001/*
002 * Copyright 2018-2019 Ping Identity Corporation
003 * All Rights Reserved.
004 */
005/*
006 * Copyright (C) 2018-2019 Ping Identity Corporation
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 java.util.concurrent.atomic.AtomicReference;
026import java.util.logging.Level;
027
028import com.unboundid.util.Debug;
029import com.unboundid.util.DebugType;
030import com.unboundid.util.ThreadSafety;
031import com.unboundid.util.ThreadSafetyLevel;
032
033
034
035/**
036 * This class provides an implementation of an LDAP connection pool health check
037 * that periodically monitors the number of available connections in the pool.
038 * If the number of available connections has been consistently greater than a
039 * specified minimum for at least a given length of time, then the number of
040 * available connections will be reduced to that minimum.  Note that the
041 * size of the pool will only be checked at interval's specified by the
042 * {@link AbstractConnectionPool#getHealthCheckIntervalMillis()} method, so it
043 * is possible that the number of available connections may have dipped below
044 * that minimum on one or more occasions between checks.  Also note that this
045 * health check can only be used on instances of the
046 * {@link LDAPConnectionPool} class; it cannot be used with
047 * {@link LDAPThreadLocalConnectionPool} instances.
048 */
049@ThreadSafety(level= ThreadSafetyLevel.COMPLETELY_THREADSAFE)
050public final class PruneUnneededConnectionsLDAPConnectionPoolHealthCheck
051       extends LDAPConnectionPoolHealthCheck
052{
053  // A reference to the first time at which the number of available connections
054  // exceeded the minimum number of available connections.  It may reference a
055  // null value if the last check indicated that the number of available
056  // connections was not larger than the configured minimum.
057  private final AtomicReference<Long>
058                     earliestTimeWithMoreThanMinAvailableConnections;
059
060  // The minimum number of connections that should be maintained in the
061  // connection pool.  This health check will only remove connections if the
062  // pool has more than this number of connections for at least the specified
063  // duration.
064  private final int minAvailableConnections;
065
066  // The minimum length of time in milliseconds that the pool should have had
067  // at least the specified minimum number of available connections before any
068  // connections may be removed.
069  private final long minDurationMillisExceedingMinAvailableConnections;
070
071
072
073  /**
074   * Creates a new instance of this LDAP connection pool health check with the
075   * provided information.
076   *
077   * @param  minAvailableConnections
078   *              The minimum number of connections that should be maintained in
079   *              the connection pool.  This health check will only remove
080   *              connections if the pool has more than this number of
081   *              connections for at least the specified duration.  A value that
082   *              is less than or equal to zero indicates that no minimum number
083   *              of connections needs to be maintained.
084   * @param  minDurationMillisExceedingMinAvailableConnections
085   *              The minimum length of time in milliseconds that the pool
086   *              should have reported at least the specified minimum number of
087   *              available connections before any connections may be removed.
088   *              Note that the number of connections will only be checked at
089   *              intervals specified by the
090   *              {@link AbstractConnectionPool#getHealthCheckIntervalMillis()}
091   *              method, so it may be possible for the number of available
092   *              connections to dip below this value one or more time between
093   *              intervals and still cause the pool to be reduced in size.  A
094   *              value that is less than or equal to zero indicates that the
095   *              pool size should be reduced to the configured minimum any time
096   *              there are more than that number of connections available.
097   */
098  public PruneUnneededConnectionsLDAPConnectionPoolHealthCheck(
099              final int minAvailableConnections,
100              final long minDurationMillisExceedingMinAvailableConnections)
101  {
102    this.minAvailableConnections = Math.max(0, minAvailableConnections);
103    this.minDurationMillisExceedingMinAvailableConnections = Math.max(0L,
104         minDurationMillisExceedingMinAvailableConnections);
105
106    earliestTimeWithMoreThanMinAvailableConnections = new AtomicReference<>();
107  }
108
109
110
111  /**
112   * Retrieves the minimum number of connections that should be maintained in
113   * the connection pool.  This health check will only remove connections if the
114   * pool has more than this number of connections for at least the specified
115   * duration.
116   *
117   * @return  The minimum number of connections that should be maintained in the
118   *          connection pool.
119   */
120  public int getMinAvailableConnections()
121  {
122    return minAvailableConnections;
123  }
124
125
126
127  /**
128   * Retrieves the minimum length of time in milliseconds that the pool should
129   * have reported at least the specified minimum number of available
130   * connections before any connections may be removed.  Note that the number of
131   * connections will only be checked at intervals specified by the
132   * {@link AbstractConnectionPool#getHealthCheckIntervalMillis()} method, so it
133   * may be possible for the number of available connections to dip below this
134   * value one or more time between intervals and still cause the pool to be
135   * reduced in size.
136   *
137   * @return  The minimum length of time in milliseconds that the pool should
138   *          have reported at least the specified minimum number of available
139   *          connections before any connections may be removed.
140   */
141  public long getMinDurationMillisExceedingMinAvailableConnections()
142  {
143    return minDurationMillisExceedingMinAvailableConnections;
144  }
145
146
147
148  /**
149   * {@inheritDoc}
150   */
151  @Override()
152  public void performPoolMaintenance(final AbstractConnectionPool pool)
153  {
154    if (! (pool instanceof LDAPConnectionPool))
155    {
156      Debug.debug(Level.WARNING, DebugType.CONNECT,
157             "Only " + LDAPConnectionPool.class.getName() +
158                  " instances may be used in conjunction with the " +
159                  "PruneUnneededConnectionsLDAPConnectionPoolHealthCheck.  " +
160                  "The provided pool had an incompatible type of " +
161                  pool.getClass().getName() + '.');
162
163      earliestTimeWithMoreThanMinAvailableConnections.set(null);
164      return;
165    }
166
167    final int availableConnections = pool.getCurrentAvailableConnections();
168    if (availableConnections <= minAvailableConnections)
169    {
170      earliestTimeWithMoreThanMinAvailableConnections.set(null);
171      return;
172    }
173
174    final Long earliestTime =
175         earliestTimeWithMoreThanMinAvailableConnections.get();
176    if (earliestTime == null)
177    {
178      if (minDurationMillisExceedingMinAvailableConnections <= 0L)
179      {
180        ((LDAPConnectionPool) pool).shrinkPool(minAvailableConnections);
181      }
182      else
183      {
184        earliestTimeWithMoreThanMinAvailableConnections.set(
185             System.currentTimeMillis());
186      }
187    }
188    else
189    {
190      final long millisWithMoreThanMinAvailableConnections =
191           System.currentTimeMillis() - earliestTime;
192      if (millisWithMoreThanMinAvailableConnections >=
193           minDurationMillisExceedingMinAvailableConnections)
194      {
195        ((LDAPConnectionPool) pool).shrinkPool(minAvailableConnections);
196        earliestTimeWithMoreThanMinAvailableConnections.set(null);
197      }
198    }
199  }
200
201
202
203  /**
204   * {@inheritDoc}
205   */
206  @Override()
207  public void toString(final StringBuilder buffer)
208  {
209    buffer.append("PruneUnneededConnectionsLDAPConnectionPoolHealthCheck(" +
210         "minAvailableConnections=");
211    buffer.append(minAvailableConnections);
212    buffer.append(", minDurationMillisExceedingMinAvailableConnections=");
213    buffer.append(minDurationMillisExceedingMinAvailableConnections);
214    buffer.append(')');
215  }
216}