1 karl 1.7 //%2004////////////////////////////////////////////////////////////////////////
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2 mike 1.1 //
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3 karl 1.7 // Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development
4 // Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
5 // Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.;
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6 karl 1.6 // IBM Corp.; EMC Corporation, The Open Group.
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7 karl 1.7 // Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
8 // IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
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9 mike 1.1 //
10 // Permission is hereby granted, free of charge, to any person obtaining a copy
11 // of this software and associated documentation files (the "Software"), to
12 // deal in the Software without restriction, including without limitation the
13 // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
14 // sell copies of the Software, and to permit persons to whom the Software is
15 // furnished to do so, subject to the following conditions:
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16 kumpf 1.3 //
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17 mike 1.1 // THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
18 // ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
19 // "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
20 // LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
21 // PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
22 // HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
23 // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
24 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 //
26 //==============================================================================
27 //
28 // Author: Jenny Yu, Hewlett-Packard Company (jenny_yu@hp.com)
29 //
30 // Modified By: Michael E. Brasher (mbrasher@bmc.com)
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31 david.dillard 1.8 // David Dillard, VERITAS Software Corp.
32 // (david.dillard@veritas.com)
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33 mike 1.1 //
34 //%/////////////////////////////////////////////////////////////////////////////
35
36 #ifndef Pegasus_InstanceDataFile_h
37 #define Pegasus_InstanceDataFile_h
38
39 #include <fstream>
40 #include <Pegasus/Common/Config.h>
41 #include <Pegasus/Common/String.h>
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42 kumpf 1.5 #include <Pegasus/Common/InternalException.h>
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43 kumpf 1.2 #include <Pegasus/Common/CIMObjectPath.h>
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44 kumpf 1.4 #include <Pegasus/Repository/Linkage.h>
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45 mike 1.1
46 PEGASUS_NAMESPACE_BEGIN
47
48 /** This class manages access to an instance data file which contains all
49 instances of a particular class.
50
51 The instances are stored in ASCII XML format one after another. A separate
52 instance index file is maintained (see InstanceIndexFile) which contains
53 an index entry for each instance in the data file. This index ties the key
54 of the instance to an offset and size within the instance file.
55
56 The index file and data file are named according to the class whose
57 instances they contain information about. The index file and data file for
58 a class named "Zebra" would be:
59
60 <pre>
61 Zebra (index file).
62 Zebra.instances (instance-file).
63 </pre>
64
65 When an instance is created, it is appended to the end of the instance
66 mike 1.1 file. When one is deleted, it is marked as free in the index file. When
67 an instance is modified, the old one is marked as deleted and the new
68 modified instance is appended to the end of the data file. Note that
69 deletion and modification may leave unused gaps in the data file. These
70 gaps are reclaimed during compaction (performed when the data file has
71 N gaps where N is some arbitrarily chosen number for now). Performing
72 compaction during each modify and delete would be extremely inefficient.
73 By postponing it until N such operations have been performed, we
74 improve performance considerably.
75
76 Note the three operations which may be performed on an instance and there
77 associated effect on the data file.
78
79 <ul>
80 <li>Create - appends an instance to the end of the file.</li>
81 <li>Modify - appends an instance to the end of the file.</li>
82 <li>Delete - has no effect on the data file</li>
83 </ul>
84
85 To avoid corruption of the data file we provide a rollback scheme. A
86 rollback file is created (the name is formed by appending ".rollback" to
87 mike 1.1 the name of the data file) which contains the original size of the data
88 file. After the modification of the data file is complete, the rollback
89 file is removed. If we discover a rollback file when we start an operation,
90 this means that the last operation did not succeed. We then rollback the
91 operation by truncating the file to its old size.
92 */
93 class PEGASUS_REPOSITORY_LINKAGE InstanceDataFile
94 {
95 public:
96
97 /** loads an instance from the data file into memory.
98
99 @param path the file path of the instance file
100 @param index the byte positon of the instance record
101 @param size the size of the instance record
102 @param data the buffer to hold the instance data
103 @return true on success.
104 */
105 static Boolean loadInstance(
106 const String& path,
107 Uint32 index,
108 mike 1.1 Uint32 size,
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109 david.dillard 1.8 Array<char>& data);
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110 mike 1.1
111 /** loads all the instances from the data file into memory.
112
113 @param path the file path of the instance file
114 @param data the buffer to hold the data
115 @return true on success.
116 */
117 static Boolean loadAllInstances(
118 const String& path,
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119 david.dillard 1.8 Array<char>& data);
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120 mike 1.1
121 /** Appends a new instance to the end of the file.
122
123 @param out the buffer containing the CIM/XML encoding of the
124 @param path the file path of the instance file
125 @param index the byte positon of the instance record
126 @return true on success
127 */
128 static Boolean appendInstance(
129 const String& path,
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130 david.dillard 1.8 const Array<char>& data,
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131 mike 1.1 Uint32& index);
132
133 /** Begin a transaction to modify this file. The effect of subsequent
134 modifications can be rolled back by calling rollbackTransaction().
135 */
136 static Boolean beginTransaction(const String& path);
137
138 /** Roll back any changes to the file since the last time
139 beginTransaction() was called.
140 */
141 static Boolean rollbackTransaction(const String& path);
142
143 /** Commit changes made after beginTransaction() was called.
144 */
145 static Boolean commitTransaction(const String& path);
146
147 /** Reorganizes the data file to reclaim free space. This is done by
148 copying over all non-free instances to a temporary file and then
149 deleting the original file and renaming the temporary file to the
150 same name as the original.
151 */
152 mike 1.1 static Boolean compact(
153 const String& path,
154 const Array<Uint32>& freeFlags,
155 const Array<Uint32>& indices,
156 const Array<Uint32>& sizes);
157
158 private:
159
160 static Boolean _openFile(
161 PEGASUS_STD(fstream)& fs,
162 const String& path,
163 int mode);
164 };
165
166 PEGASUS_NAMESPACE_END
167
168 #endif /* Pegasus_InstanceDataFile_h */
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InstanceDataFile.h
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