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StandardStManAccessor.h
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1//# StandardStManAccessor.h: Gives access to some StandardStMan functions
2//# Copyright (C) 2000,2001
3//# Associated Universities, Inc. Washington DC, USA.
4//#
5//# This library is free software; you can redistribute it and/or modify it
6//# under the terms of the GNU Library General Public License as published by
7//# the Free Software Foundation; either version 2 of the License, or (at your
8//# option) any later version.
9//#
10//# This library is distributed in the hope that it will be useful, but WITHOUT
11//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
13//# License for more details.
14//#
15//# You should have received a copy of the GNU Library General Public License
16//# along with this library; if not, write to the Free Software Foundation,
17//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
18//#
19//# Correspondence concerning AIPS++ should be addressed as follows:
20//# Internet email: aips2-request@nrao.edu.
21//# Postal address: AIPS++ Project Office
22//# National Radio Astronomy Observatory
23//# 520 Edgemont Road
24//# Charlottesville, VA 22903-2475 USA
25//#
26//# $Id$
27
28#ifndef TABLES_STANDARDSTMANACCESSOR_H
29#define TABLES_STANDARDSTMANACCESSOR_H
30
31//# Includes
32#include <casacore/casa/aips.h>
33#include <casacore/tables/DataMan/DataManAccessor.h>
34#include <casacore/casa/iosfwd.h>
35
36namespace casacore { //# NAMESPACE CASACORE - BEGIN
37
38//# Forward Declarations
39class SSMBase;
40class DataManager;
41class Table;
42class String;
43
44// <summary>
45// Give access to some StandardStMan functions
46// </summary>
47
48// <use visibility=export>
49
50// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="tStandardStMan">
51// </reviewed>
52
53// <prerequisite>
54//# Classes you should understand before using this one.
55// <li> <linkto class=StandardStMan>StandardStMan</linkto>
56// </prerequisite>
57
58// <synopsis>
59// The Table system has one or more storage managers underneath.
60// One of these possible storage managers is the
61// <linkto class=StandardStMan>StandardStMan</linkto>.
62// This storage manager uses a cache of buckets. The default
63// cache size is defined when the StandardStMan object was
64// constructed at the time the table was created.
65// <p>
66// Sometimes it can be useful to change the cache size. E.g. when
67// the table is accessed in a random way, the hit rate may drop
68// when the cache is too small. The class ROStandardStManAccessor makes
69// it possible to change the cache size in a temporary way.
70// <br>
71// It is also possible to get the cache size.
72// <p>
73// Furthermore it is possible to show some statistics (about the cache
74// and the internals of SSM classes).
75// </synopsis>
76
77// <motivation>
78// In principle a pointer to StandardStMan could be used.
79// However, that would give access to all public functions.
80// Furthermore it could not distinguish between read/write and readonly
81// tables.
82// </motivation>
83
84// <example>
85// This example shows how to set the cache size for
86// the standard storage manager with the name "SSMExample". The cache
87// size is not persistent, i.e. when the same table is reopened
88// at a later time, this cache size is not remembered.
89// <srcblock>
90// // Open a table.
91// Table table("someName.data");
92// // Set the cache size of its standard storage manager SSMExample
93// // to 5 buckets.
94// ROStandardStManAccessor accessor(table, "SSMExample");
95// accessor.setCacheSize (5);
96// </srcblock>
97// </example>
98
99//# <todo asof="$DATE:$">
100//# </todo>
101
102
104{
105public:
106
107 // Construct the object for a data manager in the table given the name
108 // of the data manager or the column.
109 // An exception is thrown if the data manager type is not the incremental
110 // storage manager.
111 ROStandardStManAccessor (const Table& table, const String& name,
112 Bool byColumn=False);
113
115
116 // Copy constructor (reference semantics).
118
119 // Assignment (reference semantics).
121 (const ROStandardStManAccessor& that);
122
123 // Set the cache size (in buckets) to be used by the
124 // storage manager.
125 // The cache size given in this way is not persistent.
126 // Only the cache size given to the constructors of the Standard
127 // storage managers, is persistent.
128 // If <src>canExceedNrBuckets=True</src>, the given cache size can be
129 // larger than the nr of buckets in the file. In this way the cache can
130 // be made large enough for a future file extension.
131 // Otherwise, it is limited to the actual number of buckets. This is useful
132 // if one wants the entire file to be cached.
133 void setCacheSize (uInt aSize, Bool canExceedNrBuckets=True);
134
135 // Get the cache size (in buckets).
137
138 // Clear the cache used by this storage manager.
139 // It will flush the cache as needed and remove all buckets from it
140 // resulting in a drop in memory used.
142
143 // Show the statistics for the base class.
144 void showBaseStatistics (ostream& anOs) const;
145
146 // Show the statistics for each index used by this storage manager.
147 void showIndexStatistics (ostream& anOs) const;
148
149
150private:
151 //# Declare the data members.
153};
154
155
156
157} //# NAMESPACE CASACORE - END
158
159#endif
ROStandardStManAccessor(const ROStandardStManAccessor &that)
Copy constructor (reference semantics).
void clearCache()
Clear the cache used by this storage manager.
void setCacheSize(uInt aSize, Bool canExceedNrBuckets=True)
Set the cache size (in buckets) to be used by the storage manager.
void showIndexStatistics(ostream &anOs) const
Show the statistics for each index used by this storage manager.
uInt getCacheSize() const
Get the cache size (in buckets).
ROStandardStManAccessor(const Table &table, const String &name, Bool byColumn=False)
Construct the object for a data manager in the table given the name of the data manager or the column...
void showBaseStatistics(ostream &anOs) const
Show the statistics for the base class.
String: the storage and methods of handling collections of characters.
Definition String.h:225
this file contains all the compiler specific defines
Definition mainpage.dox:28
const Bool False
Definition aipstype.h:44
unsigned int uInt
Definition aipstype.h:51
bool Bool
Define the standard types used by Casacore.
Definition aipstype.h:42
const Bool True
Definition aipstype.h:43