xz: Add initial support for threaded decompression.

If threading support is enabled at build time, this will
use lzma_stream_decoder_mt() even for single-threaded mode.
With memlimit_threading=0 the behavior should be identical.

This needs some work like adding --memlimit-threading=LIMIT.

The original patch from Sebastian Andrzej Siewior included
a method to get currently available RAM on Linux. It might
be one way to go but as it is Linux-only, the available-RAM
approach needs work for portability or using a fallback method
on other OSes.

The man page wasn't updated yet.
This commit is contained in:
Lasse Collin 2022-03-07 00:36:16 +02:00
parent 4cce3e27f5
commit 6c6da57ae2
1 changed files with 35 additions and 1 deletions

View File

@ -51,7 +51,7 @@ static lzma_check check;
/// This becomes false if the --check=CHECK option is used.
static bool check_default = true;
#if defined(HAVE_ENCODERS) && defined(MYTHREAD_ENABLED)
#ifdef MYTHREAD_ENABLED
static lzma_mt mt_options = {
.flags = 0,
.timeout = 300,
@ -520,9 +520,43 @@ coder_init(file_pair *pair)
break;
case FORMAT_XZ:
# ifdef MYTHREAD_ENABLED
mt_options.flags = flags;
mt_options.threads = hardware_threads_get();
// TODO: Support --memlimit-threading=LIMIT.
mt_options.memlimit_stop
= hardware_memlimit_get(MODE_DECOMPRESS);
mt_options.memlimit_threading
= mt_options.memlimit_stop;
if (mt_options.threads == 1) {
// Single-threaded mode was requested. Force
// the decoder to use minimal memory, matching
// the behavior of lzma_stream_decoder().
mt_options.memlimit_threading = 0;
} else if (mt_options.memlimit_threading
== UINT64_MAX) {
// TODO: Support --memlimit-threading=LIMIT.
//
// If lzma_physmem() fails, it returns 0 and
// we end up with a single thread.
//
// NOTE: It is assential that we never end up
// with an effectively infinite value in
// memlimit_threading!
mt_options.memlimit_threading
= lzma_physmem() / 4;
}
ret = lzma_stream_decoder_mt(&strm, &mt_options);
# else
ret = lzma_stream_decoder(&strm,
hardware_memlimit_get(
MODE_DECOMPRESS), flags);
# endif
break;
case FORMAT_LZMA: