1 karl  1.11 //%2006////////////////////////////////////////////////////////////////////////

  2 mike  1.1  //

  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.;

  6 karl  1.6  // IBM Corp.; EMC Corporation, The Open Group.

  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.

  9 karl  1.9  // Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
 10            // EMC Corporation; VERITAS Software Corporation; The Open Group.

 11 karl  1.11 // Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
 12            // EMC Corporation; Symantec Corporation; The Open Group.

 13 mike  1.1  //
 14            // Permission is hereby granted, free of charge, to any person obtaining a copy
 15            // of this software and associated documentation files (the "Software"), to
 16            // deal in the Software without restriction, including without limitation the
 17            // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 18            // sell copies of the Software, and to permit persons to whom the Software is
 19            // furnished to do so, subject to the following conditions:

 20 kumpf 1.3  // 

 21 mike  1.1  // THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
 22            // ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
 23            // "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
 24            // LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 25            // PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 26            // HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 27            // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 28            // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 29            //
 30            //==============================================================================
 31            //
 32            //%/////////////////////////////////////////////////////////////////////////////
 33            
 34            #ifndef Pegasus_InstanceDataFile_h
 35            #define Pegasus_InstanceDataFile_h
 36            
 37            #include <fstream>
 38            #include <Pegasus/Common/Config.h>
 39            #include <Pegasus/Common/String.h>

 40 kumpf 1.5  #include <Pegasus/Common/InternalException.h>

 41 kumpf 1.2  #include <Pegasus/Common/CIMObjectPath.h>

 42 kumpf 1.4  #include <Pegasus/Repository/Linkage.h>

 43 mike  1.10 #include <Pegasus/Common/Buffer.h>

 44 mike  1.1  
 45            PEGASUS_NAMESPACE_BEGIN
 46            
 47            /** This class manages access to an instance data file which contains all
 48                instances of a particular class.
 49            
 50                The instances are stored in ASCII XML format one after another. A separate
 51                instance index file is maintained (see InstanceIndexFile) which contains
 52                an index entry for each instance in the data file. This index ties the key
 53                of the instance to an offset and size within the instance file.
 54            
 55                The index file and data file are named according to the class whose
 56                instances they contain information about. The index file and data file for
 57                a class named "Zebra" would be:
 58            
 59                <pre>
 60                    Zebra (index file).
 61                    Zebra.instances (instance-file).
 62                </pre>

 63 kumpf 1.12 
 64                When an instance is created, it is appended to the end of the instance

 65 mike  1.1      file. When one is deleted, it is marked as free in the index file. When
 66                an instance is modified, the old one is marked as deleted and the new

 67 kumpf 1.12     modified instance is appended to the end of the data file. Note that

 68 mike  1.1      deletion and modification may leave unused gaps in the data file. These
 69                gaps are reclaimed during compaction (performed when the data file has
 70                N gaps where N is some arbitrarily chosen number for now). Performing
 71                compaction during each modify and delete would be extremely inefficient.

 72 kumpf 1.12     By postponing it until N such operations have been performed, we

 73 mike  1.1      improve performance considerably.
 74            
 75                Note the three operations which may be performed on an instance and there
 76                associated effect on the data file.
 77            
 78                <ul>
 79                <li>Create - appends an instance to the end of the file.</li>
 80                <li>Modify - appends an instance to the end of the file.</li>
 81                <li>Delete - has no effect on the data file</li>
 82                </ul>
 83            
 84                To avoid corruption of the data file we provide a rollback scheme. A
 85                rollback file is created (the name is formed by appending ".rollback" to
 86                the name of the data file) which contains the original size of the data
 87                file. After the modification of the data file is complete, the rollback
 88                file is removed. If we discover a rollback file when we start an operation,
 89                this means that the last operation did not succeed. We then rollback the
 90                operation by truncating the file to its old size.
 91            */
 92            class PEGASUS_REPOSITORY_LINKAGE InstanceDataFile
 93            {
 94 mike  1.1  public:

 95 kumpf 1.12 

 96 mike  1.1      /** loads an instance from the data file into memory.
 97            
 98                    @param path the file path of the instance file
 99                    @param index the byte positon of the instance record

100 kumpf 1.12         @param size the size of the instance record
101                    @param data the buffer to hold the instance data

102 mike  1.1          @return true on success.
103                */
104                static Boolean loadInstance(

105 kumpf 1.12         const String& path,
106                    Uint32 index,
107                    Uint32 size,

108 mike  1.10         Buffer& data);

109 kumpf 1.12 
110                /** loads all the instances from the data file into memory.

111 mike  1.1  
112                    @param path the file path of the instance file

113 kumpf 1.12         @param data the buffer to hold the data

114 mike  1.1          @return true on success.
115                */
116                static Boolean loadAllInstances(

117 kumpf 1.12         const String& path,

118 mike  1.10         Buffer& data);

119 kumpf 1.12 

120 mike  1.1      /** Appends a new instance to the end of the file.

121 kumpf 1.12 
122                    @param out the buffer containing the CIM/XML encoding of the

123 mike  1.1          @param path the file path of the instance file
124                    @param index the byte positon of the instance record
125                    @return true on success
126                */
127                static Boolean appendInstance(

128 kumpf 1.12         const String& path,

129 mike  1.10         const Buffer& data,

130 kumpf 1.12         Uint32& index);

131 mike  1.1  
132                /** Begin a transaction to modify this file. The effect of subsequent

133 kumpf 1.12         modifications can be rolled back by calling rollbackTransaction().

134 mike  1.1      */
135                static Boolean beginTransaction(const String& path);
136            

137 kumpf 1.12     /** Roll back any changes to the file since the last time

138 mike  1.1          beginTransaction() was called.
139                */
140                static Boolean rollbackTransaction(const String& path);
141            
142                /** Commit changes made after beginTransaction() was called.
143                */
144                static Boolean commitTransaction(const String& path);
145            
146                /** Reorganizes the data file to reclaim free space. This is done by

147 kumpf 1.12         copying over all non-free instances to a temporary file and then
148                    deleting the original file and renaming the temporary file to the
149                    same name as the original.

150 mike  1.1      */
151                static Boolean compact(

152 kumpf 1.12         const String& path,

153 mike  1.1          const Array<Uint32>& freeFlags,
154                    const Array<Uint32>& indices,
155                    const Array<Uint32>& sizes);
156            
157            private:
158            
159                static Boolean _openFile(

160 kumpf 1.12         PEGASUS_STD(fstream)& fs,
161                    const String& path,
162                    int mode);

163 mike  1.1  };
164            
165            PEGASUS_NAMESPACE_END
166            
167            #endif /* Pegasus_InstanceDataFile_h */