chore: factor out CompressorImpl into separate files (#4319)

Signed-off-by: Roman Gershman <roman@dragonflydb.io>

src/server/CMakeLists.txt

@@ -50,6 +50,7 @@ add_library(dragonfly_lib bloom_family.cc
             list_family.cc main_service.cc memory_cmd.cc rdb_load.cc rdb_save.cc replica.cc
             protocol_client.cc
             snapshot.cc script_mgr.cc server_family.cc
+            detail/compressor.cc
             detail/decompress.cc
             detail/save_stages_controller.cc
             detail/snapshot_storage.cc

src/server/detail/compressor.cc

@@ -0,0 +1,103 @@
+// Copyright 2024, DragonflyDB authors.  All rights reserved.
+// See LICENSE for licensing terms.
+//
+
+#include "server/detail/compressor.h"
+
+#include <absl/flags/flag.h>
+#include <lz4frame.h>
+#include <zstd.h>
+
+#include "base/logging.h"
+
+ABSL_FLAG(int, compression_level, 2, "The compression level to use on zstd/lz4 compression");
+
+namespace dfly::detail {
+
+using namespace std;
+
+class ZstdCompressor : public CompressorImpl {
+ public:
+  ZstdCompressor() {
+    cctx_ = ZSTD_createCCtx();
+  }
+  ~ZstdCompressor() {
+    ZSTD_freeCCtx(cctx_);
+  }
+
+  io::Result<io::Bytes> Compress(io::Bytes data);
+
+ private:
+  ZSTD_CCtx* cctx_;
+  base::PODArray<uint8_t> compr_buf_;
+};
+
+io::Result<io::Bytes> ZstdCompressor::Compress(io::Bytes data) {
+  size_t buf_size = ZSTD_compressBound(data.size());
+  if (compr_buf_.capacity() < buf_size) {
+    compr_buf_.reserve(buf_size);
+  }
+  size_t compressed_size = ZSTD_compressCCtx(cctx_, compr_buf_.data(), compr_buf_.capacity(),
+                                             data.data(), data.size(), compression_level_);
+
+  if (ZSTD_isError(compressed_size)) {
+    LOG(ERROR) << "ZSTD_compressCCtx failed with error " << ZSTD_getErrorName(compressed_size);
+    return nonstd::make_unexpected(make_error_code(errc::operation_not_supported));
+  }
+  compressed_size_total_ += compressed_size;
+  uncompressed_size_total_ += data.size();
+  return io::Bytes(compr_buf_.data(), compressed_size);
+}
+
+class Lz4Compressor : public CompressorImpl {
+ public:
+  Lz4Compressor() {
+    lz4_pref_.compressionLevel = compression_level_;
+  }
+
+  ~Lz4Compressor() {
+  }
+
+  // compress a string of data
+  io::Result<io::Bytes> Compress(io::Bytes data);
+
+ private:
+  LZ4F_preferences_t lz4_pref_ = LZ4F_INIT_PREFERENCES;
+};
+
+io::Result<io::Bytes> Lz4Compressor::Compress(io::Bytes data) {
+  lz4_pref_.frameInfo.contentSize = data.size();
+  size_t buf_size = LZ4F_compressFrameBound(data.size(), &lz4_pref_);
+  if (compr_buf_.capacity() < buf_size) {
+    compr_buf_.reserve(buf_size);
+  }
+
+  size_t frame_size = LZ4F_compressFrame(compr_buf_.data(), compr_buf_.capacity(), data.data(),
+                                         data.size(), &lz4_pref_);
+  if (LZ4F_isError(frame_size)) {
+    LOG(ERROR) << "LZ4F_compressFrame failed with error " << LZ4F_getErrorName(frame_size);
+    return nonstd::make_unexpected(make_error_code(errc::operation_not_supported));
+  }
+  compressed_size_total_ += frame_size;
+  uncompressed_size_total_ += data.size();
+  return io::Bytes(compr_buf_.data(), frame_size);
+}
+
+CompressorImpl::CompressorImpl() {
+  compression_level_ = absl::GetFlag(FLAGS_compression_level);
+}
+
+CompressorImpl::~CompressorImpl() {
+  VLOG(1) << "compressed size: " << compressed_size_total_;
+  VLOG(1) << "uncompressed size: " << uncompressed_size_total_;
+}
+
+unique_ptr<CompressorImpl> CompressorImpl::CreateZstd() {
+  return make_unique<ZstdCompressor>();
+}
+
+unique_ptr<CompressorImpl> CompressorImpl::CreateLZ4() {
+  return make_unique<Lz4Compressor>();
+}
+
+}  // namespace dfly::detail

src/server/detail/compressor.h

@@ -0,0 +1,30 @@
+// Copyright 2024, DragonflyDB authors.  All rights reserved.
+// See LICENSE for licensing terms.
+//
+
+#pragma once
+
+#include <memory>
+
+#include "base/pod_array.h"
+#include "io/io.h"
+
+namespace dfly::detail {
+
+class CompressorImpl {
+ public:
+  static std::unique_ptr<CompressorImpl> CreateZstd();
+  static std::unique_ptr<CompressorImpl> CreateLZ4();
+
+  CompressorImpl();
+  virtual ~CompressorImpl();
+  virtual io::Result<io::Bytes> Compress(io::Bytes data) = 0;
+
+ protected:
+  int compression_level_ = 1;
+  size_t compressed_size_total_ = 0;
+  size_t uncompressed_size_total_ = 0;
+  base::PODArray<uint8_t> compr_buf_;
+};
+
+}  // namespace dfly::detail

src/server/rdb_save.cc

@@ -7,8 +7,6 @@
 #include <absl/cleanup/cleanup.h>
 #include <absl/strings/str_cat.h>
 #include <absl/strings/str_format.h>
-#include <lz4frame.h>
-#include <zstd.h>
 
 #include <queue>
 
@@ -50,7 +48,6 @@ ABSL_FLAG(dfly::CompressionMode, compression_mode, dfly::CompressionMode::MULTI_
           "set 1 for single entry lzf compression,"
           "set 2 for multi entry zstd compression on df snapshot and single entry on rdb snapshot,"
           "set 3 for multi entry lz4 compression on df snapshot and single entry on rdb snapshot");
-ABSL_FLAG(int, compression_level, 2, "The compression level to use on zstd/lz4 compression");
 
 // TODO: to retire both flags in v1.27 (Jan 2025)
 ABSL_FLAG(bool, list_rdb_encode_v2, true,
@@ -228,89 +225,6 @@ uint8_t RdbObjectType(const PrimeValue& pv) {
   return 0; /* avoid warning */
 }
 
-class CompressorImpl {
- public:
-  CompressorImpl() {
-    compression_level_ = absl::GetFlag(FLAGS_compression_level);
-  }
-  virtual ~CompressorImpl() {
-    VLOG(1) << "compressed size: " << compressed_size_total_;
-    VLOG(1) << "uncompressed size: " << uncompressed_size_total_;
-  }
-  virtual io::Result<io::Bytes> Compress(io::Bytes data) = 0;
-
- protected:
-  int compression_level_ = 1;
-  size_t compressed_size_total_ = 0;
-  size_t uncompressed_size_total_ = 0;
-  base::PODArray<uint8_t> compr_buf_;
-};
-
-class ZstdCompressor : public CompressorImpl {
- public:
-  ZstdCompressor() {
-    cctx_ = ZSTD_createCCtx();
-  }
-  ~ZstdCompressor() {
-    ZSTD_freeCCtx(cctx_);
-  }
-
-  io::Result<io::Bytes> Compress(io::Bytes data);
-
- private:
-  ZSTD_CCtx* cctx_;
-  base::PODArray<uint8_t> compr_buf_;
-};
-
-io::Result<io::Bytes> ZstdCompressor::Compress(io::Bytes data) {
-  size_t buf_size = ZSTD_compressBound(data.size());
-  if (compr_buf_.capacity() < buf_size) {
-    compr_buf_.reserve(buf_size);
-  }
-  size_t compressed_size = ZSTD_compressCCtx(cctx_, compr_buf_.data(), compr_buf_.capacity(),
-                                             data.data(), data.size(), compression_level_);
-
-  if (ZSTD_isError(compressed_size)) {
-    return make_unexpected(error_code{int(compressed_size), generic_category()});
-  }
-  compressed_size_total_ += compressed_size;
-  uncompressed_size_total_ += data.size();
-  return io::Bytes(compr_buf_.data(), compressed_size);
-}
-
-class Lz4Compressor : public CompressorImpl {
- public:
-  Lz4Compressor() {
-    lz4_pref_.compressionLevel = compression_level_;
-  }
-
-  ~Lz4Compressor() {
-  }
-
-  // compress a string of data
-  io::Result<io::Bytes> Compress(io::Bytes data);
-
- private:
-  LZ4F_preferences_t lz4_pref_ = LZ4F_INIT_PREFERENCES;
-};
-
-io::Result<io::Bytes> Lz4Compressor::Compress(io::Bytes data) {
-  lz4_pref_.frameInfo.contentSize = data.size();
-  size_t buf_size = LZ4F_compressFrameBound(data.size(), &lz4_pref_);
-  if (compr_buf_.capacity() < buf_size) {
-    compr_buf_.reserve(buf_size);
-  }
-
-  size_t frame_size = LZ4F_compressFrame(compr_buf_.data(), compr_buf_.capacity(), data.data(),
-                                         data.size(), &lz4_pref_);
-  if (LZ4F_isError(frame_size)) {
-    return make_unexpected(error_code{int(frame_size), generic_category()});
-  }
-  compressed_size_total_ += frame_size;
-  uncompressed_size_total_ += data.size();
-  return io::Bytes(compr_buf_.data(), frame_size);
-}
-
 SerializerBase::SerializerBase(CompressionMode compression_mode)
     : compression_mode_(compression_mode), mem_buf_{4_KB}, tmp_buf_(nullptr) {
 }
@@ -1668,11 +1582,11 @@ void SerializerBase::AllocateCompressorOnce() {
     return;
   }
   if (compression_mode_ == CompressionMode::MULTI_ENTRY_ZSTD) {
-    compressor_impl_.reset(new ZstdCompressor());
+    compressor_impl_ = detail::CompressorImpl::CreateZstd();
   } else if (compression_mode_ == CompressionMode::MULTI_ENTRY_LZ4) {
-    compressor_impl_.reset(new Lz4Compressor());
+    compressor_impl_ = detail::CompressorImpl::CreateLZ4();
   } else {
-    CHECK(false) << "Compressor allocation should not be done";
+    LOG(FATAL) << "Invalid compression mode " << unsigned(compression_mode_);
   }
 }
 

src/server/rdb_save.h

@@ -16,6 +16,7 @@ extern "C" {
 #include "io/io.h"
 #include "io/io_buf.h"
 #include "server/common.h"
+#include "server/detail/compressor.h"
 #include "server/journal/serializer.h"
 #include "server/journal/types.h"
 #include "server/table.h"
@@ -67,7 +68,8 @@ enum class SaveMode {
   RDB,                        // Save .rdb file. Expected to read all shards.
 };
 
-enum class CompressionMode { NONE, SINGLE_ENTRY, MULTI_ENTRY_ZSTD, MULTI_ENTRY_LZ4 };
+enum class CompressionMode : uint8_t { NONE, SINGLE_ENTRY, MULTI_ENTRY_ZSTD, MULTI_ENTRY_LZ4 };
+
 CompressionMode GetDefaultCompressionMode();
 
 class RdbSaver {
@@ -147,8 +149,6 @@ class RdbSaver {
   CompressionMode compression_mode_;
 };
 
-class CompressorImpl;
-
 class SerializerBase {
  public:
   enum class FlushState { kFlushMidEntry, kFlushEndEntry };
@@ -196,7 +196,7 @@ class SerializerBase {
 
   CompressionMode compression_mode_;
   io::IoBuf mem_buf_;
-  std::unique_ptr<CompressorImpl> compressor_impl_;
+  std::unique_ptr<detail::CompressorImpl> compressor_impl_;
 
   static constexpr size_t kMinStrSizeToCompress = 256;
   static constexpr double kMinCompressionReductionPrecentage = 0.95;