Phase 2: Implement Execution Environment Abstraction (v0.3.0)

This commit implements Phase 2 of the CHORUS Task Execution Engine development plan,
providing a comprehensive execution environment abstraction layer with Docker
container sandboxing support.

## New Features

### Core Sandbox Interface
- Comprehensive ExecutionSandbox interface with isolated task execution
- Support for command execution, file I/O, environment management
- Resource usage monitoring and sandbox lifecycle management
- Standardized error handling with SandboxError types and categories

### Docker Container Sandbox Implementation
- Full Docker API integration with secure container creation
- Transparent repository mounting with configurable read/write access
- Advanced security policies with capability dropping and privilege controls
- Comprehensive resource limits (CPU, memory, disk, processes, file handles)
- Support for tmpfs mounts, masked paths, and read-only bind mounts
- Container lifecycle management with proper cleanup and health monitoring

### Security & Resource Management
- Configurable security policies with SELinux, AppArmor, and Seccomp support
- Fine-grained capability management with secure defaults
- Network isolation options with configurable DNS and proxy settings
- Resource monitoring with real-time CPU, memory, and network usage tracking
- Comprehensive ulimits configuration for process and file handle limits

### Repository Integration
- Seamless repository mounting from local paths to container workspaces
- Git configuration support with user credentials and global settings
- File inclusion/exclusion patterns for selective repository access
- Configurable permissions and ownership for mounted repositories

### Testing Infrastructure
- Comprehensive test suite with 60+ test cases covering all functionality
- Docker integration tests with Alpine Linux containers (skipped in short mode)
- Mock sandbox implementation for unit testing without Docker dependencies
- Security policy validation tests with read-only filesystem enforcement
- Resource usage monitoring and cleanup verification tests

## Technical Details

### Dependencies Added
- github.com/docker/docker v28.4.0+incompatible - Docker API client
- github.com/docker/go-connections v0.6.0 - Docker connection utilities
- github.com/docker/go-units v0.5.0 - Docker units and formatting
- Associated Docker API dependencies for complete container management

### Architecture
- Interface-driven design enabling multiple sandbox implementations
- Comprehensive configuration structures for all sandbox aspects
- Resource usage tracking with detailed metrics collection
- Error handling with retryable error classification
- Proper cleanup and resource management throughout sandbox lifecycle

### Compatibility
- Maintains backward compatibility with existing CHORUS architecture
- Designed for future integration with Phase 3 Core Task Execution Engine
- Extensible design supporting additional sandbox implementations (VM, process)

This Phase 2 implementation provides the foundation for secure, isolated task
execution that will be integrated with the AI model providers from Phase 1
in the upcoming Phase 3 development.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

vendor/go.opentelemetry.io/otel/attribute/README.md

@@ -0,0 +1,3 @@
+# Attribute
+
+[![PkgGoDev](https://pkg.go.dev/badge/go.opentelemetry.io/otel/attribute)](https://pkg.go.dev/go.opentelemetry.io/otel/attribute)

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

@@ -1,16 +1,5 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0
 
 // Package attribute provides key and value attributes.
 package attribute // import "go.opentelemetry.io/otel/attribute"

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

@@ -1,16 +1,5 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0
 
 package attribute // import "go.opentelemetry.io/otel/attribute"
 
@@ -89,7 +78,7 @@ func DefaultEncoder() Encoder {
 	defaultEncoderOnce.Do(func() {
 		defaultEncoderInstance = &defaultAttrEncoder{
 			pool: sync.Pool{
-				New: func() interface{} {
+				New: func() any {
 					return &bytes.Buffer{}
 				},
 			},
@@ -107,11 +96,11 @@ func (d *defaultAttrEncoder) Encode(iter Iterator) string {
 	for iter.Next() {
 		i, keyValue := iter.IndexedAttribute()
 		if i > 0 {
-			_, _ = buf.WriteRune(',')
+			_ = buf.WriteByte(',')
 		}
 		copyAndEscape(buf, string(keyValue.Key))
 
-		_, _ = buf.WriteRune('=')
+		_ = buf.WriteByte('=')
 
 		if keyValue.Value.Type() == STRING {
 			copyAndEscape(buf, keyValue.Value.AsString())
@@ -133,14 +122,14 @@ func copyAndEscape(buf *bytes.Buffer, val string) {
 	for _, ch := range val {
 		switch ch {
 		case '=', ',', escapeChar:
-			_, _ = buf.WriteRune(escapeChar)
+			_ = buf.WriteByte(escapeChar)
 		}
 		_, _ = buf.WriteRune(ch)
 	}
 }
 
-// Valid returns true if this encoder ID was allocated by
-// `NewEncoderID`.  Invalid encoder IDs will not be cached.
+// Valid reports whether this encoder ID was allocated by
+// [NewEncoderID]. Invalid encoder IDs will not be cached.
 func (id EncoderID) Valid() bool {
 	return id.value != 0
 }

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

@@ -0,0 +1,49 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package attribute // import "go.opentelemetry.io/otel/attribute"
+
+// 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.
+type Filter func(KeyValue) bool
+
+// NewAllowKeysFilter returns a Filter that only allows attributes with one of
+// the provided keys.
+//
+// If keys is empty a deny-all filter is returned.
+func NewAllowKeysFilter(keys ...Key) Filter {
+	if len(keys) == 0 {
+		return func(KeyValue) bool { return false }
+	}
+
+	allowed := make(map[Key]struct{}, len(keys))
+	for _, k := range keys {
+		allowed[k] = struct{}{}
+	}
+	return func(kv KeyValue) bool {
+		_, ok := allowed[kv.Key]
+		return ok
+	}
+}
+
+// NewDenyKeysFilter returns a Filter that only allows attributes
+// that do not have one of the provided keys.
+//
+// If keys is empty an allow-all filter is returned.
+func NewDenyKeysFilter(keys ...Key) Filter {
+	if len(keys) == 0 {
+		return func(KeyValue) bool { return true }
+	}
+
+	forbid := make(map[Key]struct{}, len(keys))
+	for _, k := range keys {
+		forbid[k] = struct{}{}
+	}
+	return func(kv KeyValue) bool {
+		_, ok := forbid[kv.Key]
+		return !ok
+	}
+}

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

@@ -0,0 +1,96 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+/*
+Package attribute provide several helper functions for some commonly used
+logic of processing attributes.
+*/
+package attribute // import "go.opentelemetry.io/otel/attribute/internal"
+
+import (
+	"reflect"
+)
+
+// BoolSliceValue converts a bool slice into an array with same elements as slice.
+func BoolSliceValue(v []bool) any {
+	var zero bool
+	cp := reflect.New(reflect.ArrayOf(len(v), reflect.TypeOf(zero))).Elem()
+	reflect.Copy(cp, reflect.ValueOf(v))
+	return cp.Interface()
+}
+
+// Int64SliceValue converts an int64 slice into an array with same elements as slice.
+func Int64SliceValue(v []int64) any {
+	var zero int64
+	cp := reflect.New(reflect.ArrayOf(len(v), reflect.TypeOf(zero))).Elem()
+	reflect.Copy(cp, reflect.ValueOf(v))
+	return cp.Interface()
+}
+
+// Float64SliceValue converts a float64 slice into an array with same elements as slice.
+func Float64SliceValue(v []float64) any {
+	var zero float64
+	cp := reflect.New(reflect.ArrayOf(len(v), reflect.TypeOf(zero))).Elem()
+	reflect.Copy(cp, reflect.ValueOf(v))
+	return cp.Interface()
+}
+
+// StringSliceValue converts a string slice into an array with same elements as slice.
+func StringSliceValue(v []string) any {
+	var zero string
+	cp := reflect.New(reflect.ArrayOf(len(v), reflect.TypeOf(zero))).Elem()
+	reflect.Copy(cp, reflect.ValueOf(v))
+	return cp.Interface()
+}
+
+// AsBoolSlice converts a bool array into a slice into with same elements as array.
+func AsBoolSlice(v any) []bool {
+	rv := reflect.ValueOf(v)
+	if rv.Type().Kind() != reflect.Array {
+		return nil
+	}
+	cpy := make([]bool, rv.Len())
+	if len(cpy) > 0 {
+		_ = reflect.Copy(reflect.ValueOf(cpy), rv)
+	}
+	return cpy
+}
+
+// AsInt64Slice converts an int64 array into a slice into with same elements as array.
+func AsInt64Slice(v any) []int64 {
+	rv := reflect.ValueOf(v)
+	if rv.Type().Kind() != reflect.Array {
+		return nil
+	}
+	cpy := make([]int64, rv.Len())
+	if len(cpy) > 0 {
+		_ = reflect.Copy(reflect.ValueOf(cpy), rv)
+	}
+	return cpy
+}
+
+// AsFloat64Slice converts a float64 array into a slice into with same elements as array.
+func AsFloat64Slice(v any) []float64 {
+	rv := reflect.ValueOf(v)
+	if rv.Type().Kind() != reflect.Array {
+		return nil
+	}
+	cpy := make([]float64, rv.Len())
+	if len(cpy) > 0 {
+		_ = reflect.Copy(reflect.ValueOf(cpy), rv)
+	}
+	return cpy
+}
+
+// AsStringSlice converts a string array into a slice into with same elements as array.
+func AsStringSlice(v any) []string {
+	rv := reflect.ValueOf(v)
+	if rv.Type().Kind() != reflect.Array {
+		return nil
+	}
+	cpy := make([]string, rv.Len())
+	if len(cpy) > 0 {
+		_ = reflect.Copy(reflect.ValueOf(cpy), rv)
+	}
+	return cpy
+}

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

@@ -1,16 +1,5 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0
 
 package attribute // import "go.opentelemetry.io/otel/attribute"
 
@@ -36,8 +25,8 @@ type oneIterator struct {
 	attr KeyValue
 }
 
-// Next moves the iterator to the next position. Returns false if there are no
-// more attributes.
+// Next moves the iterator to the next position.
+// Next reports whether there are more attributes.
 func (i *Iterator) Next() bool {
 	i.idx++
 	return i.idx < i.Len()
@@ -117,7 +106,8 @@ func (oi *oneIterator) advance() {
 	}
 }
 
-// Next returns true if there is another attribute available.
+// Next moves the iterator to the next position.
+// Next reports whether there is another attribute available.
 func (m *MergeIterator) Next() bool {
 	if m.one.done && m.two.done {
 		return false

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

@@ -1,16 +1,5 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0
 
 package attribute // import "go.opentelemetry.io/otel/attribute"
 
@@ -128,7 +117,7 @@ func (k Key) StringSlice(v []string) KeyValue {
 	}
 }
 
-// Defined returns true for non-empty keys.
+// Defined reports whether the key is not empty.
 func (k Key) Defined() bool {
 	return len(k) != 0
 }

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

@@ -1,16 +1,5 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0
 
 package attribute // import "go.opentelemetry.io/otel/attribute"
 
@@ -24,7 +13,7 @@ type KeyValue struct {
 	Value Value
 }
 
-// Valid returns if kv is a valid OpenTelemetry attribute.
+// Valid reports whether kv is a valid OpenTelemetry attribute.
 func (kv KeyValue) Valid() bool {
 	return kv.Key.Defined() && kv.Value.Type() != INVALID
 }

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

@@ -0,0 +1,37 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package attribute // import "go.opentelemetry.io/otel/attribute"
+
+import (
+	"math"
+)
+
+func boolToRaw(b bool) uint64 { // nolint:revive  // b is not a control flag.
+	if b {
+		return 1
+	}
+	return 0
+}
+
+func rawToBool(r uint64) bool {
+	return r != 0
+}
+
+func int64ToRaw(i int64) uint64 {
+	// Assumes original was a valid int64 (overflow not checked).
+	return uint64(i) // nolint: gosec
+}
+
+func rawToInt64(r uint64) int64 {
+	// Assumes original was a valid int64 (overflow not checked).
+	return int64(r) // nolint: gosec
+}
+
+func float64ToRaw(f float64) uint64 {
+	return math.Float64bits(f)
+}
+
+func rawToFloat64(r uint64) float64 {
+	return math.Float64frombits(r)
+}

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

@@ -1,24 +1,14 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0
 
 package attribute // import "go.opentelemetry.io/otel/attribute"
 
 import (
+	"cmp"
 	"encoding/json"
 	"reflect"
+	"slices"
 	"sort"
-	"sync"
 )
 
 type (
@@ -26,30 +16,33 @@ type (
 	// 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.
+	// 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. In addition to that type providing guarantees
+	// on stable equivalence, it may also provide performance improvements.
 	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 is a unique identifier of a Set.
+	//
+	// Distinct is designed to ensure equivalence stability: comparisons will
+	// return the same value across versions. For this reason, Distinct should
+	// always be used as a map key instead of a Set.
 	Distinct struct {
-		iface interface{}
+		iface any
 	}
 
-	// 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 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
 )
 
@@ -63,12 +56,6 @@ var (
 			iface: [0]KeyValue{},
 		},
 	}
-
-	// sortables is a pool of Sortables used to create Sets with a user does
-	// not provide one.
-	sortables = sync.Pool{
-		New: func() interface{} { return new(Sortable) },
-	}
 )
 
 // EmptySet returns a reference to a Set with no elements.
@@ -83,7 +70,7 @@ func (d Distinct) reflectValue() reflect.Value {
 	return reflect.ValueOf(d.iface)
 }
 
-// Valid returns true if this value refers to a valid Set.
+// Valid reports whether this value refers to a valid Set.
 func (d Distinct) Valid() bool {
 	return d.iface != nil
 }
@@ -133,7 +120,7 @@ func (l *Set) Value(k Key) (Value, bool) {
 	return Value{}, false
 }
 
-// HasValue tests whether a key is defined in this set.
+// HasValue reports whether a key is defined in this set.
 func (l *Set) HasValue(k Key) bool {
 	if l == nil {
 		return false
@@ -168,7 +155,7 @@ func (l *Set) Equivalent() Distinct {
 	return l.equivalent
 }
 
-// Equals returns true if the argument set is equivalent to this set.
+// Equals reports whether the argument set is equivalent to this set.
 func (l *Set) Equals(o *Set) bool {
 	return l.Equivalent() == o.Equivalent()
 }
@@ -194,13 +181,7 @@ func empty() Set {
 // 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()
-	}
-	srt := sortables.Get().(*Sortable)
-	s, _ := NewSetWithSortableFiltered(kvs, srt, nil)
-	sortables.Put(srt)
+	s, _ := NewSetWithFiltered(kvs, nil)
 	return s
 }
 
@@ -208,12 +189,10 @@ func NewSet(kvs ...KeyValue) Set {
 // 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)
+//
+// Deprecated: Use [NewSet] instead.
+func NewSetWithSortable(kvs []KeyValue, _ *Sortable) Set {
+	s, _ := NewSetWithFiltered(kvs, nil)
 	return s
 }
 
@@ -227,10 +206,37 @@ func NewSetWithFiltered(kvs []KeyValue, filter Filter) (Set, []KeyValue) {
 	if len(kvs) == 0 {
 		return empty(), nil
 	}
-	srt := sortables.Get().(*Sortable)
-	s, filtered := NewSetWithSortableFiltered(kvs, srt, filter)
-	sortables.Put(srt)
-	return s, filtered
+
+	// 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 Set{equivalent: computeDistinct(kvs[div:])}, kvs[:div]
+		}
+	}
+	return Set{equivalent: computeDistinct(kvs)}, nil
 }
 
 // NewSetWithSortableFiltered returns a new Set.
@@ -256,82 +262,71 @@ func NewSetWithFiltered(kvs []KeyValue, filter Filter) (Set, []KeyValue) {
 //
 // 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
+//
+// Deprecated: Use [NewSetWithFiltered] instead.
+func NewSetWithSortableFiltered(kvs []KeyValue, _ *Sortable, filter Filter) (Set, []KeyValue) {
+	return NewSetWithFiltered(kvs, filter)
 }
 
-// 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
+// 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]
 		}
 	}
-	excluded = kvs[:distinctPosition]
-
-	return Set{
-		equivalent: computeDistinct(kvs[distinctPosition:]),
-	}, excluded
+	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 Set{
-			equivalent: l.equivalent,
-		}, nil
+		return *l, nil
 	}
 
-	// Note: This could be refactored to avoid the temporary slice
-	// allocation, if it proves to be expensive.
-	return filterSet(l.ToSlice(), re)
+	// 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 Set{equivalent: computeDistinct(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 Set{equivalent: computeDistinct(slice[div:])}, slice[:div]
 }
 
 // computeDistinct returns a Distinct using either the fixed- or
@@ -349,48 +344,28 @@ func computeDistinct(kvs []KeyValue) Distinct {
 
 // 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{} {
+func computeDistinctFixed(kvs []KeyValue) any {
 	switch len(kvs) {
 	case 1:
-		ptr := new([1]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [1]KeyValue(kvs)
 	case 2:
-		ptr := new([2]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [2]KeyValue(kvs)
 	case 3:
-		ptr := new([3]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [3]KeyValue(kvs)
 	case 4:
-		ptr := new([4]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [4]KeyValue(kvs)
 	case 5:
-		ptr := new([5]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [5]KeyValue(kvs)
 	case 6:
-		ptr := new([6]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [6]KeyValue(kvs)
 	case 7:
-		ptr := new([7]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [7]KeyValue(kvs)
 	case 8:
-		ptr := new([8]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [8]KeyValue(kvs)
 	case 9:
-		ptr := new([9]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [9]KeyValue(kvs)
 	case 10:
-		ptr := new([10]KeyValue)
-		copy((*ptr)[:], kvs)
-		return *ptr
+		return [10]KeyValue(kvs)
 	default:
 		return nil
 	}
@@ -398,7 +373,7 @@ func computeDistinctFixed(kvs []KeyValue) interface{} {
 
 // computeDistinctReflect computes a Distinct using reflection, works for any
 // size input.
-func computeDistinctReflect(kvs []KeyValue) interface{} {
+func computeDistinctReflect(kvs []KeyValue) any {
 	at := reflect.New(reflect.ArrayOf(len(kvs), keyValueType)).Elem()
 	for i, keyValue := range kvs {
 		*(at.Index(i).Addr().Interface().(*KeyValue)) = keyValue
@@ -411,8 +386,8 @@ 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{} {
+// 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()

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

@@ -1,16 +1,5 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0
 
 package attribute // import "go.opentelemetry.io/otel/attribute"
 
@@ -20,8 +9,7 @@ import (
 	"reflect"
 	"strconv"
 
-	"go.opentelemetry.io/otel/internal"
-	"go.opentelemetry.io/otel/internal/attribute"
+	attribute "go.opentelemetry.io/otel/attribute/internal"
 )
 
 //go:generate stringer -type=Type
@@ -34,7 +22,7 @@ type Value struct {
 	vtype    Type
 	numeric  uint64
 	stringly string
-	slice    interface{}
+	slice    any
 }
 
 const (
@@ -62,7 +50,7 @@ const (
 func BoolValue(v bool) Value {
 	return Value{
 		vtype:   BOOL,
-		numeric: internal.BoolToRaw(v),
+		numeric: boolToRaw(v),
 	}
 }
 
@@ -93,7 +81,7 @@ func IntSliceValue(v []int) Value {
 func Int64Value(v int64) Value {
 	return Value{
 		vtype:   INT64,
-		numeric: internal.Int64ToRaw(v),
+		numeric: int64ToRaw(v),
 	}
 }
 
@@ -106,7 +94,7 @@ func Int64SliceValue(v []int64) Value {
 func Float64Value(v float64) Value {
 	return Value{
 		vtype:   FLOAT64,
-		numeric: internal.Float64ToRaw(v),
+		numeric: float64ToRaw(v),
 	}
 }
 
@@ -136,7 +124,7 @@ func (v Value) Type() Type {
 // AsBool returns the bool value. Make sure that the Value's type is
 // BOOL.
 func (v Value) AsBool() bool {
-	return internal.RawToBool(v.numeric)
+	return rawToBool(v.numeric)
 }
 
 // AsBoolSlice returns the []bool value. Make sure that the Value's type is
@@ -155,7 +143,7 @@ func (v Value) asBoolSlice() []bool {
 // AsInt64 returns the int64 value. Make sure that the Value's type is
 // INT64.
 func (v Value) AsInt64() int64 {
-	return internal.RawToInt64(v.numeric)
+	return rawToInt64(v.numeric)
 }
 
 // AsInt64Slice returns the []int64 value. Make sure that the Value's type is
@@ -174,7 +162,7 @@ func (v Value) asInt64Slice() []int64 {
 // AsFloat64 returns the float64 value. Make sure that the Value's
 // type is FLOAT64.
 func (v Value) AsFloat64() float64 {
-	return internal.RawToFloat64(v.numeric)
+	return rawToFloat64(v.numeric)
 }
 
 // AsFloat64Slice returns the []float64 value. Make sure that the Value's type is
@@ -211,8 +199,8 @@ func (v Value) asStringSlice() []string {
 
 type unknownValueType struct{}
 
-// AsInterface returns Value's data as interface{}.
-func (v Value) AsInterface() interface{} {
+// AsInterface returns Value's data as any.
+func (v Value) AsInterface() any {
 	switch v.Type() {
 	case BOOL:
 		return v.AsBool()
@@ -242,15 +230,27 @@ func (v Value) Emit() string {
 	case BOOL:
 		return strconv.FormatBool(v.AsBool())
 	case INT64SLICE:
-		return fmt.Sprint(v.asInt64Slice())
+		j, err := json.Marshal(v.asInt64Slice())
+		if err != nil {
+			return fmt.Sprintf("invalid: %v", v.asInt64Slice())
+		}
+		return string(j)
 	case INT64:
 		return strconv.FormatInt(v.AsInt64(), 10)
 	case FLOAT64SLICE:
-		return fmt.Sprint(v.asFloat64Slice())
+		j, err := json.Marshal(v.asFloat64Slice())
+		if err != nil {
+			return fmt.Sprintf("invalid: %v", v.asFloat64Slice())
+		}
+		return string(j)
 	case FLOAT64:
 		return fmt.Sprint(v.AsFloat64())
 	case STRINGSLICE:
-		return fmt.Sprint(v.asStringSlice())
+		j, err := json.Marshal(v.asStringSlice())
+		if err != nil {
+			return fmt.Sprintf("invalid: %v", v.asStringSlice())
+		}
+		return string(j)
 	case STRING:
 		return v.stringly
 	default:
@@ -262,7 +262,7 @@ func (v Value) Emit() string {
 func (v Value) MarshalJSON() ([]byte, error) {
 	var jsonVal struct {
 		Type  string
-		Value interface{}
+		Value any
 	}
 	jsonVal.Type = v.Type().String()
 	jsonVal.Value = v.AsInterface()