001 /*
002 * Copyright 2009-2016 UnboundID Corp.
003 * All Rights Reserved.
004 */
005 /*
006 * Copyright (C) 2009-2016 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.persist;
022
023
024
025 import java.io.Closeable;
026 import java.io.Serializable;
027
028 import com.unboundid.ldap.sdk.Entry;
029 import com.unboundid.ldap.sdk.EntrySource;
030 import com.unboundid.ldap.sdk.LDAPEntrySource;
031 import com.unboundid.ldap.sdk.LDAPException;
032 import com.unboundid.ldap.sdk.SearchResult;
033 import com.unboundid.util.ThreadSafety;
034 import com.unboundid.util.ThreadSafetyLevel;
035
036 import static com.unboundid.ldap.sdk.persist.PersistMessages.*;
037 import static com.unboundid.util.Debug.*;
038 import static com.unboundid.util.StaticUtils.*;
039
040
041
042 /**
043 * This class provides a mechanism for iterating through the objects returned
044 * by a search operation performed using one of the {@code search} methods in
045 * the {@link LDAPPersister} class. However, it has a couple of notable
046 * differences from a standard Java {@code Iterator} object:
047 * <UL>
048 * <LI>It does not have a {@code hasNext} method. Instead, the {@link #next}
049 * method will return {@code null} when there are no more objects in the
050 * set of results.</LI>
051 * <LI>The {@link #next} method may throw an exception if a problem occurs
052 * while trying to read an entry or decode it as an object of the
053 * appropriate type. This does not necessarily mean that the search is
054 * complete, and the {@link #next} method should be called again to see
055 * if there are any more objects to retrieve.</LI>
056 * <LI>If you wish to stop iterating through the results before all of them
057 * have been retrieved, then you must call the {@link #close} method
058 * </UL>
059 *
060 * @param <T> The type of object handled by this class.
061 */
062 @ThreadSafety(level=ThreadSafetyLevel.NOT_THREADSAFE)
063 public final class PersistedObjects<T>
064 implements Serializable, Closeable
065 {
066 /**
067 * The serial version UID for this serializable class.
068 */
069 private static final long serialVersionUID = 7430494946944736169L;
070
071
072
073 // The LDAP entry source that will be used to read matching entries.
074 private final EntrySource entrySource;
075
076 // The LDAP persister that will be used to decode the entries that are
077 // returned.
078 private final LDAPPersister<T> persister;
079
080
081
082 /**
083 * Creates a new {@code PersistedObjects} object that will read entries from
084 * the provided entry source.
085 *
086 * @param persister The persister that will be used to decode entries that
087 * are returned.
088 * @param entrySource The entry source that will be used to read entries
089 * returned from the search.
090 */
091 PersistedObjects(final LDAPPersister<T> persister,
092 final EntrySource entrySource)
093 {
094 this.persister = persister;
095 this.entrySource = entrySource;
096 }
097
098
099
100 /**
101 * Retrieves the next object returned from the search request. This method
102 * may block until the necessary information has been received from the
103 * server.
104 *
105 * @return The next object returned from the search request, or {@code null}
106 * if all objects have been read.
107 *
108 * @throws LDAPPersistException If a problem occurs while reading the next
109 * entry from the server, or when trying to
110 * decode that entry as an object.
111 */
112 public T next()
113 throws LDAPPersistException
114 {
115 final Entry entry;
116 try
117 {
118 entry = entrySource.nextEntry();
119 }
120 catch (Exception e)
121 {
122 debugException(e);
123
124 final Throwable cause = e.getCause();
125 if ((cause != null) && (cause instanceof LDAPException))
126 {
127 throw new LDAPPersistException((LDAPException) cause);
128 }
129 else
130 {
131 throw new LDAPPersistException(
132 ERR_OBJECT_SEARCH_RESULTS_ENTRY_SOURCE_EXCEPTION.get(
133 getExceptionMessage(e)), e);
134 }
135 }
136
137 if (entry == null)
138 {
139 return null;
140 }
141 else
142 {
143 return persister.decode(entry);
144 }
145 }
146
147
148
149 /**
150 * Indicates that you wish to stop iterating through search results and will
151 * not be retrieving any additional objects. This method MUST be called to
152 * avoid leaking resources if you stop iterating through results before the
153 * {@link #next} method returns {@code null} to indicate that there are no
154 * more objects to retrieve. This method MAY be called after the search has
155 * completed (including being called multiple times) with no adverse effects.
156 */
157 public void close()
158 {
159 entrySource.close();
160 }
161
162
163
164 /**
165 * Retrieves the search result for the search operation, if available. It
166 * will not be available until the search has completed (as indicated by a
167 * {@code null} return value from the {@link #next} method), and for some use
168 * cases it may never be available.
169 *
170 * @return The search result for the search operation, or {@code null} if it
171 * is not available (e.g., because the search has not yet completed).
172 */
173 public SearchResult getSearchResult()
174 {
175 if (entrySource instanceof LDAPEntrySource)
176 {
177 return ((LDAPEntrySource) entrySource).getSearchResult();
178 }
179 else
180 {
181 return null;
182 }
183 }
184 }