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    1   /*
    2    *  Licensed to the Apache Software Foundation (ASF) under one
    3    *  or more contributor license agreements.  See the NOTICE file
    4    *  distributed with this work for additional information
    5    *  regarding copyright ownership.  The ASF licenses this file
    6    *  to you under the Apache License, Version 2.0 (the
    7    *  "License"); you may not use this file except in compliance
    8    *  with the License.  You may obtain a copy of the License at
    9    *
    10   *    http://www.apache.org/licenses/LICENSE-2.0
    11   *
    12   *  Unless required by applicable law or agreed to in writing,
    13   *  software distributed under the License is distributed on an
    14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    15   *  KIND, either express or implied.  See the License for the
    16   *  specific language governing permissions and limitations
    17   *  under the License.
    18   *
    19   */
    20  package org.apache.mina.transport.socket.apr;
    21
    22  import org.apache.tomcat.jni.Library;
    23  import org.apache.tomcat.jni.Pool;
    24
    25  /**
    26   * Internal singleton used for initializing correctly the APR native library
    27   * and the associated root memory pool.
    28   *
    29   * It'll finalize nicely the native resources (libraries and memory pools).
    30   *
    31   * Each memory pool used in the APR transport module needs to be children of the
    32   * root pool {@link AprLibrary#getRootPool()}.
    33   *
    34   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
    35   */
    36  class AprLibrary {
    37
    38      // is APR library was initialized (load of native libraries)
    39      private static AprLibrary library = null;
    40
    41      /**
    42       * get the shared instance of APR library, if none, initialize one
    43       * @return the current APR library singleton
    44       */
    45      static synchronized AprLibrary getInstance() {
    46          if (!isInitialized())
    47              initialize();
    48          return library;
    49      }
    50
    51      /**
    52       * initialize the APR Library by loading the associated native libraries
    53       * and creating the associated singleton
    54       */
    55      private static synchronized void initialize() {
    56          if (library == null)
    57              library = new AprLibrary();
    58      }
    59
    60      /**
    61       * is the APR library was initialized.
    62       * @return true if the Library is initialized, false otherwise
    63       */
    64      static synchronized boolean isInitialized() {
    65          return library != null;
    66      }
    67
    68      // APR memory pool (package wide mother pool)
    69      private final long pool;
    70
    71      /**
    72       * APR library singleton constructor. Called only when accessing the
    73       * singleton the first time.
    74       * It's initializing an APR memory pool for the whole package (a.k.a mother or root pool).
    75       */
    76      private AprLibrary() {
    77          try {
    78              Library.initialize(null);
    79          } catch (Exception e) {
    80              throw new RuntimeException("Error loading Apache Portable Runtime (APR).", e);
    81          }
    82          pool = Pool.create(0);
    83      }
    84
    85      @Override
    86      protected void finalize() throws Throwable {
    87          super.finalize();
    88          Pool.destroy(pool);
    89      }
    90
    91      /**
    92       * get the package wide root pool, the mother of all the pool created
    93       * in APR transport module.
    94       * @return number identifying the root pool
    95       */
    96      long getRootPool() {
    97          return pool;
    98      }
    99  }