wgtmac commented on a change in pull request #679:
URL: https://github.com/apache/orc/pull/679#discussion_r609218500
##########
File path: c++/src/Compression.cc
##########
@@ -897,6 +901,70 @@ DIAGNOSTIC_POP
return true;
}
+ /**
+ * LZ4 block compression
+ */
+ class Lz4CompressionSteam: public BlockCompressionStream {
+ public:
+ Lz4CompressionSteam(OutputStream * outStream,
+ int compressionLevel,
+ uint64_t capacity,
+ uint64_t blockSize,
+ MemoryPool& pool)
+ : BlockCompressionStream(outStream,
+ compressionLevel,
+ capacity,
+ blockSize,
+ pool) {
+ this->init();
+ }
+
+ virtual std::string getName() const override {
+ return "Lz4CompressionStream";
+ }
+
+ virtual ~Lz4CompressionSteam() override {
+ this->end();
+ }
+
+ protected:
+ virtual uint64_t doBlockCompression() override;
+
+ virtual uint64_t estimateMaxCompressionSize() override {
+ return static_cast<uint64_t>(LZ4_compressBound(bufferSize));
+ }
+
+ private:
+ void init();
+ void end();
+ LZ4_stream_t *state;
+ };
+
+ uint64_t Lz4CompressionSteam::doBlockCompression() {
+ int result = LZ4_compress_fast_extState(static_cast<void*>(state),
+ reinterpret_cast<const
char*>(rawInputBuffer.data()),
+
reinterpret_cast<char*>(compressorBuffer.data()),
+ bufferSize,
+
static_cast<int>(compressorBuffer.size()),
+ level);
+ if (result == 0) {
+ throw std::runtime_error("Error during block compression using lz4.");
+ }
+ return static_cast<uint64_t>(result);
+ }
+
+ void Lz4CompressionSteam::init() {
+ state =
static_cast<LZ4_stream_t*>(malloc(static_cast<size_t>(LZ4_sizeofState())));
Review comment:
why not use LZ4_createStream() to create one and free it via
LZ4_freeStream() ?
##########
File path: c++/src/Compression.cc
##########
@@ -36,6 +36,10 @@
#define ZSTD_CLEVEL_DEFAULT 3
#endif
+#ifndef LZ4_ACCELERATION_MAX
+#define LZ4_ACCELERATION_MAX 65537
Review comment:
Why set to 65537? Will it overflows to be a negative number as the
acceleration parameter used in lz4 is of type int.
##########
File path: c++/src/Compression.cc
##########
@@ -1064,9 +1132,15 @@ DIAGNOSTIC_PUSH
(new ZSTDCompressionStream(
outStream, level, bufferCapacity, compressionBlockSize, pool));
}
+ case CompressionKind_LZ4: {
+ int level = (strategy == CompressionStrategy_SPEED) ?
+ LZ4_ACCELERATION_MAX : 1;
Review comment:
replace magic number 1 with macro ACCELERATION_DEFAULT defined in lz4.h
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