rocksdb/util/compression.cc
Siddhartha Roychowdhury fec4403ff1 Integrate WAL compression into log reader/writer. (#9642)
Summary:
Integrate the streaming compress/uncompress API into WAL compression.
The streaming compression object is stored in the log_writer along with a reusable output buffer to store the compressed buffer(s).
The streaming uncompress object is stored in the log_reader along with a reusable output buffer to store the uncompressed buffer(s).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9642

Test Plan:
Added unit tests to verify different scenarios - large buffers, split compressed buffers, etc.

Future optimizations:
The overhead for small records is quite high, so it makes sense to compress only buffers above a certain threshold and use a separate record type to indicate that those records are compressed.

Reviewed By: anand1976

Differential Revision: D34709167

Pulled By: sidroyc

fbshipit-source-id: a37a3cd1301adff6152fb3fcd23726106af07dd4
2022-03-09 15:49:53 -08:00

123 lines
3.7 KiB
C++

// Copyright (c) 2022-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "util/compression.h"
namespace ROCKSDB_NAMESPACE {
StreamingCompress* StreamingCompress::Create(CompressionType compression_type,
const CompressionOptions& opts,
uint32_t compress_format_version,
size_t max_output_len) {
switch (compression_type) {
case kZSTD: {
if (!ZSTD_Streaming_Supported()) {
return nullptr;
}
return new ZSTDStreamingCompress(opts, compress_format_version,
max_output_len);
}
default:
return nullptr;
}
}
StreamingUncompress* StreamingUncompress::Create(
CompressionType compression_type, uint32_t compress_format_version,
size_t max_output_len) {
switch (compression_type) {
case kZSTD: {
if (!ZSTD_Streaming_Supported()) {
return nullptr;
}
return new ZSTDStreamingUncompress(compress_format_version,
max_output_len);
}
default:
return nullptr;
}
}
int ZSTDStreamingCompress::Compress(const char* input, size_t input_size,
char* output, size_t* output_pos) {
assert(input != nullptr && output != nullptr && output_pos != nullptr);
*output_pos = 0;
// Don't need to compress an empty input
if (input_size == 0) {
return 0;
}
#ifndef ZSTD_STREAMING
(void)input;
(void)input_size;
(void)output;
return -1;
#else
if (input_buffer_.src == nullptr || input_buffer_.src != input) {
// New input
// Catch errors where the previous input was not fully decompressed.
assert(input_buffer_.pos == input_buffer_.size);
input_buffer_ = {input, input_size, /*pos=*/0};
} else if (input_buffer_.src == input) {
// Same input, not fully compressed.
}
ZSTD_outBuffer output_buffer = {output, max_output_len_, /*pos=*/0};
const size_t remaining =
ZSTD_compressStream2(cctx_, &output_buffer, &input_buffer_, ZSTD_e_end);
if (ZSTD_isError(remaining)) {
// Failure
Reset();
return -1;
}
// Success
*output_pos = output_buffer.pos;
return (int)remaining;
#endif
}
void ZSTDStreamingCompress::Reset() {
#ifdef ZSTD_STREAMING
ZSTD_CCtx_reset(cctx_, ZSTD_ResetDirective::ZSTD_reset_session_only);
input_buffer_ = {/*src=*/nullptr, /*size=*/0, /*pos=*/0};
#endif
}
int ZSTDStreamingUncompress::Uncompress(const char* input, size_t input_size,
char* output, size_t* output_pos) {
assert(input != nullptr && output != nullptr && output_pos != nullptr);
*output_pos = 0;
// Don't need to uncompress an empty input
if (input_size == 0) {
return 0;
}
#ifdef ZSTD_STREAMING
if (input_buffer_.src != input) {
// New input
input_buffer_ = {input, input_size, /*pos=*/0};
}
ZSTD_outBuffer output_buffer = {output, max_output_len_, /*pos=*/0};
size_t ret = ZSTD_decompressStream(dctx_, &output_buffer, &input_buffer_);
if (ZSTD_isError(ret)) {
Reset();
return -1;
}
*output_pos = output_buffer.pos;
return (int)(input_buffer_.size - input_buffer_.pos);
#else
(void)input;
(void)input_size;
(void)output;
return -1;
#endif
}
void ZSTDStreamingUncompress::Reset() {
#ifdef ZSTD_STREAMING
ZSTD_DCtx_reset(dctx_, ZSTD_ResetDirective::ZSTD_reset_session_only);
input_buffer_ = {/*src=*/nullptr, /*size=*/0, /*pos=*/0};
#endif
}
} // namespace ROCKSDB_NAMESPACE