lib/zstd
1
0
Fork 0
mirror of https://github.com/facebook/zstd.git synced 2025-07-29 11:21:22 +03:00
Code Activity

[examples] Update streaming_compression to the new API

Browse Source
This commit is contained in:
Nick Terrell
2019-03-22 14:57:23 -07:00
committed by Nick Terrell
parent 0c7668cd06
commit f5cbee988b
2 changed files with 81 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

81
examples/streaming_compression.c
View File

@ -12,51 +12,76 @@
#include <stdlib.h> // malloc, free, exit
#include <stdio.h> // fprintf, perror, feof, fopen, etc.
#include <string.h> // strlen, memset, strcat
#define ZSTD_STATIC_LINKING_ONLY // TODO: Remove once the API is stable
#include <zstd.h> // presumes zstd library is installed
#include "utils.h"
static void compressFile_orDie(const char* fname, const char* outName, int cLevel)
{
/* Open the input and output files. */
FILE* const fin = fopen_orDie(fname, "rb");
FILE* const fout = fopen_orDie(outName, "wb");
size_t const buffInSize = ZSTD_CStreamInSize(); /* can always read one full block */
/* Create the input and output buffers.
* They may be any size, but we recommend using these functions to size them.
* Performance will only suffer significantly for very tiny buffers.
*/
size_t const buffInSize = ZSTD_CStreamInSize();
void* const buffIn = malloc_orDie(buffInSize);
size_t const buffOutSize = ZSTD_CStreamOutSize(); /* can always flush a full block */
size_t const buffOutSize = ZSTD_CStreamOutSize();
void* const buffOut = malloc_orDie(buffOutSize);
ZSTD_CStream* const cstream = ZSTD_createCStream();
if (cstream==NULL) { fprintf(stderr, "ZSTD_createCStream() error \n"); exit(10); }
size_t const initResult = ZSTD_initCStream(cstream, cLevel);
if (ZSTD_isError(initResult)) {
fprintf(stderr, "ZSTD_initCStream() error : %s \n",
ZSTD_getErrorName(initResult));
exit(11);
}
/* Create the context. */
ZSTD_CCtx* const cctx = ZSTD_createCCtx();
CHECK(cctx != NULL, "ZSTD_createCCtx() failed!");
size_t read, toRead = buffInSize;
while( (read = fread_orDie(buffIn, toRead, fin)) ) {
/* Set any parameters you want.
* Here we set the compression level, and enable the checksum.
*/
CHECK_ZSTD( ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, cLevel) );
CHECK_ZSTD( ZSTD_CCtx_setParameter(cctx, ZSTD_c_checksumFlag, 1) );
/* This loop read from the input file, compresses that entire chunk,
* and writes all output produced to the output file.
*/
size_t const toRead = buffInSize;
size_t read;
while ((read = fread_orDie(buffIn, toRead, fin))) {
/* Select the flush mode.
* If the read may not be finished (read == toRead) we use
* ZSTD_e_continue. If this is the last chunk, we use ZSTD_e_end.
* Zstd optimizes the case where the first flush mode is ZSTD_e_end,
* since it knows it is compressing the entire source in one pass.
*/
int const lastChunk = (read < toRead);
ZSTD_EndDirective const mode = lastChunk ? ZSTD_e_end : ZSTD_e_continue;
/* Set the input buffer to what we just read.
* We compress until the input buffer is empty, each time flushing the
* output.
*/
ZSTD_inBuffer input = { buffIn, read, 0 };
while (input.pos < input.size) {
int finished;
do {
/* Compress into the output buffer and write all of the output to
* the file so we can reuse the buffer next iteration.
*/
ZSTD_outBuffer output = { buffOut, buffOutSize, 0 };
toRead = ZSTD_compressStream(cstream, &output , &input); /* toRead is guaranteed to be <= ZSTD_CStreamInSize() */
if (ZSTD_isError(toRead)) {
fprintf(stderr, "ZSTD_compressStream() error : %s \n",
ZSTD_getErrorName(toRead));
exit(12);
}
if (toRead > buffInSize) toRead = buffInSize; /* Safely handle case when `buffInSize` is manually changed to a value < ZSTD_CStreamInSize()*/
size_t const remaining = ZSTD_compressStream2(cctx, &output , &input, mode);
CHECK_ZSTD(remaining);
fwrite_orDie(buffOut, output.pos, fout);
}
/* If we're on the last chunk we're finished when zstd returns 0,
* which means its consumed all the input AND finished the frame.
* Otherwise, we're finished when we've consumed all the input.
*/
finished = lastChunk ? (remaining == 0) : (input.pos == input.size);
} while (!finished);
assert(input.pos == input.size);
}
ZSTD_outBuffer output = { buffOut, buffOutSize, 0 };
size_t const remainingToFlush = ZSTD_endStream(cstream, &output); /* close frame */
if (remainingToFlush) { fprintf(stderr, "not fully flushed"); exit(13); }
fwrite_orDie(buffOut, output.pos, fout);
ZSTD_freeCStream(cstream);
ZSTD_freeCCtx(cctx);
fclose_orDie(fout);
fclose_orDie(fin); free(buffIn);
fclose_orDie(fin);
free(buffIn);
free(buffOut);
}