[WIP] Initial commit

vendor/github.com/cockroachdb/pebble/sstable/compression_cgo.go

@@ -0,0 +1,34 @@
+// Copyright 2021 The LevelDB-Go and Pebble Authors. All rights reserved. Use
+// of this source code is governed by a BSD-style license that can be found in
+// the LICENSE file.
+
+//go:build cgo
+// +build cgo
+
+package sstable
+
+import (
+	"bytes"
+
+	"github.com/DataDog/zstd"
+)
+
+// decodeZstd decompresses b with the Zstandard algorithm.
+// It reuses the preallocated capacity of decodedBuf if it is sufficient.
+// On success, it returns the decoded byte slice.
+func decodeZstd(decodedBuf, b []byte) ([]byte, error) {
+	return zstd.Decompress(decodedBuf, b)
+}
+
+// encodeZstd compresses b with the Zstandard algorithm at default compression
+// level (level 3). It reuses the preallocated capacity of compressedBuf if it
+// is sufficient. The subslice `compressedBuf[:varIntLen]` should already encode
+// the length of `b` before calling encodeZstd. It returns the encoded byte
+// slice, including the `compressedBuf[:varIntLen]` prefix.
+func encodeZstd(compressedBuf []byte, varIntLen int, b []byte) []byte {
+	buf := bytes.NewBuffer(compressedBuf[:varIntLen])
+	writer := zstd.NewWriterLevel(buf, 3)
+	writer.Write(b)
+	writer.Close()
+	return buf.Bytes()
+}