opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/broker/impl/DOMForwardedWriteTransaction.java

   1 /*
   2  * Copyright (c) 2014 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.controller.md.sal.dom.broker.impl;
   9
  10 import com.google.common.base.Preconditions;
  11 import com.google.common.util.concurrent.CheckedFuture;
  12 import com.google.common.util.concurrent.Futures;
  13 import com.google.common.util.concurrent.ListenableFuture;
  14 import java.util.ArrayList;
  15 import java.util.Collection;
  16 import java.util.Map;
  17 import java.util.concurrent.Future;
  18 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  19 import org.opendaylight.controller.md.sal.common.api.TransactionStatus;
  20 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
  21 import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
  22 import org.opendaylight.controller.md.sal.common.impl.service.AbstractDataTransaction;
  23 import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
  24 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
  25 import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
  26 import org.opendaylight.yangtools.yang.common.RpcResult;
  27 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  28 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  29 import org.slf4j.Logger;
  30 import org.slf4j.LoggerFactory;
  31
  32 /**
  33  * Read-Write Transaction, which is composed of several
  34  * {@link DOMStoreWriteTransaction} transactions. A sub-transaction is selected by
  35  * {@link LogicalDatastoreType} type parameter in:
  36  *
  37  * <ul>
  38  * <li>{@link #put(LogicalDatastoreType, YangInstanceIdentifier, NormalizedNode)}
  39  * <li>{@link #delete(LogicalDatastoreType, YangInstanceIdentifier)}
  40  * <li>{@link #merge(LogicalDatastoreType, YangInstanceIdentifier, NormalizedNode)}
  41  * </ul>
  42  * <p>
  43  * {@link #commit()} will result in invocation of
  44  * {@link DOMDataCommitImplementation#submit(org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction, Iterable)}
  45  * invocation with all {@link org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort} for underlying
  46  * transactions.
  47  *
  48  * @param <T> Subtype of {@link DOMStoreWriteTransaction} which is used as
  49  *            subtransaction.
  50  */
  51 class DOMForwardedWriteTransaction<T extends DOMStoreWriteTransaction> extends
  52         AbstractDOMForwardedCompositeTransaction<LogicalDatastoreType, T> implements DOMDataWriteTransaction {
  53     @SuppressWarnings("rawtypes")
  54     private static final AtomicReferenceFieldUpdater<DOMForwardedWriteTransaction, DOMDataCommitImplementation> IMPL_UPDATER =
  55             AtomicReferenceFieldUpdater.newUpdater(DOMForwardedWriteTransaction.class, DOMDataCommitImplementation.class, "commitImpl");
  56     @SuppressWarnings("rawtypes")
  57     private static final AtomicReferenceFieldUpdater<DOMForwardedWriteTransaction, Future> FUTURE_UPDATER =
  58             AtomicReferenceFieldUpdater.newUpdater(DOMForwardedWriteTransaction.class, Future.class, "commitFuture");
  59     private static final Logger LOG = LoggerFactory.getLogger(DOMForwardedWriteTransaction.class);
  60     private static final Future<?> CANCELLED_FUTURE = Futures.immediateCancelledFuture();
  61
  62     /**
  63      * Implementation of real commit. It also acts as an indication that
  64      * the transaction is running -- which we flip atomically using
  65      * {@link #IMPL_UPDATER}.
  66      */
  67     private volatile DOMDataCommitImplementation commitImpl;
  68
  69     /**
  70      * Future task of transaction commit. It starts off as null, but is
  71      * set appropriately on {@link #submit()} and {@link #cancel()} via
  72      * {@link AtomicReferenceFieldUpdater#lazySet(Object, Object)}.
  73      *
  74      * Lazy set is safe for use because it is only referenced to in the
  75      * {@link #cancel()} slow path, where we will busy-wait for it. The
  76      * fast path gets the benefit of a store-store barrier instead of the
  77      * usual store-load barrier.
  78      */
  79     private volatile Future<?> commitFuture;
  80
  81     protected DOMForwardedWriteTransaction(final Object identifier,
  82             final Map<LogicalDatastoreType, T> backingTxs, final DOMDataCommitImplementation commitImpl) {
  83         super(identifier, backingTxs);
  84         this.commitImpl = Preconditions.checkNotNull(commitImpl, "commitImpl must not be null.");
  85     }
  86
  87     @Override
  88     public void put(final LogicalDatastoreType store, final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
  89         checkRunning(commitImpl);
  90         getSubtransaction(store).write(path, data);
  91     }
  92
  93     @Override
  94     public void delete(final LogicalDatastoreType store, final YangInstanceIdentifier path) {
  95         checkRunning(commitImpl);
  96         getSubtransaction(store).delete(path);
  97     }
  98
  99     @Override
 100     public void merge(final LogicalDatastoreType store, final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
 101         checkRunning(commitImpl);
 102         getSubtransaction(store).merge(path, data);
 103     }
 104
 105     @Override
 106     public boolean cancel() {
 107         final DOMDataCommitImplementation impl = IMPL_UPDATER.getAndSet(this, null);
 108         if (impl != null) {
 109             LOG.trace("Transaction {} cancelled before submit", getIdentifier());
 110             FUTURE_UPDATER.lazySet(this, CANCELLED_FUTURE);
 111             return true;
 112         }
 113
 114         // The transaction is in process of being submitted or cancelled. Busy-wait
 115         // for the corresponding future.
 116         Future<?> future;
 117         do {
 118             future = commitFuture;
 119         } while (future == null);
 120
 121         return future.cancel(false);
 122     }
 123
 124     @Override
 125     public ListenableFuture<RpcResult<TransactionStatus>> commit() {
 126         return AbstractDataTransaction.convertToLegacyCommitFuture(submit());
 127     }
 128
 129     @Override
 130     public CheckedFuture<Void, TransactionCommitFailedException> submit() {
 131         final DOMDataCommitImplementation impl = IMPL_UPDATER.getAndSet(this, null);
 132         checkRunning(impl);
 133
 134         final Collection<T> txns = getSubtransactions();
 135         final Collection<DOMStoreThreePhaseCommitCohort> cohorts = new ArrayList<>(txns.size());
 136
 137         // FIXME: deal with errors thrown by backed (ready and submit can fail in theory)
 138         for (DOMStoreWriteTransaction txn : txns) {
 139             cohorts.add(txn.ready());
 140         }
 141
 142         final CheckedFuture<Void, TransactionCommitFailedException> ret = impl.submit(this, cohorts);
 143         FUTURE_UPDATER.lazySet(this, ret);
 144         return ret;
 145     }
 146
 147     private void checkRunning(final DOMDataCommitImplementation impl) {
 148         Preconditions.checkState(impl != null, "Transaction %s is no longer running", getIdentifier());
 149     }
 150 }