package com.atlassian.sal.core.executor;
   
   import com.atlassian.sal.api.executor.ThreadLocalContextManager;
   
   import java.util.concurrent.Callable;
   
   import static com.google.common.base.Preconditions.checkNotNull;
   
   /**
   * A wrapping callable that copies the thread local state into the calling code
   *
   * @since 2.0
   */
  class ThreadLocalDelegateCallable<C, T> implements Callable<T> {
      private final Callable<T> delegate;
      private final ThreadLocalContextManager<C> manager;
      private final C context;
      private final ClassLoader contextClassLoader;
  
      /**
       * Create a new callable
       *
       * @param manager  The context manager to get the context from
       * @param delegate The callable to delegate to
       */
      ThreadLocalDelegateCallable(ThreadLocalContextManager<C> manager, Callable<T> delegate) {
          this.delegate = checkNotNull(delegate);
          this.manager = checkNotNull(manager);
          this.context = manager.getThreadLocalContext();
          this.contextClassLoader = Thread.currentThread().getContextClassLoader();
      }
  
      public T call() throws Exception {
          ClassLoader oldContextClassLoader = Thread.currentThread().getContextClassLoader();
          try {
              Thread.currentThread().setContextClassLoader(contextClassLoader);
              manager.setThreadLocalContext(context);
              return delegate.call();
          } finally {
              Thread.currentThread().setContextClassLoader(oldContextClassLoader);
              manager.clearThreadLocalContext();
          }
      }
  }