opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/TransactionChainProxy.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
   9 package org.opendaylight.controller.cluster.datastore;
  10
  11 import com.google.common.base.Preconditions;
  12 import java.util.Collections;
  13 import java.util.List;
  14 import java.util.concurrent.atomic.AtomicInteger;
  15 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  16 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  17 import org.opendaylight.controller.md.sal.common.api.data.TransactionChainClosedException;
  18 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
  19 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
  20 import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransactionChain;
  21 import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
  22 import scala.concurrent.Future;
  23
  24 /**
  25  * TransactionChainProxy acts as a proxy for a DOMStoreTransactionChain created on a remote shard
  26  */
  27 public class TransactionChainProxy implements DOMStoreTransactionChain {
  28
  29     private interface State {
  30         boolean isReady();
  31
  32         List<Future<Object>> getPreviousReadyFutures();
  33     }
  34
  35     private static class Allocated implements State {
  36         private final ChainedTransactionProxy transaction;
  37
  38         Allocated(ChainedTransactionProxy transaction) {
  39             this.transaction = transaction;
  40         }
  41
  42         @Override
  43         public boolean isReady() {
  44             return transaction.isReady();
  45         }
  46
  47         @Override
  48         public List<Future<Object>> getPreviousReadyFutures() {
  49             return transaction.getReadyFutures();
  50         }
  51     }
  52
  53     private static abstract class AbstractDefaultState implements State {
  54         @Override
  55         public List<Future<Object>> getPreviousReadyFutures() {
  56             return Collections.emptyList();
  57         }
  58     }
  59
  60     private static final State IDLE_STATE = new AbstractDefaultState() {
  61         @Override
  62         public boolean isReady() {
  63             return true;
  64         }
  65     };
  66
  67     private static final State CLOSED_STATE = new AbstractDefaultState() {
  68         @Override
  69         public boolean isReady() {
  70             throw new TransactionChainClosedException("Transaction chain has been closed");
  71         }
  72     };
  73
  74     private static final AtomicInteger counter = new AtomicInteger(0);
  75
  76     private final ActorContext actorContext;
  77     private final String transactionChainId;
  78     private volatile State currentState = IDLE_STATE;
  79
  80     public TransactionChainProxy(ActorContext actorContext) {
  81         this.actorContext = actorContext;
  82         transactionChainId = actorContext.getCurrentMemberName() + "-txn-chain-" + counter.incrementAndGet();
  83     }
  84
  85     public String getTransactionChainId() {
  86         return transactionChainId;
  87     }
  88
  89     @Override
  90     public DOMStoreReadTransaction newReadOnlyTransaction() {
  91         State localState = currentState;
  92         checkReadyState(localState);
  93
  94         return new ChainedTransactionProxy(actorContext, TransactionProxy.TransactionType.READ_ONLY,
  95                 transactionChainId, localState.getPreviousReadyFutures());
  96     }
  97
  98     @Override
  99     public DOMStoreReadWriteTransaction newReadWriteTransaction() {
 100         actorContext.acquireTxCreationPermit();
 101         return allocateWriteTransaction(TransactionProxy.TransactionType.READ_WRITE);
 102     }
 103
 104     @Override
 105     public DOMStoreWriteTransaction newWriteOnlyTransaction() {
 106         actorContext.acquireTxCreationPermit();
 107         return allocateWriteTransaction(TransactionProxy.TransactionType.WRITE_ONLY);
 108     }
 109
 110     @Override
 111     public void close() {
 112         currentState = CLOSED_STATE;
 113
 114         // Send a close transaction chain request to each and every shard
 115         actorContext.broadcast(new CloseTransactionChain(transactionChainId).toSerializable());
 116     }
 117
 118     private ChainedTransactionProxy allocateWriteTransaction(TransactionProxy.TransactionType type) {
 119         State localState = currentState;
 120
 121         checkReadyState(localState);
 122
 123         // Pass the ready Futures from the previous Tx.
 124         ChainedTransactionProxy txProxy = new ChainedTransactionProxy(actorContext, type,
 125                 transactionChainId, localState.getPreviousReadyFutures());
 126
 127         currentState = new Allocated(txProxy);
 128
 129         return txProxy;
 130     }
 131
 132     private void checkReadyState(State state) {
 133         Preconditions.checkState(state.isReady(), "Previous transaction is not ready yet");
 134     }
 135 }