Comments (3)
ping @pborman
from uuid.
The pool API looks pretty dangerous and unnecessary to me also.
The speed gain comes almost entirely from the buffered I/O, which did not require a new API. The remaining allocation is the UUID
itself which could be improved in a generally-useful way by having a function to fill a received pointer:
func NewRandomFromReader(r io.Reader) (UUID, error) {
var uuid UUID
return uuid, ReadRandom(r, &uuid)
}
func ReadRandom(r io.Reader, uuid *UUID) error {
_, err := io.ReadFull(r, uuid[:])
if err != nil {
return err
}
uuid[6] = (uuid[6] & 0x0f) | 0x40 // Version 4
uuid[8] = (uuid[8] & 0x3f) | 0x80 // Variant is 10
return nil
}
func BenchmarkUUID_NewBufio(b *testing.B) {
b.RunParallel(func(pb *testing.PB) {
r := bufio.NewReaderSize(rander, randPoolSize)
for pb.Next() {
_, err := NewRandomFromReader(r)
if err != nil {
b.Fatal(err)
}
}
})
}
func BenchmarkUUID_ReadRandom(b *testing.B) {
b.RunParallel(func(pb *testing.PB) {
r := bufio.NewReaderSize(rander, randPoolSize)
var uuid UUID
for pb.Next() {
err := ReadRandom(r, &uuid)
if err != nil {
b.Fatal(err)
}
}
})
}
BenchmarkUUID_NewBufio-4 6769986 176.0 ns/op 16 B/op 1 allocs/op
BenchmarkUUID_ReadRandom-4 7622210 155.6 ns/op 0 B/op 0 allocs/op
These are also lock-free (or as lock-free as the reader allows) approaches. On my system ReadRandom
consistently beats NewPooled
, I assume because of less lock contention.
from uuid.
As mentioned i a code review, these should be limited to package main. Libraries that want a different generator should call a different function. The good new is, that unlike Version 1 UUIDs, Version 4 uuids can be safely generated by multiple packages. Version 1 UUIDs are based on state and it is possible (though unlikely) for two packages to produce either the same UUIDs or UUIDs in which time goes backwards.
from uuid.
Related Issues (20)
- Is there a method to generate empty UUID v4? HOT 2
- UUID with repeat ending HOT 2
- NullUUID Scan method returns valid true on empty string HOT 2
- [Documentation] uuid.Nil is not documented properly
- `IsZero()` and `ToNullUUID` Helper Functions HOT 2
- panic: uuid: Parse(): invalid UUID length: 0 HOT 3
- Should uuid.Nil marshal to null instead of all zeroes HOT 5
- Make uuid.Nil and other values as a constant HOT 1
- Cannot get the package, connection refused
- uuid.Parse allows invalid UUID's HOT 2
- recommended to add uuid v6 and v7 support HOT 1
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- Monotonicity in UUIDv7 HOT 2
- proposal: add func uuid.Compare(a, b UUID) int HOT 4
- Incorrect uuidv6 implementation HOT 1
- uuid.Parse function does not handle empty string HOT 3
- uuid.NewString use UUID v7 instead of v4 HOT 6
- Allow to use something different than `time.Now` when generating uuids that have a time component HOT 1
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from uuid.