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    • it.tidalwave.role.spi.DefaultContextManager Maven / Gradle / Ivy

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    Roles are a powerful way for designing complex behaviours while keeping good practices such as Single Responsibility, Dependency Inversion and Interface Segregation.

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    /*
 * #%L
 * *********************************************************************************************************************
 *
 * These Foolish Things - Miscellaneous utilities
 * http://thesefoolishthings.tidalwave.it - git clone [email protected]:tidalwave/thesefoolishthings-src.git
 * %%
 * Copyright (C) 2009 - 2016 Tidalwave s.a.s. (http://tidalwave.it)
 * %%
 * *********************************************************************************************************************
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations under the License.
 *
 * *********************************************************************************************************************
 *
 * $Id$
 *
 * *********************************************************************************************************************
 * #L%
 */
package it.tidalwave.role.spi;

import javax.annotation.Nonnull;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Stack;
import it.tidalwave.util.NotFoundException;
import it.tidalwave.util.Task;
import it.tidalwave.role.ContextManager;
import lombok.extern.slf4j.Slf4j;
import static it.tidalwave.role.spi.LogUtil.*;

/***********************************************************************************************************************
 *
 * @author  Fabrizio Giudici
 * @version $Id$
 *
 **********************************************************************************************************************/
@Slf4j
public class DefaultContextManager implements ContextManager
  {
    /** Useful for troubleshooting in cases when multiple instances are erroneously created. */
    private static final boolean DUMP_STACK_AT_CREATION = Boolean.getBoolean(
            DefaultContextManager.class.getName() + ".dumpStackAtCreation");

    /** The list of global contexts, ordered by priority. */
    private final List globalContexts = new ArrayList<>();

    /** The list of local contexts, ordered by priority. */
    private final ThreadLocal> localContexts = new ThreadLocal>()
      {
        @Override @Nonnull
        protected Stack initialValue()
          {
            return new Stack<>();
          }
      };

    /*******************************************************************************************************************
     *
     *
     *
     ******************************************************************************************************************/
    public DefaultContextManager()
      {
        if (DUMP_STACK_AT_CREATION)
          {
            try
              {
                throw new RuntimeException();
              }
            catch (Exception e)
              {
                log.trace(">>>> created context manager " + this, e);
              }
          }
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override @Nonnull
    public List getContexts()
      {
        log.trace("CONTEXT MANAGER GET CONTEXTS {}", this);
        final List contexts = new ArrayList<>();
        contexts.addAll(localContexts.get());
        Collections.reverse(contexts);
        contexts.addAll(0, globalContexts);
        return contexts;
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override @Nonnull
    public  T findContextOfType (final @Nonnull Class contextType)
      throws NotFoundException
      {
        for (final Object context : getContexts())
          {
            if (contextType.isAssignableFrom(context.getClass()))
              {
                return contextType.cast(context);
              }
          }

        throw new NotFoundException("No current context of type " + contextType);
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override
    public void addGlobalContext (final @Nonnull Object context)
      {
        globalContexts.add(context);
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override
    public void removeGlobalContext (final @Nonnull Object context)
      {
        globalContexts.remove(context);
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override
    public void addLocalContext (final @Nonnull Object context)
      {
        localContexts.get().push(context);
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override
    public void removeLocalContext (final @Nonnull Object context)
      {
        localContexts.get().remove(context);
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override @Nonnull
    public  V runWithContext (final @Nonnull Object context,
                                                      final @Nonnull Task task)
      throws T
      {
        return runWithContexts(Collections.singletonList(context), task);
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override @Nonnull
    public  V runWithContexts (final @Nonnull List contexts,
                                                       final @Nonnull Task task)
      throws T
      {
        final String taskId = shortId(task);
        final String contextIds = shortIds(contexts);

        try
          {
            log.trace("runWithContexts({}, {})", contextIds, taskId);

            for (final Object context : contexts)
              {
                addLocalContext(context);
              }

            if (log.isTraceEnabled())
              {
                log.trace(">>>> contexts now: {} - {}", getContexts(), this);
              }

            return task.run();
          }
        finally
          {
            for (final Object context : contexts)
              {
                removeLocalContext(context);
              }

            log.trace(">>>> runWithContexts({}, {}) completed", contextIds, taskId);
          }
      }
  }
    
    
    
    

    




    
    
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