path: root/src/tools/rcc/rcc.h
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authorThiago Macieira <>2018-10-31 17:06:21 -0700
committerThiago Macieira <>2018-12-11 03:57:37 +0000
commit2c9ac4fc3fe0b8f39e7f7a93894b56e49fd3d887 (patch)
tree312f6f3dc88adaac3b1c986638f7b0ccc93c3dc3 /src/tools/rcc/rcc.h
parentf25bc30d8d9d13fffd34213dfbf5e7373a18222a (diff)
RCC: Add support for Zstandard compression
[ChangeLog][RCC] RCC now supports compressing content using the Zstandard ( algorithm. Compared to zlib, it compresses better for the same CPU time, so this algorithm is the default. To go back to the previous algorithm, pass command-line option --compress-algo=zlib. Compression levels range from 1 (fastest, least compression) to 19 (slowest, best compression). Level 0 tells the library to choose an implementation-defined default. \ The default compression level is "heuristic" (level -1): under this mode, RCC will attempt a very fast compression (level 1) and check if the file was sufficiently compressed. If it was, then RCC will compress again using an implementation-defined level. The following are the 4 biggest files we store as resources in qtbase: Orig Size Name 2197605 src/corelib/mimetypes/mime/packages/ 2462423 tests/auto/corelib/tools/qchar/data/NormalizationTest.txt 6878748 tests/auto/other/qcomplextext/data/BidiCharacterTest.txt 7959972 tests/auto/other/qcomplextext/data/BidiTest.txt The current RCC (zlib, level -1 "default" and level 9), produces for those files: L(-1) Compr. L9 Compr. Decomp. Name Ratio CPU time Ratio CPU time CPU time BidiCharacterTest.txt 16.9:1 106.1ms 17.2:1 789.3ms 5.1ms BidiTest.txt 6.3:1 228.0ms 6.1:1 1646.3ms 10.9ms 7.0:1 17.5ms 7.1:1 53.6ms 2.6ms NormalizationTest.txt 5.8:1 41.2ms 5.9:1 256.4ms 3.4ms Zstandard produces the following for levels 1 ("check"), 14 ("store") and 19 ("best"): L1 Compr. L14 Compr. L19 Compr. Decomp Name Ratio time Ratio time Ratio CPU time time BidiCharacterTest.txt 15.8:1 8.0ms 26.1:1 168.9ms 49.2:1 2504.7ms 3.8ms BidiTest.txt 8.2:1 17.0ms 8.7:1 323.9ms 14.9:1 1700.9ms 12.1ms 6.7:1 4.0ms 8.7:1 63.3ms 9.5:1 642.5ms 1.7ms NormalizationTest.txt 5.7:1 5.0ms 7.5:1 54.0ms 8.4:1 447.3ms 3.0ms This shows use of zstd at the default RCC level settings always produce smaller outputs compared to the current zlib-based defaults, with roughly 50% CPU increase. It also produces better results at less CPU time than the best compression zlib has to offer. More importantly, the decompression time reduces in all cases (the numbers listed are for max compression, with slightly better results for the defaults). For the sake of comparison, the same files compressed with libxz at levels 3 and 6: Level 3 Level 6 Decompr. Name Ratio CPU Ratio CPU time BidiCharacterTest.txt 28.5:1 109.1ms 42.9:1 1390.5ms 16.7ms BidiTest.txt 10.7:1 281.0ms 18.4:1 2333.1ms 43.6ms 9.1:1 62.0ms 10.2:1 499.1ms 12.0ms NormalizationTest.txt 10.2:1 75.5ms 13.2:1 417.6ms 14.7ms LZMA at level 3 consumes roughly the same CPU time as Zstd at level 14 and produces incrementally smaller results, but the decompression time increases considerably. It's not a good trade-off for the Qt resource system. Change-Id: I343f2beed55440a7ac0bfffd1562d754bd71d964 Reviewed-by: Lars Knoll <> Reviewed-by: Oswald Buddenhagen <>
Diffstat (limited to 'src/tools/rcc/rcc.h')
1 files changed, 7 insertions, 0 deletions
diff --git a/src/tools/rcc/rcc.h b/src/tools/rcc/rcc.h
index 5c6823e56f..fe8ed21fb3 100644
--- a/src/tools/rcc/rcc.h
+++ b/src/tools/rcc/rcc.h
@@ -36,6 +36,8 @@
#include <qhash.h>
#include <qstring.h>
+typedef struct ZSTD_CCtx_s ZSTD_CCtx;
class RCCFileInfo;
@@ -80,6 +82,7 @@ public:
enum class CompressionAlgorithm {
+ Zstd,
None = -1
@@ -138,6 +141,10 @@ private:
void writeByteArray(const QByteArray &);
void write(const char *, int len);
+#if QT_CONFIG(zstd)
+ ZSTD_CCtx *m_zstdCCtx;
const Strings m_strings;
RCCFileInfo *m_root;
QStringList m_fileNames;