diff options
Diffstat (limited to 'vendor/github.com/cespare/xxhash/v2/xxhash_unsafe.go')
-rw-r--r-- | vendor/github.com/cespare/xxhash/v2/xxhash_unsafe.go | 57 |
1 files changed, 0 insertions, 57 deletions
diff --git a/vendor/github.com/cespare/xxhash/v2/xxhash_unsafe.go b/vendor/github.com/cespare/xxhash/v2/xxhash_unsafe.go deleted file mode 100644 index 376e0ca2e..000000000 --- a/vendor/github.com/cespare/xxhash/v2/xxhash_unsafe.go +++ /dev/null @@ -1,57 +0,0 @@ -// +build !appengine - -// This file encapsulates usage of unsafe. -// xxhash_safe.go contains the safe implementations. - -package xxhash - -import ( - "unsafe" -) - -// In the future it's possible that compiler optimizations will make these -// XxxString functions unnecessary by realizing that calls such as -// Sum64([]byte(s)) don't need to copy s. See https://golang.org/issue/2205. -// If that happens, even if we keep these functions they can be replaced with -// the trivial safe code. - -// NOTE: The usual way of doing an unsafe string-to-[]byte conversion is: -// -// var b []byte -// bh := (*reflect.SliceHeader)(unsafe.Pointer(&b)) -// bh.Data = (*reflect.StringHeader)(unsafe.Pointer(&s)).Data -// bh.Len = len(s) -// bh.Cap = len(s) -// -// Unfortunately, as of Go 1.15.3 the inliner's cost model assigns a high enough -// weight to this sequence of expressions that any function that uses it will -// not be inlined. Instead, the functions below use a different unsafe -// conversion designed to minimize the inliner weight and allow both to be -// inlined. There is also a test (TestInlining) which verifies that these are -// inlined. -// -// See https://github.com/golang/go/issues/42739 for discussion. - -// Sum64String computes the 64-bit xxHash digest of s. -// It may be faster than Sum64([]byte(s)) by avoiding a copy. -func Sum64String(s string) uint64 { - b := *(*[]byte)(unsafe.Pointer(&sliceHeader{s, len(s)})) - return Sum64(b) -} - -// WriteString adds more data to d. It always returns len(s), nil. -// It may be faster than Write([]byte(s)) by avoiding a copy. -func (d *Digest) WriteString(s string) (n int, err error) { - d.Write(*(*[]byte)(unsafe.Pointer(&sliceHeader{s, len(s)}))) - // d.Write always returns len(s), nil. - // Ignoring the return output and returning these fixed values buys a - // savings of 6 in the inliner's cost model. - return len(s), nil -} - -// sliceHeader is similar to reflect.SliceHeader, but it assumes that the layout -// of the first two words is the same as the layout of a string. -type sliceHeader struct { - s string - cap int -} |