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OpenTSDB is a distributed, scalable Time Series Database (TSDB) written on top of HBase. OpenTSDB was written to address a common need: store, index and serve metrics collected from computer systems (network gear, operating systems, applications) at a large scale, and make this data easily accessible and graphable.

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// This file is part of OpenTSDB.
// Copyright (C) 2010-2012  The OpenTSDB Authors.
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 2.1 of the License, or (at your
// option) any later version.  This program is distributed in the hope that it
// will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
// General Public License for more details.  You should have received a copy
// of the GNU Lesser General Public License along with this program.  If not,
// see .
package tsd.client;

import com.google.gwt.event.dom.client.BlurEvent;
import com.google.gwt.event.dom.client.BlurHandler;
import com.google.gwt.event.dom.client.ChangeEvent;
import com.google.gwt.event.dom.client.ChangeHandler;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.DomEvent;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyPressEvent;
import com.google.gwt.event.dom.client.KeyPressHandler;
import com.google.gwt.event.shared.EventHandler;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.DeferredCommand;

/**
 * Handler for multiple events that indicate that the widget may have changed.
 * 
 * This handler is just a convenient 4-in-1 handler that can be re-used on a
 * wide range of widgets such as {@code TextBox} and its derivative,
 * {@code CheckBox}, {@code ListBox} etc.
 */
abstract class EventsHandler implements BlurHandler, ChangeHandler,
         ClickHandler, KeyPressHandler {

  /**
   * Called after one of the events (click, blur, change or "enter"
   * is pressed) occurs.
   * 
   * This method is NOT called while the event is happening.  It's invoked via
   * a {@link DeferredCommand deferred command}.  This entails that the event
   * can't be cancelled as it has already executed.  The reason the call is
   * deferred is that this way, things like {@code SuggestBox}s will have
   * already done their auto-completion by the time this method is called, and
   * thus the handler will see the suggested text instead of the partial input
   * being typed by the user.
   * @param event The event that occurred.
   */
  protected abstract  void onEvent(DomEvent event);

  public final void onClick(final ClickEvent event) {
    scheduleEvent(event);
  }

  public final void onBlur(final BlurEvent event) {
    scheduleEvent(event);
  }

  public final void onChange(final ChangeEvent event) {
    scheduleEvent(event);
  }

  public final void onKeyPress(final KeyPressEvent event) {
    if (event.getCharCode() == KeyCodes.KEY_ENTER) {
      scheduleEvent(event);
    }
  }

  /** Executes the event using a deferred command. */
  private  void scheduleEvent(final DomEvent event) {
    DeferredCommand.addCommand(new Command() {
      public void execute() {
        onEvent(event);
      }
    });
  }

}