com.helger.scope.IScope Maven / Gradle / Ivy

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/*
 * Copyright (C) 2014-2024 Philip Helger (www.helger.com)
 * philip[at]helger[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.helger.scope;

import java.util.function.Consumer;
import java.util.function.Function;

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

import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.annotation.ReturnsMutableObject;
import com.helger.commons.collection.attr.IAttributeContainerAny;
import com.helger.commons.collection.impl.CommonsHashMap;
import com.helger.commons.collection.impl.ICommonsMap;
import com.helger.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. public and secure
 * application in one web 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 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 only 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 aConsumer
   *        The consumer to be executed. May not be null. The
   *        parameter to the runnable is this scope.
   */
  void runAtomic (@Nonnull Consumer  aConsumer);

  /**
   * Perform stuff as a single action. All actions are executed in a write-lock!
   *
   * @param aFunction
   *        The function to be executed. May not be null. The
   *        parameter to the callable is this scope.
   * @return The result from the callable. May be null.
   * @param 
   *        The return type of the callable
   */
  @Nullable
   T runAtomic (@Nonnull Function  aFunction);

  /**
   * @return The mutable scope attributes. Never null.
   */
  @Nonnull
  @ReturnsMutableObject
  IAttributeContainerAny  attrs ();

  /**
   * @return The non-null map with all contained attributes that
   *         implement the {@link IScopeRenewalAware} interface. May be empty.
   */
  @Nonnull
  @ReturnsMutableCopy
  default ICommonsMap  getAllScopeRenewalAwareAttributes ()
  {
    final ICommonsMap  ret = new CommonsHashMap <> ();
    attrs ().forEach ( (n, v) -> {
      if (v instanceof IScopeRenewalAware)
        ret.put (n, (IScopeRenewalAware) v);
    });
    return ret;
  }
}