casacore
LatticeCache.h
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1 //# LatticeCache: Cache for accessing a Lattice in Tiles
2 //# Copyright (C) 1995,1996,1997,1999,2000,2001
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 LATTICES_LATTICECACHE_H
29 #define LATTICES_LATTICECACHE_H
30 
31 
32 //# Includes
33 #include <casacore/casa/aips.h>
34 #include <casacore/casa/Arrays/Array.h>
35 #include <casacore/casa/Arrays/Vector.h>
36 #include <casacore/casa/Containers/Block.h>
37 
38 //# Forward Declarations
39 #include <casacore/casa/iosfwd.h>
40 namespace casacore { //# NAMESPACE CASACORE - BEGIN
41 
42 template <class T> class Block;
43 template <class T> class Lattice;
44 
45 // <summary> a class for caching image access via tiles</summary>
46 //
47 // <use visibility=export>
48 //
49 // <reviewed reviewer="" date="" tests="" demos="">
50 // </reviewed>
51 //
52 // <prerequisite>
53 // <li> <linkto class=Lattice>Lattice</linkto>
54 // </prerequisite>
55 //
56 // <etymology>
57 // This class divides an image into Tiles that are stored in
58 // a Cache.
59 // </etymology>
60 //
61 // <synopsis>
62 // An image is divided into tiles of a specified shape. Access to the
63 // image pixels is via these tiles. A cache of active tiles is kept
64 // in memory up to a specified limit in memory allocation. Tiles
65 // are flushed to disk using a Least-Recently-Used Criterion.
66 //
67 // The tile size specified is the maximum dimension. Near the edge,
68 // smaller tiles are returned if necessary.
69 //
70 // The offset needed to get back to true pixels is also available.
71 //
72 // The cache hit rate for a sufficient number of random accesses
73 // goes as the ratio of cache size to image size.
74 //
75 // Tiles may be overlapped. If there is any overlap then the
76 // caller is responsible for dealing with the overlap. Normally
77 // one will only want overlapping windows for additive operations
78 // in which case the additive flag to the constructor should be
79 // used.
80 // </synopsis>
81 //
82 // <example>
83 // <srcblock>
84 // </srcblock>
85 //
86 // </example>
87 //
88 // <motivation>
89 // To aid in gridding
90 // </motivation>
91 //
92 // <todo asof="1997/02/27">
93 // </todo>
94 
95 template <class T> class LatticeCache
96 {
97 public:
98 
99  // Constructor: cachesize in units of T. tileOverlap is the fractional
100  // overlap between neighbouring tile.
103 
105 
107 
108  virtual ~LatticeCache();
109 
110  // Return the tile for a given location
111  // <group>
112  Array<T>& tile(IPosition& cacheLoc, const IPosition& tileLoc, Bool discard=True);
113  Array<T>& tile(const IPosition& tileLoc, Bool discard=True);
114  // </group>
115 
116  // const version is needed
117  const Array<T>& tile(const IPosition& tileLoc);
118 
119  // Return the IPosition for the start of this tile
120  IPosition& cacheLocation(IPosition& cacheLoc, const IPosition& tileLoc);
121 
122  // Show the statistics of cache access
123  virtual void showCacheStatistics(ostream& os);
124 
125  // Clear the statistics of cache access
126  virtual void clearCacheStatistics();
127 
128  // Flush contents
129  virtual void flush();
130 
131 protected:
132 
134 
140 
147 
148  Int getFreeTile(Bool readonly);
149 
153 
155  void readTile(Int tile, Bool readonly);
156 
158 };
159 
160 
161 } //# NAMESPACE CASACORE - END
162 
163 #ifndef CASACORE_NO_AUTO_TEMPLATES
164 #include <casacore/lattices/Lattices/LatticeCache.tcc>
165 #endif //# CASACORE_NO_AUTO_TEMPLATES
166 #endif
simple 1-D array
Definition: Block.h:200
Array< T > & tile(const IPosition &tileLoc, Bool discard=True)
Block< IPosition > tileLocs
Definition: LatticeCache.h:150
IPosition & cacheLocation(IPosition &cacheLoc, const IPosition &tileLoc)
Return the IPosition for the start of this tile.
void writeTile(Int tile)
Vector< Float > tileOverlap
Definition: LatticeCache.h:138
virtual void clearCacheStatistics()
Clear the statistics of cache access.
virtual void showCacheStatistics(ostream &os)
Show the statistics of cache access.
LatticeCache< T > & operator=(const LatticeCache< T > &other)
Lattice< T > * image_p
Definition: LatticeCache.h:157
LatticeCache(Lattice< T > &image, Int cacheSize, IPosition tileShape, Vector< Float > &tileOverlap, Bool additive)
Constructor: cachesize in units of T.
const Array< T > & tile(const IPosition &tileLoc)
const version is needed
Vector< Int > tileOffsetVec
Definition: LatticeCache.h:137
Block< Array< T > > tileContents
Definition: LatticeCache.h:152
Block< Int > tileSequence
Definition: LatticeCache.h:151
Vector< Int > tileShapeVec
Definition: LatticeCache.h:137
Int getFreeTile(Bool readonly)
void readTile(Int tile, Bool readonly)
LatticeCache(const LatticeCache< T > &other)
Array< T > & tile(IPosition &cacheLoc, const IPosition &tileLoc, Bool discard=True)
Return the tile for a given location.
virtual void flush()
Flush contents.
this file contains all the compiler specific defines
Definition: mainpage.dox:28
int Int
Definition: aipstype.h:50
bool Bool
Define the standard types used by Casacore.
Definition: aipstype.h:42
const Bool True
Definition: aipstype.h:43