001/*
002 * Copyright 2009-2014 UnboundID Corp.
003 * All Rights Reserved.
004 */
005/*
006 * Copyright (C) 2009-2014 UnboundID Corp.
007 *
008 * This program is free software; you can redistribute it and/or modify
009 * it under the terms of the GNU General Public License (GPLv2 only)
010 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
011 * as published by the Free Software Foundation.
012 *
013 * This program is distributed in the hope that it will be useful,
014 * but WITHOUT ANY WARRANTY; without even the implied warranty of
015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
016 * GNU General Public License for more details.
017 *
018 * You should have received a copy of the GNU General Public License
019 * along with this program; if not, see <http://www.gnu.org/licenses>.
020 */
021package com.unboundid.ldap.sdk;
022
023
024
025import com.unboundid.util.Extensible;
026import com.unboundid.util.ThreadSafety;
027import com.unboundid.util.ThreadSafetyLevel;
028
029import static com.unboundid.ldap.sdk.LDAPMessages.*;
030import static com.unboundid.util.StaticUtils.*;
031
032
033
034/**
035 * This class provides an API that may be used to determine whether connections
036 * associated with a connection pool are valid and suitable for use.  It
037 * provides the ability to check the validity of a connection at the following
038 * times:
039 * <UL>
040 *   <LI>Whenever a new connection is created for use in the pool, the
041 *       {@link #ensureNewConnectionValid(LDAPConnection)} method will be called
042 *       before making that connection available.  The default implementation
043 *       provided in this class does not perform any kind of processing, but
044 *       subclasses may override this behavior if desired.</LI>
045 *   <LI>Whenever a connection is checked out from the pool (including
046 *       connections checked out internally for operations performed in the
047 *       pool), the {@link #ensureConnectionValidForCheckout(LDAPConnection)}
048 *       method will be called.  The default implementation provided in this
049 *       class does not perform any kind of processing, but subclasses may
050 *       override this behavior if desired.</LI>
051 *   <LI>Whenever a connection is released back to the pool (including
052 *       connections checked out internally for operations performed in the
053 *       pool), the {@link #ensureConnectionValidForRelease(LDAPConnection)}
054 *       method will be called.  The default implementation provided in this
055 *       class does not perform any kind of processing, but subclasses may
056 *       override this behavior if desired.</LI>
057 *   <LI>The {@link #ensureConnectionValidForContinuedUse(LDAPConnection)}
058 *       method will be invoked periodically by a background thread created by
059 *       the connection pool to determine whether available connections within
060 *       the pool are still valid.  The default implementation provided in this
061 *       class does not perform any kind of processing, but subclasses may
062 *       override this behavior if desired.</LI>
063 *   <LI>The {@link #ensureConnectionValidAfterException} method may be invoked
064 *       if an exception is caught while processing an operation with a
065 *       connection which is part of a connection pool.  The default
066 *       implementation provided in this class only examines the result code of
067 *       the provided exception and uses the
068 *       {@link ResultCode#isConnectionUsable(ResultCode)} method to make the
069 *       determination, but subclasses may override this behavior if
070 *       desired.</LI>
071 * </UL>
072 * Note that health check implementations should be designed so that they are
073 * suitable for use with connections having any authentication state.  The
074 * {@link #ensureNewConnectionValid(LDAPConnection)} method will be invoked on
075 * unauthenticated connections, and the remaining health check methods will be
076 * invoked using whatever credentials are assigned to connections in the
077 * associated connection pool.
078 */
079@Extensible()
080@ThreadSafety(level=ThreadSafetyLevel.INTERFACE_THREADSAFE)
081public class LDAPConnectionPoolHealthCheck
082{
083  /**
084   * Creates a new instance of this LDAP connection pool health check.
085   */
086  public LDAPConnectionPoolHealthCheck()
087  {
088    // No implementation is required.
089  }
090
091
092
093  /**
094   * Performs any desired processing to determine whether the provided new
095   * connection is available to be checked out and used for processing
096   * operations.  This method will be invoked by either {@link ServerSet} used
097   * by the connection pool (if it supports enhanced health checking) or by the
098   * connection pool itself at the time that a new connection is created.
099   *
100   * @param  connection  The connection to be examined.
101   *
102   * @throws  LDAPException  If a problem is detected which suggests that the
103   *                         provided connection is not suitable for use.
104   */
105  public void ensureNewConnectionValid(final LDAPConnection connection)
106         throws LDAPException
107  {
108    // No processing is performed in this default implementation.
109  }
110
111
112
113  /**
114   * Performs any desired processing to determine whether the provided
115   * connection is available to be checked out and used for processing
116   * operations.  This method will be invoked by the
117   * {@link LDAPConnectionPool#getConnection()} method before handing out a
118   * connection.  This method should return normally if the connection is
119   * believed to be valid, or should throw an {@code LDAPException} if a problem
120   * is detected.
121   *
122   * @param  connection  The connection to be examined.
123   *
124   * @throws  LDAPException  If a problem is detected which suggests that the
125   *                         provided connection is not suitable for use.
126   */
127  public void ensureConnectionValidForCheckout(final LDAPConnection connection)
128         throws LDAPException
129  {
130    // No processing is performed in this default implementation.
131  }
132
133
134
135  /**
136   * Performs any desired processing to determine whether the provided
137   * connection is valid and should be released back to the pool to be used for
138   * processing other operations.  This method will be invoked by the
139   * {@link LDAPConnectionPool#releaseConnection(LDAPConnection)} method before
140   * making the connection available for use in processing other operations.
141   * This method should return normally if the connection is believed to be
142   * valid, or should throw an {@code LDAPException} if a problem is detected.
143   *
144   * @param  connection  The connection to be examined.
145   *
146   * @throws  LDAPException  If a problem is detected which suggests that the
147   *                         provided connection is not suitable for use.
148   */
149  public void ensureConnectionValidForRelease(final LDAPConnection connection)
150         throws LDAPException
151  {
152    // No processing is performed in this default implementation.
153  }
154
155
156
157  /**
158   * Performs any desired processing to determine whether the provided
159   * connection is valid and should continue to be made available for
160   * processing operations.  This method will be periodically invoked by a
161   * background thread used to test availability of connections within the pool.
162   * This method should return normally if the connection is believed to be
163   * valid, or should throw an {@code LDAPException} if a problem is detected.
164   *
165   * @param  connection  The connection to be examined.
166   *
167   * @throws  LDAPException  If a problem is detected which suggests that the
168   *                         provided connection is not suitable for use.
169   */
170  public void ensureConnectionValidForContinuedUse(
171                   final LDAPConnection connection)
172         throws LDAPException
173  {
174    // No processing is performed in this default implementation.
175  }
176
177
178
179  /**
180   * Indicates whether the provided connection may still be considered valid
181   * after an attempt to process an operation yielded the given exception.  This
182   * method will be invoked by the
183   * {@link LDAPConnectionPool#releaseConnectionAfterException} method, and it
184   * may also be manually invoked by external callers if an exception is
185   * encountered while processing an operation on a connection checked out from
186   * the pool.  It may make a determination based solely on the provided
187   * exception, or it may also attempt to use the provided connection to further
188   * test its validity.  This method should return normally if the connection is
189   * believed to be valid, or should throw an {@code LDAPException} if a problem
190   * is detected.
191   *
192   * @param  connection  The connection to be examined.
193   * @param  exception   The exception that was caught while processing an
194   *                     operation on the connection.
195   *
196   * @throws  LDAPException  If a problem is detected which suggests that the
197   *                         provided connection is not suitable for use.
198   */
199  public void ensureConnectionValidAfterException(
200                   final LDAPConnection connection,
201                   final LDAPException exception)
202         throws LDAPException
203  {
204    if (! ResultCode.isConnectionUsable(exception.getResultCode()))
205    {
206      throw new LDAPException(ResultCode.SERVER_DOWN,
207           ERR_POOL_HEALTH_CHECK_CONN_INVALID_AFTER_EXCEPTION.get(
208                getExceptionMessage(exception)),
209           exception);
210    }
211  }
212
213
214
215  /**
216   * Retrieves a string representation of this LDAP connection pool health
217   * check.
218   *
219   * @return  A string representation of this LDAP connection pool health check.
220   */
221  @Override()
222  public final String toString()
223  {
224    final StringBuilder buffer = new StringBuilder();
225    toString(buffer);
226    return buffer.toString();
227  }
228
229
230
231  /**
232   * Appends a string representation of this LDAP connection pool health check
233   * to the provided buffer.
234   *
235   * @param  buffer  The buffer to which the information should be appended.
236   */
237  public void toString(final StringBuilder buffer)
238  {
239    buffer.append("LDAPConnectionPoolHealthCheck()");
240  }
241}