internal/impl: optimize reflect methods
This change performs two optimizations:
* It uses a pre-constructed rangeInfos slice to iterate over
all the fields. This is more performant since iterating over a slice
is faster than iterating over a map. Furthermore, this slice
does not contain fields that are part of a oneof. If a oneof has
N fields, the time to check presence on the oneof is now O(1)
instead of O(N).
* It uses a dense field info slice that is optmized for the common
case where the field number is relatively low and close in value
to the index itself.
We also fix a minor bug in the construction of oneofInfo where
it wasn't treating a typed nil pointer to a wrapper struct as if
it were unset. This ensures WhichOneof and Has always agree.
name old time/op new time/op delta
Reflect/Has-4 7.81µs ± 3% 6.74µs ± 3% -13.61% (p=0.000 n=9+9)
Reflect/Get-4 12.7µs ± 1% 11.3µs ± 4% -10.85% (p=0.000 n=8+10)
Reflect/Set-4 19.5µs ± 5% 17.8µs ± 2% -8.99% (p=0.000 n=10+10)
Reflect/Clear-4 12.0µs ± 4% 10.2µs ± 3% -14.86% (p=0.000 n=9+10)
Reflect/Range-4 6.58µs ± 1% 4.17µs ± 2% -36.65% (p=0.000 n=8+9)
Change-Id: I2c48b4d3fb6103ab238924950529ded0d37f8c8a
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/196358
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/impl/message_reflect_field.go b/internal/impl/message_reflect_field.go
index e384aa3..63b4055 100644
--- a/internal/impl/message_reflect_field.go
+++ b/internal/impl/message_reflect_field.go
@@ -435,7 +435,11 @@
if rv.IsNil() {
return 0
}
- return wrappersByType[rv.Elem().Type().Elem()]
+ rv = rv.Elem()
+ if rv.IsNil() {
+ return 0
+ }
+ return wrappersByType[rv.Type().Elem()]
},
}
}