Merge pull request #165 from rw/go-faster

Go speed improvements

go/builder.go

@@ -31,11 +31,38 @@ func NewBuilder(initialSize int) *Builder {
 	return b
 }
 
+// Reset truncates the underlying Builder buffer, facilitating alloc-free
+// reuse of a Builder.
+func (b *Builder) Reset() {
+	if b.Bytes != nil {
+		b.Bytes = b.Bytes[:cap(b.Bytes)]
+	}
+
+	if b.vtables != nil {
+		b.vtables = b.vtables[:0]
+	}
+
+	if b.vtable != nil {
+		b.vtable = b.vtable[:0]
+	}
+
+	b.head = UOffsetT(len(b.Bytes))
+	b.minalign = 1
+}
+
 // StartObject initializes bookkeeping for writing a new object.
 func (b *Builder) StartObject(numfields int) {
 	b.notNested()
 	// use 32-bit offsets so that arithmetic doesn't overflow.
+	if cap(b.vtable) < numfields || b.vtable == nil {
 		b.vtable = make([]UOffsetT, numfields)
+	} else {
+		b.vtable = b.vtable[:numfields]
+		for i := 0; i < len(b.vtable); i++ {
+			b.vtable[i] = 0
+		}
+	}
+
 	b.objectEnd = b.Offset()
 	b.minalign = 1
 }
@@ -137,7 +164,7 @@ func (b *Builder) WriteVtable() (n UOffsetT) {
 			SOffsetT(existingVtable)-SOffsetT(objectOffset))
 	}
 
-	b.vtable = nil
+	b.vtable = b.vtable[:0]
 	return objectOffset
 }
 
@@ -155,13 +182,20 @@ func (b *Builder) growByteBuffer() {
 	if (int64(len(b.Bytes)) & int64(0xC0000000)) != 0 {
 		panic("cannot grow buffer beyond 2 gigabytes")
 	}
-	newSize := len(b.Bytes) * 2
-	if newSize == 0 {
-		newSize = 1
+	newLen := len(b.Bytes) * 2
+	if newLen == 0 {
+		newLen = 1
+	}
+
+	if cap(b.Bytes) >= newLen {
+		b.Bytes = b.Bytes[:newLen]
+	} else {
+		extension := make([]byte, newLen-len(b.Bytes))
+		b.Bytes = append(b.Bytes, extension...)
 	}
-	bytes2 := make([]byte, newSize)
-	copy(bytes2[newSize-len(b.Bytes):], b.Bytes)
-	b.Bytes = bytes2
+
+	middle := newLen / 2
+	copy(b.Bytes[middle:], b.Bytes[:middle])
 }
 
 // Head gives the start of useful data in the underlying byte buffer.
@@ -247,16 +281,20 @@ func (b *Builder) EndVector(vectorNumElems int) UOffsetT {
 
 // CreateString writes a null-terminated string as a vector.
 func (b *Builder) CreateString(s string) UOffsetT {
+	return b.CreateByteString([]byte(s))
+}
+
+// CreateByteString writes a byte slice as a string (null-terminated).
+func (b *Builder) CreateByteString(s []byte) UOffsetT {
 	b.Prep(int(SizeUOffsetT), (len(s)+1)*SizeByte)
 	b.PlaceByte(0)
 
-	x := []byte(s)
-	l := UOffsetT(len(x))
+	l := UOffsetT(len(s))
 
 	b.head -= l
-	copy(b.Bytes[b.head:b.head+l], x)
+	copy(b.Bytes[b.head:b.head+l], s)
 
-	return b.EndVector(len(x))
+	return b.EndVector(len(s))
 }
 
 // CreateByteVector writes a ubyte vector
@@ -274,7 +312,7 @@ func (b *Builder) CreateByteVector(v []byte) UOffsetT {
 func (b *Builder) notNested() {
 	// Check that no other objects are being built while making this
 	// object. If not, panic:
-	if b.vtable != nil {
+	if len(b.vtable) > 0 {
 		panic("non-inline data write inside of object")
 	}
 }

src/idl_gen_go.cpp

@@ -238,7 +238,7 @@ static void GetStringField(const StructDef &struct_def,
   code += " " +  MakeCamel(field.name);
   code += "() " + TypeName(field) + " ";
   code += OffsetPrefix(field) + "\t\treturn " + GenGetter(field.value.type);
-  code += "(o + rcv._tab.Pos)\n\t}\n\treturn \"\"\n";
+  code += "(o + rcv._tab.Pos)\n\t}\n\treturn nil\n";
   code += "}\n\n";
 }
 
@@ -301,7 +301,7 @@ static void GetMemberOfVectorOfNonStruct(const StructDef &struct_def,
   code += NumToString(InlineSize(vectortype)) + "))\n";
   code += "\t}\n";
   if (vectortype.base_type == BASE_TYPE_STRING) {
-    code += "\treturn \"\"\n";
+    code += "\treturn nil\n";
   } else {
     code += "\treturn 0\n";
   }
@@ -573,7 +573,7 @@ static void GenEnum(const EnumDef &enum_def, std::string *code_ptr) {
 // Returns the function name that is able to read a value of the given type.
 static std::string GenGetter(const Type &type) {
   switch (type.base_type) {
-    case BASE_TYPE_STRING: return "rcv._tab.String";
+    case BASE_TYPE_STRING: return "rcv._tab.ByteVector";
     case BASE_TYPE_UNION: return "rcv._tab.Union";
     case BASE_TYPE_VECTOR: return GenGetter(type.VectorType());
     default:
@@ -626,7 +626,7 @@ static std::string GenTypeBasic(const Type &type) {
 static std::string GenTypePointer(const Type &type) {
   switch (type.base_type) {
     case BASE_TYPE_STRING:
-      return "string";
+      return "[]byte";
     case BASE_TYPE_VECTOR:
       return GenTypeGet(type.VectorType());
     case BASE_TYPE_STRUCT:

src/idl_parser.cpp

@@ -971,6 +971,8 @@ void Parser::ParseDecl() {
   CheckClash("Type", BASE_TYPE_UNION);
   CheckClash("_length", BASE_TYPE_VECTOR);
   CheckClash("Length", BASE_TYPE_VECTOR);
+  CheckClash("_byte_vector", BASE_TYPE_STRING);
+  CheckClash("ByteVector", BASE_TYPE_STRING);
   Expect('}');
 }
 

tests/GoTest.sh

@@ -43,6 +43,8 @@ GOPATH=${go_path} go test flatbuffers_test \
                      --test.coverpkg=github.com/google/flatbuffers/go \
                      --cpp_data=${test_dir}/monsterdata_test.mon \
                      --out_data=${test_dir}/monsterdata_go_wire.mon \
+                     --test.bench=. \
+                     --test.benchtime=3s \
                      --fuzz=true \
                      --fuzz_fields=4 \
                      --fuzz_objects=10000

tests/MyGame/Example/Monster.go

@@ -50,12 +50,12 @@ func (rcv *Monster) Hp() int16 {
 	return 100
 }
 
-func (rcv *Monster) Name() string {
+func (rcv *Monster) Name() []byte {
 	o := flatbuffers.UOffsetT(rcv._tab.Offset(10))
 	if o != 0 {
-		return rcv._tab.String(o + rcv._tab.Pos)
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
 	}
-	return ""
+	return nil
 }
 
 func (rcv *Monster) Inventory(j int) byte {
@@ -130,13 +130,13 @@ func (rcv *Monster) Test4Length() int {
 	return 0
 }
 
-func (rcv *Monster) Testarrayofstring(j int) string {
+func (rcv *Monster) Testarrayofstring(j int) []byte {
 	o := flatbuffers.UOffsetT(rcv._tab.Offset(24))
 	if o != 0 {
 		a := rcv._tab.Vector(o)
-		return rcv._tab.String(a + flatbuffers.UOffsetT(j * 4))
+		return rcv._tab.ByteVector(a + flatbuffers.UOffsetT(j * 4))
 	}
-	return ""
+	return nil
 }
 
 func (rcv *Monster) TestarrayofstringLength() int {

tests/MyGame/Example/Stat.go

@@ -14,12 +14,12 @@ func (rcv *Stat) Init(buf []byte, i flatbuffers.UOffsetT) {
 	rcv._tab.Pos = i
 }
 
-func (rcv *Stat) Id() string {
+func (rcv *Stat) Id() []byte {
 	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
 	if o != 0 {
-		return rcv._tab.String(o + rcv._tab.Pos)
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
 	}
-	return ""
+	return nil
 }
 
 func (rcv *Stat) Val() int64 {

tests/go_test.go

@@ -132,7 +132,7 @@ func CheckReadBuffer(buf []byte, offset flatbuffers.UOffsetT, fail func(string,
 		fail(FailString("mana", 150, got))
 	}
 
-	if got := monster.Name(); "MyMonster" != got {
+	if got := monster.Name(); !bytes.Equal([]byte("MyMonster"), got) {
 		fail(FailString("name", "MyMonster", got))
 	}
 
@@ -210,7 +210,7 @@ func CheckReadBuffer(buf []byte, offset flatbuffers.UOffsetT, fail func(string,
 	var monster2 example.Monster
 	monster2.Init(table2.Bytes, table2.Pos)
 
-	if got := monster2.Name(); "Fred" != got {
+	if got := monster2.Name(); !bytes.Equal([]byte("Fred"), got) {
 		fail(FailString("monster2.Name()", "Fred", got))
 	}
 
@@ -268,11 +268,11 @@ func CheckReadBuffer(buf []byte, offset flatbuffers.UOffsetT, fail func(string,
 		fail(FailString("Testarrayofstring length", 2, got))
 	}
 
-	if got := monster.Testarrayofstring(0); "test1" != got {
+	if got := monster.Testarrayofstring(0); !bytes.Equal([]byte("test1"), got) {
 		fail(FailString("Testarrayofstring(0)", "test1", got))
 	}
 
-	if got := monster.Testarrayofstring(1); "test2" != got {
+	if got := monster.Testarrayofstring(1); !bytes.Equal([]byte("test2"), got) {
 		fail(FailString("Testarrayofstring(1)", "test2", got))
 	}
 }
@@ -533,6 +533,15 @@ func CheckByteLayout(fail func(string, ...interface{})) {
 	check([]byte{4, 0, 0, 0, 'm', 'o', 'o', 'p', 0, 0, 0, 0, // 0-terminated, 3-byte pad
 		3, 0, 0, 0, 'f', 'o', 'o', 0})
 
+	// test 6b: CreateByteString
+
+	b = flatbuffers.NewBuilder(0)
+	b.CreateByteString([]byte("foo"))
+	check([]byte{3, 0, 0, 0, 'f', 'o', 'o', 0}) // 0-terminated, no pad
+	b.CreateByteString([]byte("moop"))
+	check([]byte{4, 0, 0, 0, 'm', 'o', 'o', 'p', 0, 0, 0, 0, // 0-terminated, 3-byte pad
+		3, 0, 0, 0, 'f', 'o', 'o', 0})
+
 	// test 7: empty vtable
 	b = flatbuffers.NewBuilder(0)
 	b.StartObject(0)
@@ -1185,3 +1194,128 @@ func BenchmarkVtableDeduplication(b *testing.B) {
 		builder.EndObject()
 	}
 }
+
+// BenchmarkParseGold measures the speed of parsing the 'gold' data
+// used throughout this test suite.
+func BenchmarkParseGold(b *testing.B) {
+	buf, offset := CheckGeneratedBuild(b.Fatalf)
+	monster := example.GetRootAsMonster(buf, offset)
+
+	// use these to prevent allocations:
+	reuse_pos := example.Vec3{}
+	reuse_test3 := example.Test{}
+	reuse_table2 := flatbuffers.Table{}
+	reuse_monster2 := example.Monster{}
+	reuse_test4_0 := example.Test{}
+	reuse_test4_1 := example.Test{}
+
+	b.SetBytes(int64(len(buf[offset:])))
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		monster.Hp()
+		monster.Mana()
+		name := monster.Name()
+		_ = name[0]
+		_ = name[len(name)-1]
+
+		monster.Pos(&reuse_pos)
+		reuse_pos.X()
+		reuse_pos.Y()
+		reuse_pos.Z()
+		reuse_pos.Test1()
+		reuse_pos.Test2()
+		reuse_pos.Test3(&reuse_test3)
+		reuse_test3.A()
+		reuse_test3.B()
+		monster.TestType()
+		monster.Test(&reuse_table2)
+		reuse_monster2.Init(reuse_table2.Bytes, reuse_table2.Pos)
+		name2 := reuse_monster2.Name()
+		_ = name2[0]
+		_ = name2[len(name2)-1]
+		monster.InventoryLength()
+		l := monster.InventoryLength()
+		for i := 0; i < l; i++ {
+			monster.Inventory(i)
+		}
+		monster.Test4Length()
+		monster.Test4(&reuse_test4_0, 0)
+		monster.Test4(&reuse_test4_1, 1)
+
+		reuse_test4_0.A()
+		reuse_test4_0.B()
+		reuse_test4_1.A()
+		reuse_test4_1.B()
+
+		monster.TestarrayofstringLength()
+		str0 := monster.Testarrayofstring(0)
+		_ = str0[0]
+		_ = str0[len(str0)-1]
+		str1 := monster.Testarrayofstring(1)
+		_ = str1[0]
+		_ = str1[len(str1)-1]
+	}
+}
+
+// BenchmarkBuildGold uses generated code to build the example Monster.
+func BenchmarkBuildGold(b *testing.B) {
+	buf, offset := CheckGeneratedBuild(b.Fatalf)
+	bytes_length := int64(len(buf[offset:]))
+
+	reuse_str := []byte("MyMonster")
+	reuse_test1 := []byte("test1")
+	reuse_test2 := []byte("test2")
+	reuse_fred := []byte("Fred")
+
+	b.SetBytes(bytes_length)
+	bldr := flatbuffers.NewBuilder(0)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		bldr.Reset()
+
+		str := bldr.CreateByteString(reuse_str)
+		test1 := bldr.CreateByteString(reuse_test1)
+		test2 := bldr.CreateByteString(reuse_test2)
+		fred := bldr.CreateByteString(reuse_fred)
+
+		example.MonsterStartInventoryVector(bldr, 5)
+		bldr.PrependByte(4)
+		bldr.PrependByte(3)
+		bldr.PrependByte(2)
+		bldr.PrependByte(1)
+		bldr.PrependByte(0)
+		inv := bldr.EndVector(5)
+
+		example.MonsterStart(bldr)
+		example.MonsterAddName(bldr, fred)
+		mon2 := example.MonsterEnd(bldr)
+
+		example.MonsterStartTest4Vector(bldr, 2)
+		example.CreateTest(bldr, 10, 20)
+		example.CreateTest(bldr, 30, 40)
+		test4 := bldr.EndVector(2)
+
+		example.MonsterStartTestarrayofstringVector(bldr, 2)
+		bldr.PrependUOffsetT(test2)
+		bldr.PrependUOffsetT(test1)
+		testArrayOfString := bldr.EndVector(2)
+
+		example.MonsterStart(bldr)
+
+		pos := example.CreateVec3(bldr, 1.0, 2.0, 3.0, 3.0, 2, 5, 6)
+		example.MonsterAddPos(bldr, pos)
+
+		example.MonsterAddHp(bldr, 80)
+		example.MonsterAddName(bldr, str)
+		example.MonsterAddInventory(bldr, inv)
+		example.MonsterAddTestType(bldr, 1)
+		example.MonsterAddTest(bldr, mon2)
+		example.MonsterAddTest4(bldr, test4)
+		example.MonsterAddTestarrayofstring(bldr, testArrayOfString)
+		mon := example.MonsterEnd(bldr)
+
+		bldr.Finish(mon)
+	}
+}