Source Code Cross Referenced for CachedRow.java in  » Database-DBMS » hsql » org » hsqldb » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Database DBMS » hsql » org.hsqldb 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /* Copyright (c) 1995-2000, The Hypersonic SQL Group.
002:         * All rights reserved.
003:         *
004:         * Redistribution and use in source and binary forms, with or without
005:         * modification, are permitted provided that the following conditions are met:
006:         *
007:         * Redistributions of source code must retain the above copyright notice, this
008:         * list of conditions and the following disclaimer.
009:         *
010:         * Redistributions in binary form must reproduce the above copyright notice,
011:         * this list of conditions and the following disclaimer in the documentation
012:         * and/or other materials provided with the distribution.
013:         *
014:         * Neither the name of the Hypersonic SQL Group nor the names of its
015:         * contributors may be used to endorse or promote products derived from this
016:         * software without specific prior written permission.
017:         *
018:         * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
019:         * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
020:         * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
021:         * ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
022:         * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
023:         * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
024:         * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025:         * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
026:         * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027:         * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028:         * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029:         *
030:         * This software consists of voluntary contributions made by many individuals 
031:         * on behalf of the Hypersonic SQL Group.
032:         *
033:         *
034:         * For work added by the HSQL Development Group:
035:         *
036:         * Copyright (c) 2001-2005, The HSQL Development Group
037:         * All rights reserved.
038:         *
039:         * Redistribution and use in source and binary forms, with or without
040:         * modification, are permitted provided that the following conditions are met:
041:         *
042:         * Redistributions of source code must retain the above copyright notice, this
043:         * list of conditions and the following disclaimer.
044:         *
045:         * Redistributions in binary form must reproduce the above copyright notice,
046:         * this list of conditions and the following disclaimer in the documentation
047:         * and/or other materials provided with the distribution.
048:         *
049:         * Neither the name of the HSQL Development Group nor the names of its
050:         * contributors may be used to endorse or promote products derived from this
051:         * software without specific prior written permission.
052:         *
053:         * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
054:         * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
055:         * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
056:         * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
057:         * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
058:         * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
059:         * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
060:         * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
061:         * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
062:         * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
063:         * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
064:         */
065:
066:        package org.hsqldb;
067:
068:        import java.io.IOException;
069:
070:        import org.hsqldb.lib.IntLookup;
071:        import org.hsqldb.lib.java.JavaSystem;
072:        import org.hsqldb.rowio.RowInputInterface;
073:        import org.hsqldb.rowio.RowOutputInterface;
074:
075:        // fredt@users 20020221 - patch 513005 by sqlbob@users (RMP)
076:        // fredt@users 20020920 - patch 1.7.1 - refactoring to cut memory footprint
077:        // fredt@users 20021205 - patch 1.7.2 - enhancements
078:        // fredt@users 20021215 - doc 1.7.2 - javadoc comments
079:        // boucherb@users - 20040411 - doc 1.7.2 - javadoc comments
080:
081:        /**
082:         *  In-memory representation of a disk-based database row object with  methods
083:         *  for serialization and de-serialization. <p>
084:         *
085:         *  A CachedRow is normally part of a circular double linked list which
086:         *  contains all of the Rows currently in the Cache for the database. It is
087:         *  unlinked from this list when it is freed from the Cache to make way for
088:         *  other rows.
089:         *
090:         *  New class from the Hypersonic Original
091:         *
092:         * @author Thomas Mueller (Hypersonic SQL Group)
093:         * @version    1.7.2
094:         * @since Hypersonic SQL
095:         */
096:        public class CachedRow extends Row {
097:
098:            static final int NO_POS = -1;
099:
100:            //
101:            protected Table tTable;
102:            int storageSize;
103:
104:            /**
105:             *  Flag indicating unwritten data.
106:             */
107:            protected boolean hasDataChanged;
108:
109:            /**
110:             *  Flag indicating Node data has changed.
111:             */
112:            boolean hasNodesChanged;
113:
114:            /**
115:             *  Default constructor used only in subclasses.
116:             */
117:            CachedRow() {
118:            }
119:
120:            public static CachedRow newCachedRow(Table t, Object[] o)
121:                    throws HsqlException {
122:
123:                if (t.isText) {
124:                    return new CachedDataRow(t, o);
125:                } else {
126:                    return new CachedRow(t, o);
127:                }
128:            }
129:
130:            /**
131:             *  Constructor for new Rows.  Variable hasDataChanged is set to true in
132:             *  order to indicate the data needs saving.
133:             *
134:             * @param t table
135:             * @param o row data
136:             * @throws HsqlException if a database access error occurs
137:             */
138:            CachedRow(Table t, Object[] o) throws HsqlException {
139:
140:                tTable = t;
141:
142:                int indexcount = t.getIndexCount();
143:
144:                nPrimaryNode = Node.newNode(this , 0, t);
145:
146:                Node n = nPrimaryNode;
147:
148:                for (int i = 1; i < indexcount; i++) {
149:                    n.nNext = Node.newNode(this , i, t);
150:                    n = n.nNext;
151:                }
152:
153:                oData = o;
154:                hasDataChanged = hasNodesChanged = true;
155:            }
156:
157:            /**
158:             *  Constructor when read from the disk into the Cache.
159:             *
160:             * @param t table
161:             * @param in data source
162:             * @throws IOException
163:             * @throws HsqlException
164:             */
165:            public CachedRow(Table t, RowInputInterface in) throws IOException,
166:                    HsqlException {
167:
168:                tTable = t;
169:                iPos = in.getPos();
170:                storageSize = in.getSize();
171:
172:                int indexcount = t.getIndexCount();
173:
174:                nPrimaryNode = Node.newNode(this , in, 0, t);
175:
176:                Node n = nPrimaryNode;
177:
178:                for (int i = 1; i < indexcount; i++) {
179:                    n.nNext = Node.newNode(this , in, i, t);
180:                    n = n.nNext;
181:                }
182:
183:                oData = in.readData(tTable.getColumnTypes());
184:            }
185:
186:            private void readRowInfo(RowInputInterface in) throws IOException,
187:                    HsqlException {
188:
189:                // for use when additional transaction info is attached to rows
190:            }
191:
192:            /**
193:             *  This method is called only when the Row is deleted from the database
194:             *  table. The links with all the other objects apart from the data
195:             *  are removed.
196:             *
197:             * @throws HsqlException
198:             */
199:            public void delete() throws HsqlException {
200:
201:                super .delete();
202:
203:                hasNodesChanged = hasDataChanged = false;
204:                tTable = null;
205:            }
206:
207:            public int getStorageSize() {
208:                return storageSize;
209:            }
210:
211:            /**
212:             * Sets the file position for the row
213:             *
214:             * @param pos position in data file
215:             */
216:            public void setPos(int pos) {
217:                iPos = pos;
218:            }
219:
220:            /**
221:             * Sets flag for Node data change.
222:             */
223:            void setChanged() {
224:                hasNodesChanged = true;
225:            }
226:
227:            /**
228:             * Returns true if Node data has changed.
229:             *
230:             * @return boolean
231:             */
232:            public boolean hasChanged() {
233:                return hasNodesChanged;
234:            }
235:
236:            /**
237:             * Returns the Table to which this Row belongs.
238:             *
239:             * @return Table
240:             */
241:            public Table getTable() {
242:                return tTable;
243:            }
244:
245:            /**
246:             * returned size does not include the row size written at the beginning
247:             */
248:            public int getRealSize(RowOutputInterface out) {
249:                return tTable.getIndexCount() * DiskNode.SIZE_IN_BYTE
250:                        + out.getSize(this );
251:            }
252:
253:            public void setStorageSize(int size) {
254:                storageSize = size;
255:            }
256:
257:            /**
258:             * Returns true if any of the Nodes for this row is a root node.
259:             * Used only in Cache.java to avoid removing the row from the cache.
260:             *
261:             * @return boolean
262:             * @throws HsqlException
263:             */
264:            synchronized public boolean isKeepInMemory() {
265:
266:                Node n = nPrimaryNode;
267:
268:                while (n != null) {
269:                    if (n.isRoot()) {
270:                        return true;
271:                    }
272:
273:                    n = n.nNext;
274:                }
275:
276:                return false;
277:            }
278:
279:            /**
280:             *  Using the internal reference to the Table, returns the current cached
281:             *  Row. Valid for deleted rows only before any subsequent insert or
282:             *  update on any cached table.<p>
283:             *
284:             *  Access to tables while performing the internal operations for an
285:             *  SQL statement result in CachedRow objects to be cleared from the cache.
286:             *  This method returns the CachedRow, loading it to the cache if it is not
287:             *  there.
288:             * @return the current Row in Cache for this Object
289:             * @throws HsqlException
290:             */
291:            synchronized Row getUpdatedRow() throws HsqlException {
292:                return tTable == null ? null : (CachedRow) tTable.rowStore
293:                        .get(iPos);
294:            }
295:
296:            /**
297:             * used in CachedDataRow
298:             */
299:            void setNewNodes() {
300:            }
301:
302:            /**
303:             *  Used exclusively by Cache to save the row to disk. New implementation
304:             *  in 1.7.2 writes out only the Node data if the table row data has not
305:             *  changed. This situation accounts for the majority of invocations as
306:             *  for each row deleted or inserted, the Nodes for several other rows
307:             *  will change.
308:             *
309:             * @param output data source
310:             * @throws IOException
311:             * @throws HsqlException
312:             */
313:            public void write(RowOutputInterface out) {
314:
315:                try {
316:                    writeNodes(out);
317:
318:                    if (hasDataChanged) {
319:                        out.writeData(oData, tTable);
320:                        out.writeEnd();
321:
322:                        hasDataChanged = false;
323:                    }
324:                } catch (IOException e) {
325:                }
326:            }
327:
328:            private void writeRowInfo(RowOutputInterface out) {
329:
330:                // for use when additional transaction info is attached to rows
331:            }
332:
333:            public void write(RowOutputInterface out, IntLookup lookup) {
334:
335:                out.writeSize(storageSize);
336:
337:                Node rownode = nPrimaryNode;
338:
339:                while (rownode != null) {
340:                    ((DiskNode) rownode).writeTranslate(out, lookup);
341:
342:                    rownode = rownode.nNext;
343:                }
344:
345:                out.writeData(getData(), getTable());
346:                out.writeEnd();
347:            }
348:
349:            /**
350:             *  Writes the Nodes, immediately after the row size.
351:             *
352:             * @param out
353:             *
354:             * @throws IOException
355:             * @throws HsqlException
356:             */
357:            private void writeNodes(RowOutputInterface out) throws IOException {
358:
359:                out.writeSize(storageSize);
360:
361:                Node n = nPrimaryNode;
362:
363:                while (n != null) {
364:                    n.write(out);
365:
366:                    n = n.nNext;
367:                }
368:
369:                hasNodesChanged = false;
370:            }
371:
372:            /**
373:             * With CACHED tables there may possibly exist two copies of the row.
374:             * All copies will have the same iPos.
375:             *
376:             * @param obj row to compare
377:             * @return boolean
378:             */
379:            public boolean equals(Object obj) {
380:
381:                if (obj == this ) {
382:                    return true;
383:                }
384:
385:                if (obj instanceof  CachedRow) {
386:                    return ((CachedRow) obj).iPos == iPos;
387:                }
388:
389:                return false;
390:            }
391:
392:            /**
393:             * Hash code is valid only until a modification to the cache
394:             *
395:             * @return file position of row
396:             */
397:            public int hashCode() {
398:                return iPos;
399:            }
400:        }
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