Merge pull request #220 from aiquestion/v4_restframe

fix: reset frame when read to EOF to release buffer in Block

bench_test.go

@@ -84,6 +84,7 @@ var (
 	digitsLZ4 = mustLoadFile("testdata/e.txt.lz4")
 	twainLZ4  = mustLoadFile("testdata/Mark.Twain-Tom.Sawyer.txt.lz4")
 	randomLZ4 = mustLoadFile("testdata/random.data.lz4")
+	repeatLz4 = mustLoadFile("testdata/repeat.txt.lz4")
 )
 
 func benchmarkUncompress(b *testing.B, compressed []byte) {
@@ -160,3 +161,19 @@ func BenchmarkWriterReset(b *testing.B) {
 		_ = zw.Close()
 	}
 }
+
+func BenchmarkReaderNoReset(b *testing.B) {
+	compressed := repeatLz4
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		r := bytes.NewReader(compressed)
+		zr := lz4.NewReader(r)
+		buf := bytes.NewBuffer(nil)
+		_, err := buf.ReadFrom(zr)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}

reader.go

@@ -135,6 +135,8 @@ func (r *Reader) Read(buf []byte) (n int, err error) {
 				}
 				lz4block.Put(r.data)
 				r.data = nil
+				// reset frame to release the buffer held by Block
+				r.frame.Reset(r.num)
 				return
 			default:
 				return
@@ -157,9 +159,9 @@ func (r *Reader) Read(buf []byte) (n int, err error) {
 }
 
 // read uncompresses the next block as follow:
-// - if buf has enough room, the block is uncompressed into it directly
-//   and the lenght of used space is returned
-// - else, the uncompress data is stored in r.data and 0 is returned
+//   - if buf has enough room, the block is uncompressed into it directly
+//     and the lenght of used space is returned
+//   - else, the uncompress data is stored in r.data and 0 is returned
 func (r *Reader) read(buf []byte) (int, error) {
 	block := r.frame.Blocks.Block
 	_, err := block.Read(r.frame, r.src, r.cum)