gob: updates to the debugging tool.
- complex numbers now supported.
- entirely independent of standard decode code.
- parser has no read-ahead; that is, the scanning works
simply by reading the values as they arrive, not by trying
to count bytes for message boundaries, a proof of concept
for the pending rewrite of the regular decoder.
R=rsc, r2
CC=golang-dev
https://golang.org/cl/4084044
diff --git a/src/pkg/gob/debug.go b/src/pkg/gob/debug.go
index 8d024e0..e458390 100644
--- a/src/pkg/gob/debug.go
+++ b/src/pkg/gob/debug.go
@@ -98,26 +98,38 @@
return n, e
}
+type debugger struct {
+ mutex sync.Mutex
+ remain int // the number of bytes known to remain in the input
+ remainingKnown bool // the value of 'remain' is valid
+ r *peekReader
+ wireType map[typeId]*wireType
+ tmp []byte // scratch space for decoding uints.
+}
+
// dump prints the next nBytes of the input.
// It arranges to print the output aligned from call to
// call, to make it easy to see what has been consumed.
-func (deb *debugger) dump(nBytes int, format string, args ...interface{}) {
+func (deb *debugger) dump(format string, args ...interface{}) {
if !dumpBytes {
return
}
fmt.Fprintf(os.Stderr, format+" ", args...)
- if nBytes < 0 {
- fmt.Fprintf(os.Stderr, "nbytes is negative! %d\n", nBytes)
+ if !deb.remainingKnown {
return
}
- data := make([]byte, nBytes)
+ if deb.remain < 0 {
+ fmt.Fprintf(os.Stderr, "remaining byte count is negative! %d\n", deb.remain)
+ return
+ }
+ data := make([]byte, deb.remain)
n, _ := deb.r.peek(data)
if n == 0 {
os.Stderr.Write(empty)
return
}
b := new(bytes.Buffer)
- fmt.Fprint(b, "{\n")
+ fmt.Fprintf(b, "[%d]{\n", deb.remain)
// Blanks until first byte
lineLength := 0
if n := len(data); n%10 != 0 {
@@ -141,13 +153,6 @@
os.Stderr.Write(b.Bytes())
}
-type debugger struct {
- mutex sync.Mutex
- r *peekReader
- wireType map[typeId]*wireType
- tmp []byte // scratch space for decoding uints.
-}
-
// Debug prints a human-readable representation of the gob data read from r.
func Debug(r io.Reader) {
fmt.Fprintln(os.Stderr, "Start of debugging")
@@ -156,37 +161,36 @@
wireType: make(map[typeId]*wireType),
tmp: make([]byte, 16),
}
+ if b, ok := r.(*bytes.Buffer); ok {
+ deb.remain = b.Len()
+ deb.remainingKnown = true
+ }
deb.gobStream()
}
-// toInt turns an encoded uint64 into an int, according to the marshaling rules.
-func toInt(x uint64) int64 {
- i := int64(x >> 1)
- if x&1 != 0 {
- i = ^i
+// note that we've consumed some bytes
+func (deb *debugger) consumed(n int) {
+ if deb.remainingKnown {
+ deb.remain -= n
}
- return i
}
-// readInt returns the next int, which must be present,
-// and the number of bytes it consumed.
+// int64 decodes and returns the next integer, which must be present.
// Don't call this if you could be at EOF.
-func (deb *debugger) readInt() (i int64, w int) {
- var u uint64
- u, w = deb.readUint()
- return toInt(u), w
+func (deb *debugger) int64() int64 {
+ return toInt(deb.uint64())
}
-// readUint returns the next uint, which must be present.
-// and the number of bytes it consumed.
+// uint64 returns and decodes the next unsigned integer, which must be present.
// Don't call this if you could be at EOF.
// TODO: handle errors better.
-func (deb *debugger) readUint() (x uint64, w int) {
+func (deb *debugger) uint64() uint64 {
n, w, err := decodeUintReader(deb.r, deb.tmp)
if err != nil {
errorf("debug: read error: %s", err)
}
- return n, w
+ deb.consumed(w)
+ return n
}
// GobStream:
@@ -208,8 +212,8 @@
if n < 0 {
return false
}
- deb.dump(int(n), "Message of length %d", n)
- deb.message(indent, n)
+ deb.dump("Delimited message of length %d", n)
+ deb.message(indent)
}
return true
}
@@ -220,18 +224,19 @@
// an EOF is acceptable now. If it is and one is found,
// the return value is negative.
func (deb *debugger) loadBlock(eofOK bool) int {
- n64, _, err := decodeUintReader(deb.r, deb.tmp)
+ n64, w, err := decodeUintReader(deb.r, deb.tmp) // deb.uint64 will error at EOF
if err != nil {
if eofOK && err == os.EOF {
return -1
}
errorf("debug: unexpected error: %s", err)
}
+ deb.consumed(w)
n := int(n64)
if n < 0 {
errorf("huge value for message length: %d", n64)
}
- return n
+ return int(n)
}
// Message:
@@ -242,209 +247,198 @@
// uint(lengthOfTypeDefinition) TypeDefinition
// TypedValue:
// int(typeId) Value
-func (deb *debugger) message(indent tab, n int) bool {
+func (deb *debugger) message(indent tab) bool {
for {
// Convert the uint64 to a signed integer typeId
- uid, w := deb.readInt()
+ uid := deb.int64()
id := typeId(uid)
- n -= w
- deb.dump(n, "type id=%d", id)
+ deb.dump("type id=%d", id)
if id < 0 {
- n -= deb.typeDefinition(indent, -id, n)
- n = deb.loadBlock(false)
- deb.dump(n, "Message of length %d", n)
+ deb.typeDefinition(indent, -id)
+ n := deb.loadBlock(false)
+ deb.dump("Message of length %d", n)
continue
} else {
- deb.value(indent, id, n)
+ deb.value(indent, id)
break
}
}
return true
}
+// Helper methods to make it easy to scan a type descriptor.
+
+// common returns the CommonType at the input point.
+func (deb *debugger) common() CommonType {
+ fieldNum := -1
+ name := ""
+ id := typeId(0)
+ for {
+ delta := deb.delta(-1)
+ if delta == 0 {
+ break
+ }
+ fieldNum += delta
+ switch fieldNum {
+ case 0:
+ name = deb.string()
+ case 1:
+ // Id typeId
+ id = deb.typeId()
+ default:
+ errorf("corrupted CommonType")
+ }
+ }
+ return CommonType{name, id}
+}
+
+// uint returns the unsigned int at the input point, as a uint (not uint64).
+func (deb *debugger) uint() uint {
+ return uint(deb.uint64())
+}
+
+// int returns the signed int at the input point, as an int (not int64).
+func (deb *debugger) int() int {
+ return int(deb.int64())
+}
+
+// typeId returns the type id at the input point.
+func (deb *debugger) typeId() typeId {
+ return typeId(deb.int64())
+}
+
+// string returns the string at the input point.
+func (deb *debugger) string() string {
+ x := int(deb.uint64())
+ b := make([]byte, x)
+ nb, _ := deb.r.Read(b)
+ if nb != x {
+ errorf("corrupted type")
+ }
+ deb.consumed(nb)
+ return string(b)
+}
+
+// delta returns the field delta at the input point. The expect argument,
+// if non-negative, identifies what the value should be.
+func (deb *debugger) delta(expect int) int {
+ delta := int(deb.uint64())
+ if delta < 0 || (expect >= 0 && delta != expect) {
+ errorf("gob decode: corrupted type: delta %d expected %d", delta, expect)
+ }
+ return delta
+}
+
// TypeDefinition:
// [int(-typeId) (already read)] encodingOfWireType
-func (deb *debugger) typeDefinition(indent tab, id typeId, n int) int {
- deb.dump(n, "type definition for id %d", id)
+func (deb *debugger) typeDefinition(indent tab, id typeId) {
+ deb.dump("type definition for id %d", id)
// Encoding is of a wireType. Decode the structure as usual
fieldNum := -1
- m := 0
-
- // Closures to make it easy to scan.
-
- // Read a uint from the input
- getUint := func() uint {
- i, w := deb.readUint()
- m += w
- n -= w
- return uint(i)
- }
- // Read an int from the input
- getInt := func() int {
- i, w := deb.readInt()
- m += w
- n -= w
- return int(i)
- }
- // Read a string from the input
- getString := func() string {
- u, w := deb.readUint()
- x := int(u)
- m += w
- n -= w
- b := make([]byte, x)
- nb, _ := deb.r.Read(b)
- if nb != x {
- errorf("corrupted type")
- }
- m += x
- n -= x
- return string(b)
- }
- // Read a typeId from the input
- getTypeId := func() typeId {
- return typeId(getInt())
- }
- // Read a delta from the input.
- getDelta := func(expect int) int {
- u, w := deb.readUint()
- m += w
- n -= w
- delta := int(u)
- if delta < 0 || (expect >= 0 && delta != expect) {
- errorf("gob decode: corrupted type: delta %d expected %d", delta, expect)
- }
- return int(u)
- }
- // Read a CommonType from the input
- common := func() CommonType {
- fieldNum := -1
- name := ""
- id := typeId(0)
- for {
- delta := getDelta(-1)
- if delta == 0 {
- break
- }
- fieldNum += delta
- switch fieldNum {
- case 0:
- name = getString()
- case 1:
- // Id typeId
- id = getTypeId()
- default:
- errorf("corrupted CommonType")
- }
- }
- return CommonType{name, id}
- }
-
wire := new(wireType)
// A wireType defines a single field.
- delta := getDelta(-1)
+ delta := deb.delta(-1)
fieldNum += delta
switch fieldNum {
case 0: // array type, one field of {{Common}, elem, length}
// Field number 0 is CommonType
- getDelta(1)
- com := common()
+ deb.delta(1)
+ com := deb.common()
// Field number 1 is type Id of elem
- getDelta(1)
- id := getTypeId()
+ deb.delta(1)
+ id := deb.typeId()
// Field number 3 is length
- getDelta(1)
- length := getInt()
+ deb.delta(1)
+ length := deb.int()
wire.ArrayT = &arrayType{com, id, length}
case 1: // slice type, one field of {{Common}, elem}
// Field number 0 is CommonType
- getDelta(1)
- com := common()
+ deb.delta(1)
+ com := deb.common()
// Field number 1 is type Id of elem
- getDelta(1)
- id := getTypeId()
+ deb.delta(1)
+ id := deb.typeId()
wire.SliceT = &sliceType{com, id}
case 2: // struct type, one field of {{Common}, []fieldType}
// Field number 0 is CommonType
- getDelta(1)
- com := common()
+ deb.delta(1)
+ com := deb.common()
// Field number 1 is slice of FieldType
- getDelta(1)
- numField := int(getUint())
+ deb.delta(1)
+ numField := int(deb.uint())
field := make([]*fieldType, numField)
for i := 0; i < numField; i++ {
field[i] = new(fieldType)
- getDelta(1) // field 0 of fieldType: name
- field[i].Name = getString()
- getDelta(1) // field 1 of fieldType: id
- field[i].Id = getTypeId()
- getDelta(0) // end of fieldType
+ deb.delta(1) // field 0 of fieldType: name
+ field[i].Name = deb.string()
+ deb.delta(1) // field 1 of fieldType: id
+ field[i].Id = deb.typeId()
+ deb.delta(0) // end of fieldType
}
wire.StructT = &structType{com, field}
case 3: // map type, one field of {{Common}, key, elem}
// Field number 0 is CommonType
- getDelta(1)
- com := common()
+ deb.delta(1)
+ com := deb.common()
// Field number 1 is type Id of key
- getDelta(1)
- keyId := getTypeId()
+ deb.delta(1)
+ keyId := deb.typeId()
wire.SliceT = &sliceType{com, id}
// Field number 2 is type Id of elem
- getDelta(1)
- elemId := getTypeId()
+ deb.delta(1)
+ elemId := deb.typeId()
wire.MapT = &mapType{com, keyId, elemId}
default:
errorf("bad field in type %d", fieldNum)
}
deb.printWireType(indent, wire)
- getDelta(0) // end inner type (arrayType, etc.)
- getDelta(0) // end wireType
+ deb.delta(0) // end inner type (arrayType, etc.)
+ deb.delta(0) // end wireType
// Remember we've seen this type.
deb.wireType[id] = wire
- return m
}
// Value:
// SingletonValue | StructValue
-func (deb *debugger) value(indent tab, id typeId, n int) int {
+func (deb *debugger) value(indent tab, id typeId) {
wire, ok := deb.wireType[id]
if ok && wire.StructT != nil {
- return deb.structValue(indent, id, n)
+ deb.structValue(indent, id)
+ } else {
+ deb.singletonValue(indent, id)
}
- return deb.singletonValue(indent, id, n)
}
// SingletonValue:
// uint(0) FieldValue
-func (deb *debugger) singletonValue(indent tab, id typeId, n int) int {
- deb.dump(n, "Singleton value")
+func (deb *debugger) singletonValue(indent tab, id typeId) {
+ deb.dump("Singleton value")
// is it a builtin type?
wire := deb.wireType[id]
_, ok := builtinIdToType[id]
if !ok && wire == nil {
errorf("type id %d not defined", id)
}
- m, w := deb.readUint()
+ m := deb.uint64()
if m != 0 {
- errorf("expected zero; got %d", n)
+ errorf("expected zero; got %d", m)
}
- return w + deb.fieldValue(indent, id, n-w)
+ deb.fieldValue(indent, id)
}
// InterfaceValue:
// NilInterfaceValue | NonNilInterfaceValue
-func (deb *debugger) interfaceValue(indent tab, n int) int {
- deb.dump(n, "Start of interface value")
- nameLen, w := deb.readUint()
- n -= w
- if n == 0 {
- return w + deb.nilInterfaceValue(indent)
+func (deb *debugger) interfaceValue(indent tab) {
+ deb.dump("Start of interface value")
+ if nameLen := deb.uint64(); nameLen == 0 {
+ deb.nilInterfaceValue(indent)
+ } else {
+ deb.nonNilInterfaceValue(indent, int(nameLen))
}
- return w + deb.nonNilInterfaceValue(indent, int(nameLen), n)
}
// NilInterfaceValue:
@@ -463,35 +457,27 @@
// int(concreteTypeId) DelimitedValue
// DelimitedValue:
// uint(length) Value
-func (deb *debugger) nonNilInterfaceValue(indent tab, nameLen, n int) int {
+func (deb *debugger) nonNilInterfaceValue(indent tab, nameLen int) {
// ConcreteTypeName
b := make([]byte, nameLen)
deb.r.Read(b) // TODO: CHECK THESE READS!!
- w := nameLen
- n -= nameLen
+ deb.consumed(nameLen)
name := string(b)
- fmt.Fprintf(os.Stderr, "%sinterface value, type %q length %d\n", indent, name, n)
for {
- x, width := deb.readInt()
- n -= w
- w += width
- id := typeId(x)
+ id := deb.typeId()
if id < 0 {
- deb.typeDefinition(indent, -id, n)
- n = deb.loadBlock(false)
- deb.dump(n, "Message of length %d", n)
+ deb.typeDefinition(indent, -id)
+ n := deb.loadBlock(false)
+ deb.dump("Nested message of length %d", n)
} else {
// DelimitedValue
- x, width := deb.readUint() // in case we want to ignore the value; we don't.
- n -= w
- w += width
- fmt.Fprintf(os.Stderr, "%sinterface value, type %q id=%d; length %d\n", indent, name, id, x)
- ZZ := w + deb.value(indent, id, int(x))
- return ZZ
+ x := deb.uint64() // in case we want to ignore the value; we don't.
+ fmt.Fprintf(os.Stderr, "%sinterface value, type %q id=%d; valueLength %d\n", indent, name, id, x)
+ deb.value(indent, id)
+ break
}
}
- panic("not reached")
}
// printCommonType prints a common type; used by printWireType.
@@ -529,13 +515,15 @@
// fieldValue prints a value of any type, such as a struct field.
// FieldValue:
// builtinValue | ArrayValue | MapValue | SliceValue | StructValue | InterfaceValue
-func (deb *debugger) fieldValue(indent tab, id typeId, n int) int {
+func (deb *debugger) fieldValue(indent tab, id typeId) {
_, ok := builtinIdToType[id]
if ok {
if id == tInterface {
- return deb.interfaceValue(indent, n)
+ deb.interfaceValue(indent)
+ } else {
+ deb.printBuiltin(indent, id)
}
- return deb.printBuiltin(indent, id, n)
+ return
}
wire, ok := deb.wireType[id]
if !ok {
@@ -543,105 +531,104 @@
}
switch {
case wire.ArrayT != nil:
- return deb.arrayValue(indent, wire, n)
+ deb.arrayValue(indent, wire)
case wire.MapT != nil:
- return deb.mapValue(indent, wire, n)
+ deb.mapValue(indent, wire)
case wire.SliceT != nil:
- return deb.sliceValue(indent, wire, n)
+ deb.sliceValue(indent, wire)
case wire.StructT != nil:
- return deb.structValue(indent, id, n)
+ deb.structValue(indent, id)
+ default:
+ panic("bad wire type for field")
}
- panic("unreached")
}
// printBuiltin prints a value not of a fundamental type, that is,
// one whose type is known to gobs at bootstrap time.
-func (deb *debugger) printBuiltin(indent tab, id typeId, n int) int {
+func (deb *debugger) printBuiltin(indent tab, id typeId) {
switch id {
case tBool:
- x, w := deb.readInt()
+ x := deb.int64()
if x == 0 {
fmt.Fprintf(os.Stderr, "%sfalse\n", indent)
} else {
fmt.Fprintf(os.Stderr, "%strue\n", indent)
}
- return w
case tInt:
- x, w := deb.readInt()
+ x := deb.int64()
fmt.Fprintf(os.Stderr, "%s%d\n", indent, x)
- return w
case tUint:
- x, w := deb.readInt()
+ x := deb.int64()
fmt.Fprintf(os.Stderr, "%s%d\n", indent, x)
- return w
case tFloat:
- x, w := deb.readUint()
+ x := deb.uint64()
fmt.Fprintf(os.Stderr, "%s%g\n", indent, floatFromBits(x))
- return w
+ case tComplex:
+ r := deb.uint64()
+ i := deb.uint64()
+ fmt.Fprintf(os.Stderr, "%s%g+%gi\n", indent, floatFromBits(r), floatFromBits(i))
case tBytes:
- x, w := deb.readUint()
+ x := int(deb.uint64())
b := make([]byte, x)
deb.r.Read(b)
+ deb.consumed(x)
fmt.Fprintf(os.Stderr, "%s{% x}=%q\n", indent, b, b)
- return w + int(x)
case tString:
- x, w := deb.readUint()
+ x := int(deb.uint64())
b := make([]byte, x)
deb.r.Read(b)
+ deb.consumed(x)
fmt.Fprintf(os.Stderr, "%s%q\n", indent, b)
- return w + int(x)
default:
- fmt.Print("unknown\n")
+ panic("unknown builtin")
}
- panic("unknown builtin")
}
// ArrayValue:
// uint(n) FieldValue*n
-func (deb *debugger) arrayValue(indent tab, wire *wireType, n int) int {
+func (deb *debugger) arrayValue(indent tab, wire *wireType) {
elemId := wire.ArrayT.Elem
- u, w := deb.readUint()
+ u := deb.uint64()
length := int(u)
for i := 0; i < length; i++ {
- w += deb.fieldValue(indent, elemId, n-w)
+ deb.fieldValue(indent, elemId)
}
if length != wire.ArrayT.Len {
fmt.Fprintf(os.Stderr, "%s(wrong length for array: %d should be %d)\n", indent, length, wire.ArrayT.Len)
}
- return w
}
// MapValue:
// uint(n) (FieldValue FieldValue)*n [n (key, value) pairs]
-func (deb *debugger) mapValue(indent tab, wire *wireType, n int) int {
+func (deb *debugger) mapValue(indent tab, wire *wireType) {
keyId := wire.MapT.Key
elemId := wire.MapT.Elem
- u, w := deb.readUint()
+ u := deb.uint64()
length := int(u)
for i := 0; i < length; i++ {
- w += deb.fieldValue(indent+1, keyId, n-w)
- w += deb.fieldValue(indent+1, elemId, n-w)
+ deb.fieldValue(indent+1, keyId)
+ deb.fieldValue(indent+1, elemId)
}
- return w
}
// SliceValue:
// uint(n) (n FieldValue)
-func (deb *debugger) sliceValue(indent tab, wire *wireType, n int) int {
+func (deb *debugger) sliceValue(indent tab, wire *wireType) {
elemId := wire.SliceT.Elem
- u, w := deb.readUint()
+ u := deb.uint64()
length := int(u)
+ deb.dump("Start of slice of length %d", length)
+
for i := 0; i < length; i++ {
- w += deb.fieldValue(indent, elemId, n-w)
+ deb.fieldValue(indent, elemId)
}
- return w
}
// StructValue:
// (uint(fieldDelta) FieldValue)*
-func (deb *debugger) structValue(indent tab, id typeId, n int) int {
- deb.dump(n, "Start of struct value of %q id=%d\n<<\n", id.name(), id)
+func (deb *debugger) structValue(indent tab, id typeId) {
+ deb.dump("Start of struct value of %q id=%d\n<<\n", id.name(), id)
fmt.Fprintf(os.Stderr, "%s%s struct {\n", indent, id.name())
wire, ok := deb.wireType[id]
if !ok {
@@ -650,26 +637,20 @@
strct := wire.StructT
fieldNum := -1
indent++
- w := 0
for {
- delta, wid := deb.readUint()
- w += wid
- n -= wid
+ delta := deb.uint64()
if delta == 0 { // struct terminator is zero delta fieldnum
break
}
fieldNum += int(delta)
if fieldNum < 0 || fieldNum >= len(strct.Field) {
- deb.dump(n, "field number out of range: prevField=%d delta=%d", fieldNum-int(delta), delta)
+ deb.dump("field number out of range: prevField=%d delta=%d", fieldNum-int(delta), delta)
break
}
fmt.Fprintf(os.Stderr, "%sfield %d:\t%s\n", indent, fieldNum, wire.StructT.Field[fieldNum].Name)
- wid = deb.fieldValue(indent+1, strct.Field[fieldNum].Id, n)
- w += wid
- n -= wid
+ deb.fieldValue(indent+1, strct.Field[fieldNum].Id)
}
indent--
fmt.Fprintf(os.Stderr, "%s} // end %s struct\n", indent, id.name())
- deb.dump(n, ">> End of struct value of type %d %q", id, id.name())
- return w
+ deb.dump(">> End of struct value of type %d %q", id, id.name())
}
