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Commit c28fa513 authored by Rob Pike's avatar Rob Pike
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gob: error cleanup 2 

Simplify error handling during the compilation phase.

R=rsc
CC=golang-dev
https://golang.org/cl/2652042
parent f593b37f
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Inline Side-by-side
Showing with 63 additions and 122 deletions
src/pkg/gob/decode.go
View file @ c28fa513
......@@ -27,8 +27,7 @@ var (
type decodeState struct {
// The buffer is stored with an extra indirection because it may be replaced
// if we load a type during decode (when reading an interface value).
b **bytes.Buffer
// err os.Error
b **bytes.Buffer
fieldnum int // the last field number read.
buf []byte
}
......@@ -77,14 +76,13 @@ func decodeUintReader(r io.Reader, buf []byte) (x uint64, err os.Error) {
}
// decodeUint reads an encoded unsigned integer from state.r.
// Sets state.err. If state.err is already non-nil, it does nothing.
// Does not check for overflow.
func decodeUint(state *decodeState) (x uint64) {
b, err := state.b.ReadByte()
if err != nil {
error(err)
}
if b <= 0x7f { // includes state.err != nil
if b <= 0x7f {
return uint64(b)
}
nb := -int(int8(b))
......@@ -105,7 +103,6 @@ func decodeUint(state *decodeState) (x uint64) {
}
// decodeInt reads an encoded signed integer from state.r.
// Sets state.err. If state.err is already non-nil, it does nothing.
// Does not check for overflow.
func decodeInt(state *decodeState) int64 {
x := decodeUint(state)
......@@ -672,7 +669,7 @@ var decIgnoreOpMap = map[typeId]decOp{
// Return the decoding op for the base type under rt and
// the indirection count to reach it.
func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp, int, os.Error) {
func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp, int) {
typ, indir := indirect(rt)
var op decOp
k := typ.Kind()
......@@ -685,10 +682,7 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp
case *reflect.ArrayType:
name = "element of " + name
elemId := dec.wireType[wireId].arrayT.Elem
elemOp, elemIndir, err := dec.decOpFor(elemId, t.Elem(), name)
if err != nil {
return nil, 0, err
}
elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name)
ovfl := overflow(name)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
decodeArray(t, state, uintptr(p), elemOp, t.Elem().Size(), t.Len(), i.indir, elemIndir, ovfl)
......@@ -698,14 +692,8 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp
name = "element of " + name
keyId := dec.wireType[wireId].mapT.Key
elemId := dec.wireType[wireId].mapT.Elem
keyOp, keyIndir, err := dec.decOpFor(keyId, t.Key(), name)
if err != nil {
return nil, 0, err
}
elemOp, elemIndir, err := dec.decOpFor(elemId, t.Elem(), name)
if err != nil {
return nil, 0, err
}
keyOp, keyIndir := dec.decOpFor(keyId, t.Key(), name)
elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name)
ovfl := overflow(name)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
up := unsafe.Pointer(p)
......@@ -724,10 +712,7 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp
} else {
elemId = dec.wireType[wireId].sliceT.Elem
}
elemOp, elemIndir, err := dec.decOpFor(elemId, t.Elem(), name)
if err != nil {
return nil, 0, err
}
elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name)
ovfl := overflow(name)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
decodeSlice(t, state, uintptr(p), elemOp, t.Elem().Size(), i.indir, elemIndir, ovfl)
......@@ -737,7 +722,7 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp
// Generate a closure that calls out to the engine for the nested type.
enginePtr, err := dec.getDecEnginePtr(wireId, typ)
if err != nil {
return nil, 0, err
error(err)
}
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
// indirect through enginePtr to delay evaluation for recursive structs
......@@ -753,13 +738,13 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp
}
}
if op == nil {
return nil, 0, os.ErrorString("gob: decode can't handle type " + rt.String())
errorf("gob: decode can't handle type %s", rt.String())
}
return op, indir, nil
return op, indir
}
// Return the decoding op for a field that has no destination.
func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
func (dec *Decoder) decIgnoreOpFor(wireId typeId) decOp {
op, ok := decIgnoreOpMap[wireId]
if !ok {
if wireId == tInterface {
......@@ -768,7 +753,7 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
dec.ignoreInterface(state)
}
return op, nil
return op
}
// Special cases
wire := dec.wireType[wireId]
......@@ -777,10 +762,7 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
panic("internal error: can't find ignore op for type " + wireId.string())
case wire.arrayT != nil:
elemId := wire.arrayT.Elem
elemOp, err := dec.decIgnoreOpFor(elemId)
if err != nil {
return nil, err
}
elemOp := dec.decIgnoreOpFor(elemId)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
ignoreArray(state, elemOp, wire.arrayT.Len)
}
......@@ -788,24 +770,15 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
case wire.mapT != nil:
keyId := dec.wireType[wireId].mapT.Key
elemId := dec.wireType[wireId].mapT.Elem
keyOp, err := dec.decIgnoreOpFor(keyId)
if err != nil {
return nil, err
}
elemOp, err := dec.decIgnoreOpFor(elemId)
if err != nil {
return nil, err
}
keyOp := dec.decIgnoreOpFor(keyId)
elemOp := dec.decIgnoreOpFor(elemId)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
ignoreMap(state, keyOp, elemOp)
}
case wire.sliceT != nil:
elemId := wire.sliceT.Elem
elemOp, err := dec.decIgnoreOpFor(elemId)
if err != nil {
return nil, err
}
elemOp := dec.decIgnoreOpFor(elemId)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
ignoreSlice(state, elemOp)
}
......@@ -814,7 +787,7 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
// Generate a closure that calls out to the engine for the nested type.
enginePtr, err := dec.getIgnoreEnginePtr(wireId)
if err != nil {
return nil, err
error(err)
}
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
// indirect through enginePtr to delay evaluation for recursive structs
......@@ -823,9 +796,9 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
}
}
if op == nil {
return nil, os.ErrorString("ignore can't handle type " + wireId.string())
errorf("ignore can't handle type %s", wireId.string())
}
return op, nil
return op
}
// Are these two gob Types compatible?
......@@ -892,10 +865,7 @@ func (dec *Decoder) compileSingle(remoteId typeId, rt reflect.Type) (engine *dec
if !dec.compatibleType(rt, remoteId) {
return nil, os.ErrorString("gob: wrong type received for local value " + name)
}
op, indir, err := dec.decOpFor(remoteId, rt, name)
if err != nil {
return nil, err
}
op, indir := dec.decOpFor(remoteId, rt, name)
ovfl := os.ErrorString(`value for "` + name + `" out of range`)
engine.instr[singletonField] = decInstr{op, singletonField, indir, 0, ovfl}
engine.numInstr = 1
......@@ -903,6 +873,7 @@ func (dec *Decoder) compileSingle(remoteId typeId, rt reflect.Type) (engine *dec
}
func (dec *Decoder) compileDec(remoteId typeId, rt reflect.Type) (engine *decEngine, err os.Error) {
defer catchError(&err)
srt, ok := rt.(*reflect.StructType)
if !ok {
return dec.compileSingle(remoteId, rt)
......@@ -916,8 +887,7 @@ func (dec *Decoder) compileDec(remoteId typeId, rt reflect.Type) (engine *decEng
wireStruct = dec.wireType[remoteId].structT
}
if wireStruct == nil {
return nil, os.ErrorString("gob: type mismatch in decoder: want struct type " +
rt.String() + "; got non-struct")
errorf("gob: type mismatch in decoder: want struct type %s; got non-struct", rt.String())
}
engine = new(decEngine)
engine.instr = make([]decInstr, len(wireStruct.field))
......@@ -929,22 +899,14 @@ func (dec *Decoder) compileDec(remoteId typeId, rt reflect.Type) (engine *decEng
ovfl := overflow(wireField.name)
// TODO(r): anonymous names
if !present {
op, err := dec.decIgnoreOpFor(wireField.id)
if err != nil {
return nil, err
}
op := dec.decIgnoreOpFor(wireField.id)
engine.instr[fieldnum] = decInstr{op, fieldnum, 0, 0, ovfl}
continue
}
if !dec.compatibleType(localField.Type, wireField.id) {
return nil, os.ErrorString("gob: wrong type (" +
localField.Type.String() + ") for received field " +
wireStruct.name + "." + wireField.name)
}
op, indir, err := dec.decOpFor(wireField.id, localField.Type, localField.Name)
if err != nil {
return nil, err
errorf("gob: wrong type (%s) for received field %s.%s", localField.Type, wireStruct.name, wireField.name)
}
op, indir := dec.decOpFor(wireField.id, localField.Type, localField.Name)
engine.instr[fieldnum] = decInstr{op, fieldnum, indir, uintptr(localField.Offset), ovfl}
engine.numInstr++
}
......
src/pkg/gob/encode.go
View file @ c28fa513
......@@ -35,8 +35,7 @@ func newEncoderState(b *bytes.Buffer) *encoderState {
// Otherwise the value is written in big-endian byte order preceded
// by the byte length, negated.
// encodeUint writes an encoded unsigned integer to state.b. Sets state.err.
// If state.err is already non-nil, it does nothing.
// encodeUint writes an encoded unsigned integer to state.b.
func encodeUint(state *encoderState, x uint64) {
if x <= 0x7F {
err := state.b.WriteByte(uint8(x))
......@@ -60,8 +59,8 @@ func encodeUint(state *encoderState, x uint64) {
}
// encodeInt writes an encoded signed integer to state.w.
// The low bit of the encoding says whether to bit complement the (other bits of the) uint to recover the int.
// Sets state.err. If state.err is already non-nil, it does nothing.
// The low bit of the encoding says whether to bit complement the (other bits of the)
// uint to recover the int.
func encodeInt(state *encoderState, i int64) {
var x uint64
if i < 0 {
......@@ -319,8 +318,7 @@ type encEngine struct {
const singletonField = 0
func encodeSingle(engine *encEngine, b *bytes.Buffer, basep uintptr) (err os.Error) {
defer catchError(&err)
func encodeSingle(engine *encEngine, b *bytes.Buffer, basep uintptr) {
state := newEncoderState(b)
state.fieldnum = singletonField
// There is no surrounding struct to frame the transmission, so we must
......@@ -330,15 +328,13 @@ func encodeSingle(engine *encEngine, b *bytes.Buffer, basep uintptr) (err os.Err
p := unsafe.Pointer(basep) // offset will be zero
if instr.indir > 0 {
if p = encIndirect(p, instr.indir); p == nil {
return nil
return
}
}
instr.op(instr, state, p)
return
}
func encodeStruct(engine *encEngine, b *bytes.Buffer, basep uintptr) (err os.Error) {
defer catchError(&err)
func encodeStruct(engine *encEngine, b *bytes.Buffer, basep uintptr) {
state := newEncoderState(b)
state.fieldnum = -1
for i := 0; i < len(engine.instr); i++ {
......@@ -351,7 +347,6 @@ func encodeStruct(engine *encEngine, b *bytes.Buffer, basep uintptr) (err os.Err
}
instr.op(instr, state, p)
}
return nil
}
func encodeArray(b *bytes.Buffer, p uintptr, op encOp, elemWid uintptr, elemIndir int, length int) {
......@@ -452,7 +447,7 @@ var encOpMap = []encOp{
// Return the encoding op for the base type under rt and
// the indirection count to reach it.
func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int, os.Error) {
func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
typ, indir := indirect(rt)
var op encOp
k := typ.Kind()
......@@ -468,10 +463,7 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int, os.Error) {
break
}
// Slices have a header; we decode it to find the underlying array.
elemOp, indir, err := enc.encOpFor(t.Elem())
if err != nil {
return nil, 0, err
}
elemOp, indir := enc.encOpFor(t.Elem())
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
slice := (*reflect.SliceHeader)(p)
if slice.Len == 0 {
......@@ -482,23 +474,14 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int, os.Error) {
}
case *reflect.ArrayType:
// True arrays have size in the type.
elemOp, indir, err := enc.encOpFor(t.Elem())
if err != nil {
return nil, 0, err
}
elemOp, indir := enc.encOpFor(t.Elem())
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
state.update(i)
encodeArray(state.b, uintptr(p), elemOp, t.Elem().Size(), indir, t.Len())
}
case *reflect.MapType:
keyOp, keyIndir, err := enc.encOpFor(t.Key())
if err != nil {
return nil, 0, err
}
elemOp, elemIndir, err := enc.encOpFor(t.Elem())
if err != nil {
return nil, 0, err
}
keyOp, keyIndir := enc.encOpFor(t.Key())
elemOp, elemIndir := enc.encOpFor(t.Elem())
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
// Maps cannot be accessed by moving addresses around the way
// that slices etc. can. We must recover a full reflection value for
......@@ -513,10 +496,7 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int, os.Error) {
}
case *reflect.StructType:
// Generate a closure that calls out to the engine for the nested type.
_, err := enc.getEncEngine(typ)
if err != nil {
return nil, 0, err
}
enc.getEncEngine(typ)
info := mustGetTypeInfo(typ)
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
state.update(i)
......@@ -538,66 +518,65 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int, os.Error) {
}
}
if op == nil {
return op, indir, os.ErrorString("gob enc: can't happen: encode type " + rt.String())
errorf("gob enc: can't happen: encode type %s", rt.String())
}
return op, indir, nil
return op, indir
}
// The local Type was compiled from the actual value, so we know it's compatible.
func (enc *Encoder) compileEnc(rt reflect.Type) (*encEngine, os.Error) {
func (enc *Encoder) compileEnc(rt reflect.Type) *encEngine {
srt, isStruct := rt.(*reflect.StructType)
engine := new(encEngine)
if isStruct {
engine.instr = make([]encInstr, srt.NumField()+1) // +1 for terminator
for fieldnum := 0; fieldnum < srt.NumField(); fieldnum++ {
f := srt.Field(fieldnum)
op, indir, err := enc.encOpFor(f.Type)
if err != nil {
return nil, err
}
op, indir := enc.encOpFor(f.Type)
engine.instr[fieldnum] = encInstr{op, fieldnum, indir, uintptr(f.Offset)}
}
engine.instr[srt.NumField()] = encInstr{encStructTerminator, 0, 0, 0}
} else {
engine.instr = make([]encInstr, 1)
op, indir, err := enc.encOpFor(rt)
if err != nil {
return nil, err
}
op, indir := enc.encOpFor(rt)
engine.instr[0] = encInstr{op, singletonField, indir, 0} // offset is zero
}
return engine, nil
return engine
}
// typeLock must be held (or we're in initialization and guaranteed single-threaded).
// The reflection type must have all its indirections processed out.
func (enc *Encoder) getEncEngine(rt reflect.Type) (*encEngine, os.Error) {
info, err := getTypeInfo(rt)
if err != nil {
return nil, err
func (enc *Encoder) getEncEngine(rt reflect.Type) *encEngine {
info, err1 := getTypeInfo(rt)
if err1 != nil {
error(err1)
}
if info.encoder == nil {
// mark this engine as underway before compiling to handle recursive types.
info.encoder = new(encEngine)
info.encoder, err = enc.compileEnc(rt)
info.encoder = enc.compileEnc(rt)
}
return info.encoder, err
return info.encoder
}
func (enc *Encoder) encode(b *bytes.Buffer, value reflect.Value) os.Error {
// Put this in a function so we can hold the lock only while compiling, not when encoding.
func (enc *Encoder) lockAndGetEncEngine(rt reflect.Type) *encEngine {
typeLock.Lock()
defer typeLock.Unlock()
return enc.getEncEngine(rt)
}
func (enc *Encoder) encode(b *bytes.Buffer, value reflect.Value) (err os.Error) {
defer catchError(&err)
// Dereference down to the underlying object.
rt, indir := indirect(value.Type())
for i := 0; i < indir; i++ {
value = reflect.Indirect(value)
}
typeLock.Lock()
engine, err := enc.getEncEngine(rt)
typeLock.Unlock()
if err != nil {
return err
}
engine := enc.lockAndGetEncEngine(rt)
if value.Type().Kind() == reflect.Struct {
return encodeStruct(engine, b, value.Addr())
encodeStruct(engine, b, value.Addr())
} else {
encodeSingle(engine, b, value.Addr())
}
return encodeSingle(engine, b, value.Addr())
return nil
}
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