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gob: several fixes.

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1) Be sure to use the eval-time encoder/decoder rather than
the compile-time decoder.  In a few cases the receiver for
the compiling encoder was being pickled incorrectly into a
closure.
(This is the fix for issue 1238).

2) Get the innermost name right when given a pointer to an
unnamed type.

3) Use a count to delineate interface values, making it
possible to ignore values without having a concrete type
to encode into.  This is a protocol change but only for the
new feature, so it shouldn't affect anyone.  The old test
worked because, amazingly, it depended on bug #1.

Fixes #1238.

R=rsc, albert.strasheim
CC=golang-dev
https://golang.org/cl/2806041
This commit is contained in:
Rob Pike 2010-10-31 13:41:30 -07:00
parent f62772b1e5
commit 7f7cb166c8
7 changed files with 104 additions and 77 deletions
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47
src/pkg/gob/encode.go
View file

@ -20,14 +20,15 @@ const uint64Size = unsafe.Sizeof(uint64(0))
// number is initialized to -1 so 0 comes out as delta(1). A delta of
// 0 terminates the structure.
type encoderState struct {
enc *Encoder
b *bytes.Buffer
sendZero bool // encoding an array element or map key/value pair; send zero values
fieldnum int // the last field number written.
buf [1 + uint64Size]byte // buffer used by the encoder; here to avoid allocation.
}
func newEncoderState(b *bytes.Buffer) *encoderState {
return &encoderState{b: b}
func newEncoderState(enc *Encoder, b *bytes.Buffer) *encoderState {
return &encoderState{enc: enc, b: b}
}
// Unsigned integers have a two-state encoding. If the number is less
@ -318,8 +319,8 @@ type encEngine struct {
const singletonField = 0
func encodeSingle(engine *encEngine, b *bytes.Buffer, basep uintptr) {
state := newEncoderState(b)
func (enc *Encoder) encodeSingle(b *bytes.Buffer, engine *encEngine, basep uintptr) {
state := newEncoderState(enc, b)
state.fieldnum = singletonField
// There is no surrounding struct to frame the transmission, so we must
// generate data even if the item is zero. To do this, set sendZero.
@ -334,8 +335,8 @@ func encodeSingle(engine *encEngine, b *bytes.Buffer, basep uintptr) {
instr.op(instr, state, p)
}
func encodeStruct(engine *encEngine, b *bytes.Buffer, basep uintptr) {
state := newEncoderState(b)
func (enc *Encoder) encodeStruct(b *bytes.Buffer, engine *encEngine, basep uintptr) {
state := newEncoderState(enc, b)
state.fieldnum = -1
for i := 0; i < len(engine.instr); i++ {
instr := &engine.instr[i]
@ -349,8 +350,8 @@ func encodeStruct(engine *encEngine, b *bytes.Buffer, basep uintptr) {
}
}
func encodeArray(b *bytes.Buffer, p uintptr, op encOp, elemWid uintptr, elemIndir int, length int) {
state := newEncoderState(b)
func (enc *Encoder) encodeArray(b *bytes.Buffer, p uintptr, op encOp, elemWid uintptr, elemIndir int, length int) {
state := newEncoderState(enc, b)
state.fieldnum = -1
state.sendZero = true
encodeUint(state, uint64(length))
@ -378,8 +379,8 @@ func encodeReflectValue(state *encoderState, v reflect.Value, op encOp, indir in
op(nil, state, unsafe.Pointer(v.Addr()))
}
func encodeMap(b *bytes.Buffer, mv *reflect.MapValue, keyOp, elemOp encOp, keyIndir, elemIndir int) {
state := newEncoderState(b)
func (enc *Encoder) encodeMap(b *bytes.Buffer, mv *reflect.MapValue, keyOp, elemOp encOp, keyIndir, elemIndir int) {
state := newEncoderState(enc, b)
state.fieldnum = -1
state.sendZero = true
keys := mv.Keys()
@ -395,7 +396,7 @@ func encodeMap(b *bytes.Buffer, mv *reflect.MapValue, keyOp, elemOp encOp, keyIn
// by the concrete value. A nil value gets sent as the empty string for the name,
// followed by no value.
func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv *reflect.InterfaceValue) {
state := newEncoderState(b)
state := newEncoderState(enc, b)
state.fieldnum = -1
state.sendZero = true
if iv.IsNil() {
@ -416,8 +417,14 @@ func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv *reflect.InterfaceValue)
}
// Send (and maybe first define) the type id.
enc.sendTypeDescriptor(typ)
// Send the value.
err = enc.encode(state.b, iv.Elem())
// Encode the value into a new buffer.
data := new(bytes.Buffer)
err = enc.encode(data, iv.Elem())
if err != nil {
error(err)
}
encodeUint(state, uint64(data.Len()))
_, err = state.b.Write(data.Bytes())
if err != nil {
error(err)
}
@ -470,14 +477,14 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
return
}
state.update(i)
encodeArray(state.b, slice.Data, elemOp, t.Elem().Size(), indir, int(slice.Len))
state.enc.encodeArray(state.b, slice.Data, elemOp, t.Elem().Size(), indir, int(slice.Len))
}
case *reflect.ArrayType:
// True arrays have size in the type.
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())
state.enc.encodeArray(state.b, uintptr(p), elemOp, t.Elem().Size(), indir, t.Len())
}
case *reflect.MapType:
keyOp, keyIndir := enc.encOpFor(t.Key())
@ -492,7 +499,7 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
return
}
state.update(i)
encodeMap(state.b, mv, keyOp, elemOp, keyIndir, elemIndir)
state.enc.encodeMap(state.b, mv, keyOp, elemOp, keyIndir, elemIndir)
}
case *reflect.StructType:
// Generate a closure that calls out to the engine for the nested type.
@ -501,7 +508,7 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
state.update(i)
// indirect through info to delay evaluation for recursive structs
encodeStruct(info.encoder, state.b, uintptr(p))
state.enc.encodeStruct(state.b, info.encoder, uintptr(p))
}
case *reflect.InterfaceType:
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
@ -513,7 +520,7 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
return
}
state.update(i)
enc.encodeInterface(state.b, iv)
state.enc.encodeInterface(state.b, iv)
}
}
}
@ -574,9 +581,9 @@ func (enc *Encoder) encode(b *bytes.Buffer, value reflect.Value) (err os.Error)
}
engine := enc.lockAndGetEncEngine(rt)
if value.Type().Kind() == reflect.Struct {
encodeStruct(engine, b, value.Addr())
enc.encodeStruct(b, engine, value.Addr())
} else {
encodeSingle(engine, b, value.Addr())
enc.encodeSingle(b, engine, value.Addr())
}
return nil
}