feat(telemetry): instrument inference duration and frame age

vendor/go.opentelemetry.io/otel/sdk/metric/aggregator/aggregator.go

@@ -0,0 +1,52 @@
+// 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 aggregator // import "go.opentelemetry.io/otel/sdk/metric/aggregator"
+
+import (
+	"fmt"
+	"math"
+
+	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+)
+
+// NewInconsistentAggregatorError formats an error describing an attempt to
+// Checkpoint or Merge different-type aggregators.  The result can be unwrapped as
+// an ErrInconsistentType.
+func NewInconsistentAggregatorError(a1, a2 export.Aggregator) error {
+	return fmt.Errorf("%w: %T and %T", aggregation.ErrInconsistentType, a1, a2)
+}
+
+// RangeTest is a common routine for testing for valid input values.
+// This rejects NaN values.  This rejects negative values when the
+// metric instrument does not support negative values, including
+// monotonic counter metrics and absolute Histogram metrics.
+func RangeTest(num number.Number, descriptor *sdkapi.Descriptor) error {
+	numberKind := descriptor.NumberKind()
+
+	if numberKind == number.Float64Kind && math.IsNaN(num.AsFloat64()) {
+		return aggregation.ErrNaNInput
+	}
+
+	switch descriptor.InstrumentKind() {
+	case sdkapi.CounterInstrumentKind, sdkapi.CounterObserverInstrumentKind:
+		if num.IsNegative(numberKind) {
+			return aggregation.ErrNegativeInput
+		}
+	}
+	return nil
+}

vendor/go.opentelemetry.io/otel/sdk/metric/aggregator/exact/exact.go

@@ -0,0 +1,130 @@
+// 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 exact // import "go.opentelemetry.io/otel/sdk/metric/aggregator/exact"
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator"
+)
+
+type (
+	// Aggregator aggregates events that form a distribution, keeping
+	// an array with the exact set of values.
+	Aggregator struct {
+		lock    sync.Mutex
+		samples []aggregation.Point
+	}
+)
+
+var _ export.Aggregator = &Aggregator{}
+var _ aggregation.Points = &Aggregator{}
+var _ aggregation.Count = &Aggregator{}
+
+// New returns cnt many new exact aggregators, which aggregate recorded
+// measurements by storing them in an array.  This type uses a mutex
+// for Update() and SynchronizedMove() concurrency.
+func New(cnt int) []Aggregator {
+	return make([]Aggregator, cnt)
+}
+
+// Aggregation returns an interface for reading the state of this aggregator.
+func (c *Aggregator) Aggregation() aggregation.Aggregation {
+	return c
+}
+
+// Kind returns aggregation.ExactKind.
+func (c *Aggregator) Kind() aggregation.Kind {
+	return aggregation.ExactKind
+}
+
+// Count returns the number of values in the checkpoint.
+func (c *Aggregator) Count() (uint64, error) {
+	return uint64(len(c.samples)), nil
+}
+
+// Points returns access to the raw data set.
+func (c *Aggregator) Points() ([]aggregation.Point, error) {
+	return c.samples, nil
+}
+
+// SynchronizedMove saves the current state to oa and resets the current state to
+// the empty set, taking a lock to prevent concurrent Update() calls.
+func (c *Aggregator) SynchronizedMove(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+
+	if oa != nil && o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	if o != nil {
+		o.samples = c.samples
+	}
+	c.samples = nil
+
+	return nil
+}
+
+// Update adds the recorded measurement to the current data set.
+// Update takes a lock to prevent concurrent Update() and SynchronizedMove()
+// calls.
+func (c *Aggregator) Update(_ context.Context, number number.Number, desc *sdkapi.Descriptor) error {
+	now := time.Now()
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.samples = append(c.samples, aggregation.Point{
+		Number: number,
+		Time:   now,
+	})
+
+	return nil
+}
+
+// Merge combines two data sets into one.
+func (c *Aggregator) Merge(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+	if o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+
+	c.samples = combine(c.samples, o.samples)
+	return nil
+}
+
+func combine(a, b []aggregation.Point) []aggregation.Point {
+	result := make([]aggregation.Point, 0, len(a)+len(b))
+
+	for len(a) != 0 && len(b) != 0 {
+		if a[0].Time.Before(b[0].Time) {
+			result = append(result, a[0])
+			a = a[1:]
+		} else {
+			result = append(result, b[0])
+			b = b[1:]
+		}
+	}
+	result = append(result, a...)
+	result = append(result, b...)
+	return result
+}

vendor/go.opentelemetry.io/otel/sdk/metric/aggregator/histogram/histogram.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 histogram // import "go.opentelemetry.io/otel/sdk/metric/aggregator/histogram"
+
+import (
+	"context"
+	"sort"
+	"sync"
+
+	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator"
+)
+
+// Note: This code uses a Mutex to govern access to the exclusive
+// aggregator state.  This is in contrast to a lock-free approach
+// (as in the Go prometheus client) that was reverted here:
+// https://github.com/open-telemetry/opentelemetry-go/pull/669
+
+type (
+	// Aggregator observe events and counts them in pre-determined buckets.
+	// It also calculates the sum and count of all events.
+	Aggregator struct {
+		lock       sync.Mutex
+		boundaries []float64
+		kind       number.Kind
+		state      *state
+	}
+
+	// config describes how the histogram is aggregated.
+	config struct {
+		// explicitBoundaries support arbitrary bucketing schemes.  This
+		// is the general case.
+		explicitBoundaries []float64
+	}
+
+	// Option configures a histogram config.
+	Option interface {
+		// apply sets one or more config fields.
+		apply(*config)
+	}
+
+	// state represents the state of a histogram, consisting of
+	// the sum and counts for all observed values and
+	// the less than equal bucket count for the pre-determined boundaries.
+	state struct {
+		bucketCounts []uint64
+		sum          number.Number
+		count        uint64
+	}
+)
+
+// WithExplicitBoundaries sets the ExplicitBoundaries configuration option of a config.
+func WithExplicitBoundaries(explicitBoundaries []float64) Option {
+	return explicitBoundariesOption{explicitBoundaries}
+}
+
+type explicitBoundariesOption struct {
+	boundaries []float64
+}
+
+func (o explicitBoundariesOption) apply(config *config) {
+	config.explicitBoundaries = o.boundaries
+}
+
+// defaultExplicitBoundaries have been copied from prometheus.DefBuckets.
+//
+// Note we anticipate the use of a high-precision histogram sketch as
+// the standard histogram aggregator for OTLP export.
+// (https://github.com/open-telemetry/opentelemetry-specification/issues/982).
+var defaultFloat64ExplicitBoundaries = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}
+
+// defaultInt64ExplicitBoundaryMultiplier determines the default
+// integer histogram boundaries.
+const defaultInt64ExplicitBoundaryMultiplier = 1e6
+
+// defaultInt64ExplicitBoundaries applies a multiplier to the default
+// float64 boundaries: [ 5K, 10K, 25K, ..., 2.5M, 5M, 10M ]
+var defaultInt64ExplicitBoundaries = func(bounds []float64) (asint []float64) {
+	for _, f := range bounds {
+		asint = append(asint, defaultInt64ExplicitBoundaryMultiplier*f)
+	}
+	return
+}(defaultFloat64ExplicitBoundaries)
+
+var _ export.Aggregator = &Aggregator{}
+var _ aggregation.Sum = &Aggregator{}
+var _ aggregation.Count = &Aggregator{}
+var _ aggregation.Histogram = &Aggregator{}
+
+// New returns a new aggregator for computing Histograms.
+//
+// A Histogram observe events and counts them in pre-defined buckets.
+// And also provides the total sum and count of all observations.
+//
+// Note that this aggregator maintains each value using independent
+// atomic operations, which introduces the possibility that
+// checkpoints are inconsistent.
+func New(cnt int, desc *sdkapi.Descriptor, opts ...Option) []Aggregator {
+	var cfg config
+
+	if desc.NumberKind() == number.Int64Kind {
+		cfg.explicitBoundaries = defaultInt64ExplicitBoundaries
+	} else {
+		cfg.explicitBoundaries = defaultFloat64ExplicitBoundaries
+	}
+
+	for _, opt := range opts {
+		opt.apply(&cfg)
+	}
+
+	aggs := make([]Aggregator, cnt)
+
+	// Boundaries MUST be ordered otherwise the histogram could not
+	// be properly computed.
+	sortedBoundaries := make([]float64, len(cfg.explicitBoundaries))
+
+	copy(sortedBoundaries, cfg.explicitBoundaries)
+	sort.Float64s(sortedBoundaries)
+
+	for i := range aggs {
+		aggs[i] = Aggregator{
+			kind:       desc.NumberKind(),
+			boundaries: sortedBoundaries,
+		}
+		aggs[i].state = aggs[i].newState()
+	}
+	return aggs
+}
+
+// Aggregation returns an interface for reading the state of this aggregator.
+func (c *Aggregator) Aggregation() aggregation.Aggregation {
+	return c
+}
+
+// Kind returns aggregation.HistogramKind.
+func (c *Aggregator) Kind() aggregation.Kind {
+	return aggregation.HistogramKind
+}
+
+// Sum returns the sum of all values in the checkpoint.
+func (c *Aggregator) Sum() (number.Number, error) {
+	return c.state.sum, nil
+}
+
+// Count returns the number of values in the checkpoint.
+func (c *Aggregator) Count() (uint64, error) {
+	return c.state.count, nil
+}
+
+// Histogram returns the count of events in pre-determined buckets.
+func (c *Aggregator) Histogram() (aggregation.Buckets, error) {
+	return aggregation.Buckets{
+		Boundaries: c.boundaries,
+		Counts:     c.state.bucketCounts,
+	}, nil
+}
+
+// SynchronizedMove saves the current state into oa and resets the current state to
+// the empty set.  Since no locks are taken, there is a chance that
+// the independent Sum, Count and Bucket Count are not consistent with each
+// other.
+func (c *Aggregator) SynchronizedMove(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+
+	if oa != nil && o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+
+	if o != nil {
+		// Swap case: This is the ordinary case for a
+		// synchronous instrument, where the SDK allocates two
+		// Aggregators and lock contention is anticipated.
+		// Reset the target state before swapping it under the
+		// lock below.
+		o.clearState()
+	}
+
+	c.lock.Lock()
+	if o != nil {
+		c.state, o.state = o.state, c.state
+	} else {
+		// No swap case: This is the ordinary case for an
+		// asynchronous instrument, where the SDK allocates a
+		// single Aggregator and there is no anticipated lock
+		// contention.
+		c.clearState()
+	}
+	c.lock.Unlock()
+
+	return nil
+}
+
+func (c *Aggregator) newState() *state {
+	return &state{
+		bucketCounts: make([]uint64, len(c.boundaries)+1),
+	}
+}
+
+func (c *Aggregator) clearState() {
+	for i := range c.state.bucketCounts {
+		c.state.bucketCounts[i] = 0
+	}
+	c.state.sum = 0
+	c.state.count = 0
+}
+
+// Update adds the recorded measurement to the current data set.
+func (c *Aggregator) Update(_ context.Context, number number.Number, desc *sdkapi.Descriptor) error {
+	kind := desc.NumberKind()
+	asFloat := number.CoerceToFloat64(kind)
+
+	bucketID := len(c.boundaries)
+	for i, boundary := range c.boundaries {
+		if asFloat < boundary {
+			bucketID = i
+			break
+		}
+	}
+	// Note: Binary-search was compared using the benchmarks. The following
+	// code is equivalent to the linear search above:
+	//
+	//     bucketID := sort.Search(len(c.boundaries), func(i int) bool {
+	//         return asFloat < c.boundaries[i]
+	//     })
+	//
+	// The binary search wins for very large boundary sets, but
+	// the linear search performs better up through arrays between
+	// 256 and 512 elements, which is a relatively large histogram, so we
+	// continue to prefer linear search.
+
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	c.state.count++
+	c.state.sum.AddNumber(kind, number)
+	c.state.bucketCounts[bucketID]++
+
+	return nil
+}
+
+// Merge combines two histograms that have the same buckets into a single one.
+func (c *Aggregator) Merge(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+	if o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+
+	c.state.sum.AddNumber(desc.NumberKind(), o.state.sum)
+	c.state.count += o.state.count
+
+	for i := 0; i < len(c.state.bucketCounts); i++ {
+		c.state.bucketCounts[i] += o.state.bucketCounts[i]
+	}
+	return nil
+}

vendor/go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue/lastvalue.go

@@ -0,0 +1,135 @@
+// 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 lastvalue // import "go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue"
+
+import (
+	"context"
+	"sync/atomic"
+	"time"
+	"unsafe"
+
+	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator"
+)
+
+type (
+
+	// Aggregator aggregates lastValue events.
+	Aggregator struct {
+		// value is an atomic pointer to *lastValueData.  It is never nil.
+		value unsafe.Pointer
+	}
+
+	// lastValueData stores the current value of a lastValue along with
+	// a sequence number to determine the winner of a race.
+	lastValueData struct {
+		// value is the int64- or float64-encoded Set() data
+		//
+		// value needs to be aligned for 64-bit atomic operations.
+		value number.Number
+
+		// timestamp indicates when this record was submitted.
+		// this can be used to pick a winner when multiple
+		// records contain lastValue data for the same labels due
+		// to races.
+		timestamp time.Time
+	}
+)
+
+var _ export.Aggregator = &Aggregator{}
+var _ aggregation.LastValue = &Aggregator{}
+
+// An unset lastValue has zero timestamp and zero value.
+var unsetLastValue = &lastValueData{}
+
+// New returns a new lastValue aggregator.  This aggregator retains the
+// last value and timestamp that were recorded.
+func New(cnt int) []Aggregator {
+	aggs := make([]Aggregator, cnt)
+	for i := range aggs {
+		aggs[i] = Aggregator{
+			value: unsafe.Pointer(unsetLastValue),
+		}
+	}
+	return aggs
+}
+
+// Aggregation returns an interface for reading the state of this aggregator.
+func (g *Aggregator) Aggregation() aggregation.Aggregation {
+	return g
+}
+
+// Kind returns aggregation.LastValueKind.
+func (g *Aggregator) Kind() aggregation.Kind {
+	return aggregation.LastValueKind
+}
+
+// LastValue returns the last-recorded lastValue value and the
+// corresponding timestamp.  The error value aggregation.ErrNoData
+// will be returned if (due to a race condition) the checkpoint was
+// computed before the first value was set.
+func (g *Aggregator) LastValue() (number.Number, time.Time, error) {
+	gd := (*lastValueData)(g.value)
+	if gd == unsetLastValue {
+		return 0, time.Time{}, aggregation.ErrNoData
+	}
+	return gd.value.AsNumber(), gd.timestamp, nil
+}
+
+// SynchronizedMove atomically saves the current value.
+func (g *Aggregator) SynchronizedMove(oa export.Aggregator, _ *sdkapi.Descriptor) error {
+	if oa == nil {
+		atomic.StorePointer(&g.value, unsafe.Pointer(unsetLastValue))
+		return nil
+	}
+	o, _ := oa.(*Aggregator)
+	if o == nil {
+		return aggregator.NewInconsistentAggregatorError(g, oa)
+	}
+	o.value = atomic.SwapPointer(&g.value, unsafe.Pointer(unsetLastValue))
+	return nil
+}
+
+// Update atomically sets the current "last" value.
+func (g *Aggregator) Update(_ context.Context, number number.Number, desc *sdkapi.Descriptor) error {
+	ngd := &lastValueData{
+		value:     number,
+		timestamp: time.Now(),
+	}
+	atomic.StorePointer(&g.value, unsafe.Pointer(ngd))
+	return nil
+}
+
+// Merge combines state from two aggregators.  The most-recently set
+// value is chosen.
+func (g *Aggregator) Merge(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+	if o == nil {
+		return aggregator.NewInconsistentAggregatorError(g, oa)
+	}
+
+	ggd := (*lastValueData)(atomic.LoadPointer(&g.value))
+	ogd := (*lastValueData)(atomic.LoadPointer(&o.value))
+
+	if ggd.timestamp.After(ogd.timestamp) {
+		return nil
+	}
+
+	g.value = unsafe.Pointer(ogd)
+	return nil
+}

vendor/go.opentelemetry.io/otel/sdk/metric/aggregator/minmaxsumcount/mmsc.go

@@ -0,0 +1,165 @@
+// 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 minmaxsumcount // import "go.opentelemetry.io/otel/sdk/metric/aggregator/minmaxsumcount"
+
+import (
+	"context"
+	"sync"
+
+	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator"
+)
+
+type (
+	// Aggregator aggregates events that form a distribution,
+	// keeping only the min, max, sum, and count.
+	Aggregator struct {
+		lock sync.Mutex
+		kind number.Kind
+		state
+	}
+
+	state struct {
+		sum   number.Number
+		min   number.Number
+		max   number.Number
+		count uint64
+	}
+)
+
+var _ export.Aggregator = &Aggregator{}
+var _ aggregation.MinMaxSumCount = &Aggregator{}
+
+// New returns a new aggregator for computing the min, max, sum, and
+// count.
+//
+// This type uses a mutex for Update() and SynchronizedMove() concurrency.
+func New(cnt int, desc *sdkapi.Descriptor) []Aggregator {
+	kind := desc.NumberKind()
+	aggs := make([]Aggregator, cnt)
+	for i := range aggs {
+		aggs[i] = Aggregator{
+			kind:  kind,
+			state: emptyState(kind),
+		}
+	}
+	return aggs
+}
+
+// Aggregation returns an interface for reading the state of this aggregator.
+func (c *Aggregator) Aggregation() aggregation.Aggregation {
+	return c
+}
+
+// Kind returns aggregation.MinMaxSumCountKind.
+func (c *Aggregator) Kind() aggregation.Kind {
+	return aggregation.MinMaxSumCountKind
+}
+
+// Sum returns the sum of values in the checkpoint.
+func (c *Aggregator) Sum() (number.Number, error) {
+	return c.sum, nil
+}
+
+// Count returns the number of values in the checkpoint.
+func (c *Aggregator) Count() (uint64, error) {
+	return c.count, nil
+}
+
+// Min returns the minimum value in the checkpoint.
+// The error value aggregation.ErrNoData will be returned
+// if there were no measurements recorded during the checkpoint.
+func (c *Aggregator) Min() (number.Number, error) {
+	if c.count == 0 {
+		return 0, aggregation.ErrNoData
+	}
+	return c.min, nil
+}
+
+// Max returns the maximum value in the checkpoint.
+// The error value aggregation.ErrNoData will be returned
+// if there were no measurements recorded during the checkpoint.
+func (c *Aggregator) Max() (number.Number, error) {
+	if c.count == 0 {
+		return 0, aggregation.ErrNoData
+	}
+	return c.max, nil
+}
+
+// SynchronizedMove saves the current state into oa and resets the current state to
+// the empty set.
+func (c *Aggregator) SynchronizedMove(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+
+	if oa != nil && o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+	c.lock.Lock()
+	if o != nil {
+		o.state = c.state
+	}
+	c.state = emptyState(c.kind)
+	c.lock.Unlock()
+
+	return nil
+}
+
+func emptyState(kind number.Kind) state {
+	return state{
+		count: 0,
+		sum:   0,
+		min:   kind.Maximum(),
+		max:   kind.Minimum(),
+	}
+}
+
+// Update adds the recorded measurement to the current data set.
+func (c *Aggregator) Update(_ context.Context, number number.Number, desc *sdkapi.Descriptor) error {
+	kind := desc.NumberKind()
+
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.count++
+	c.sum.AddNumber(kind, number)
+	if number.CompareNumber(kind, c.min) < 0 {
+		c.min = number
+	}
+	if number.CompareNumber(kind, c.max) > 0 {
+		c.max = number
+	}
+	return nil
+}
+
+// Merge combines two data sets into one.
+func (c *Aggregator) Merge(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+	if o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+
+	c.count += o.count
+	c.sum.AddNumber(desc.NumberKind(), o.sum)
+
+	if c.min.CompareNumber(desc.NumberKind(), o.min) > 0 {
+		c.min.SetNumber(o.min)
+	}
+	if c.max.CompareNumber(desc.NumberKind(), o.max) < 0 {
+		c.max.SetNumber(o.max)
+	}
+	return nil
+}

vendor/go.opentelemetry.io/otel/sdk/metric/aggregator/sum/sum.go

@@ -0,0 +1,106 @@
+// 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 sum // import "go.opentelemetry.io/otel/sdk/metric/aggregator/sum"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator"
+)
+
+// Aggregator aggregates counter events.
+type Aggregator struct {
+	// current holds current increments to this counter record
+	// current needs to be aligned for 64-bit atomic operations.
+	value number.Number
+}
+
+var _ export.Aggregator = &Aggregator{}
+var _ export.Subtractor = &Aggregator{}
+var _ aggregation.Sum = &Aggregator{}
+
+// New returns a new counter aggregator implemented by atomic
+// operations.  This aggregator implements the aggregation.Sum
+// export interface.
+func New(cnt int) []Aggregator {
+	return make([]Aggregator, cnt)
+}
+
+// Aggregation returns an interface for reading the state of this aggregator.
+func (c *Aggregator) Aggregation() aggregation.Aggregation {
+	return c
+}
+
+// Kind returns aggregation.SumKind.
+func (c *Aggregator) Kind() aggregation.Kind {
+	return aggregation.SumKind
+}
+
+// Sum returns the last-checkpointed sum.  This will never return an
+// error.
+func (c *Aggregator) Sum() (number.Number, error) {
+	return c.value, nil
+}
+
+// SynchronizedMove atomically saves the current value into oa and resets the
+// current sum to zero.
+func (c *Aggregator) SynchronizedMove(oa export.Aggregator, _ *sdkapi.Descriptor) error {
+	if oa == nil {
+		c.value.SetRawAtomic(0)
+		return nil
+	}
+	o, _ := oa.(*Aggregator)
+	if o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+	o.value = c.value.SwapNumberAtomic(number.Number(0))
+	return nil
+}
+
+// Update atomically adds to the current value.
+func (c *Aggregator) Update(_ context.Context, num number.Number, desc *sdkapi.Descriptor) error {
+	c.value.AddNumberAtomic(desc.NumberKind(), num)
+	return nil
+}
+
+// Merge combines two counters by adding their sums.
+func (c *Aggregator) Merge(oa export.Aggregator, desc *sdkapi.Descriptor) error {
+	o, _ := oa.(*Aggregator)
+	if o == nil {
+		return aggregator.NewInconsistentAggregatorError(c, oa)
+	}
+	c.value.AddNumber(desc.NumberKind(), o.value)
+	return nil
+}
+
+func (c *Aggregator) Subtract(opAgg, resAgg export.Aggregator, descriptor *sdkapi.Descriptor) error {
+	op, _ := opAgg.(*Aggregator)
+	if op == nil {
+		return aggregator.NewInconsistentAggregatorError(c, opAgg)
+	}
+
+	res, _ := resAgg.(*Aggregator)
+	if res == nil {
+		return aggregator.NewInconsistentAggregatorError(c, resAgg)
+	}
+
+	res.value = c.value
+	res.value.AddNumber(descriptor.NumberKind(), number.NewNumberSignChange(descriptor.NumberKind(), op.value))
+	return nil
+}