package us.codecraft.webmagic.scripts;
   
   import javax.script.ScriptEngine;
   import javax.script.ScriptEngineManager;
   
   import us.codecraft.webmagic.scripts.languages.Language;
   
   import java.util.concurrent.LinkedBlockingQueue;
   import java.util.concurrent.atomic.AtomicInteger;
  
  /**
   * @author code4crafter@gmail.com
   * @since 0.4.1
   */
  public class ScriptEnginePool {
  
      private final AtomicInteger availableCount;
  
      private final LinkedBlockingQueue<ScriptEngine> scriptEngines = new LinkedBlockingQueue<ScriptEngine>();
  
      public ScriptEnginePool(Language language,int size) {
          this.availableCount = new AtomicInteger(size);
          for (int i=0;i<size;i++){
              ScriptEngineManager manager = new ScriptEngineManager();
              ScriptEngine engine = manager.getEngineByName(language.getEngineName());
              scriptEngines.add(engine);
          }
      }
  
      public ScriptEngine getEngine() {
          availableCount.decrementAndGet();
          return scriptEngines.poll();
      }
  
      public void release(ScriptEngine scriptEngine){
          scriptEngines.add(scriptEngine);
          availableCount.incrementAndGet();
      }
  
  }