Struct xz2::stream::MtStreamBuilder
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[src]
pub struct MtStreamBuilder { /* fields omitted */ }Builder to create a multi-threaded stream encoder.
Methods
impl MtStreamBuilder[src]
fn new() -> MtStreamBuilder
Creates a new blank builder to create a multithreaded encoding Stream.
fn threads(&mut self, threads: u32) -> &mut Self
Configures the number of worker threads to use
fn block_size(&mut self, block_size: u64) -> &mut Self
Configures the maximum uncompressed size of a block
The encoder will start a new .xz block every block_size bytes.
Using FullFlush or FullBarrier with process the caller may tell
liblzma to start a new block earlier.
With LZMA2, a recommended block size is 2-4 times the LZMA2 dictionary size. With very small dictionaries, it is recommended to use at least 1 MiB block size for good compression ratio, even if this is more than four times the dictionary size. Note that these are only recommendations for typical use cases; feel free to use other values. Just keep in mind that using a block size less than the LZMA2 dictionary size is waste of RAM.
Set this to 0 to let liblzma choose the block size depending on the
compression options. For LZMA2 it will be 3*dict_size or 1 MiB,
whichever is more.
For each thread, about 3 * block_size bytes of memory will be
allocated. This may change in later liblzma versions. If so, the memory
usage will probably be reduced, not increased.
fn timeout_ms(&mut self, timeout: u32) -> &mut Self
Timeout to allow process to return early
Multithreading can make liblzma to consume input and produce output in a very bursty way: it may first read a lot of input to fill internal buffers, then no input or output occurs for a while.
In single-threaded mode, process won't return until it has either
consumed all the input or filled the output buffer. If this is done in
multithreaded mode, it may cause a call process to take even tens of
seconds, which isn't acceptable in all applications.
To avoid very long blocking times in process, a timeout (in
milliseconds) may be set here. If process would block longer than this number of milliseconds, it will return withOk`. Reasonable
values are 100 ms or more. The xz command line tool uses 300 ms.
If long blocking times are fine for you, set timeout to a special
value of 0, which will disable the timeout mechanism and will make
process block until all the input is consumed or the output
buffer has been filled.
fn preset(&mut self, preset: u32) -> &mut Self
Compression preset (level and possible flags)
The preset is set just like with Stream::new_easy_encoder. The preset
is ignored if filters below have been specified.
fn filters(&mut self, filters: Filters) -> &mut Self
Configure a custom filter chain
fn check(&mut self, check: Check) -> &mut Self
Configures the integrity check type
fn memusage(&self) -> u64
Calculate approximate memory usage of multithreaded .xz encoder
fn encoder(&self) -> Result<Stream, Error>
Initialize multithreaded .xz stream encoder.