region: Simplify buffer funcs in compressor.go

Replace `growBuffer` with 'append' and `resizeBufferCap` with
`slices.Grow`. These are equivalent after undoing the unintentional
change from commit 1fee39f. Benchmarks show the performance is
equivalent to the code before commit 1fee39f.

Also replace some deprecated calls to rand funcs.

region/compressor.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"slices"
 
 	"github.com/tsuna/gohbase/compression"
 )
@@ -25,24 +26,6 @@ func min(x, y uint32) int {
 	return int(y)
 }
 
-func growBuffer(b []byte, sz int) []byte {
-	l := len(b) + sz
-	if l <= cap(b) {
-		return b[:l]
-	}
-	return append(b, make([]byte, sz)...)
-}
-
-func resizeBufferCap(b []byte, capacity int) []byte {
-	if capacity <= cap(b) {
-		return b
-	}
-
-	b2 := make([]byte, capacity)
-	copy(b2, b)
-	return b2[:len(b)]
-}
-
 func (c *compressor) compressCellblocks(cbs net.Buffers, uncompressedLen uint32) []byte {
 	b := newBuffer(4)
 
@@ -62,7 +45,7 @@ func (c *compressor) compressCellblocks(cbs net.Buffers, uncompressedLen uint32)
 
 		// grow for chunk length
 		lenOffset = len(b)
-		b = growBuffer(b, 4)
+		b = append(b, make([]byte, 4)...)
 
 		b, chunkLen = c.Encode(uncompressedBuffer[:n], b)
 
@@ -122,7 +105,7 @@ func (c *compressor) decompressCellblocks(b []byte) ([]byte, error) {
 			return nil, fmt.Errorf("failed to read uncompressed block length: %w", err)
 		}
 
-		out = resizeBufferCap(out, len(out)+int(uncompressedBlockLen))
+		out = slices.Grow(out, int(uncompressedBlockLen))
 
 		// read and decompress encoded chunks until whole block is read
 		var uncompressedSoFar uint32

region/compressor_test.go

@@ -170,13 +170,13 @@ func benchmarkDecompressCellblocks(b *testing.B, blockLen int, blocksCount int)
 	b.ReportAllocs()
 
 	data := make([]byte, blockLen)
-	rand.Seed(int64(b.N))
+	r := rand.New(rand.NewSource(42))
 
 	c := &compressor{Codec: mockCodec{}}
 
 	var compressedCellblocks []byte
 	for i := 0; i < blocksCount; i++ {
-		_, err := rand.Read(data)
+		_, err := r.Read(data)
 		if err != nil {
 			b.FailNow()
 		}