geode-core/src/main/java/org/apache/geode/internal/statistics/VMStatsContractFactory.java

/*
 * 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.geode.internal.statistics;

import org.apache.geode.StatisticsFactory;
import org.apache.geode.SystemFailure;
import org.apache.geode.internal.stats50.VMStats50;

/**
 * Factory used to produce an instance of VMStatsContract.
 */
public class VMStatsContractFactory {
  /**
   * Create and return a VMStatsContract.
   */
  public static VMStatsContract create(StatisticsFactory f, long id) {
    VMStatsContract result;
    try {
      result = new VMStats50(f, id);
    } catch (VirtualMachineError err) {
      SystemFailure.initiateFailure(err);
      // If this ever returns, rethrow the error. We're poisoned
      // now, so don't let this thread continue.
      throw err;
    } catch (Throwable ignore) {
      // Now that we no longer support 1.4 I'm not sure why we would get here.
      // But just in case other vm vendors don't support mxbeans I've left
      // this logic in that will create a simple VMStats instance.
      // Whenever you catch Error or Throwable, you must also
      // catch VirtualMachineError (see above). However, there is
      // _still_ a possibility that you are dealing with a cascading
      // error condition, so you also need to check to see if the JVM
      // is still usable:
      SystemFailure.checkFailure();
      // log.warning("Could not create 5.0 VMStats", ignore);
      // couldn't create the 1.5 version so create the old 1.4 version
      result = new VMStats(f, id);
    }
    return result;
  }

  private VMStatsContractFactory() {
    // private so no instances allowed. static methods only
  }
}