Location.java

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 * and Distribution License("CDDL") (collectively, the "License").  You
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 * obtain a copy of the License at
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package org.glassfish.contextpropagation;

import java.util.EnumSet;

import org.glassfish.contextpropagation.bootstrap.ContextBootstrap;

/**
 * The Location class provides information about the current location of the 
 * request relative to the point where it originally entered the system. As
 * the request hops from one region of the system to the next (from thread to 
 * thread or from process to process) the Location is updated to reflect the
 * changes in location.
 *
 */
public class Location implements ViewCapable, ContextLifecycle {
  public static final EnumSet<PropagationMode> PROP_MODES = PropagationMode.defaultSetOneway();
  private View view;
  public static final String KEY = "org.glassfish.contextpropagation.Location";
  private String origin;
  private String locationId;
  private short lastChildId = 0;
  
  /*
   * Implemented as a ViewCapable custom context so that Location may be 
   * propagated
   */
  protected Location(View aView) {
    view = aView;
  }
  
  /**
   * @return The original unique identifier for the request. This identifier
   * is generated by the process where the request was originally submitted.
   */
  public String getOrigin() {
    return origin == null ? ContextBootstrap.getGuid() : origin; 
  }
  
  /* For future implementation public short[] getBreadCrumbs() {
  } provides a more compact way of representing the location id*/
  
  /**
   * @return a unique String illustrating the shortest path between 
   * the original location where
   * the request entered the system and current location.
   */
  public String getLocationId() {
    return "[" + getLocationIdInternal() + "]";
  }
  
  private String getLocationIdInternal() {
    return locationId == null ? "0" : locationId; 
  }

  @Override
  public void contextChanged(Object replacementContext) { /* NO-OP */ }

  @Override
  public void contextAdded() {
    origin = view.get("origin");
    view.put("origin", getOrigin(), PROP_MODES);
    locationId = view.get("locationId");
  }

  @Override
  public void contextRemoved() { /* NO-OP */}

  @Override
  public ViewCapable contextToPropagate() {
    view.put("locationId", getLocationIdInternal() + ", " + ++lastChildId, PROP_MODES);
    return this;
  }
  
  // For future implementation public short[] getTravelLog(); Provides the full
  // itinerary followed by the request
}