001    /*
002     * Copyright 2009-2015 UnboundID Corp.
003     * All Rights Reserved.
004     */
005    /*
006     * Copyright (C) 2009-2015 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     */
021    package com.unboundid.ldap.sdk;
022    
023    
024    
025    import com.unboundid.util.Extensible;
026    import com.unboundid.util.ThreadSafety;
027    import com.unboundid.util.ThreadSafetyLevel;
028    
029    import static com.unboundid.ldap.sdk.LDAPMessages.*;
030    import 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)
081    public 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    }