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.causeway.commons.internal.debug;
  
  import java.lang.management.ManagementFactory;
  import java.lang.management.MemoryPoolMXBean;
  
  import org.apache.causeway.commons.functional.ThrowingRunnable;
  
  /**
   * <h1>- internal use only -</h1>
   * <p>
   * Memory Usage Utility
   * <p>
   * <b>WARNING</b>: Do <b>NOT</b> use any of the classes provided by this package! <br/>
   * These may be changed or removed without notice!
   * </p>
   * @since 3.4.0
   */
  public record _MemoryUsage(long usedInKibiBytes) {
  
      // -- UTILITIES
  
      static int indent = 0;
  
      public static _MemoryUsage measureMetaspace(final ThrowingRunnable runnable) {
          var before = metaspace();
          var after = (_MemoryUsage) null;
          try {
              runnable.run();
          } catch (Throwable e) {
          } finally {
              after = metaspace();
          }
          return after.minus(before);
      }
  
      // -- FACTORY
  
      private static _MemoryUsage metaspace() {
          for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {
              if (pool.getName().contains("Metaspace")) {
                  return new _MemoryUsage(pool.getUsage());
              }
          }
          throw new RuntimeException("Metaspace Usage not found");
      }
  
      // -- NON CANONICAL CONSTRUCTOR
  
      private _MemoryUsage(java.lang.management.MemoryUsage usage) {
          this(usage.getUsed() / 1024);
      }
  
      @Override
      public String toString() {
          return String.format("%,d KiB", usedInKibiBytes);
      }
  
      // -- HELPER
  
      private _MemoryUsage minus(_MemoryUsage before) {
          return new _MemoryUsage(this.usedInKibiBytes - before.usedInKibiBytes);
      }
  
  }
  