What are the changes in the underlying structure of slice in Go language? Is it no longer a SliceHeader, but an unsafeheader.Slice?

The evolution of the underlying structure of Go language Slice

Go version 1.20 has adjusted the underlying structure of Slice, which has attracted the attention of developers, especially for developers who are familiar with reflect.SliceHeader . This article will dig into this change in depth and answer whether reflect.SliceHeader has been deprecated and whether unsafeheader.Slice is its replacement.

background

In Go version 1.20, reflect.SliceHeader and reflect.StringHeader are deprecated, replaced by new structures and functions. This move is designed to enhance security and avoid garbage recycling issues.

Specific changes

Go 1.20 marks reflect.SliceHeader as deprecated, and it is recommended to use unsafe.Slice or unsafe.SliceData instead. The new structure uses unsafe.Pointer instead of uintptr , which improves security and avoids the impact of garbage collection.

 // deprecated: use unsafe.slice or unsafe.slicedata instead.
type sliceheader struct {
    ...
}

The unsafe.Slice structure came into being, and its Data field can ensure that the referenced data will not be garbage collected, which is different from reflect.SliceHeader .

 // Unlike reflect.SliceHeader, its Data field is sufficient to guarantee the
// data it references will not be garbage collected.
type Slice struct {
    ...
}

In addition, Go 1.20 also introduced three new functions: unsafe.SliceData , unsafe.String and unsafe.StringData Together with the unsafe.Slice function introduced in Go 1.17, it provides complete Slice and String value construction and parsing capabilities without relying on its specific representation.

About Go official GitHub repository search

The article mentions the difficulty of searching for code in Go's official GitHub repository. The search function of Go's official GitHub repository does have limitations, especially in terms of code search. It is recommended to use more precise search syntax or other methods to find the required code snippet.

To sum up, Go version 1.20 has adjusted the underlying structure of Slice, reflect.SliceHeader is replaced by unsafe.Slice , and new functions are introduced to support this change. This move improves security and simplifies operations on Slice and String.

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