chore: Cut out some useless allocations when computing payset commitments (algorand#5840)

Author: jannotti

crypto/hashes.go

@@ -118,7 +118,7 @@ func (z *HashFactory) Validate() error {
 }
 
 // GenericHashObj Makes it easier to sum using hash interface and Hashable interface
-func GenericHashObj(hsh hash.Hash, h Hashable) []byte {
+func GenericHashObj[H Hashable](hsh hash.Hash, h H) []byte {
 	rep := HashRep(h)
 	return hashBytes(hsh, rep)
 }

crypto/merklearray/layer.go

@@ -37,14 +37,14 @@ type pair struct {
 	hashDigestSize int
 }
 
-func (p *pair) ToBeHashed() (protocol.HashID, []byte) {
+func (p pair) ToBeHashed() (protocol.HashID, []byte) {
 	// hashing of internal node will always be fixed length.
 	// If one of the children is missing we use [0...0].
 	// The size of the slice is based on the relevant hash function output size
 	buf := make([]byte, 2*p.hashDigestSize)
 	copy(buf[:], p.l[:])
 	copy(buf[len(p.l):], p.r[:])
-	return protocol.MerkleArrayNode, buf[:]
+	return protocol.MerkleArrayNode, buf
 }
 
 func upWorker(ws *workerState, in Layer, out Layer, h hash.Hash) {
@@ -69,7 +69,7 @@ func upWorker(ws *workerState, in Layer, out Layer, h hash.Hash) {
 				p.r = in[i+1]
 			}
 
-			out[i/2] = crypto.GenericHashObj(h, &p)
+			out[i/2] = crypto.GenericHashObj(h, p)
 		}
 
 		batchSize += 2

crypto/merklearray/merkle_test.go

@@ -1172,12 +1172,13 @@ func merkleCommitBench(b *testing.B, hashType crypto.HashType) {
 		msg := make(TestBuf, sz)
 		crypto.RandBytes(msg[:])
 
-		for cnt := 10; cnt <= 10000000; cnt *= 10 {
+		for cnt := 10; cnt <= 100000; cnt *= 10 {
 			var a TestRepeatingArray
 			a.item = msg
 			a.count = uint64(cnt)
 
 			b.Run(fmt.Sprintf("Item%d/Count%d", sz, cnt), func(b *testing.B) {
+				b.ReportAllocs()
 				for i := 0; i < b.N; i++ {
 					tree, err := Build(a, crypto.HashFactory{HashType: hashType})
 					require.NoError(b, err)
@@ -1205,6 +1206,7 @@ func benchmarkMerkleProve1M(b *testing.B, hashType crypto.HashType) {
 	require.NoError(b, err)
 
 	b.ResetTimer()
+	b.ReportAllocs()
 
 	for i := uint64(0); i < uint64(b.N); i++ {
 		_, err := tree.Prove([]uint64{i % a.count})
@@ -1238,6 +1240,7 @@ func benchmarkMerkleVerify1M(b *testing.B, hashType crypto.HashType) {
 	}
 
 	b.ResetTimer()
+	b.ReportAllocs()
 
 	for i := uint64(0); i < uint64(b.N); i++ {
 		err := Verify(root, map[uint64]crypto.Hashable{i % a.count: msg}, proofs[i])

crypto/merklearray/partial.go

@@ -118,7 +118,7 @@ func (pl partialLayer) up(s *siblings, l uint64, doHash bool, hsh hash.Hash) (pa
 				p.l = siblingHash
 				p.r = posHash
 			}
-			nextLayerHash = crypto.GenericHashObj(hsh, &p)
+			nextLayerHash = crypto.GenericHashObj(hsh, p)
 		}
 
 		res = append(res, layerItem{