content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.beam.runners.dataflow.worker.profiler;
  
  /**
   * API for enabling/disabling dataflow profiling agent.
   *
   * <p>The profiling agent profiles all application threads. Enabling or disabling the profiler is a
   * global action that affects all threads.
   *
   * <p>This MUST stay in this package. It is implemented via JNI.
   */
  public class Profiler {
  
    /**
     * Enable collection of profiling data.
     *
     * <p>Profiling is done on a preset schedule, it may not start immediately.
     *
     * @throws java.lang.UnsatisfiedLinkError if the agent hasn't been loaded.
     */
    public static native void enable();
  
    /**
     * Disable collection of profiling data.
     *
     * <p>If a profile is currently being collected, it will run to completion.
     *
     * @throws java.lang.UnsatisfiedLinkError if the agent hasn't been loaded.
     */
    public static native void disable();
  
    /**
     * Registers a nonzero index to be used in a subsequent call to {@link #setAttribute}. The value
     * is permanently registered for the lifetime of the JVM. Registering the same string multiple
     * times will return the same value.
     *
     * @return a nonzero index representing the string, to be used on calls to {@link #setAttribute}.
     * @throws java.lang.UnsatisfiedLinkError if the agent hasn't been loaded.
     */
    public static native int registerAttribute(String value);
  
    /**
     * Sets attribute for the current thread. Can be called before profiling is enabled or while
     * profiling is active. Attributes must be either 0 (to clear attributes), or a value returned by
     * {@link #registerAttribute}. The current attribute persists during profile {@link
     * #enable}/{@link #disable}.
     *
     * <p>Samples collected by this thread will be annotated with the string associated to this value.
     *
     * @return the previous value of the thread attribute.
     * @throws java.lang.UnsatisfiedLinkError if the agent hasn't been loaded.
     */
    public static native int setAttribute(int value);
  
    /**
     * Gets attribute for the current thread. Can be called before profiling is enabled or while
     * profiling is active. Will return the value passed to the most recent call to setAttribute from
     * this thread.
     *
     * @return the previous value of the thread attribute.
     * @throws java.lang.UnsatisfiedLinkError if the agent hasn't been loaded.
     */
    public static native int getAttribute();
  }
  