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Library for handling scopes in a generic way
There is a newer version: 6.4.4
/**
 * Copyright (C) 2006-2015 phloc systems
 * http://www.phloc.com
 * office[at]phloc[dot]com
 *
 * 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.
 */
package com.phloc.scopes;

import java.util.Map;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import com.phloc.commons.annotations.ReturnsMutableCopy;
import com.phloc.commons.callback.INonThrowingCallableWithParameter;
import com.phloc.commons.callback.INonThrowingRunnableWithParameter;
import com.phloc.commons.collections.attrs.IAttributeContainer;
import com.phloc.commons.id.IHasID;

/**
 * This interface is used for all the common stuff of a scope. The following
 * types of scopes are present: Global scope - once and only once
 
 * Application context - scope for an application (e.g. pDAF3 Config and View
 * application)
 Session scope - for each user created session
 
 * Session application context - scope for an application within a session
 * Request scope - for each user request


 * IMPORTANT: implementations of {@link IScope} must be thread safe!
 * 
 * @author Philip Helger
 */
public interface IScope extends IAttributeContainer, IHasID 
{
  /**
   * Init the scope. In contrast to the constructor of a scope, this happens
   * after the scope has been registered in the scope manager.
   */
  void initScope ();

  /**
   * Get the ID of this scope. Each scope retrieves a unique ID within its type
   * of scope (request, session, application). This method needs to be callable
   * anytime and should not throw any exception!
   * 
   * @return the non-null ID of this context.
   */
  String getID ();

  /**
   * @return true if this scope is neither in destruction nor
   *         destroyed.
   * @see #isInDestruction()
   * @see #isDestroyed()
   */
  boolean isValid ();

  /**
   * @return true if the scope is currently in the process of
   *         destruction.
   */
  boolean isInDestruction ();

  /**
   * @return true if the scope was already destroyed. This is
   *         especially important for long running scopes.
   */
  boolean isDestroyed ();

  /**
   * Destroys the scopes and all child scopes. This method is automatically
   * called, when a scope goes out of scope :)
   */
  void destroyScope ();

  /**
   * Perform stuff as a single action. All actions are executed in a write-lock!
   * 
   * @param aRunnable
   *        The action to be executed. May not be null.
   */
  void runAtomic (@Nonnull INonThrowingRunnableWithParameter  aRunnable);

  /**
   * Perform stuff as a single action. All actions are executed in a write-lock!
   * 
   * @param aCallable
   *        The action to be executed. May not be null.
   * @return The result from the callable. May be null.
   */
  @Nullable
   T runAtomic (@Nonnull INonThrowingCallableWithParameter  aCallable);

  /**
   * @return The non-null map with all contained attributes that
   *         implement the {@link IScopeRenewalAware} interface. May be empty.
   */
  @Nonnull
  @ReturnsMutableCopy
  Map  getAllScopeRenewalAwareAttributes ();
}