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* Copyright 2009 Red Hat Inc. and/or its affiliates and other

* contributors as indicated by the @author tags. All rights reserved.

* See the copyright.txt in the distribution for a full listing of

* individual contributors.

*

* This is free software; you can redistribute it and/or modify it

* under the terms of the GNU Lesser General Public License as

* published by the Free Software Foundation; either version 2.1 of

* the License, or (at your option) any later version.

*

* This software is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

* Lesser General Public License for more details.

*

* You should have received a copy of the GNU Lesser General Public

* License along with this software; if not, write to the Free

* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

* 02110-1301 USA, or see the FSF site: http://www.fsf.org.

*/

* Takes care of replicating modifications to other caches in a cluster.

*

* @author Bela Ban

* @since 4.0

*/

   protected CommandsFactory cf;

   private StateTransferManager stateTransferManager;

   private boolean isPessimisticCache;

   private static final Log log = LogFactory.getLog(ReplicationInterceptor.class);

   private static final boolean trace = log.isTraceEnabled();

   @Override

   protected Log getLog() {

      return log;

   }

   @Inject

   public void init(CommandsFactory cf, StateTransferManager stateTransferManager) {

      this.cf = cf;

      this.stateTransferManager = stateTransferManager;

   }

   @Start

   public void start() {

      isPessimisticCache = cacheConfiguration.transaction().lockingMode() == LockingMode.PESSIMISTIC;

   }

   @Override

   public Object visitCommitCommand(TxInvocationContext ctx, CommitCommand command) throws Throwable {

      if (!ctx.isInTxScope()) throw new IllegalStateException("This should not be possible!");

      if (shouldInvokeRemoteTxCommand(ctx)) {

         sendCommitCommand(command);

      }

      return invokeNextInterceptor(ctx, command);

   }

   private void sendCommitCommand(CommitCommand command)

         throws TimeoutException, InterruptedException {

      // may need to resend, so make the commit command synchronous

      // TODO keep the list of prepared nodes or the view id when the prepare command was sent to know whether we need to resend the prepare info

      rpcManager.invokeRemotely(null, command, cacheConfiguration.transaction().syncCommitPhase(), true);

   }

   @Override

   public Object visitPrepareCommand(TxInvocationContext ctx, PrepareCommand command) throws Throwable {

      Object retVal = invokeNextInterceptor(ctx, command);

      if (shouldInvokeRemoteTxCommand(ctx)) {

         broadcastPrepare(ctx, command);

         ((LocalTxInvocationContext) ctx).remoteLocksAcquired(rpcManager.getTransport().getMembers());

      }

      return retVal;

   }

   protected void broadcastPrepare(TxInvocationContext context, PrepareCommand command) {

      boolean async = cacheConfiguration.clustering().cacheMode() == CacheMode.REPL_ASYNC;

      rpcManager.broadcastRpcCommand(command, !async, false);

   }

   @Override

   public Object visitRollbackCommand(TxInvocationContext ctx, RollbackCommand command) throws Throwable {

      if (shouldInvokeRemoteTxCommand(ctx) && !Configurations.isOnePhaseCommit(cacheConfiguration)) {

         rpcManager.broadcastRpcCommand(command, cacheConfiguration.transaction().syncRollbackPhase(), true);

      }

      return invokeNextInterceptor(ctx, command);

   }

   @Override

   public Object visitGetKeyValueCommand(InvocationContext ctx, GetKeyValueCommand command) throws Throwable {

      try {

         Object returnValue = invokeNextInterceptor(ctx, command);

         // need to check in the context as well since a null retval is not necessarily an indication of the entry not being

         // available.  It could just have been removed in the same tx beforehand.  Also don't bother with a remote get if

         // the entry is mapped to the local node.

         if (returnValue == null && ctx.isOriginLocal()) {

            if (needsRemoteGet(ctx, command)) {

               returnValue = remoteGet(ctx, command, false);

            }

         }

         return returnValue;

      } catch (SuspectException e) {

         // retry

         return visitGetKeyValueCommand(ctx, command);

      }

   }

  

   @Override

   public Object visitLockControlCommand(TxInvocationContext ctx, LockControlCommand command) throws Throwable {

      Object retVal = invokeNextInterceptor(ctx, command);

      if (ctx.isOriginLocal()) {

         //unlock will happen async as it is a best effort

         boolean sync = !command.isUnlock();

         ((LocalTxInvocationContext) ctx).remoteLocksAcquired(rpcManager.getTransport().getMembers());

         rpcManager.broadcastRpcCommand(command, sync, false);

      }

      return retVal;

   }

   private boolean needsRemoteGet(InvocationContext ctx, AbstractDataCommand command) {

      Object key = command.getKey();

      final CacheEntry entry;

      return !command.hasFlag(Flag.CACHE_MODE_LOCAL)

            && !command.hasFlag(Flag.SKIP_REMOTE_LOOKUP)   //todo [anistor] do we need this? it should normally be used only in distributed mode, never in replicated mode

            && !stateTransferManager.getCacheTopology().getReadConsistentHash().isKeyLocalToNode(rpcManager.getAddress(), key)

            && ((entry = ctx.lookupEntry(key)) == null || entry.isNull() || entry.isLockPlaceholder());

   }

   //todo [anistor] need to revise these methods

   /**

    * This method retrieves an entry from a remote cache.

    * <p/>

    * This method only works if a) this is a locally originating invocation and b) the entry in question is not local to

    * the current cache instance and c) the entry is not in L1.  If either of a, b or c does not hold true, this method

    * returns a null and doesn't do anything.

    *

    *

    * @param ctx invocation context

    * @param command

    * @return value of a remote get, or null

    * @throws Throwable if there are problems

    */

   private Object remoteGet(InvocationContext ctx, AbstractDataCommand command, boolean isWrite) throws Throwable {

      Object key = command.getKey();

      if (trace) {

         log.tracef("Key %s is not yet available on %s, so we may need to look elsewhere", key, rpcManager.getAddress());

      }

      boolean acquireRemoteLock = false;

      if (ctx.isInTxScope()) {

         TxInvocationContext txContext = (TxInvocationContext) ctx;

         acquireRemoteLock = isWrite && isPessimisticCache && !txContext.getAffectedKeys().contains(key);

      }

      // attempt a remote lookup

      InternalCacheEntry ice = retrieveFromRemoteSource(key, ctx, acquireRemoteLock, command.getFlags());

      if (acquireRemoteLock) {

         ((TxInvocationContext) ctx).addAffectedKey(key);

      }

      return ice != null ? ice.getValue() : null;

   }

   private InternalCacheEntry retrieveFromRemoteSource(Object key, InvocationContext ctx, boolean acquireRemoteLock, Set<Flag> flags) {

      GlobalTransaction gtx = acquireRemoteLock ? ((TxInvocationContext)ctx).getGlobalTransaction() : null;

      ClusteredGetCommand get = cf.buildClusteredGetCommand(key, flags, acquireRemoteLock, gtx);

      List<Address> targets = new ArrayList<Address>(stateTransferManager.getCacheTopology().getReadConsistentHash().locateOwners(key));

      // if any of the recipients has left the cluster since the command was issued, just don't wait for its response

      targets.retainAll(rpcManager.getTransport().getMembers());

      ResponseFilter filter = new ClusteredGetResponseValidityFilter(targets, rpcManager.getAddress());

      Map<Address, Response> responses = rpcManager.invokeRemotely(targets, get, ResponseMode.WAIT_FOR_VALID_RESPONSE,

            cacheConfiguration.clustering().sync().replTimeout(), true, filter);

      if (!responses.isEmpty()) {

         for (Response r : responses.values()) {

            if (r instanceof SuccessfulResponse) {

               InternalCacheValue cacheValue = (InternalCacheValue) ((SuccessfulResponse) r).getResponseValue();

               return cacheValue.toInternalCacheEntry(key);

            }

         }

      }

      return null;

   }

   @Override

   public Object visitPutKeyValueCommand(InvocationContext ctx, PutKeyValueCommand command) throws Throwable {

      return handleCrudMethod(ctx, command);

   }

   @Override

   public Object visitPutMapCommand(InvocationContext ctx, PutMapCommand command) throws Throwable {

      return handleCrudMethod(ctx, command);

   }

   @Override

   public Object visitRemoveCommand(InvocationContext ctx, RemoveCommand command) throws Throwable {

      return handleCrudMethod(ctx, command);

   }

   @Override

   public Object visitClearCommand(InvocationContext ctx, ClearCommand command) throws Throwable {

      return handleCrudMethod(ctx, command);

   }

   @Override

   public Object visitReplaceCommand(InvocationContext ctx, ReplaceCommand command) throws Throwable {

      return handleCrudMethod(ctx, command);

   }

   /**

    * If we are within one transaction we won't do any replication as replication would only be performed at commit

    * time. If the operation didn't originate locally we won't do any replication either.

    */

   private Object handleCrudMethod(final InvocationContext ctx, final WriteCommand command) throws Throwable {

      // FIRST pass this call up the chain.  Only if it succeeds (no exceptions) locally do we attempt to replicate.

      final Object returnValue = invokeNextInterceptor(ctx, command);

      if (!isLocalModeForced(command) && command.isSuccessful() && ctx.isOriginLocal() && !ctx.isInTxScope()) {

         rpcManager.broadcastRpcCommand(command, isSynchronous(command));

      }

      return returnValue;

   }

}