chore: migrate to gitea

vendor/go.opentelemetry.io/otel/attribute/set.go

@@ -0,0 +1,436 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package attribute // import "go.opentelemetry.io/otel/attribute"
+
+import (
+	"cmp"
+	"encoding/json"
+	"reflect"
+	"slices"
+	"sort"
+
+	"go.opentelemetry.io/otel/attribute/internal/xxhash"
+)
+
+type (
+	// Set is the representation for a distinct attribute set. It manages an
+	// immutable set of attributes, with an internal cache for storing
+	// attribute encodings.
+	//
+	// This type will remain comparable for backwards compatibility. The
+	// equivalence of Sets across versions is not guaranteed to be stable.
+	// Prior versions may find two Sets to be equal or not when compared
+	// directly (i.e. ==), but subsequent versions may not. Users should use
+	// the Equals method to ensure stable equivalence checking.
+	//
+	// Users should also use the Distinct returned from Equivalent as a map key
+	// instead of a Set directly. Set has relatively poor performance when used
+	// as a map key compared to Distinct.
+	Set struct {
+		hash uint64
+		data any
+	}
+
+	// Distinct is an identifier of a Set which is very likely to be unique.
+	//
+	// Distinct should be used as a map key instead of a Set for to provide better
+	// performance for map operations.
+	Distinct struct {
+		hash uint64
+	}
+
+	// Sortable implements sort.Interface, used for sorting KeyValue.
+	//
+	// Deprecated: This type is no longer used. It was added as a performance
+	// optimization for Go < 1.21 that is no longer needed (Go < 1.21 is no
+	// longer supported by the module).
+	Sortable []KeyValue
+)
+
+// Compile time check these types remain comparable.
+var (
+	_ = isComparable(Set{})
+	_ = isComparable(Distinct{})
+)
+
+func isComparable[T comparable](t T) T { return t }
+
+var (
+	// keyValueType is used in computeDistinctReflect.
+	keyValueType = reflect.TypeOf(KeyValue{})
+
+	// emptyHash is the hash of an empty set.
+	emptyHash = xxhash.New().Sum64()
+
+	// userDefinedEmptySet is an empty set. It was mistakenly exposed to users
+	// as something they can assign to, so it must remain addressable and
+	// mutable.
+	//
+	// This is kept for backwards compatibility, but should not be used in new code.
+	userDefinedEmptySet = &Set{
+		hash: emptyHash,
+		data: [0]KeyValue{},
+	}
+
+	emptySet = Set{
+		hash: emptyHash,
+		data: [0]KeyValue{},
+	}
+)
+
+// EmptySet returns a reference to a Set with no elements.
+//
+// This is a convenience provided for optimized calling utility.
+func EmptySet() *Set {
+	// Continue to return the pointer to the user-defined empty set for
+	// backwards-compatibility.
+	//
+	// New code should not use this, instead use emptySet.
+	return userDefinedEmptySet
+}
+
+// Valid reports whether this value refers to a valid Set.
+func (d Distinct) Valid() bool { return d.hash != 0 }
+
+// reflectValue abbreviates reflect.ValueOf(d).
+func (l Set) reflectValue() reflect.Value {
+	return reflect.ValueOf(l.data)
+}
+
+// Len returns the number of attributes in this set.
+func (l *Set) Len() int {
+	if l == nil || l.hash == 0 {
+		return 0
+	}
+	return l.reflectValue().Len()
+}
+
+// Get returns the KeyValue at ordered position idx in this set.
+func (l *Set) Get(idx int) (KeyValue, bool) {
+	if l == nil || l.hash == 0 {
+		return KeyValue{}, false
+	}
+	value := l.reflectValue()
+
+	if idx >= 0 && idx < value.Len() {
+		// Note: The Go compiler successfully avoids an allocation for
+		// the interface{} conversion here:
+		return value.Index(idx).Interface().(KeyValue), true
+	}
+
+	return KeyValue{}, false
+}
+
+// Value returns the value of a specified key in this set.
+func (l *Set) Value(k Key) (Value, bool) {
+	if l == nil || l.hash == 0 {
+		return Value{}, false
+	}
+	rValue := l.reflectValue()
+	vlen := rValue.Len()
+
+	idx := sort.Search(vlen, func(idx int) bool {
+		return rValue.Index(idx).Interface().(KeyValue).Key >= k
+	})
+	if idx >= vlen {
+		return Value{}, false
+	}
+	keyValue := rValue.Index(idx).Interface().(KeyValue)
+	if k == keyValue.Key {
+		return keyValue.Value, true
+	}
+	return Value{}, false
+}
+
+// HasValue reports whether a key is defined in this set.
+func (l *Set) HasValue(k Key) bool {
+	if l == nil {
+		return false
+	}
+	_, ok := l.Value(k)
+	return ok
+}
+
+// Iter returns an iterator for visiting the attributes in this set.
+func (l *Set) Iter() Iterator {
+	return Iterator{
+		storage: l,
+		idx:     -1,
+	}
+}
+
+// ToSlice returns the set of attributes belonging to this set, sorted, where
+// keys appear no more than once.
+func (l *Set) ToSlice() []KeyValue {
+	iter := l.Iter()
+	return iter.ToSlice()
+}
+
+// Equivalent returns a value that may be used as a map key. Equal Distinct
+// values are very likely to be equivalent attribute Sets. Distinct value of any
+// attribute set with the same elements as this, where sets are made unique by
+// choosing the last value in the input for any given key.
+func (l *Set) Equivalent() Distinct {
+	if l == nil || l.hash == 0 {
+		return Distinct{hash: emptySet.hash}
+	}
+	return Distinct{hash: l.hash}
+}
+
+// Equals reports whether the argument set is equivalent to this set.
+func (l *Set) Equals(o *Set) bool {
+	if l.Equivalent() != o.Equivalent() {
+		return false
+	}
+	if l == nil || l.hash == 0 {
+		l = &emptySet
+	}
+	if o == nil || o.hash == 0 {
+		o = &emptySet
+	}
+	return l.data == o.data
+}
+
+// Encoded returns the encoded form of this set, according to encoder.
+func (l *Set) Encoded(encoder Encoder) string {
+	if l == nil || encoder == nil {
+		return ""
+	}
+
+	return encoder.Encode(l.Iter())
+}
+
+// NewSet returns a new Set. See the documentation for
+// NewSetWithSortableFiltered for more details.
+//
+// Except for empty sets, this method adds an additional allocation compared
+// with calls that include a Sortable.
+func NewSet(kvs ...KeyValue) Set {
+	s, _ := NewSetWithFiltered(kvs, nil)
+	return s
+}
+
+// NewSetWithSortable returns a new Set. See the documentation for
+// NewSetWithSortableFiltered for more details.
+//
+// This call includes a Sortable option as a memory optimization.
+//
+// Deprecated: Use [NewSet] instead.
+func NewSetWithSortable(kvs []KeyValue, _ *Sortable) Set {
+	s, _ := NewSetWithFiltered(kvs, nil)
+	return s
+}
+
+// NewSetWithFiltered returns a new Set. See the documentation for
+// NewSetWithSortableFiltered for more details.
+//
+// This call includes a Filter to include/exclude attribute keys from the
+// return value. Excluded keys are returned as a slice of attribute values.
+func NewSetWithFiltered(kvs []KeyValue, filter Filter) (Set, []KeyValue) {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return emptySet, nil
+	}
+
+	// Stable sort so the following de-duplication can implement
+	// last-value-wins semantics.
+	slices.SortStableFunc(kvs, func(a, b KeyValue) int {
+		return cmp.Compare(a.Key, b.Key)
+	})
+
+	position := len(kvs) - 1
+	offset := position - 1
+
+	// The requirements stated above require that the stable
+	// result be placed in the end of the input slice, while
+	// overwritten values are swapped to the beginning.
+	//
+	// De-duplicate with last-value-wins semantics.  Preserve
+	// duplicate values at the beginning of the input slice.
+	for ; offset >= 0; offset-- {
+		if kvs[offset].Key == kvs[position].Key {
+			continue
+		}
+		position--
+		kvs[offset], kvs[position] = kvs[position], kvs[offset]
+	}
+	kvs = kvs[position:]
+
+	if filter != nil {
+		if div := filteredToFront(kvs, filter); div != 0 {
+			return newSet(kvs[div:]), kvs[:div]
+		}
+	}
+	return newSet(kvs), nil
+}
+
+// NewSetWithSortableFiltered returns a new Set.
+//
+// Duplicate keys are eliminated by taking the last value.  This
+// re-orders the input slice so that unique last-values are contiguous
+// at the end of the slice.
+//
+// This ensures the following:
+//
+// - Last-value-wins semantics
+// - Caller sees the reordering, but doesn't lose values
+// - Repeated call preserve last-value wins.
+//
+// Note that methods are defined on Set, although this returns Set. Callers
+// can avoid memory allocations by:
+//
+// - allocating a Sortable for use as a temporary in this method
+// - allocating a Set for storing the return value of this constructor.
+//
+// The result maintains a cache of encoded attributes, by attribute.EncoderID.
+// This value should not be copied after its first use.
+//
+// The second []KeyValue return value is a list of attributes that were
+// excluded by the Filter (if non-nil).
+//
+// Deprecated: Use [NewSetWithFiltered] instead.
+func NewSetWithSortableFiltered(kvs []KeyValue, _ *Sortable, filter Filter) (Set, []KeyValue) {
+	return NewSetWithFiltered(kvs, filter)
+}
+
+// filteredToFront filters slice in-place using keep function. All KeyValues that need to
+// be removed are moved to the front. All KeyValues that need to be kept are
+// moved (in-order) to the back. The index for the first KeyValue to be kept is
+// returned.
+func filteredToFront(slice []KeyValue, keep Filter) int {
+	n := len(slice)
+	j := n
+	for i := n - 1; i >= 0; i-- {
+		if keep(slice[i]) {
+			j--
+			slice[i], slice[j] = slice[j], slice[i]
+		}
+	}
+	return j
+}
+
+// Filter returns a filtered copy of this Set. See the documentation for
+// NewSetWithSortableFiltered for more details.
+func (l *Set) Filter(re Filter) (Set, []KeyValue) {
+	if re == nil {
+		return *l, nil
+	}
+
+	// Iterate in reverse to the first attribute that will be filtered out.
+	n := l.Len()
+	first := n - 1
+	for ; first >= 0; first-- {
+		kv, _ := l.Get(first)
+		if !re(kv) {
+			break
+		}
+	}
+
+	// No attributes will be dropped, return the immutable Set l and nil.
+	if first < 0 {
+		return *l, nil
+	}
+
+	// Copy now that we know we need to return a modified set.
+	//
+	// Do not do this in-place on the underlying storage of *Set l. Sets are
+	// immutable and filtering should not change this.
+	slice := l.ToSlice()
+
+	// Don't re-iterate the slice if only slice[0] is filtered.
+	if first == 0 {
+		// It is safe to assume len(slice) >= 1 given we found at least one
+		// attribute above that needs to be filtered out.
+		return newSet(slice[1:]), slice[:1]
+	}
+
+	// Move the filtered slice[first] to the front (preserving order).
+	kv := slice[first]
+	copy(slice[1:first+1], slice[:first])
+	slice[0] = kv
+
+	// Do not re-evaluate re(slice[first+1:]).
+	div := filteredToFront(slice[1:first+1], re) + 1
+	return newSet(slice[div:]), slice[:div]
+}
+
+// newSet returns a new set based on the sorted and uniqued kvs.
+func newSet(kvs []KeyValue) Set {
+	s := Set{
+		hash: hashKVs(kvs),
+		data: computeDataFixed(kvs),
+	}
+	if s.data == nil {
+		s.data = computeDataReflect(kvs)
+	}
+	return s
+}
+
+// computeDataFixed computes a Set data for small slices. It returns nil if the
+// input is too large for this code path.
+func computeDataFixed(kvs []KeyValue) any {
+	switch len(kvs) {
+	case 1:
+		return [1]KeyValue(kvs)
+	case 2:
+		return [2]KeyValue(kvs)
+	case 3:
+		return [3]KeyValue(kvs)
+	case 4:
+		return [4]KeyValue(kvs)
+	case 5:
+		return [5]KeyValue(kvs)
+	case 6:
+		return [6]KeyValue(kvs)
+	case 7:
+		return [7]KeyValue(kvs)
+	case 8:
+		return [8]KeyValue(kvs)
+	case 9:
+		return [9]KeyValue(kvs)
+	case 10:
+		return [10]KeyValue(kvs)
+	default:
+		return nil
+	}
+}
+
+// computeDataReflect computes a Set data using reflection, works for any size
+// input.
+func computeDataReflect(kvs []KeyValue) any {
+	at := reflect.New(reflect.ArrayOf(len(kvs), keyValueType)).Elem()
+	for i, keyValue := range kvs {
+		*(at.Index(i).Addr().Interface().(*KeyValue)) = keyValue
+	}
+	return at.Interface()
+}
+
+// MarshalJSON returns the JSON encoding of the Set.
+func (l *Set) MarshalJSON() ([]byte, error) {
+	return json.Marshal(l.data)
+}
+
+// MarshalLog is the marshaling function used by the logging system to represent this Set.
+func (l Set) MarshalLog() any {
+	kvs := make(map[string]string)
+	for _, kv := range l.ToSlice() {
+		kvs[string(kv.Key)] = kv.Value.Emit()
+	}
+	return kvs
+}
+
+// Len implements sort.Interface.
+func (l *Sortable) Len() int {
+	return len(*l)
+}
+
+// Swap implements sort.Interface.
+func (l *Sortable) Swap(i, j int) {
+	(*l)[i], (*l)[j] = (*l)[j], (*l)[i]
+}
+
+// Less implements sort.Interface.
+func (l *Sortable) Less(i, j int) bool {
+	return (*l)[i].Key < (*l)[j].Key
+}