lib/logstorage: improve performance for streamID.marshalString() by more than 2x

The streamID.marshalString() is executed in hot path if the query selects _stream_id field.

Command to run the benchmark:

go test ./lib/logstorage/ -run=NONE -bench=BenchmarkStreamIDMarshalString -benchtime=5s

Results before the commit:

BenchmarkStreamIDMarshalString-16    	438480714	        14.04 ns/op	  71.23 MB/s	       0 B/op	       0 allocs/op

Results after the commit:

BenchmarkStreamIDMarshalString-16    	982459660	         6.049 ns/op	 165.30 MB/s	       0 B/op	       0 allocs/op

Author: valyala

lib/logstorage/stream_id.go

@@ -28,10 +28,8 @@ func (sid *streamID) reset() {
 
 // marshalString returns _stream_id value for the given sid.
 func (sid *streamID) marshalString(dst []byte) []byte {
-	bb := bbPool.Get()
-	bb.B = sid.marshal(bb.B)
-	dst = hex.AppendEncode(dst, bb.B)
-	bbPool.Put(bb)
+	dst = sid.tenantID.marshalString(dst)
+	dst = sid.id.marshalString(dst)
 	return dst
 }
 

lib/logstorage/tenant_id.go

@@ -44,6 +44,12 @@ func (tid *TenantID) less(a *TenantID) bool {
 	return tid.ProjectID < a.ProjectID
 }
 
+func (tid *TenantID) marshalString(dst []byte) []byte {
+	n := uint64(tid.AccountID)<<32 | uint64(tid.ProjectID)
+	dst = marshalUint64Hex(dst, n)
+	return dst
+}
+
 // marshal appends the marshaled tid to dst and returns the result
 func (tid *TenantID) marshal(dst []byte) []byte {
 	dst = encoding.MarshalUint32(dst, tid.AccountID)

lib/logstorage/u128.go

@@ -32,6 +32,30 @@ func (u *u128) equal(a *u128) bool {
 	return u.hi == a.hi && u.lo == a.lo
 }
 
+func (u *u128) marshalString(dst []byte) []byte {
+	dst = marshalUint64Hex(dst, u.hi)
+	dst = marshalUint64Hex(dst, u.lo)
+	return dst
+}
+
+func marshalUint64Hex(dst []byte, n uint64) []byte {
+	dst = marshalByteHex(dst, byte(n>>56))
+	dst = marshalByteHex(dst, byte(n>>48))
+	dst = marshalByteHex(dst, byte(n>>40))
+	dst = marshalByteHex(dst, byte(n>>32))
+	dst = marshalByteHex(dst, byte(n>>24))
+	dst = marshalByteHex(dst, byte(n>>16))
+	dst = marshalByteHex(dst, byte(n>>8))
+	dst = marshalByteHex(dst, byte(n))
+	return dst
+}
+
+func marshalByteHex(dst []byte, x byte) []byte {
+	return append(dst, hexByteMap[(x>>4)&15], hexByteMap[x&15])
+}
+
+var hexByteMap = [16]byte{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}
+
 // marshal appends the marshaled u to dst and returns the result.
 func (u *u128) marshal(dst []byte) []byte {
 	dst = encoding.MarshalUint64(dst, u.hi)