CheckpointFileReader


1   /*-
2    * See the file LICENSE for redistribution information.
3    *
4    * Copyright (c) 2002,2006 Oracle.  All rights reserved.
5    *
6    * $Id: CheckpointFileReader.java,v 1.26 2006/10/30 21:14:20 bostic Exp $
7    */
8   
9   package com.sleepycat.je.log;
10  
11  import java.io.IOException  ;
12  import java.nio.ByteBuffer  ;
13  
14  import com.sleepycat.je.DatabaseException;
15  import com.sleepycat.je.dbi.EnvironmentImpl;
16  
17  /**
18   * CheckpointFileReader searches for root and checkpoint entries.
19   */
20  public class CheckpointFileReader extends FileReader {
21      /* Status about the last entry. */
22      private boolean isRoot;
23      private boolean isCheckpointEnd;
24      private boolean isCheckpointStart;
25  
26      /**
27       * Create this reader to start at a given LSN.
28       */
29      public CheckpointFileReader(EnvironmentImpl env,
30                                  int readBufferSize, 
31                                  boolean forward,
32                                  long startLsn,
33                                  long finishLsn,
34                                  long endOfFileLsn) 
35          throws IOException  , DatabaseException {
36  
37          super(env, readBufferSize, forward, startLsn,
38            null, endOfFileLsn, finishLsn);
39      }
40  
41      /** 
42       * @return true if this is a targetted entry.
43       */
44      protected boolean isTargetEntry(byte logEntryTypeNumber,
45                                      byte logEntryTypeVersion) {
46          boolean isTarget = false;
47          isRoot = false;
48          isCheckpointEnd = false;
49          isCheckpointStart = false;
50          if (LogEntryType.LOG_CKPT_END.equalsType(logEntryTypeNumber,
51                           logEntryTypeVersion)) {
52              isTarget = true;
53              isCheckpointEnd = true;
54          } else if (LogEntryType.LOG_CKPT_START.equalsType(logEntryTypeNumber,
55                                                          logEntryTypeVersion)) {
56              isTarget = true;
57              isCheckpointStart = true;
58          } else if (LogEntryType.LOG_ROOT.equalsType(logEntryTypeNumber,
59                              logEntryTypeVersion)) {
60              isTarget = true;
61              isRoot = true;
62          }
63          return isTarget;
64      }
65      
66      /**
67       * This reader instantiate the first object of a given log entry
68       */
69      protected boolean processEntry(ByteBuffer   entryBuffer)
70          throws DatabaseException {
71  
72          /* Don't need to read the entry, since we just use the LSN. */
73          return true;
74      }
75  
76      /**
77       * @return true if last entry was a root entry.
78       */
79      public boolean isRoot() {
80          return isRoot;
81      }
82  
83      /**
84       * @return true if last entry was a checkpoint end entry.
85       */
86      public boolean isCheckpointEnd() {
87          return isCheckpointEnd;
88      }
89  
90      /**
91       * @return true if last entry was a checkpoint start entry.
92       */
93      public boolean isCheckpointStart() {
94          return isCheckpointStart;
95      }
96  }
97
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