feat: initial tracing support (#1623)

8 files changed, 1268 insertions, 0 deletions

diff --git a/vendor/go.opentelemetry.io/otel/attribute/doc.go b/vendor/go.opentelemetry.io/otel/attribute/doc.go
new file mode 100644
index 000000000..dafe7424d
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/doc.go
@@ -0,0 +1,16 @@
+// 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 provides key and value attributes.
+package attribute // import "go.opentelemetry.io/otel/attribute"
diff --git a/vendor/go.opentelemetry.io/otel/attribute/encoder.go b/vendor/go.opentelemetry.io/otel/attribute/encoder.go
new file mode 100644
index 000000000..fe2bc5766
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/encoder.go
@@ -0,0 +1,146 @@
+// 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 (
+	"bytes"
+	"sync"
+	"sync/atomic"
+)
+
+type (
+	// Encoder is a mechanism for serializing an attribute set into a specific
+	// string representation that supports caching, to avoid repeated
+	// serialization. An example could be an exporter encoding the attribute
+	// set into a wire representation.
+	Encoder interface {
+		// Encode returns the serialized encoding of the attribute set using
+		// its Iterator. This result may be cached by a attribute.Set.
+		Encode(iterator Iterator) string
+
+		// ID returns a value that is unique for each class of attribute
+		// encoder. Attribute encoders allocate these using `NewEncoderID`.
+		ID() EncoderID
+	}
+
+	// EncoderID is used to identify distinct Encoder
+	// implementations, for caching encoded results.
+	EncoderID struct {
+		value uint64
+	}
+
+	// defaultAttrEncoder uses a sync.Pool of buffers to reduce the number of
+	// allocations used in encoding attributes. This implementation encodes a
+	// comma-separated list of key=value, with '/'-escaping of '=', ',', and
+	// '\'.
+	defaultAttrEncoder struct {
+		// pool is a pool of attribute set builders. The buffers in this pool
+		// grow to a size that most attribute encodings will not allocate new
+		// memory.
+		pool sync.Pool // *bytes.Buffer
+	}
+)
+
+// escapeChar is used to ensure uniqueness of the attribute encoding where
+// keys or values contain either '=' or ','.  Since there is no parser needed
+// for this encoding and its only requirement is to be unique, this choice is
+// arbitrary.  Users will see these in some exporters (e.g., stdout), so the
+// backslash ('\') is used as a conventional choice.
+const escapeChar = '\\'
+
+var (
+	_ Encoder = &defaultAttrEncoder{}
+
+	// encoderIDCounter is for generating IDs for other attribute encoders.
+	encoderIDCounter uint64
+
+	defaultEncoderOnce     sync.Once
+	defaultEncoderID       = NewEncoderID()
+	defaultEncoderInstance *defaultAttrEncoder
+)
+
+// NewEncoderID returns a unique attribute encoder ID. It should be called
+// once per each type of attribute encoder. Preferably in init() or in var
+// definition.
+func NewEncoderID() EncoderID {
+	return EncoderID{value: atomic.AddUint64(&encoderIDCounter, 1)}
+}
+
+// DefaultEncoder returns an attribute encoder that encodes attributes in such
+// a way that each escaped attribute's key is followed by an equal sign and
+// then by an escaped attribute's value. All key-value pairs are separated by
+// a comma.
+//
+// Escaping is done by prepending a backslash before either a backslash, equal
+// sign or a comma.
+func DefaultEncoder() Encoder {
+	defaultEncoderOnce.Do(func() {
+		defaultEncoderInstance = &defaultAttrEncoder{
+			pool: sync.Pool{
+				New: func() interface{} {
+					return &bytes.Buffer{}
+				},
+			},
+		}
+	})
+	return defaultEncoderInstance
+}
+
+// Encode is a part of an implementation of the AttributeEncoder interface.
+func (d *defaultAttrEncoder) Encode(iter Iterator) string {
+	buf := d.pool.Get().(*bytes.Buffer)
+	defer d.pool.Put(buf)
+	buf.Reset()
+
+	for iter.Next() {
+		i, keyValue := iter.IndexedAttribute()
+		if i > 0 {
+			_, _ = buf.WriteRune(',')
+		}
+		copyAndEscape(buf, string(keyValue.Key))
+
+		_, _ = buf.WriteRune('=')
+
+		if keyValue.Value.Type() == STRING {
+			copyAndEscape(buf, keyValue.Value.AsString())
+		} else {
+			_, _ = buf.WriteString(keyValue.Value.Emit())
+		}
+	}
+	return buf.String()
+}
+
+// ID is a part of an implementation of the AttributeEncoder interface.
+func (*defaultAttrEncoder) ID() EncoderID {
+	return defaultEncoderID
+}
+
+// copyAndEscape escapes `=`, `,` and its own escape character (`\`),
+// making the default encoding unique.
+func copyAndEscape(buf *bytes.Buffer, val string) {
+	for _, ch := range val {
+		switch ch {
+		case '=', ',', escapeChar:
+			_, _ = buf.WriteRune(escapeChar)
+		}
+		_, _ = buf.WriteRune(ch)
+	}
+}
+
+// Valid returns true if this encoder ID was allocated by
+// `NewEncoderID`.  Invalid encoder IDs will not be cached.
+func (id EncoderID) Valid() bool {
+	return id.value != 0
+}
diff --git a/vendor/go.opentelemetry.io/otel/attribute/iterator.go b/vendor/go.opentelemetry.io/otel/attribute/iterator.go
new file mode 100644
index 000000000..841b271fb
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/iterator.go
@@ -0,0 +1,161 @@
+// 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"
+
+// Iterator allows iterating over the set of attributes in order, sorted by
+// key.
+type Iterator struct {
+	storage *Set
+	idx     int
+}
+
+// MergeIterator supports iterating over two sets of attributes while
+// eliminating duplicate values from the combined set. The first iterator
+// value takes precedence.
+type MergeIterator struct {
+	one     oneIterator
+	two     oneIterator
+	current KeyValue
+}
+
+type oneIterator struct {
+	iter Iterator
+	done bool
+	attr KeyValue
+}
+
+// Next moves the iterator to the next position. Returns false if there are no
+// more attributes.
+func (i *Iterator) Next() bool {
+	i.idx++
+	return i.idx < i.Len()
+}
+
+// Label returns current KeyValue. Must be called only after Next returns
+// true.
+//
+// Deprecated: Use Attribute instead.
+func (i *Iterator) Label() KeyValue {
+	return i.Attribute()
+}
+
+// Attribute returns the current KeyValue of the Iterator. It must be called
+// only after Next returns true.
+func (i *Iterator) Attribute() KeyValue {
+	kv, _ := i.storage.Get(i.idx)
+	return kv
+}
+
+// IndexedLabel returns current index and attribute. Must be called only
+// after Next returns true.
+//
+// Deprecated: Use IndexedAttribute instead.
+func (i *Iterator) IndexedLabel() (int, KeyValue) {
+	return i.idx, i.Attribute()
+}
+
+// IndexedAttribute returns current index and attribute. Must be called only
+// after Next returns true.
+func (i *Iterator) IndexedAttribute() (int, KeyValue) {
+	return i.idx, i.Attribute()
+}
+
+// Len returns a number of attributes in the iterated set.
+func (i *Iterator) Len() int {
+	return i.storage.Len()
+}
+
+// ToSlice is a convenience function that creates a slice of attributes from
+// the passed iterator. The iterator is set up to start from the beginning
+// before creating the slice.
+func (i *Iterator) ToSlice() []KeyValue {
+	l := i.Len()
+	if l == 0 {
+		return nil
+	}
+	i.idx = -1
+	slice := make([]KeyValue, 0, l)
+	for i.Next() {
+		slice = append(slice, i.Attribute())
+	}
+	return slice
+}
+
+// NewMergeIterator returns a MergeIterator for merging two attribute sets.
+// Duplicates are resolved by taking the value from the first set.
+func NewMergeIterator(s1, s2 *Set) MergeIterator {
+	mi := MergeIterator{
+		one: makeOne(s1.Iter()),
+		two: makeOne(s2.Iter()),
+	}
+	return mi
+}
+
+func makeOne(iter Iterator) oneIterator {
+	oi := oneIterator{
+		iter: iter,
+	}
+	oi.advance()
+	return oi
+}
+
+func (oi *oneIterator) advance() {
+	if oi.done = !oi.iter.Next(); !oi.done {
+		oi.attr = oi.iter.Attribute()
+	}
+}
+
+// Next returns true if there is another attribute available.
+func (m *MergeIterator) Next() bool {
+	if m.one.done && m.two.done {
+		return false
+	}
+	if m.one.done {
+		m.current = m.two.attr
+		m.two.advance()
+		return true
+	}
+	if m.two.done {
+		m.current = m.one.attr
+		m.one.advance()
+		return true
+	}
+	if m.one.attr.Key == m.two.attr.Key {
+		m.current = m.one.attr // first iterator attribute value wins
+		m.one.advance()
+		m.two.advance()
+		return true
+	}
+	if m.one.attr.Key < m.two.attr.Key {
+		m.current = m.one.attr
+		m.one.advance()
+		return true
+	}
+	m.current = m.two.attr
+	m.two.advance()
+	return true
+}
+
+// Label returns the current value after Next() returns true.
+//
+// Deprecated: Use Attribute instead.
+func (m *MergeIterator) Label() KeyValue {
+	return m.current
+}
+
+// Attribute returns the current value after Next() returns true.
+func (m *MergeIterator) Attribute() KeyValue {
+	return m.current
+}
diff --git a/vendor/go.opentelemetry.io/otel/attribute/key.go b/vendor/go.opentelemetry.io/otel/attribute/key.go
new file mode 100644
index 000000000..0656a04e4
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/key.go
@@ -0,0 +1,134 @@
+// 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"
+
+// Key represents the key part in key-value pairs. It's a string. The
+// allowed character set in the key depends on the use of the key.
+type Key string
+
+// Bool creates a KeyValue instance with a BOOL Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- Bool(name, value).
+func (k Key) Bool(v bool) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: BoolValue(v),
+	}
+}
+
+// BoolSlice creates a KeyValue instance with a BOOLSLICE Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- BoolSlice(name, value).
+func (k Key) BoolSlice(v []bool) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: BoolSliceValue(v),
+	}
+}
+
+// Int creates a KeyValue instance with an INT64 Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- Int(name, value).
+func (k Key) Int(v int) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: IntValue(v),
+	}
+}
+
+// IntSlice creates a KeyValue instance with an INT64SLICE Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- IntSlice(name, value).
+func (k Key) IntSlice(v []int) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: IntSliceValue(v),
+	}
+}
+
+// Int64 creates a KeyValue instance with an INT64 Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- Int64(name, value).
+func (k Key) Int64(v int64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Int64Value(v),
+	}
+}
+
+// Int64Slice creates a KeyValue instance with an INT64SLICE Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- Int64Slice(name, value).
+func (k Key) Int64Slice(v []int64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Int64SliceValue(v),
+	}
+}
+
+// Float64 creates a KeyValue instance with a FLOAT64 Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- Float64(name, value).
+func (k Key) Float64(v float64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Float64Value(v),
+	}
+}
+
+// Float64Slice creates a KeyValue instance with a FLOAT64SLICE Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- Float64(name, value).
+func (k Key) Float64Slice(v []float64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Float64SliceValue(v),
+	}
+}
+
+// String creates a KeyValue instance with a STRING Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- String(name, value).
+func (k Key) String(v string) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: StringValue(v),
+	}
+}
+
+// StringSlice creates a KeyValue instance with a STRINGSLICE Value.
+//
+// If creating both a key and value at the same time, use the provided
+// convenience function instead -- StringSlice(name, value).
+func (k Key) StringSlice(v []string) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: StringSliceValue(v),
+	}
+}
+
+// Defined returns true for non-empty keys.
+func (k Key) Defined() bool {
+	return len(k) != 0
+}
diff --git a/vendor/go.opentelemetry.io/otel/attribute/kv.go b/vendor/go.opentelemetry.io/otel/attribute/kv.go
new file mode 100644
index 000000000..1ddf3ce05
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/kv.go
@@ -0,0 +1,86 @@
+// 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 (
+	"fmt"
+)
+
+// KeyValue holds a key and value pair.
+type KeyValue struct {
+	Key   Key
+	Value Value
+}
+
+// Valid returns if kv is a valid OpenTelemetry attribute.
+func (kv KeyValue) Valid() bool {
+	return kv.Key.Defined() && kv.Value.Type() != INVALID
+}
+
+// Bool creates a KeyValue with a BOOL Value type.
+func Bool(k string, v bool) KeyValue {
+	return Key(k).Bool(v)
+}
+
+// BoolSlice creates a KeyValue with a BOOLSLICE Value type.
+func BoolSlice(k string, v []bool) KeyValue {
+	return Key(k).BoolSlice(v)
+}
+
+// Int creates a KeyValue with an INT64 Value type.
+func Int(k string, v int) KeyValue {
+	return Key(k).Int(v)
+}
+
+// IntSlice creates a KeyValue with an INT64SLICE Value type.
+func IntSlice(k string, v []int) KeyValue {
+	return Key(k).IntSlice(v)
+}
+
+// Int64 creates a KeyValue with an INT64 Value type.
+func Int64(k string, v int64) KeyValue {
+	return Key(k).Int64(v)
+}
+
+// Int64Slice creates a KeyValue with an INT64SLICE Value type.
+func Int64Slice(k string, v []int64) KeyValue {
+	return Key(k).Int64Slice(v)
+}
+
+// Float64 creates a KeyValue with a FLOAT64 Value type.
+func Float64(k string, v float64) KeyValue {
+	return Key(k).Float64(v)
+}
+
+// Float64Slice creates a KeyValue with a FLOAT64SLICE Value type.
+func Float64Slice(k string, v []float64) KeyValue {
+	return Key(k).Float64Slice(v)
+}
+
+// String creates a KeyValue with a STRING Value type.
+func String(k, v string) KeyValue {
+	return Key(k).String(v)
+}
+
+// StringSlice creates a KeyValue with a STRINGSLICE Value type.
+func StringSlice(k string, v []string) KeyValue {
+	return Key(k).StringSlice(v)
+}
+
+// Stringer creates a new key-value pair with a passed name and a string
+// value generated by the passed Stringer interface.
+func Stringer(k string, v fmt.Stringer) KeyValue {
+	return Key(k).String(v.String())
+}
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
+}
diff --git a/vendor/go.opentelemetry.io/otel/attribute/type_string.go b/vendor/go.opentelemetry.io/otel/attribute/type_string.go
new file mode 100644
index 000000000..e584b2477
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/type_string.go
@@ -0,0 +1,31 @@
+// Code generated by "stringer -type=Type"; DO NOT EDIT.
+
+package attribute
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[INVALID-0]
+	_ = x[BOOL-1]
+	_ = x[INT64-2]
+	_ = x[FLOAT64-3]
+	_ = x[STRING-4]
+	_ = x[BOOLSLICE-5]
+	_ = x[INT64SLICE-6]
+	_ = x[FLOAT64SLICE-7]
+	_ = x[STRINGSLICE-8]
+}
+
+const _Type_name = "INVALIDBOOLINT64FLOAT64STRINGBOOLSLICEINT64SLICEFLOAT64SLICESTRINGSLICE"
+
+var _Type_index = [...]uint8{0, 7, 11, 16, 23, 29, 38, 48, 60, 71}
+
+func (i Type) String() string {
+	if i < 0 || i >= Type(len(_Type_index)-1) {
+		return "Type(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Type_name[_Type_index[i]:_Type_index[i+1]]
+}
diff --git a/vendor/go.opentelemetry.io/otel/attribute/value.go b/vendor/go.opentelemetry.io/otel/attribute/value.go
new file mode 100644
index 000000000..cb21dd5c0
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/attribute/value.go
@@ -0,0 +1,270 @@
+// 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"
+	"fmt"
+	"reflect"
+	"strconv"
+
+	"go.opentelemetry.io/otel/internal"
+	"go.opentelemetry.io/otel/internal/attribute"
+)
+
+//go:generate stringer -type=Type
+
+// Type describes the type of the data Value holds.
+type Type int // nolint: revive  // redefines builtin Type.
+
+// Value represents the value part in key-value pairs.
+type Value struct {
+	vtype    Type
+	numeric  uint64
+	stringly string
+	slice    interface{}
+}
+
+const (
+	// INVALID is used for a Value with no value set.
+	INVALID Type = iota
+	// BOOL is a boolean Type Value.
+	BOOL
+	// INT64 is a 64-bit signed integral Type Value.
+	INT64
+	// FLOAT64 is a 64-bit floating point Type Value.
+	FLOAT64
+	// STRING is a string Type Value.
+	STRING
+	// BOOLSLICE is a slice of booleans Type Value.
+	BOOLSLICE
+	// INT64SLICE is a slice of 64-bit signed integral numbers Type Value.
+	INT64SLICE
+	// FLOAT64SLICE is a slice of 64-bit floating point numbers Type Value.
+	FLOAT64SLICE
+	// STRINGSLICE is a slice of strings Type Value.
+	STRINGSLICE
+)
+
+// BoolValue creates a BOOL Value.
+func BoolValue(v bool) Value {
+	return Value{
+		vtype:   BOOL,
+		numeric: internal.BoolToRaw(v),
+	}
+}
+
+// BoolSliceValue creates a BOOLSLICE Value.
+func BoolSliceValue(v []bool) Value {
+	return Value{vtype: BOOLSLICE, slice: attribute.BoolSliceValue(v)}
+}
+
+// IntValue creates an INT64 Value.
+func IntValue(v int) Value {
+	return Int64Value(int64(v))
+}
+
+// IntSliceValue creates an INTSLICE Value.
+func IntSliceValue(v []int) Value {
+	var int64Val int64
+	cp := reflect.New(reflect.ArrayOf(len(v), reflect.TypeOf(int64Val)))
+	for i, val := range v {
+		cp.Elem().Index(i).SetInt(int64(val))
+	}
+	return Value{
+		vtype: INT64SLICE,
+		slice: cp.Elem().Interface(),
+	}
+}
+
+// Int64Value creates an INT64 Value.
+func Int64Value(v int64) Value {
+	return Value{
+		vtype:   INT64,
+		numeric: internal.Int64ToRaw(v),
+	}
+}
+
+// Int64SliceValue creates an INT64SLICE Value.
+func Int64SliceValue(v []int64) Value {
+	return Value{vtype: INT64SLICE, slice: attribute.Int64SliceValue(v)}
+}
+
+// Float64Value creates a FLOAT64 Value.
+func Float64Value(v float64) Value {
+	return Value{
+		vtype:   FLOAT64,
+		numeric: internal.Float64ToRaw(v),
+	}
+}
+
+// Float64SliceValue creates a FLOAT64SLICE Value.
+func Float64SliceValue(v []float64) Value {
+	return Value{vtype: FLOAT64SLICE, slice: attribute.Float64SliceValue(v)}
+}
+
+// StringValue creates a STRING Value.
+func StringValue(v string) Value {
+	return Value{
+		vtype:    STRING,
+		stringly: v,
+	}
+}
+
+// StringSliceValue creates a STRINGSLICE Value.
+func StringSliceValue(v []string) Value {
+	return Value{vtype: STRINGSLICE, slice: attribute.StringSliceValue(v)}
+}
+
+// Type returns a type of the Value.
+func (v Value) Type() Type {
+	return v.vtype
+}
+
+// AsBool returns the bool value. Make sure that the Value's type is
+// BOOL.
+func (v Value) AsBool() bool {
+	return internal.RawToBool(v.numeric)
+}
+
+// AsBoolSlice returns the []bool value. Make sure that the Value's type is
+// BOOLSLICE.
+func (v Value) AsBoolSlice() []bool {
+	if v.vtype != BOOLSLICE {
+		return nil
+	}
+	return v.asBoolSlice()
+}
+
+func (v Value) asBoolSlice() []bool {
+	return attribute.AsBoolSlice(v.slice)
+}
+
+// AsInt64 returns the int64 value. Make sure that the Value's type is
+// INT64.
+func (v Value) AsInt64() int64 {
+	return internal.RawToInt64(v.numeric)
+}
+
+// AsInt64Slice returns the []int64 value. Make sure that the Value's type is
+// INT64SLICE.
+func (v Value) AsInt64Slice() []int64 {
+	if v.vtype != INT64SLICE {
+		return nil
+	}
+	return v.asInt64Slice()
+}
+
+func (v Value) asInt64Slice() []int64 {
+	return attribute.AsInt64Slice(v.slice)
+}
+
+// AsFloat64 returns the float64 value. Make sure that the Value's
+// type is FLOAT64.
+func (v Value) AsFloat64() float64 {
+	return internal.RawToFloat64(v.numeric)
+}
+
+// AsFloat64Slice returns the []float64 value. Make sure that the Value's type is
+// FLOAT64SLICE.
+func (v Value) AsFloat64Slice() []float64 {
+	if v.vtype != FLOAT64SLICE {
+		return nil
+	}
+	return v.asFloat64Slice()
+}
+
+func (v Value) asFloat64Slice() []float64 {
+	return attribute.AsFloat64Slice(v.slice)
+}
+
+// AsString returns the string value. Make sure that the Value's type
+// is STRING.
+func (v Value) AsString() string {
+	return v.stringly
+}
+
+// AsStringSlice returns the []string value. Make sure that the Value's type is
+// STRINGSLICE.
+func (v Value) AsStringSlice() []string {
+	if v.vtype != STRINGSLICE {
+		return nil
+	}
+	return v.asStringSlice()
+}
+
+func (v Value) asStringSlice() []string {
+	return attribute.AsStringSlice(v.slice)
+}
+
+type unknownValueType struct{}
+
+// AsInterface returns Value's data as interface{}.
+func (v Value) AsInterface() interface{} {
+	switch v.Type() {
+	case BOOL:
+		return v.AsBool()
+	case BOOLSLICE:
+		return v.asBoolSlice()
+	case INT64:
+		return v.AsInt64()
+	case INT64SLICE:
+		return v.asInt64Slice()
+	case FLOAT64:
+		return v.AsFloat64()
+	case FLOAT64SLICE:
+		return v.asFloat64Slice()
+	case STRING:
+		return v.stringly
+	case STRINGSLICE:
+		return v.asStringSlice()
+	}
+	return unknownValueType{}
+}
+
+// Emit returns a string representation of Value's data.
+func (v Value) Emit() string {
+	switch v.Type() {
+	case BOOLSLICE:
+		return fmt.Sprint(v.asBoolSlice())
+	case BOOL:
+		return strconv.FormatBool(v.AsBool())
+	case INT64SLICE:
+		return fmt.Sprint(v.asInt64Slice())
+	case INT64:
+		return strconv.FormatInt(v.AsInt64(), 10)
+	case FLOAT64SLICE:
+		return fmt.Sprint(v.asFloat64Slice())
+	case FLOAT64:
+		return fmt.Sprint(v.AsFloat64())
+	case STRINGSLICE:
+		return fmt.Sprint(v.asStringSlice())
+	case STRING:
+		return v.stringly
+	default:
+		return "unknown"
+	}
+}
+
+// MarshalJSON returns the JSON encoding of the Value.
+func (v Value) MarshalJSON() ([]byte, error) {
+	var jsonVal struct {
+		Type  string
+		Value interface{}
+	}
+	jsonVal.Type = v.Type().String()
+	jsonVal.Value = v.AsInterface()
+	return json.Marshal(jsonVal)
+}