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// SPDX-License-Identifier: 0BSD
///////////////////////////////////////////////////////////////////////////////
//
/// \file 04_compress_easy_mt.c
/// \brief Compress in multi-call mode using LZMA2 in multi-threaded mode
///
/// Usage: ./04_compress_easy_mt < INFILE > OUTFILE
///
/// Example: ./04_compress_easy_mt < foo > foo.xz
//
// Author: Lasse Collin
//
///////////////////////////////////////////////////////////////////////////////
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <lzma.h>
static bool
init_encoder(lzma_stream *strm)
{
// The threaded encoder takes the options as pointer to
// a lzma_mt structure.
lzma_mt mt = {
// No flags are needed.
.flags = 0,
// Let liblzma determine a sane block size.
.block_size = 0,
// Use no timeout for lzma_code() calls by setting timeout
// to zero. That is, sometimes lzma_code() might block for
// a long time (from several seconds to even minutes).
// If this is not OK, for example due to progress indicator
// needing updates, specify a timeout in milliseconds here.
// See the documentation of lzma_mt in lzma/container.h for
// information how to choose a reasonable timeout.
.timeout = 0,
// Use the default preset (6) for LZMA2.
// To use a preset, filters must be set to NULL.
.preset = LZMA_PRESET_DEFAULT,
.filters = NULL,
// Use CRC64 for integrity checking. See also
// 01_compress_easy.c about choosing the integrity check.
.check = LZMA_CHECK_CRC64,
};
// Detect how many threads the CPU supports.
mt.threads = lzma_cputhreads();
// If the number of CPU cores/threads cannot be detected,
// use one thread. Note that this isn't the same as the normal
// single-threaded mode as this will still split the data into
// blocks and use more RAM than the normal single-threaded mode.
// You may want to consider using lzma_easy_encoder() or
// lzma_stream_encoder() instead of lzma_stream_encoder_mt() if
// lzma_cputhreads() returns 0 or 1.
if (mt.threads == 0)
mt.threads = 1;
// If the number of CPU cores/threads exceeds threads_max,
// limit the number of threads to keep memory usage lower.
// The number 8 is arbitrarily chosen and may be too low or
// high depending on the compression preset and the computer
// being used.
//
// FIXME: A better way could be to check the amount of RAM
// (or available RAM) and use lzma_stream_encoder_mt_memusage()
// to determine if the number of threads should be reduced.
const uint32_t threads_max = 8;
if (mt.threads > threads_max)
mt.threads = threads_max;
// Initialize the threaded encoder.
lzma_ret ret = lzma_stream_encoder_mt(strm, &mt);
if (ret == LZMA_OK)
return true;
const char *msg;
switch (ret) {
case LZMA_MEM_ERROR:
msg = "Memory allocation failed";
break;
case LZMA_OPTIONS_ERROR:
// We are no longer using a plain preset so this error
// message has been edited accordingly compared to
// 01_compress_easy.c.
msg = "Specified filter chain is not supported";
break;
case LZMA_UNSUPPORTED_CHECK:
msg = "Specified integrity check is not supported";
break;
default:
msg = "Unknown error, possibly a bug";
break;
}
fprintf(stderr, "Error initializing the encoder: %s (error code %u)\n",
msg, ret);
return false;
}
// This function is identical to the one in 01_compress_easy.c.
static bool
compress(lzma_stream *strm, FILE *infile, FILE *outfile)
{
lzma_action action = LZMA_RUN;
uint8_t inbuf[BUFSIZ];
uint8_t outbuf[BUFSIZ];
strm->next_in = NULL;
strm->avail_in = 0;
strm->next_out = outbuf;
strm->avail_out = sizeof(outbuf);
while (true) {
if (strm->avail_in == 0 && !feof(infile)) {
strm->next_in = inbuf;
strm->avail_in = fread(inbuf, 1, sizeof(inbuf),
infile);
if (ferror(infile)) {
fprintf(stderr, "Read error: %s\n",
strerror(errno));
return false;
}
if (feof(infile))
action = LZMA_FINISH;
}
lzma_ret ret = lzma_code(strm, action);
if (strm->avail_out == 0 || ret == LZMA_STREAM_END) {
size_t write_size = sizeof(outbuf) - strm->avail_out;
if (fwrite(outbuf, 1, write_size, outfile)
!= write_size) {
fprintf(stderr, "Write error: %s\n",
strerror(errno));
return false;
}
strm->next_out = outbuf;
strm->avail_out = sizeof(outbuf);
}
if (ret != LZMA_OK) {
if (ret == LZMA_STREAM_END)
return true;
const char *msg;
switch (ret) {
case LZMA_MEM_ERROR:
msg = "Memory allocation failed";
break;
case LZMA_DATA_ERROR:
msg = "File size limits exceeded";
break;
default:
msg = "Unknown error, possibly a bug";
break;
}
fprintf(stderr, "Encoder error: %s (error code %u)\n",
msg, ret);
return false;
}
}
}
extern int
main(void)
{
lzma_stream strm = LZMA_STREAM_INIT;
bool success = init_encoder(&strm);
if (success)
success = compress(&strm, stdin, stdout);
lzma_end(&strm);
if (fclose(stdout)) {
fprintf(stderr, "Write error: %s\n", strerror(errno));
success = false;
}
return success ? EXIT_SUCCESS : EXIT_FAILURE;
}
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