package com.atlassian.plugin.instrumentation;
   
   import com.atlassian.instrumentation.operations.OpTimer;
   
   import javax.annotation.Nonnull;
   import java.io.Closeable;
   import java.util.Optional;
   
   import static com.google.common.base.Preconditions.checkNotNull;
  
  /**
   * Wrapper around an {@link OpTimer} that may be safely used even if that class is not present in the class loader.
   * <p>
   * This wrapper implements {@link Closeable}
   * <p>
   * Note to maintainers: extreme care must be taken to ensure that <code>OpTimer</code> not accessed at runtime if it is
   * not present.
   *
   * @see PluginSystemInstrumentation
   * @since 4.1
   */
  public class Timer implements Closeable {
      private final Optional<OpTimer> opTimer;
  
      Timer(@Nonnull Optional<OpTimer> opTimer) {
          this.opTimer = checkNotNull(opTimer);
      }
  
      /**
       * Retrieve the timer, if instrumentation is present and enabled.
       */
      public Optional<OpTimer> getOpTimer() {
          return opTimer;
      }
  
      /**
       * End the timer, if instrumentation is present and enabled.
       */
      @Override
      public void close() {
          if (opTimer.isPresent()) {
              opTimer.get().end();
          }
      }
  }