optimize copying slice when toValue and fromValue are different types#238
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tujun233 wants to merge 1 commit intojinzhu:masterfrom
Open
optimize copying slice when toValue and fromValue are different types#238tujun233 wants to merge 1 commit intojinzhu:masterfrom
tujun233 wants to merge 1 commit intojinzhu:masterfrom
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Pull request overview
This PR aims to speed up slice copying when source and destination slices have different element types by avoiding a redundant second deep-copy pass for each element.
Changes:
- Simplifies slice element assignment in
copier()by directlySet-ing the computeddestintoto[i]when types are assignable. - Removes the
set(...)/copier(...)fallback previously used when overwriting an existing slice element.
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| if isSlice && to.Kind() == reflect.Slice { | ||
| if dest.Addr().Type().AssignableTo(to.Type().Elem()) { | ||
| if to.Len() < i+1 { | ||
| to.Set(reflect.Append(to, dest.Addr())) | ||
| } else { | ||
| isSet, err := set(to.Index(i), dest.Addr(), opt.DeepCopy, converters) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if !isSet { | ||
| // ignore error while copy slice element | ||
| err = copier(to.Index(i).Addr().Interface(), dest.Addr().Interface(), opt) | ||
| if err != nil { | ||
| continue | ||
| } | ||
| } | ||
| to.Index(i).Set(dest.Addr()) | ||
| } |
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| if isSlice && to.Kind() == reflect.Slice { | ||
| if dest.Addr().Type().AssignableTo(to.Type().Elem()) { | ||
| if to.Len() < i+1 { | ||
| to.Set(reflect.Append(to, dest.Addr())) | ||
| } else { | ||
| isSet, err := set(to.Index(i), dest.Addr(), opt.DeepCopy, converters) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if !isSet { | ||
| // ignore error while copy slice element | ||
| err = copier(to.Index(i).Addr().Interface(), dest.Addr().Interface(), opt) | ||
| if err != nil { | ||
| continue | ||
| } | ||
| } | ||
| to.Index(i).Set(dest.Addr()) | ||
| } | ||
| } else if dest.Type().AssignableTo(to.Type().Elem()) { | ||
| if to.Len() < i+1 { | ||
| to.Set(reflect.Append(to, dest)) | ||
| } else { | ||
| isSet, err := set(to.Index(i), dest, opt.DeepCopy, converters) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if !isSet { | ||
| // ignore error while copy slice element | ||
| err = copier(to.Index(i).Addr().Interface(), dest.Interface(), opt) | ||
| if err != nil { | ||
| continue | ||
| } | ||
| } | ||
| to.Index(i).Set(dest) | ||
| } |
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Hi !
when using copier, I found a problem that when dst and src are different type slice, existing code will perform two deep-copy for one element in a slice (from -> dest and dest -> to).
when I perform a deepcopy from []*model.XXX to []*business.XXX, the second picture shows that the fromValue of next stack becomes a business.XXX. It will affect the speed of copying. dest is already deepcopy of from, so I think directly using .set is ok.