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Compression.h
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1// @(#)root/zip:$Id$
2// Author: David Dagenhart May 2011
3
4/*************************************************************************
5 * Copyright (C) 1995-2011, Rene Brun and Fons Rademakers. *
6 * All rights reserved. *
7 * *
8 * For the licensing terms see $ROOTSYS/LICENSE. *
9 * For the list of contributors see $ROOTSYS/README/CREDITS. *
10 *************************************************************************/
11
12#ifndef ROOT_Compression
13#define ROOT_Compression
14
15#include "RtypesCore.h"
16
17namespace ROOT {
18
19/// The global settings depend on a global variable named R__ZipMode which can be
20/// modified by a global function named R__SetZipMode. Both are defined in Bits.h.
21///
22/// - The default is to use the global setting and the default of the global
23/// setting is to use the ZLIB compression algorithm.
24/// - The LZMA algorithm (from the XZ package) is also available. The LZMA
25/// compression usually results in greater compression factors, but takes
26/// more CPU time and memory when compressing. LZMA memory usage is particularly
27/// high for compression levels 8 and 9.
28/// - Finally, the LZ4 package results in worse compression ratios
29/// than ZLIB but achieves much faster decompression rates.
30///
31/// The current algorithms support level 1 to 9. The higher the level the greater
32/// the compression and more CPU time and memory resources used during compression.
33/// Level 0 means no compression.
34///
35/// Recommendation for the compression algorithm's levels:
36/// - ZLIB is recommended to be used with compression level 1 [101]
37/// - LZMA is recommended to be used with compression level 7-8 (higher is better,
38/// since in the case of LZMA we don't care about compression/decompression speed)
39/// [207 - 208]
40/// - LZ4 is recommended to be used with compression level 4 [404]
41/// - ZSTD is recommended to be used with compression level 5 [505]
42
44 struct EDefaults { /// Note: this is only temporarily a struct and will become a enum class hence the name convention
45 /// used.
46 enum EValues {
47 /// Use the global compression setting for this process; may be affected by rootrc.
49 /// Use the compile-time default setting
51 /// Use the default analysis setting; fast reading but poor compression ratio
53 /// Use the new recommended general-purpose setting; it is a best trade-off between compression ratio/decompression speed
55 /// Use the setting that results in the smallest files; very slow read and write
57 };
58 };
59 struct ELevel { /// Note: this is only temporarily a struct and will become a enum class hence the name convention
60 /// used.
61 enum EValues {
62 /// Some objects use this value to denote that the compression algorithm
63 /// should be inherited from the parent object
65 /// Compression level reserved for "uncompressed state"
67 /// Compression level reserved when we are not sure what to use (1 is for the fastest compression)
69 /// Compression level reserved for ZLIB compression algorithm (fastest compression)
71 /// Compression level reserved for LZ4 compression algorithm (trade-off between file ratio/decompression speed)
73 /// Compression level reserved for ZSYD compression algorithm (trade-off between file ratio/decompression speed)
75 /// Compression level reserved for old ROOT compression algorithm
77 /// Compression level reserved for LZMA compression algorithm (slowest compression with smallest files)
78 kDefaultLZMA = 7
79 };
80 };
81 struct EAlgorithm { /// Note: this is only temporarily a struct and will become a enum class hence the name
82 /// convention used.
83 enum EValues {
84 /// Some objects use this value to denote that the compression algorithm
85 /// should be inherited from the parent object (e.g., TBranch should get the algorithm from the TTree)
87 /// Use the global compression algorithm
89 /// Use ZLIB compression
91 /// Use LZMA compression
93 /// Use the old compression algorithm
95 /// Use LZ4 compression
97 /// Use ZSTD compression
99 /// Undefined compression algorithm (must be kept the last of the list in case a new algorithm is added).
101 };
102 };
103};
104
106 /// Deprecated name, do *not* use:
108 /// Deprecated name, do *not* use:
110 /// Deprecated name, do *not* use:
112 /// Deprecated name, do *not* use:
114 /// Deprecated name, do *not* use:
116 /// Deprecated name, do *not* use:
118 /// Deprecated name, do *not* use:
120 /// Deprecated name, do *not* use:
123
124int CompressionSettings(RCompressionSetting::EAlgorithm algorithm, int compressionLevel);
125/// Deprecated name, do *not* use:
126int CompressionSettings(ROOT::ECompressionAlgorithm algorithm, int compressionLevel);
127} // namespace ROOT
128
129#endif
tbb::task_arena is an alias of tbb::interface7::task_arena, which doesn't allow to forward declare tb...
ECompressionAlgorithm
Definition: Compression.h:105
@ kZSTD
Deprecated name, do not use:
Definition: Compression.h:119
@ kLZMA
Deprecated name, do not use:
Definition: Compression.h:113
@ kZLIB
Deprecated name, do not use:
Definition: Compression.h:111
@ kOldCompressionAlgo
Deprecated name, do not use:
Definition: Compression.h:115
@ kUseGlobalCompressionSetting
Deprecated name, do not use:
Definition: Compression.h:107
@ kUseGlobalSetting
Deprecated name, do not use:
Definition: Compression.h:109
@ kLZ4
Deprecated name, do not use:
Definition: Compression.h:117
@ kUndefinedCompressionAlgorithm
Deprecated name, do not use:
Definition: Compression.h:121
int CompressionSettings(RCompressionSetting::EAlgorithm algorithm, int compressionLevel)
EValues
Note: this is only temporarily a struct and will become a enum class hence the name.
Definition: Compression.h:83
@ kUseGlobal
Use the global compression algorithm.
Definition: Compression.h:88
@ kOldCompressionAlgo
Use the old compression algorithm.
Definition: Compression.h:94
@ kZSTD
Use ZSTD compression.
Definition: Compression.h:98
@ kUndefined
Undefined compression algorithm (must be kept the last of the list in case a new algorithm is added).
Definition: Compression.h:100
@ kInherit
Some objects use this value to denote that the compression algorithm should be inherited from the par...
Definition: Compression.h:86
@ kZLIB
Use ZLIB compression.
Definition: Compression.h:90
@ kLZMA
Use LZMA compression.
Definition: Compression.h:92
EValues
Note: this is only temporarily a struct and will become a enum class hence the name convention used.
Definition: Compression.h:46
@ kUseAnalysis
Use the default analysis setting; fast reading but poor compression ratio.
Definition: Compression.h:52
@ kUseGlobal
Use the global compression setting for this process; may be affected by rootrc.
Definition: Compression.h:48
@ kUseCompiledDefault
Use the compile-time default setting.
Definition: Compression.h:50
@ kUseSmallest
Use the setting that results in the smallest files; very slow read and write.
Definition: Compression.h:56
@ kUseGeneralPurpose
Use the new recommended general-purpose setting; it is a best trade-off between compression ratio/dec...
Definition: Compression.h:54
EValues
Note: this is only temporarily a struct and will become a enum class hence the name convention used.
Definition: Compression.h:61
@ kInherit
Some objects use this value to denote that the compression algorithm should be inherited from the par...
Definition: Compression.h:64
@ kUseMin
Compression level reserved when we are not sure what to use (1 is for the fastest compression)
Definition: Compression.h:68
@ kDefaultOld
Compression level reserved for old ROOT compression algorithm.
Definition: Compression.h:76
@ kUncompressed
Compression level reserved for "uncompressed state".
Definition: Compression.h:66
@ kDefaultLZMA
Compression level reserved for LZMA compression algorithm (slowest compression with smallest files)
Definition: Compression.h:78
@ kDefaultZSTD
Compression level reserved for ZSYD compression algorithm (trade-off between file ratio/decompression...
Definition: Compression.h:74
@ kDefaultZLIB
Compression level reserved for ZLIB compression algorithm (fastest compression)
Definition: Compression.h:70
@ kDefaultLZ4
Compression level reserved for LZ4 compression algorithm (trade-off between file ratio/decompression ...
Definition: Compression.h:72
The global settings depend on a global variable named R__ZipMode which can be modified by a global fu...
Definition: Compression.h:43