When --flush-timeout=TIMEOUT is used, xz will use
LZMA_SYNC_FLUSH if read() would block and at least
TIMEOUT milliseconds has elapsed since the previous flush.
This can be useful in realtime-like use cases where the
data is simultanously decompressed by another process
(possibly on a different computer). If new uncompressed
input data is produced slowly, without this option xz could
buffer the data for a long time until it would become
decompressible from the output.
If TIMEOUT is 0, the feature is disabled. This is the default.
This commit affects the compression side. Using xz for
the decompression side for the above purpose doesn't work
yet so well because there is quite a bit of input and
output buffering when decompressing.
The --long-help or man page were not updated yet.
The details of this feature may change.
Testing for end of file was no longer correct after full flushing
became possible with --block-size=SIZE and --block-list=SIZES.
There was no bug in practice though because xz just made a few
unneeded zero-byte reads.
This switches units from microseconds to milliseconds.
New clock_gettime(CLOCK_MONOTONIC) will be used if available.
There is still a fallback to gettimeofday().
There was somewhat illogical behavior when --extreme was
specified and mixed with custom filter chains.
Before this commit, "xz -9 --lzma2 -e" was equivalent
to "xz --lzma2". After it is equivalent to "xz -6e"
(all earlier preset options get forgotten when a custom
filter chain is specified and the default preset is 6
to which -e is applied). I find this less illogical.
This also affects the meaning of "xz -9e --lzma2 -7".
Earlier it was equivalent to "xz -7e" (the -e specified
before a custom filter chain wasn't forgotten). Now it
is "xz -7". Note that "xz -7e" still is the same as "xz -e7".
Hopefully very few cared about this in the first place,
so pretty much no one should even notice this change.
Thanks to Conley Moorhous.
Now the following works as you would expect:
echo foo | xz > foo.xz
echo bar | xz >> foo.xz
( xz -dc --single-stream ; xz -dc --single-stream ) < foo.xz
Note that it doesn't work if the input is not seekable
or if there is Stream Padding between the concatenated
.xz Streams.
For several people, the limiter causes bigger problems that
it solves, so it is better to have it disabled by default.
Those who want to have a limiter by default need to enable
it via the environment variable XZ_DEFAULTS.
Support for environment variable XZ_DEFAULTS was added. It is
parsed before XZ_OPT and technically identical with it. The
intended uses differ quite a bit though; see the man page.
The memory usage limit can now be set separately for
compression and decompression using --memlimit-compress and
--memlimit-decompress. To set both at once, -M or --memlimit
can be used. --memory was retained as a legacy alias for
--memlimit for backwards compatibility.
The semantics of --info-memory were changed in backwards
incompatible way. Compatibility wasn't meaningful due to
changes in the memory usage limiter functionality.
The memory usage limiter info is no longer shown at the
bottom of xz --long -help.
The memory usage limiter support for removed completely from xzdec.
xz's man page was updated to match the above changes. Various
unrelated fixes were also made to the man page.
message_filters_to_str() converts the filter chain to
a string. message_filters_show() replaces the original
message_filters().
uint32_to_optstr() was also added to show the dictionary
size in nicer format when possible.
The opening of the destination file is now delayed a little.
The coder is initialized, and if decompressing, the memory
usage of the first Block compared against the memory
usage limit before the destination file is opened. This
means that if --force was used, the old "target" file won't
be deleted so easily when something goes wrong very early.
Thanks to Mark K for the bug report.
The above fix required some changes to progress message
handling. Now there is a separate function for setting and
printing the filename. It is used also in list.c.
list_file() now handles stdin correctly (gives an error).
A useless check for user_abort was removed from file_io.c.
a regular file.
Sparse file creation can be disabled with --no-sparse.
I don't promise yet that the name of this option won't
change before 5.0.0. It's possible that the code, that
checks when it is safe to use sparse output on stdout,
is not good enough, and a more flexible command line
option is needed to configure sparse file handling.
files as is to standard output.
This feature is needed to be more compatible with gzip's
behavior. This was more complicated to implement than it
sounds, because the way liblzma is able to return errors with
files of only a few bytes in size. xz now has its own file
type detection code and no longer uses lzma_auto_decoder().
