Docs: Add example program for threaded encoding.
I didn't add -DLZMA_UNSTABLE to Makefile so one has to
specify it manually as long as LZMA_UNSTABLE is needed.
diff --git a/doc/examples/04_compress_easy_mt.c b/doc/examples/04_compress_easy_mt.c
new file mode 100644
index 0000000..121d3b1
--- /dev/null
+++ b/doc/examples/04_compress_easy_mt.c
@@ -0,0 +1,184 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#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,
+
+ // Set the number of threads to use.
+ // FIXME: Add how to autodetect a reasonable number.
+ .threads = 4,
+
+ // 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,
+ };
+
+ // 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;
+}
diff --git a/doc/examples/Makefile b/doc/examples/Makefile
index 644dc32..0f3d185 100644
--- a/doc/examples/Makefile
+++ b/doc/examples/Makefile
@@ -12,7 +12,8 @@
PROGS = \
01_compress_easy \
02_decompress \
- 03_compress_custom
+ 03_compress_custom \
+ 04_compress_easy_mt
all: $(PROGS)
