RecordInput


1   /*-
2    * See the file LICENSE for redistribution information.
3    *
4    * Copyright (c) 2002,2006 Oracle.  All rights reserved.
5    *
6    * $Id: RecordInput.java,v 1.4 2006/10/30 21:14:32 bostic Exp $
7    */
8   
9   package com.sleepycat.persist.impl;
10  
11  import com.sleepycat.bind.tuple.TupleInput;
12  import com.sleepycat.je.DatabaseEntry;
13  
14  /**
15   * Implements EntityInput to read record key-data pairs.  Extends TupleInput to
16   * implement the subset of TupleInput methods that are defined in the
17   * EntityInput interface.
18   *
19   * @author Mark Hayes
20   */
21  class RecordInput extends TupleInput implements EntityInput {
22  
23      private Catalog catalog;
24      private boolean rawAccess;
25      private VisitedObjects visited;
26      private DatabaseEntry priKeyEntry;
27      private int priKeyFormatId;
28  
29      /**
30       * Creates a new input with a empty/null VisitedObjects set.
31       */
32      RecordInput(Catalog catalog,
33                  boolean rawAccess,
34                  DatabaseEntry priKeyEntry,
35                  int priKeyFormatId,
36                  byte[] buffer,
37                  int offset,
38                  int length) {
39          super(buffer, offset, length);
40          this.catalog = catalog;
41          this.rawAccess = rawAccess;
42          this.priKeyEntry = priKeyEntry;
43          this.priKeyFormatId = priKeyFormatId;
44      }
45  
46      /**
47       * Copy contructor where a new offset can be specified.
48       */
49      private RecordInput(RecordInput other, int offset) {
50          this(other.catalog, other.rawAccess, other.priKeyEntry,
51               other.priKeyFormatId, other.buf, offset, other.len);
52          visited = other.visited;
53      }
54  
55      /**
56       * Copy contructor where a DatabaseEntry can be specified.
57       */
58      private RecordInput(RecordInput other, DatabaseEntry entry) {
59          this(other.catalog, other.rawAccess, other.priKeyEntry,
60               other.priKeyFormatId, entry.getData(), entry.getOffset(),
61               entry.getSize());
62          visited = other.visited;
63      }
64  
65      /**
66       * @see EntityInput#getCatalog
67       */
68      public Catalog getCatalog() {
69          return catalog;
70      }
71      
72      /**
73       * @see EntityInput#isRawAccess
74       */
75      public boolean isRawAccess() {
76          return rawAccess;
77      }
78  
79      /**
80       * @see EntityInput#setRawAccess
81       */
82      public boolean setRawAccess(boolean rawAccessParam) {
83          boolean original = rawAccess;
84          rawAccess = rawAccessParam;
85          return original;
86      }
87  
88      /**
89       * @see EntityInput#readObject
90       */
91      public Object   readObject() {
92  
93          /* Save the current offset before reading the format ID. */
94          int visitedOffset = off;
95          RecordInput useInput = this;
96          int formatId = readPackedInt();
97          Object   o = null;
98  
99          /* For a zero format ID, return a null instance. */
100         if (formatId == Format.ID_NULL) {
101             return null;
102         }
103 
104         /* For a negative format ID, lookup an already visited instance. */
105         if (formatId < 0) {
106             int offset = (-(formatId + 1));
107             if (visited != null) {
108                 o = visited.getObject(offset);
109             }
110             if (o != null) {
111                 /* Return a previously visited object. */
112                 return o;
113             } else {
114 
115                 /*
116                  * When reading starts from a non-zero offset, we may have to
117                  * go back in the stream and read the referenced object.  This
118                  * happens when reading secondary key fields.
119                  */
120                 visitedOffset = offset;
121                 if (offset == EntityOutput.PRI_KEY_VISITED_OFFSET) {
122                     assert priKeyEntry != null && priKeyFormatId > 0;
123                     useInput = new RecordInput(this, priKeyEntry);
124                     formatId = priKeyFormatId;
125                 } else {
126                     useInput = new RecordInput(this, offset);
127                     formatId = useInput.readPackedInt();
128                 }
129             }
130         }
131 
132         /* Create the object using the format indicated. */
133         Format format = catalog.getFormat(formatId);
134         Reader reader = format.getReader();
135         o = reader.newInstance(useInput, rawAccess);
136 
137         /*
138          * Add newly created object to the set of visited objects.  This must
139          * be done before calling Reader.readObject, in case the object
140          * contains a reference to itself.
141          */
142         if (visited == null) {
143             visited = new VisitedObjects();
144         }
145         visited.add(o, visitedOffset);
146 
147         /*
148          * Finish reading the object.  Then replace it in the visited list in
149          * case a converted object is returned by readObject.
150          */
151         Object   o2 = reader.readObject(o, useInput, rawAccess);
152         if (o != o2) {
153             visited.replaceObject(o, o2);
154         }
155         return o2;
156     }
157 
158     /**
159      * @see EntityInput#readKeyObject
160      */
161     public Object   readKeyObject(Format format) {
162 
163         /* Create and read the object using the given key format. */
164         Reader reader = format.getReader();
165         Object   o = reader.newInstance(this, rawAccess);
166         return reader.readObject(o, this, rawAccess);
167     }
168 
169     /**
170      * Called when copying secondary keys, for an input that is positioned on
171      * the secondary key field.  Handles references to previously occurring
172      * objects, returning a different RecordInput than this one if appropriate.
173      */
174     KeyLocation getKeyLocation(Format fieldFormat) {
175         RecordInput input = this;
176         if (!fieldFormat.isPrimitive()) {
177             int formatId = input.readPackedInt();
178             if (formatId == Format.ID_NULL) {
179                 /* Key field is null. */
180                 return null;
181             }
182             if (formatId < 0) {
183                 int offset = (-(formatId + 1));
184                 if (offset == EntityOutput.PRI_KEY_VISITED_OFFSET) {
185                     assert priKeyEntry != null && priKeyFormatId > 0;
186                     input = new RecordInput(this, priKeyEntry);
187                     formatId = priKeyFormatId;
188                 } else {
189                     input = new RecordInput(this, offset);
190                     formatId = input.readPackedInt();
191                 }
192             }
193             fieldFormat = catalog.getFormat(formatId);
194         }
195         /* Key field is non-null. */
196         return new KeyLocation(input, fieldFormat);
197     }
198 
199     /**
200      * @see EntityInput#registerPriKeyObject
201      */
202     public void registerPriKeyObject(Object   o) {
203 
204         /*
205          * PRI_KEY_VISITED_OFFSET is used as the visited offset to indicate
206          * that the visited object is stored in the primary key byte array.
207          */
208         if (visited == null) {
209             visited = new VisitedObjects();
210         }
211         visited.add(o, EntityOutput.PRI_KEY_VISITED_OFFSET);
212     }
213 
214     /**
215      * @see EntityInput#skipField
216      */
217     public void skipField(Format declaredFormat) {
218         if (declaredFormat != null && declaredFormat.isPrimitive()) {
219             declaredFormat.skipContents(this);
220         } else {
221             int formatId = readPackedInt();
222             if (formatId > 0) {
223                 Format format = catalog.getFormat(formatId);
224                 format.skipContents(this);
225             }
226         }
227     }
228 
229     public int readArrayLength() {
230         return readPackedInt();
231     }
232 
233     public int readEnumConstant(String  [] names) {
234         return readPackedInt();
235     }
236 }
237
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