DefaultContextManager.java

/*
 * *********************************************************************************************************************
 *
 * TheseFoolishThings: Miscellaneous utilities
 * http://tidalwave.it/projects/thesefoolishthings
 *
 * Copyright (C) 2009 - 2023 by 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.
 *
 * *********************************************************************************************************************
 *
 * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
 * git clone https://github.com/tidalwave-it/thesefoolishthings-src
 *
 * *********************************************************************************************************************
 */
package it.tidalwave.role.impl;

import javax.annotation.Nonnull;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.Stack;
import it.tidalwave.util.ContextManager;
import lombok.extern.slf4j.Slf4j;
import static it.tidalwave.util.CollectionUtils.reversed;
import static it.tidalwave.util.ShortNames.*;

/***********************************************************************************************************************
 *
 * @author  Fabrizio Giudici
 *
 **********************************************************************************************************************/
@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<Object> globalContexts = Collections.synchronizedList(new ArrayList<>());

    /** The list of local contexts, ordered by priority. */
    private final ThreadLocal<Stack<Object>> localContexts = new ThreadLocal<>()
      {
        @Override @Nonnull
        protected Stack<Object> 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<Object> getContexts()
      {
        final var contexts = reversed(new ArrayList<>(localContexts.get()));
        contexts.addAll(0, globalContexts);
        return contexts;
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override @Nonnull @SuppressWarnings("BoundedWildcard")
    public <T> Optional<T> findContextOfType (@Nonnull final Class<T> contextType)
      {
        for (final var context : getContexts())
          {
            if (contextType.isAssignableFrom(context.getClass()))
              {
                return Optional.of(contextType.cast(context));
              }
          }

        return Optional.empty();
      }

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

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

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

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

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Override @Nonnull
    public <T, E extends Throwable> T runEWithContexts (@Nonnull final SupplierWithException<T, E> supplier,
                                                        @Nonnull final Object ... contexts)
            throws E
      {
        log.trace("runWithContexts({}, {})", shortId(supplier), shortIds(contexts));

        try (final var __ = binder(contexts))
          {
            if (log.isTraceEnabled())
              {
                log.trace(">>>> contexts now: {} - {}", shortIds(getContexts()), this);
              }

            final var result = supplier.get();
            log.trace(">>>> runWithContexts({}, {}) completed", shortId(supplier), shortIds(contexts));
            return result;
          }
      }
  }