private static final AtomicLong COUNTER = new AtomicLong();
  99
 100     private final InMemoryDOMDataTreeShard parentShard;
 101     private final Collection<DOMDataTreeIdentifier> prefixes;
 102     private final Idle idleState = new Idle(this);
 103
 104     private static final AtomicReferenceFieldUpdater<InMemoryDOMDataTreeShardProducer, State> STATE_UPDATER =
 105             AtomicReferenceFieldUpdater.newUpdater(InMemoryDOMDataTreeShardProducer.class, State.class, "state");
 106     private volatile State state;
 107
 108     private InMemoryShardDataModificationFactory modificationFactory;
 109
 110     InMemoryDOMDataTreeShardProducer(final InMemoryDOMDataTreeShard parentShard,
 111             final Collection<DOMDataTreeIdentifier> prefixes,
 112             final InMemoryShardDataModificationFactory modificationFactory) {
 113         this.parentShard = requireNonNull(parentShard);
 114         this.prefixes = ImmutableSet.copyOf(prefixes);
 115         this.modificationFactory = requireNonNull(modificationFactory);
 116         state = idleState;
 117     }
 118
 119     @Override
 120     public InmemoryDOMDataTreeShardWriteTransaction createTransaction() {
 121         final String transactionId = nextIdentifier();
 122
 123         State localState;
 124         InmemoryDOMDataTreeShardWriteTransaction ret;
 125         do {
 126             localState = state;
 127             ret = parentShard.createTransaction(transactionId, this, localState.getSnapshot(transactionId));
 128         } while (!STATE_UPDATER.compareAndSet(this, localState, new Allocated(ret)));
 129
 130         return ret;
 131     }
 132
 133     void transactionReady(final InmemoryDOMDataTreeShardWriteTransaction tx, final DataTreeModification modification) {
 134         final State localState = state;
 135         LOG.debug("Transaction was readied {}, current state {}", tx.getIdentifier(), localState);
 136
 137         if (localState instanceof Allocated) {
 138             final Allocated allocated = (Allocated) localState;
 139             final InmemoryDOMDataTreeShardWriteTransaction transaction = allocated.getTransaction();
 140             checkState(tx.equals(transaction), "Mis-ordered ready transaction %s last allocated was %s", tx,
 141                 transaction);
 142             allocated.setSnapshot(modification);
 143         } else {
 144             LOG.debug("Ignoring transaction {} readiness due to state {}", tx, localState);
 145         }
 146     }
 147
 148     /**
 149      * Notify the base logic that a previously-submitted transaction has been committed successfully.
 150      *
 151      * @param transaction Transaction which completed successfully.
 152      */
 153     void onTransactionCommited(final InmemoryDOMDataTreeShardWriteTransaction transaction) {
 154         // If the committed transaction was the one we allocated last,
 155         // we clear it and the ready snapshot, so the next transaction
 156         // allocated refers to the data tree directly.
 157         final State localState = state;
 158         LOG.debug("Transaction {} commit done, current state {}", transaction.getIdentifier(), localState);
 159
 160         if (!(localState instanceof Allocated)) {
 161             // This can legally happen if the chain is shut down before the transaction was committed
 162             // by the backend.
 163             LOG.debug("Ignoring successful transaction {} in state {}", transaction, localState);
 164             return;
 165         }
 166
 167         final Allocated allocated = (Allocated) localState;
 168         final InmemoryDOMDataTreeShardWriteTransaction tx = allocated.getTransaction();
 169         if (!tx.equals(transaction)) {
 170             LOG.debug("Ignoring non-latest successful transaction {} in state {}", transaction, allocated);
 171             return;
 172         }
 173
 174         if (!STATE_UPDATER.compareAndSet(this, localState, idleState)) {
 175             LOG.debug("Producer {} has already transitioned from {} to {}, not making it idle", this,
 176                     localState, state);
 177         }
 178     }
 179
 180     void transactionAborted(final InmemoryDOMDataTreeShardWriteTransaction tx) {
 181         final State localState = state;
 182         if (localState instanceof Allocated) {
 183             final Allocated allocated = (Allocated) localState;
 184             if (allocated.getTransaction().equals(tx)) {
 185                 final boolean success = STATE_UPDATER.compareAndSet(this, localState, idleState);
 186                 if (!success) {
 187                     LOG.warn("Transaction {} aborted, but producer {} state already transitioned from {} to {}",
 188                             tx, this, localState, state);
 189                 }
 190             }
 191         }
 192     }
 193
 194     private static String nextIdentifier() {
 195         return "INMEMORY-SHARD-TX-" + COUNTER.getAndIncrement();
 196     }
 197
 198     DataTreeSnapshot takeSnapshot() {
 199         return parentShard.takeSnapshot();
 200     }
 201
 202     @Override
 203     public Collection<DOMDataTreeIdentifier> getPrefixes() {
 204         return prefixes;
 205     }
 206
 207     InMemoryShardDataModificationFactory getModificationFactory() {
 208         return modificationFactory;
 209     }
 210
 211     void setModificationFactory(final InMemoryShardDataModificationFactory modificationFactory) {
 212         this.modificationFactory = requireNonNull(modificationFactory);
 213     }
 214 }