note that the size of individual compressed blocks will vary more wildly with this modification.
But it seems good enough for a first test, and fix the speed regression issue.
Further refinements can be attempted later.
using real latin sentences from Cicero.
Compression ratio lower again, closer to "real" text,
now level 6 is way better than level 4.
level 5 is still lower than level 4,
but at least it's now higher than level 3.
makes compression a bit less good,
hence a bit more comparable with real text (though still too easy to compress).
level 6 is now stronger than level 4, by a hair.
However, there is still a ratio dip at level 5.
this generator replaces the statistical generator
for the general case when no statistic is requested.
Generated data features a compression level speed / ratio curve
which is more in line with expectation.
To the best of my knowledge:
* `_WIN32` and `_WIN64` are defined by the compiler,
* `WIN32` and `WIN64` are defined by the user, to indicate whatever
the user chooses them to indicate. They mean 32-bit and 64-bit Windows
compilation by convention only.
See:
https://accu.org/journals/overload/24/132/wilson_2223/
Windows compilers in general, and MSVC in particular, have been defining
`_WIN32` and `_WIN64` for a long time, provably at least since Visual Studio
2015, and in practice as early as in the days of 16-bit Windows.
See:
https://learn.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=msvc-140https://learn.microsoft.com/en-us/windows/win32/winprog64/the-tools
Tests used to be inconsistent, sometimes testing `_WIN32`, sometimes
`_WIN32` and `WIN32`. This brings consistency to Windows detection.
They are Linux-like environments under Windows and have all the tools needed to support staged installation and testing.
Beware: this only affects the make build system.
For some reasons when LTO is enabled, the compiler complains about statbuf variable not being correctly initialized, even though the variable has an assert != NULL just few lines below (FIO_getDictFileStat)
This is the fixed build failure:
x86_64-linux-gnu-gcc -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=. -flto=auto -ffat-lto-objects -fstack-protector-strong -Wformat -Werror=format-security -fdebug-prefix-map=/<<PKGBUILDDIR>>=/usr/src/libzstd-1.5.5+dfsg2-1 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat -g -Werror -Wa,--noexecstack -Wdate-time -D_FORTIFY_SOURCE=2 -DXXH_NAMESPACE=ZSTD_ -DDEBUGLEVEL=1 -DZSTD_LEGACY_SUPPORT=5 -DZSTD_MULTITHREAD -DZSTD_GZCOMPRESS -DZSTD_GZDECOMPRESS -DZSTD_LZMACOMPRESS -DZSTD_LZMADECOMPRESS -DZSTD_LZ4COMPRESS -DZSTD_LZ4DECOMPRESS -DZSTD_LEGACY_SUPPORT=5 -c -MT obj/conf_086c46a51a716b674719b8acb8484eb8/zstdcli_trace.o -MMD -MP -MF obj/conf_086c46a51a716b674719b8acb8484eb8/zstdcli_trace.d -o obj/conf_086c46a51a716b674719b8acb8484eb8/zstdcli_trace.o zstdcli_trace.c
In function ‘UTIL_isRegularFileStat’,
inlined from ‘UTIL_getFileSizeStat’ at util.c:524:10,
inlined from ‘FIO_createDResources’ at fileio.c:2230:30:
util.c:209:12: error: ‘statbuf.st_mode’ may be used uninitialized [-Werror=maybe-uninitialized]
209 | return S_ISREG(statbuf->st_mode) != 0;
| ^
fileio.c: In function ‘FIO_createDResources’:
fileio.c:2223:12: note: ‘statbuf’ declared here
2223 | stat_t statbuf;
| ^
lto1: all warnings being treated as errors
decompression features automatic support of sparse files,
aka a form of "compression" where entire blocks consists only of zeroes.
This only works for some compatible file systems (like ext4),
others simply ignore it (like afs).
Triggering this feature relies of `fseek()`.
But `fseek()` is not compatible with non-seekable devices, such as pipes.
Therefore it's disabled for pipes.
However, there are other objects which are not compatible with `fseek()`, such as block devices.
Changed the logic, so that `fseek()` (and therefore sparse write) is only automatically enabled on regular files.
Note that this automatic behavior can always be overridden by explicit commands `--sparse` and `--no-sparse`.
fix#3583
Bytef and uInt are zlib types, not available when zlib is disabled
Fixes: 1598e6c634 ("Async write for decompression")
Fixes: cc0657f27d ("AsyncIO compression part 2 - added async read and asyncio to compression code (#3022)")
