The embedded `nocmp` field and other similar fields are unused in tests
and the rest of our code.
We can get the effect of `nocmp` without embedding the fields by using
`_ nocmp` as a field.
Add safe `String()` methods for atomic types that replicate the same
behavior as `fmt.Sprintf("%v", x.Load())` without the allocations.
As with json.Marshaler/Unmarshaler, we've omitted the `atomic.Value`
type for now.
Resolves#50
It is currently possible to make non-atomic comparisons of atomic
values:
x := atomic.NewInt32(1)
y := atomic.NewInt32(1)
fmt.Println(*x == *y)
This is undesirable because it loads the value in a non-atomic way. The
correct method is,
x := atomic.NewInt32(1)
y := atomic.NewInt32(1)
fmt.Println(x.Load() == y.Load())
To prevent this, disallow comparison of atomic values by embedding an
uncomparable array into atomics. The empty array adds no runtime cost,
and does not increase the in-memory size of the structs. Inspired by
[go4.org/mem#RO][1].
[1]: 3dbcd07079/mem.go (L42)
Note that the Value struct, which embeds `"sync/atomic".Value` was also
changed. This will break usages in the following form, but that's
acceptable because unkeyed struct literals are among the exceptions
stated in the [Go 1 compatibility expectations][2].
import (
syncatomic "sync/atomic"
"go.uber.org/atomic"
)
atomic.Value{syncatomic.Value{..}}
[2]: https://golang.org/doc/go1compat#expectationsResolves#72
Generated files should contain the following comment in the first few
lines for them to be considered generated by GitHub.
Code generated by <executable>
The additional `@generated` tag does the same for Phabricator.
Rather than hand-writing the atomic integers, generate them
automatically from the same template. The generator is at
internal/gen-atomicint.
To ensure these are never out of date, add another `make` target which
verifies that the working tree is left unchanged after regenerating
code.
In anticipation of automatically generating these definitions, pull the
definitions of the various integer types into their own files as well as
their tests.
This will make it easier to review the changes when each of these files
is generated independently and automatically.
