Making Value opaque means we can drop the interface kludges
in favor of a significantly simpler and faster representation.
v.Kind() will be a prime candidate for inlining too.
On a Thinkpad X201s using -benchtime 10:
benchmark old ns/op new ns/op delta
json.BenchmarkCodeEncoder 284391780 157415960 -44.65%
json.BenchmarkCodeMarshal 286979140 158992020 -44.60%
json.BenchmarkCodeDecoder 717175800 388288220 -45.86%
json.BenchmarkCodeUnmarshal 734470500 404548520 -44.92%
json.BenchmarkCodeUnmarshalReuse 707172280 385258720 -45.52%
json.BenchmarkSkipValue 24630036 18557062 -24.66%
benchmark old MB/s new MB/s speedup
json.BenchmarkCodeEncoder 6.82 12.33 1.81x
json.BenchmarkCodeMarshal 6.76 12.20 1.80x
json.BenchmarkCodeDecoder 2.71 5.00 1.85x
json.BenchmarkCodeUnmarshal 2.64 4.80 1.82x
json.BenchmarkCodeUnmarshalReuse 2.74 5.04 1.84x
json.BenchmarkSkipValue 77.92 103.42 1.33x
I cannot explain why BenchmarkSkipValue gets faster.
Maybe it is one of those code alignment things.
R=iant, r, gri, r
CC=golang-dev
https://golang.org/cl/5373101
Got rid of all the magic mystery globals. Now
for %N, %T, and %S, the flags +,- and # set a sticky
debug, sym and export mode, only visible in the new fmt.c.
Default is error mode. Handle h and l flags consistently with
the least side effects, so we can now change
things without worrying about unrelated things
breaking.
fixes#2361
R=rsc
CC=golang-dev
https://golang.org/cl/5316043
Had been allowing it for use by fmt, but it is too hard to lock down.
Fix other packages not to depend on it.
R=r, r
CC=golang-dev
https://golang.org/cl/5266054
This allows code that wants to handle
[]byte separately to get at the actual slice
instead of just at individual bytes.
It seems to come up often enough.
R=r
CC=golang-dev
https://golang.org/cl/4942051
Each package using struct field tags assumes that
it is the only package storing data in the tag.
This CL adds support in package reflect for sharing
tags between multiple packages. In this scheme, the
tags must be of the form
key:"value" key2:"value2"
(raw strings help when writing that tag in Go source).
reflect.StructField's Tag field now has type StructTag
(a string type), which has method Get(key string) string
that returns the associated value.
Clients of json and xml will need to be updated.
Code that says
type T struct {
X int "name"
}
should become
type T struct {
X int `json:"name"` // or `xml:"name"`
}
Use govet to identify struct tags that need to be changed
to use the new syntax.
R=r, r, dsymonds, bradfitz, kevlar, fvbommel, n13m3y3r
CC=golang-dev
https://golang.org/cl/4645069
When GOMAXPROCS>1, the testing framework runs in parallel with the
test itself and may do a small number of allocations, so allow the
"noAllocs" condition to admit just a few.
Fixes#1782.
R=rsc
CC=golang-dev, rsc
https://golang.org/cl/4533041
go/types: update for export data format change
reflect: require package qualifiers to match during interface check
runtime: require package qualifiers to match during interface check
test: fixed bug324, adapt to be silent
Fixes#1550.
Issue 1536 remains open.
R=gri, ken2, r
CC=golang-dev
https://golang.org/cl/4442071
This CL makes reflect require that values be assignable to the target type
in exactly the same places where that is the rule in Go. It also adds
the Implements and AssignableTo methods so that callers can check
the types themselves so as to avoid a panic.
Before this CL, reflect required strict type identity.
This CL expands Call to accept and correctly marshal arbitrary
argument lists for variadic functions; it introduces CallSlice for use
in the case where the slice for the variadic argument is already known.
Fixes#327.
Fixes#1212.
R=r, dsymonds
CC=golang-dev
https://golang.org/cl/4439058
* Reduces malloc counts during gob encoder/decoder test from 6/6 to 3/5.
The current reflect uses Set to mean two subtly different things.
(1) If you have a reflect.Value v, it might just represent
itself (as in v = reflect.NewValue(42)), in which case calling
v.Set only changed v, not any other data in the program.
(2) If you have a reflect Value v derived from a pointer
or a slice (as in x := []int{42}; v = reflect.NewValue(x).Index(0)),
v represents the value held there. Changing x[0] affects the
value returned by v.Int(), and calling v.Set affects x[0].
This was not really by design; it just happened that way.
The motivation for the new reflect implementation was
to remove mallocs. The use case (1) has an implicit malloc
inside it. If you can do:
v := reflect.NewValue(0)
v.Set(42)
i := v.Int() // i = 42
then that implies that v is referring to some underlying
chunk of memory in order to remember the 42; that is,
NewValue must have allocated some memory.
Almost all the time you are using reflect the goal is to
inspect or to change other data, not to manipulate data
stored solely inside a reflect.Value.
This CL removes use case (1), so that an assignable
reflect.Value must always refer to some other piece of data
in the program. Put another way, removing this case would
make
v := reflect.NewValue(0)
v.Set(42)
as illegal as
0 = 42.
It would also make this illegal:
x := 0
v := reflect.NewValue(x)
v.Set(42)
for the same reason. (Note that right now, v.Set(42) "succeeds"
but does not change the value of x.)
If you really wanted to make v refer to x, you'd start with &x
and dereference it:
x := 0
v := reflect.NewValue(&x).Elem() // v = *&x
v.Set(42)
It's pretty rare, except in tests, to want to use NewValue and then
call Set to change the Value itself instead of some other piece of
data in the program. I haven't seen it happen once yet while
making the tree build with this change.
For the same reasons, reflect.Zero (formerly reflect.MakeZero)
would also return an unassignable, unaddressable value.
This invalidates the (awkward) idiom:
pv := ... some Ptr Value we have ...
v := reflect.Zero(pv.Type().Elem())
pv.PointTo(v)
which, when the API changed, turned into:
pv := ... some Ptr Value we have ...
v := reflect.Zero(pv.Type().Elem())
pv.Set(v.Addr())
In both, it is far from clear what the code is trying to do. Now that
it is possible, this CL adds reflect.New(Type) Value that does the
obvious thing (same as Go's new), so this code would be replaced by:
pv := ... some Ptr Value we have ...
pv.Set(reflect.New(pv.Type().Elem()))
The changes just described can be confusing to think about,
but I believe it is because the old API was confusing - it was
conflating two different kinds of Values - and that the new API
by itself is pretty simple: you can only Set (or call Addr on)
a Value if it actually addresses some real piece of data; that is,
only if it is the result of dereferencing a Ptr or indexing a Slice.
If you really want the old behavior, you'd get it by translating:
v := reflect.NewValue(x)
into
v := reflect.New(reflect.Typeof(x)).Elem()
v.Set(reflect.NewValue(x))
Gofix will not be able to help with this, because whether
and how to change the code depends on whether the original
code meant use (1) or use (2), so the developer has to read
and think about the code.
You can see the effect on packages in the tree in
https://golang.org/cl/4423043/.
R=r
CC=golang-dev
https://golang.org/cl/4435042
Type is now an interface that implements all the possible type methods.
Instead of a type switch on a reflect.Type t, switch on t.Kind().
If a method is invoked on the wrong kind of type (for example,
calling t.Field(0) when t.Kind() != Struct), the call panics.
There is one method renaming: t.(*ChanType).Dir() is now t.ChanDir().
Value is now a struct value that implements all the possible value methods.
Instead of a type switch on a reflect.Value v, switch on v.Kind().
If a method is invoked on the wrong kind of value (for example,
calling t.Recv() when t.Kind() != Chan), the call panics.
Since Value is now a struct, not an interface, its zero value
cannot be compared to nil. Instead of v != nil, use v.IsValid().
Instead of other uses of nil as a Value, use Value{}, the zero value.
Many methods have been renamed, most due to signature conflicts:
OLD NEW
v.(*ArrayValue).Elem v.Index
v.(*BoolValue).Get v.Bool
v.(*BoolValue).Set v.SetBool
v.(*ChanType).Dir v.ChanDir
v.(*ChanValue).Get v.Pointer
v.(*ComplexValue).Get v.Complex
v.(*ComplexValue).Overflow v.OverflowComplex
v.(*ComplexValue).Set v.SetComplex
v.(*FloatValue).Get v.Float
v.(*FloatValue).Overflow v.OverflowFloat
v.(*FloatValue).Set v.SetFloat
v.(*FuncValue).Get v.Pointer
v.(*InterfaceValue).Get v.InterfaceData
v.(*IntValue).Get v.Int
v.(*IntValue).Overflow v.OverflowInt
v.(*IntValue).Set v.SetInt
v.(*MapValue).Elem v.MapIndex
v.(*MapValue).Get v.Pointer
v.(*MapValue).Keys v.MapKeys
v.(*MapValue).SetElem v.SetMapIndex
v.(*PtrValue).Get v.Pointer
v.(*SliceValue).Elem v.Index
v.(*SliceValue).Get v.Pointer
v.(*StringValue).Get v.String
v.(*StringValue).Set v.SetString
v.(*UintValue).Get v.Uint
v.(*UintValue).Overflow v.OverflowUint
v.(*UintValue).Set v.SetUint
v.(*UnsafePointerValue).Get v.Pointer
v.(*UnsafePointerValue).Set v.SetPointer
Part of the motivation for this change is to enable a more
efficient implementation of Value, one that does not allocate
memory during most operations. To reduce the size of the CL,
this CL's implementation is a wrapper around the old API.
Later CLs will make the implementation more efficient without
changing the API.
Other CLs to be submitted at the same time as this one
add support for this change to gofix (4343047) and update
the Go source tree (4353043).
R=gri, iant, niemeyer, r, rog, gustavo, r2
CC=golang-dev
https://golang.org/cl/4281055
This change makes it possible to take the address of a
struct field or slice element in order to call a method that
requires a pointer receiver.
Existing code that uses the Value.Addr method will have
to change (as gob does in this CL) to call UnsafeAddr instead.
R=r, rog
CC=golang-dev
https://golang.org/cl/4239052
I have written a tool to verify Printf calls, and although it's not
ready to be reviewed yet it's already uncovered a spate of problems
in the repository. I'm sending this CL to break the changes into
pieces; as the tool improves it will find more, I'm sure.
R=rsc
CC=golang-dev
https://golang.org/cl/3427043
(Argument: For any *PtrValue p, it should
always be possible to do: p.PointTo(p.Elem()),
even if p.Elem() is nil.)
Fixes#1028.
R=rsc
CC=golang-dev, r
https://golang.org/cl/1938044
parsing and printing to new syntax.
Use -oldparser to parse the old syntax,
use -oldprinter to print the old syntax.
2) Change default gofmt formatting settings
to use tabs for indentation only and to use
spaces for alignment. This will make the code
alignment insensitive to an editor's tabwidth.
Use -spaces=false to use tabs for alignment.
3) Manually changed src/exp/parser/parser_test.go
so that it doesn't try to parse the parser's
source files using the old syntax (they have
new syntax now).
4) gofmt -w src misc test/bench
4th set of files.
R=rsc
CC=golang-dev
https://golang.org/cl/180049
- enabled for function declarations (not just function literals)
- applied gofmt -w $GOROOT/src
(look for instance at src/pkg/debug/elf/elf.go)
R=r, rsc
CC=go-dev
http://go/go-review/1026006
