1 files changed, 424 insertions, 0 deletions
diff --git a/vendor/go.opentelemetry.io/otel/attribute/set.go b/vendor/go.opentelemetry.io/otel/attribute/set.go
new file mode 100644
index 000000000..26be59832
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/set.go
@@ -0,0 +1,424 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package attribute // import "go.opentelemetry.io/otel/attribute"
+
+import (
+	"encoding/json"
+	"reflect"
+	"sort"
+)
+
+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 supports the Equivalent method of comparison using values of
+	// type Distinct.
+	Set struct {
+		equivalent Distinct
+	}
+
+	// Distinct wraps a variable-size array of KeyValue, constructed with keys
+	// in sorted order. This can be used as a map key or for equality checking
+	// between Sets.
+	Distinct struct {
+		iface interface{}
+	}
+
+	// Filter supports removing certain attributes from attribute sets. When
+	// the filter returns true, the attribute will be kept in the filtered
+	// attribute set. When the filter returns false, the attribute is excluded
+	// from the filtered attribute set, and the attribute instead appears in
+	// the removed list of excluded attributes.
+	Filter func(KeyValue) bool
+
+	// Sortable implements sort.Interface, used for sorting KeyValue. This is
+	// an exported type to support a memory optimization. A pointer to one of
+	// these is needed for the call to sort.Stable(), which the caller may
+	// provide in order to avoid an allocation. See NewSetWithSortable().
+	Sortable []KeyValue
+)
+
+var (
+	// keyValueType is used in computeDistinctReflect.
+	keyValueType = reflect.TypeOf(KeyValue{})
+
+	// emptySet is returned for empty attribute sets.
+	emptySet = &Set{
+		equivalent: Distinct{
+			iface: [0]KeyValue{},
+		},
+	}
+)
+
+// EmptySet returns a reference to a Set with no elements.
+//
+// This is a convenience provided for optimized calling utility.
+func EmptySet() *Set {
+	return emptySet
+}
+
+// reflectValue abbreviates reflect.ValueOf(d).
+func (d Distinct) reflectValue() reflect.Value {
+	return reflect.ValueOf(d.iface)
+}
+
+// Valid returns true if this value refers to a valid Set.
+func (d Distinct) Valid() bool {
+	return d.iface != nil
+}
+
+// Len returns the number of attributes in this set.
+func (l *Set) Len() int {
+	if l == nil || !l.equivalent.Valid() {
+		return 0
+	}
+	return l.equivalent.reflectValue().Len()
+}
+
+// Get returns the KeyValue at ordered position idx in this set.
+func (l *Set) Get(idx int) (KeyValue, bool) {
+	if l == nil {
+		return KeyValue{}, false
+	}
+	value := l.equivalent.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 {
+		return Value{}, false
+	}
+	rValue := l.equivalent.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 tests 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. The Distinct type
+// guarantees that the result will equal the equivalent. 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.equivalent.Valid() {
+		return emptySet.equivalent
+	}
+	return l.equivalent
+}
+
+// Equals returns true if the argument set is equivalent to this set.
+func (l *Set) Equals(o *Set) bool {
+	return l.Equivalent() == o.Equivalent()
+}
+
+// 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())
+}
+
+func empty() Set {
+	return Set{
+		equivalent: emptySet.equivalent,
+	}
+}
+
+// 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 {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return empty()
+	}
+	s, _ := NewSetWithSortableFiltered(kvs, new(Sortable), 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.
+func NewSetWithSortable(kvs []KeyValue, tmp *Sortable) Set {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return empty()
+	}
+	s, _ := NewSetWithSortableFiltered(kvs, tmp, 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 empty(), nil
+	}
+	return NewSetWithSortableFiltered(kvs, new(Sortable), filter)
+}
+
+// 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).
+func NewSetWithSortableFiltered(kvs []KeyValue, tmp *Sortable, filter Filter) (Set, []KeyValue) {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return empty(), nil
+	}
+
+	*tmp = kvs
+
+	// Stable sort so the following de-duplication can implement
+	// last-value-wins semantics.
+	sort.Stable(tmp)
+
+	*tmp = nil
+
+	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]
+	}
+	if filter != nil {
+		return filterSet(kvs[position:], filter)
+	}
+	return Set{
+		equivalent: computeDistinct(kvs[position:]),
+	}, nil
+}
+
+// filterSet reorders kvs so that included keys are contiguous at the end of
+// the slice, while excluded keys precede the included keys.
+func filterSet(kvs []KeyValue, filter Filter) (Set, []KeyValue) {
+	var excluded []KeyValue
+
+	// Move attributes that do not match the filter so they're adjacent before
+	// calling computeDistinct().
+	distinctPosition := len(kvs)
+
+	// Swap indistinct keys forward and distinct keys toward the
+	// end of the slice.
+	offset := len(kvs) - 1
+	for ; offset >= 0; offset-- {
+		if filter(kvs[offset]) {
+			distinctPosition--
+			kvs[offset], kvs[distinctPosition] = kvs[distinctPosition], kvs[offset]
+			continue
+		}
+	}
+	excluded = kvs[:distinctPosition]
+
+	return Set{
+		equivalent: computeDistinct(kvs[distinctPosition:]),
+	}, excluded
+}
+
+// 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 Set{
+			equivalent: l.equivalent,
+		}, nil
+	}
+
+	// Note: This could be refactored to avoid the temporary slice
+	// allocation, if it proves to be expensive.
+	return filterSet(l.ToSlice(), re)
+}
+
+// computeDistinct returns a Distinct using either the fixed- or
+// reflect-oriented code path, depending on the size of the input. The input
+// slice is assumed to already be sorted and de-duplicated.
+func computeDistinct(kvs []KeyValue) Distinct {
+	iface := computeDistinctFixed(kvs)
+	if iface == nil {
+		iface = computeDistinctReflect(kvs)
+	}
+	return Distinct{
+		iface: iface,
+	}
+}
+
+// computeDistinctFixed computes a Distinct for small slices. It returns nil
+// if the input is too large for this code path.
+func computeDistinctFixed(kvs []KeyValue) interface{} {
+	switch len(kvs) {
+	case 1:
+		ptr := new([1]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 2:
+		ptr := new([2]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 3:
+		ptr := new([3]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 4:
+		ptr := new([4]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 5:
+		ptr := new([5]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 6:
+		ptr := new([6]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 7:
+		ptr := new([7]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 8:
+		ptr := new([8]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 9:
+		ptr := new([9]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 10:
+		ptr := new([10]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	default:
+		return nil
+	}
+}
+
+// computeDistinctReflect computes a Distinct using reflection, works for any
+// size input.
+func computeDistinctReflect(kvs []KeyValue) interface{} {
+	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.equivalent.iface)
+}
+
+// MarshalLog is the marshaling function used by the logging system to represent this exporter.
+func (l Set) MarshalLog() interface{} {
+	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
+}