zstd: Remove unused decompression buffer (#470)

Author: klauspost

zstd/blockdec.go

@@ -76,12 +76,11 @@ type blockDec struct {
 // Window size of the block.
 WindowSize uint64
 
-history chan *history
-input chan struct{}
-result chan decodeOutput
-sequenceBuf []seq
-err error
-decWG sync.WaitGroup
+history chan *history
+input chan struct{}
+result chan decodeOutput
+err error
+decWG sync.WaitGroup
 
 // Frame to use for singlethreaded decoding.
 // Should not be used by the decoder itself since parent may be another frame.
@@ -512,18 +511,7 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 nSeqs = 0x7f00 + int(in[1]) + (int(in[2]) << 8)
 in = in[3:]
 }
-// Allocate sequences
-if cap(b.sequenceBuf) < nSeqs {
-if b.lowMem {
-b.sequenceBuf = make([]seq, nSeqs)
-} else {
-// Allocate max
-b.sequenceBuf = make([]seq, nSeqs, maxSequences)
-}
-} else {
-// Reuse buffer
-b.sequenceBuf = b.sequenceBuf[:nSeqs]
-}
+
 var seqs = &sequenceDecs{}
 if nSeqs > 0 {
 if len(in) < 1 {