mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-05-14 02:22:39 +00:00
405 lines
7.6 KiB
Go
405 lines
7.6 KiB
Go
package structr
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import (
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"reflect"
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"sync"
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"unsafe"
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"github.com/zeebo/xxh3"
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)
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var hash_pool sync.Pool
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func get_hasher() *xxh3.Hasher {
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v := hash_pool.Get()
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if v == nil {
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v = new(xxh3.Hasher)
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}
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return v.(*xxh3.Hasher)
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}
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func hash_sum(fields []structfield, h *xxh3.Hasher, key []any) (Hash, bool) {
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if len(key) != len(fields) {
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panicf("incorrect number key parts: want=%d received=%d",
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len(key),
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len(fields),
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)
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}
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var zero bool
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h.Reset()
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for i, part := range key {
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zero = fields[i].hasher(h, part) || zero
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}
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// See: https://github.com/Cyan4973/xxHash/issues/453#issuecomment-696838445
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//
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// In order to extract 32-bit from a good 64-bit hash result,
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// there are many possible choices, which are all valid.
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// I would typically grab the lower 32-bit and call it a day.
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//
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// Grabbing any other 32-bit (the upper part for example) is fine too.
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//
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// xoring higher and lower bits makes more sense whenever the produced hash offers dubious quality.
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// FNV, for example, has poor mixing in its lower bits, so it's better to mix with the higher bits.
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//
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// XXH3 already performs significant output mixing before returning the data,
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// so it's not beneficial to add another xorfold stage.
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return uint64ToHash(h.Sum64()), zero
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}
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func hasher(t reflect.Type) func(*xxh3.Hasher, any) bool {
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switch t.Kind() {
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case reflect.Int,
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reflect.Uint,
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reflect.Uintptr:
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switch unsafe.Sizeof(int(0)) {
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case 4:
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return hash32bit
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case 8:
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return hash64bit
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default:
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panic("unexpected platform int size")
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}
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case reflect.Int8,
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reflect.Uint8:
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return hash8bit
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case reflect.Int16,
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reflect.Uint16:
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return hash16bit
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case reflect.Int32,
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reflect.Uint32,
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reflect.Float32:
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return hash32bit
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case reflect.Int64,
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reflect.Uint64,
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reflect.Float64,
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reflect.Complex64:
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return hash64bit
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case reflect.String:
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return hashstring
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case reflect.Pointer:
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switch t.Elem().Kind() {
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case reflect.Int,
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reflect.Uint,
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reflect.Uintptr:
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switch unsafe.Sizeof(int(0)) {
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case 4:
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return hash32bitptr
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case 8:
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return hash64bitptr
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default:
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panic("unexpected platform int size")
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}
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case reflect.Int8,
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reflect.Uint8:
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return hash8bitptr
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case reflect.Int16,
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reflect.Uint16:
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return hash16bitptr
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case reflect.Int32,
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reflect.Uint32,
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reflect.Float32:
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return hash32bitptr
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case reflect.Int64,
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reflect.Uint64,
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reflect.Float64,
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reflect.Complex64:
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return hash64bitptr
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case reflect.String:
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return hashstringptr
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}
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case reflect.Slice:
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switch t.Elem().Kind() {
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case reflect.Int,
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reflect.Uint,
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reflect.Uintptr:
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switch unsafe.Sizeof(int(0)) {
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case 4:
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return hash32bitslice
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case 8:
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return hash64bitslice
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default:
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panic("unexpected platform int size")
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}
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case reflect.Int8,
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reflect.Uint8:
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return hash8bitslice
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case reflect.Int16,
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reflect.Uint16:
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return hash16bitslice
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case reflect.Int32,
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reflect.Uint32,
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reflect.Float32:
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return hash32bitslice
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case reflect.Int64,
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reflect.Uint64,
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reflect.Float64,
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reflect.Complex64:
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return hash64bitslice
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case reflect.String:
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return hashstringslice
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}
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}
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switch {
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case t.Implements(reflect.TypeOf((*interface{ MarshalBinary() ([]byte, error) })(nil)).Elem()):
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return hashbinarymarshaler
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case t.Implements(reflect.TypeOf((*interface{ Bytes() []byte })(nil)).Elem()):
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return hashbytesmethod
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case t.Implements(reflect.TypeOf((*interface{ String() string })(nil)).Elem()):
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return hashstringmethod
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case t.Implements(reflect.TypeOf((*interface{ MarshalText() ([]byte, error) })(nil)).Elem()):
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return hashtextmarshaler
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case t.Implements(reflect.TypeOf((*interface{ MarshalJSON() ([]byte, error) })(nil)).Elem()):
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return hashjsonmarshaler
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}
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panic("unhashable type")
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}
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func hash8bit(h *xxh3.Hasher, a any) bool {
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u := *(*uint8)(data_ptr(a))
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_, _ = h.Write([]byte{u})
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return u == 0
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}
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func hash8bitptr(h *xxh3.Hasher, a any) bool {
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u := (*uint8)(data_ptr(a))
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if u == nil {
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_, _ = h.Write([]byte{
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0,
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})
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return true
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} else {
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_, _ = h.Write([]byte{
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1,
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byte(*u),
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})
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return false
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}
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}
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func hash8bitslice(h *xxh3.Hasher, a any) bool {
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b := *(*[]byte)(data_ptr(a))
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_, _ = h.Write(b)
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return b == nil
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}
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func hash16bit(h *xxh3.Hasher, a any) bool {
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u := *(*uint16)(data_ptr(a))
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_, _ = h.Write([]byte{
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byte(u),
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byte(u >> 8),
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})
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return u == 0
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}
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func hash16bitptr(h *xxh3.Hasher, a any) bool {
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u := (*uint16)(data_ptr(a))
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if u == nil {
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_, _ = h.Write([]byte{
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0,
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})
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return true
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} else {
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_, _ = h.Write([]byte{
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1,
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byte(*u),
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byte(*u >> 8),
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})
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return false
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}
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}
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func hash16bitslice(h *xxh3.Hasher, a any) bool {
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u := *(*[]uint16)(data_ptr(a))
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for i := range u {
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_, _ = h.Write([]byte{
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byte(u[i]),
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byte(u[i] >> 8),
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})
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}
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return u == nil
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}
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func hash32bit(h *xxh3.Hasher, a any) bool {
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u := *(*uint32)(data_ptr(a))
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_, _ = h.Write([]byte{
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byte(u),
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byte(u >> 8),
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byte(u >> 16),
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byte(u >> 24),
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})
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return u == 0
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}
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func hash32bitptr(h *xxh3.Hasher, a any) bool {
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u := (*uint32)(data_ptr(a))
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if u == nil {
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_, _ = h.Write([]byte{
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0,
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})
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return true
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} else {
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_, _ = h.Write([]byte{
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1,
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byte(*u),
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byte(*u >> 8),
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byte(*u >> 16),
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byte(*u >> 24),
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})
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return false
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}
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}
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func hash32bitslice(h *xxh3.Hasher, a any) bool {
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u := *(*[]uint32)(data_ptr(a))
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for i := range u {
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_, _ = h.Write([]byte{
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byte(u[i]),
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byte(u[i] >> 8),
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byte(u[i] >> 16),
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byte(u[i] >> 24),
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})
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}
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return u == nil
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}
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func hash64bit(h *xxh3.Hasher, a any) bool {
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u := *(*uint64)(data_ptr(a))
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_, _ = h.Write([]byte{
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byte(u),
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byte(u >> 8),
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byte(u >> 16),
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byte(u >> 24),
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byte(u >> 32),
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byte(u >> 40),
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byte(u >> 48),
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byte(u >> 56),
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})
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return u == 0
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}
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func hash64bitptr(h *xxh3.Hasher, a any) bool {
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u := (*uint64)(data_ptr(a))
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if u == nil {
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_, _ = h.Write([]byte{
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0,
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})
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return true
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} else {
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_, _ = h.Write([]byte{
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1,
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byte(*u),
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byte(*u >> 8),
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byte(*u >> 16),
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byte(*u >> 24),
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byte(*u >> 32),
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byte(*u >> 40),
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byte(*u >> 48),
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byte(*u >> 56),
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})
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return false
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}
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}
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func hash64bitslice(h *xxh3.Hasher, a any) bool {
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u := *(*[]uint64)(data_ptr(a))
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for i := range u {
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_, _ = h.Write([]byte{
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byte(u[i]),
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byte(u[i] >> 8),
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byte(u[i] >> 16),
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byte(u[i] >> 24),
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byte(u[i] >> 32),
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byte(u[i] >> 40),
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byte(u[i] >> 48),
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byte(u[i] >> 56),
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})
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}
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return u == nil
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}
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func hashstring(h *xxh3.Hasher, a any) bool {
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s := *(*string)(data_ptr(a))
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_, _ = h.WriteString(s)
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return s == ""
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}
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func hashstringptr(h *xxh3.Hasher, a any) bool {
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s := (*string)(data_ptr(a))
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if s == nil {
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_, _ = h.Write([]byte{
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0,
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})
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return true
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} else {
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_, _ = h.Write([]byte{
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1,
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})
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_, _ = h.WriteString(*s)
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return false
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}
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}
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func hashstringslice(h *xxh3.Hasher, a any) bool {
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s := *(*[]string)(data_ptr(a))
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for i := range s {
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_, _ = h.WriteString(s[i])
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}
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return s == nil
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}
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func hashbinarymarshaler(h *xxh3.Hasher, a any) bool {
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i := a.(interface{ MarshalBinary() ([]byte, error) })
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b, _ := i.MarshalBinary()
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_, _ = h.Write(b)
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return b == nil
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}
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func hashbytesmethod(h *xxh3.Hasher, a any) bool {
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i := a.(interface{ Bytes() []byte })
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b := i.Bytes()
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_, _ = h.Write(b)
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return b == nil
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}
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func hashstringmethod(h *xxh3.Hasher, a any) bool {
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i := a.(interface{ String() string })
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s := i.String()
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_, _ = h.WriteString(s)
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return s == ""
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}
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func hashtextmarshaler(h *xxh3.Hasher, a any) bool {
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i := a.(interface{ MarshalText() ([]byte, error) })
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b, _ := i.MarshalText()
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_, _ = h.Write(b)
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return b == nil
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}
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func hashjsonmarshaler(h *xxh3.Hasher, a any) bool {
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i := a.(interface{ MarshalJSON() ([]byte, error) })
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b, _ := i.MarshalJSON()
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_, _ = h.Write(b)
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return b == nil
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}
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