1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2001, 2015 Oracle and/or its affiliates. All rights reserved.
*
* $Id$
*/
package com.sleepycat.db;
import com.sleepycat.db.internal.DbConstants;
import com.sleepycat.db.internal.DbLogc;
/**
The LogCursor object is the handle for a cursor into the log files,
supporting sequential access to the records stored in log files.
<p>
The handle is not free-threaded. Once the {@link com.sleepycat.db.LogCursor#close LogCursor.close}
method is called, the handle may not be accessed again, regardless of
that method's success or failure.
*/
public class LogCursor {
/* package */ DbLogc logc;
/* package */ LogCursor(final DbLogc logc) {
this.logc = logc;
}
/* package */
static LogCursor wrap(DbLogc logc) {
return (logc == null) ? null : new LogCursor(logc);
}
/**
Discard the log cursor. After close() has been called, regardless of its
return, the cursor handle may not be used again.
*/
public synchronized void close()
throws DatabaseException {
logc.close(0);
}
/**
Return the LogSequenceNumber and log record to which the log cursor
currently refers.
<p>
@param lsn
The returned LogSequenceNumber.
<p>
@param data
The returned log record. The data field is set to the record
retrieved, and the size field indicates the number of bytes in
the record.
<p>
@return
The status of the operation.
<p>
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus getCurrent(final LogSequenceNumber lsn,
final DatabaseEntry data)
throws DatabaseException {
return OperationStatus.fromInt(
logc.get(lsn, data, DbConstants.DB_CURRENT));
}
/**
Return the next LogSequenceNumber and log record.
<p>
The current log position is advanced to the next record in the log,
and its LogSequenceNumber and data are returned. If the cursor has
not been initialized, the first available log record in the log will
be returned.
<p>
@param lsn
The returned LogSequenceNumber.
<p>
@param data
The returned log record.
<p>
@return
The status of the operation; a return of NOTFOUND indicates the last
log record has already been returned or the log is empty.
<p>
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus getNext(final LogSequenceNumber lsn,
final DatabaseEntry data)
throws DatabaseException {
return OperationStatus.fromInt(
logc.get(lsn, data, DbConstants.DB_NEXT));
}
/**
Return the first LogSequenceNumber and log record.
<p>
The current log position is set to the first record in the log,
and its LogSequenceNumber and data are returned.
<p>
@param lsn
The returned LogSequenceNumber.
<p>
@param data
The returned log record.
<p>
@return
The status of the operation; a return of NOTFOUND indicates the log
is empty.
<p>
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus getFirst(final LogSequenceNumber lsn,
final DatabaseEntry data)
throws DatabaseException {
return OperationStatus.fromInt(
logc.get(lsn, data, DbConstants.DB_FIRST));
}
/**
Return the last LogSequenceNumber and log record.
<p>
The current log position is set to the last record in the log,
and its LogSequenceNumber and data are returned.
<p>
@param lsn
The returned LogSequenceNumber.
<p>
@param data
The returned log record.
<p>
@return
The status of the operation; a return of NOTFOUND indicates the log
is empty.
<p>
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus getLast(final LogSequenceNumber lsn,
final DatabaseEntry data)
throws DatabaseException {
return OperationStatus.fromInt(
logc.get(lsn, data, DbConstants.DB_LAST));
}
/**
Return the previous LogSequenceNumber and log record.
<p>
The current log position is advanced to the previous record in the log,
and its LogSequenceNumber and data are returned. If the cursor has
not been initialized, the last available log record in the log will
be returned.
<p>
@param lsn
The returned LogSequenceNumber.
<p>
@param data
The returned log record.
<p>
@return
The status of the operation; a return of NOTFOUND indicates the first
log record has already been returned or the log is empty.
<p>
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus getPrev(final LogSequenceNumber lsn,
final DatabaseEntry data)
throws DatabaseException {
return OperationStatus.fromInt(
logc.get(lsn, data, DbConstants.DB_PREV));
}
/**
Return a specific log record.
<p>
The current log position is set to the specified record in the log,
and its data is returned.
<p>
@param lsn
The specified LogSequenceNumber.
<p>
@param data
The returned log record.
<p>
@return
The status of the operation.
<p>
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus set(final LogSequenceNumber lsn,
final DatabaseEntry data)
throws DatabaseException {
return OperationStatus.fromInt(
logc.get(lsn, data, DbConstants.DB_SET));
}
/**
Get the log file version.
<p>
@return
The log file version.
<p>
<p>
@throws DatabaseException if a failure occurs.
*/
public int version()
throws DatabaseException {
return logc.version(0);
}
}
|
