mirror of
https://github.com/open-telemetry/opentelemetry-go.git
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a485d0ec64
* Update License header for all source files - Add Apache 2.0 header to source files that did not have one. - Update all existing headers dated to 2019 to be 2020 - Remove comma from License header to comply with the Apache 2.0 guidelines. * Update Copyright notice Use the standard Copyright notices outlined by the [CNCF](https://github.com/cncf/foundation/blob/master/copyright-notices.md#copyright-notices)
626 lines
17 KiB
Go
626 lines
17 KiB
Go
// Copyright The OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package metric
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import (
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"context"
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"fmt"
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"os"
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"reflect"
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"runtime"
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"sort"
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"sync"
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"sync/atomic"
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"go.opentelemetry.io/otel/api/core"
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"go.opentelemetry.io/otel/api/metric"
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api "go.opentelemetry.io/otel/api/metric"
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export "go.opentelemetry.io/otel/sdk/export/metric"
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"go.opentelemetry.io/otel/sdk/export/metric/aggregator"
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"go.opentelemetry.io/otel/sdk/resource"
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)
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type (
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// SDK implements the OpenTelemetry Meter API. The SDK is
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// bound to a single export.Batcher in `New()`.
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//
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// The SDK supports a Collect() API to gather and export
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// current data. Collect() should be arranged according to
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// the batcher model. Push-based batchers will setup a
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// timer to call Collect() periodically. Pull-based batchers
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// will call Collect() when a pull request arrives.
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SDK struct {
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// current maps `mapkey` to *record.
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current sync.Map
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// asyncInstruments is a set of
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// `*asyncInstrument` instances
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asyncInstruments sync.Map
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// empty is the (singleton) result of Labels()
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// w/ zero arguments.
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empty labels
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// currentEpoch is the current epoch number. It is
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// incremented in `Collect()`.
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currentEpoch int64
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// batcher is the configured batcher+configuration.
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batcher export.Batcher
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// lencoder determines how labels are uniquely encoded.
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labelEncoder export.LabelEncoder
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// collectLock prevents simultaneous calls to Collect().
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collectLock sync.Mutex
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// errorHandler supports delivering errors to the user.
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errorHandler ErrorHandler
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// resource represents the entity producing telemetry.
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resource resource.Resource
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}
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syncInstrument struct {
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instrument
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}
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// orderedLabels is a variable-size array of core.KeyValue
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// suitable for use as a map key.
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orderedLabels interface{}
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// labels implements the OpenTelemetry LabelSet API,
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// represents an internalized set of labels that may be used
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// repeatedly.
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labels struct {
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meter *SDK
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// ordered is the output of sorting and deduplicating
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// the labels, copied into an array of the correct
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// size for use as a map key.
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ordered orderedLabels
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// sortSlice has a single purpose - as a temporary
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// place for sorting during labels creation to avoid
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// allocation
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sortSlice sortedLabels
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// cachedValue contains a `reflect.Value` of the `ordered`
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// member
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cachedValue reflect.Value
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// cachedEncoded contains an encoded version of the
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// `ordered` member
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cachedEncoded string
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}
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// mapkey uniquely describes a metric instrument in terms of
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// its InstrumentID and the encoded form of its LabelSet.
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mapkey struct {
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descriptor *metric.Descriptor
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ordered orderedLabels
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}
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// record maintains the state of one metric instrument. Due
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// the use of lock-free algorithms, there may be more than one
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// `record` in existence at a time, although at most one can
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// be referenced from the `SDK.current` map.
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record struct {
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// refMapped keeps track of refcounts and the mapping state to the
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// SDK.current map.
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refMapped refcountMapped
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// modified is an atomic boolean that tracks if the current record
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// was modified since the last Collect().
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//
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// modified has to be aligned for 64-bit atomic operations.
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modified int64
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// labels is the LabelSet passed by the user.
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labels *labels
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// inst is a pointer to the corresponding instrument.
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inst *syncInstrument
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// recorder implements the actual RecordOne() API,
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// depending on the type of aggregation. If nil, the
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// metric was disabled by the exporter.
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recorder export.Aggregator
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}
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instrument struct {
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meter *SDK
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descriptor metric.Descriptor
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}
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asyncInstrument struct {
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instrument
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// recorders maps ordered labels to the pair of
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// labelset and recorder
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recorders map[orderedLabels]labeledRecorder
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callback func(func(core.Number, api.LabelSet))
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}
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labeledRecorder struct {
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recorder export.Aggregator
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labels *labels
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modifiedEpoch int64
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}
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ErrorHandler func(error)
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)
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var (
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_ api.MeterImpl = &SDK{}
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_ api.LabelSet = &labels{}
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_ api.AsyncImpl = &asyncInstrument{}
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_ api.SyncImpl = &syncInstrument{}
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_ api.BoundSyncImpl = &record{}
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_ api.Resourcer = &SDK{}
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_ export.LabelStorage = &labels{}
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kvType = reflect.TypeOf(core.KeyValue{})
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)
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func (inst *instrument) Descriptor() api.Descriptor {
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return inst.descriptor
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}
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func (a *asyncInstrument) Implementation() interface{} {
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return a
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}
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func (s *syncInstrument) Implementation() interface{} {
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return s
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}
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func (a *asyncInstrument) observe(number core.Number, ls api.LabelSet) {
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if err := aggregator.RangeTest(number, &a.descriptor); err != nil {
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a.meter.errorHandler(err)
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return
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}
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recorder := a.getRecorder(ls)
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if recorder == nil {
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// The instrument is disabled according to the
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// AggregationSelector.
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return
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}
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if err := recorder.Update(context.Background(), number, &a.descriptor); err != nil {
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a.meter.errorHandler(err)
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return
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}
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}
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func (a *asyncInstrument) getRecorder(ls api.LabelSet) export.Aggregator {
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labels := a.meter.labsFor(ls)
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lrec, ok := a.recorders[labels.ordered]
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if ok {
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lrec.modifiedEpoch = a.meter.currentEpoch
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a.recorders[labels.ordered] = lrec
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return lrec.recorder
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}
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rec := a.meter.batcher.AggregatorFor(&a.descriptor)
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if a.recorders == nil {
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a.recorders = make(map[orderedLabels]labeledRecorder)
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}
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// This may store nil recorder in the map, thus disabling the
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// asyncInstrument for the labelset for good. This is intentional,
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// but will be revisited later.
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a.recorders[labels.ordered] = labeledRecorder{
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recorder: rec,
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labels: labels,
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modifiedEpoch: a.meter.currentEpoch,
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}
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return rec
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}
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func (m *SDK) SetErrorHandler(f ErrorHandler) {
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m.errorHandler = f
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}
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func (s *syncInstrument) acquireHandle(ls *labels) *record {
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// Create lookup key for sync.Map (one allocation)
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mk := mapkey{
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descriptor: &s.descriptor,
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ordered: ls.ordered,
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}
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if actual, ok := s.meter.current.Load(mk); ok {
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// Existing record case, only one allocation so far.
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rec := actual.(*record)
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if rec.refMapped.ref() {
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// At this moment it is guaranteed that the entry is in
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// the map and will not be removed.
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return rec
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}
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// This entry is no longer mapped, try to add a new entry.
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}
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// There's a memory allocation here.
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rec := &record{
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labels: ls,
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inst: s,
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refMapped: refcountMapped{value: 2},
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modified: 0,
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recorder: s.meter.batcher.AggregatorFor(&s.descriptor),
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}
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for {
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// Load/Store: there's a memory allocation to place `mk` into
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// an interface here.
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if actual, loaded := s.meter.current.LoadOrStore(mk, rec); loaded {
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// Existing record case. Cannot change rec here because if fail
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// will try to add rec again to avoid new allocations.
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oldRec := actual.(*record)
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if oldRec.refMapped.ref() {
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// At this moment it is guaranteed that the entry is in
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// the map and will not be removed.
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return oldRec
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}
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// This loaded entry is marked as unmapped (so Collect will remove
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// it from the map immediately), try again - this is a busy waiting
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// strategy to wait until Collect() removes this entry from the map.
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//
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// This can be improved by having a list of "Unmapped" entries for
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// one time only usages, OR we can make this a blocking path and use
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// a Mutex that protects the delete operation (delete only if the old
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// record is associated with the key).
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// Let collector get work done to remove the entry from the map.
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runtime.Gosched()
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continue
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}
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// The new entry was added to the map, good to go.
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return rec
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}
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}
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func (s *syncInstrument) Bind(ls api.LabelSet) api.BoundSyncImpl {
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labs := s.meter.labsFor(ls)
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return s.acquireHandle(labs)
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}
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func (s *syncInstrument) RecordOne(ctx context.Context, number core.Number, ls api.LabelSet) {
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ourLs := s.meter.labsFor(ls)
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h := s.acquireHandle(ourLs)
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defer h.Unbind()
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h.RecordOne(ctx, number)
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}
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// New constructs a new SDK for the given batcher. This SDK supports
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// only a single batcher.
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//
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// The SDK does not start any background process to collect itself
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// periodically, this responsbility lies with the batcher, typically,
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// depending on the type of export. For example, a pull-based
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// batcher will call Collect() when it receives a request to scrape
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// current metric values. A push-based batcher should configure its
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// own periodic collection.
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func New(batcher export.Batcher, labelEncoder export.LabelEncoder, opts ...Option) *SDK {
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c := &Config{ErrorHandler: DefaultErrorHandler}
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for _, opt := range opts {
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opt.Apply(c)
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}
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m := &SDK{
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empty: labels{
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ordered: [0]core.KeyValue{},
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},
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batcher: batcher,
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labelEncoder: labelEncoder,
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errorHandler: c.ErrorHandler,
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resource: c.Resource,
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}
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m.empty.meter = m
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m.empty.cachedValue = reflect.ValueOf(m.empty.ordered)
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return m
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}
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func DefaultErrorHandler(err error) {
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fmt.Fprintln(os.Stderr, "Metrics SDK error:", err)
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}
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// Labels returns a LabelSet corresponding to the arguments. Passed labels
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// are sorted and de-duplicated, with last-value-wins semantics. Note that
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// sorting and deduplicating happens in-place to avoid allocation, so the
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// passed slice will be modified.
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func (m *SDK) Labels(kvs ...core.KeyValue) api.LabelSet {
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// Check for empty set.
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if len(kvs) == 0 {
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return &m.empty
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}
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ls := &labels{ // allocation
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meter: m,
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sortSlice: kvs,
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}
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// Sort and de-duplicate. Note: this use of `ls.sortSlice`
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// avoids an allocation by using the address-able field rather
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// than `kvs`.
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sort.Stable(&ls.sortSlice)
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ls.sortSlice = nil
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oi := 1
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for i := 1; i < len(kvs); i++ {
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if kvs[i-1].Key == kvs[i].Key {
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// Overwrite the value for "last-value wins".
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kvs[oi-1].Value = kvs[i].Value
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continue
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}
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kvs[oi] = kvs[i]
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oi++
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}
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kvs = kvs[0:oi]
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ls.computeOrdered(kvs)
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return ls
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}
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func (ls *labels) NumLabels() int {
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return ls.cachedValue.Len()
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}
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func (ls *labels) GetLabel(idx int) core.KeyValue {
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return ls.cachedValue.Index(idx).Interface().(core.KeyValue)
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}
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func (ls *labels) computeOrdered(kvs []core.KeyValue) {
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ls.ordered = computeOrderedFixed(kvs)
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if ls.ordered == nil {
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ls.ordered = computeOrderedReflect(kvs)
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}
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ls.cachedValue = reflect.ValueOf(ls.ordered)
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}
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func (ls *labels) ensureEncoded(encoder export.LabelEncoder) {
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if ls.cachedEncoded != "" {
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return
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}
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iter := export.NewLabelIterator(ls)
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ls.cachedEncoded = encoder.Encode(iter)
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}
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func computeOrderedFixed(kvs []core.KeyValue) orderedLabels {
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switch len(kvs) {
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case 1:
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ptr := new([1]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 2:
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ptr := new([2]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 3:
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ptr := new([3]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 4:
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ptr := new([4]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 5:
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ptr := new([5]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 6:
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ptr := new([6]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 7:
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ptr := new([7]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 8:
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ptr := new([8]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 9:
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ptr := new([9]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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case 10:
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ptr := new([10]core.KeyValue)
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copy((*ptr)[:], kvs)
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return *ptr
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default:
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return nil
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}
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}
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func computeOrderedReflect(kvs []core.KeyValue) interface{} {
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at := reflect.New(reflect.ArrayOf(len(kvs), kvType)).Elem()
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for i, kv := range kvs {
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*(at.Index(i).Addr().Interface().(*core.KeyValue)) = kv
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}
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return at.Interface()
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}
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// labsFor sanitizes the input LabelSet. The input will be rejected
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// if it was created by another Meter instance, for example.
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func (m *SDK) labsFor(ls api.LabelSet) *labels {
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if del, ok := ls.(api.LabelSetDelegate); ok {
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ls = del.Delegate()
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}
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if l, _ := ls.(*labels); l != nil && l.meter == m {
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return l
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}
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return &m.empty
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}
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func (m *SDK) NewSyncInstrument(descriptor api.Descriptor) (api.SyncImpl, error) {
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return &syncInstrument{
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instrument: instrument{
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descriptor: descriptor,
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meter: m,
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},
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}, nil
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}
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func (m *SDK) NewAsyncInstrument(descriptor api.Descriptor, callback func(func(core.Number, api.LabelSet))) (api.AsyncImpl, error) {
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a := &asyncInstrument{
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instrument: instrument{
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descriptor: descriptor,
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meter: m,
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},
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callback: callback,
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}
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m.asyncInstruments.Store(a, nil)
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return a, nil
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}
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// Collect traverses the list of active records and observers and
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// exports data for each active instrument. Collect() may not be
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// called concurrently.
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//
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// During the collection pass, the export.Batcher will receive
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// one Export() call per current aggregation.
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//
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// Returns the number of records that were checkpointed.
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func (m *SDK) Collect(ctx context.Context) int {
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m.collectLock.Lock()
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defer m.collectLock.Unlock()
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checkpointed := m.collectRecords(ctx)
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checkpointed += m.collectAsync(ctx)
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m.currentEpoch++
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return checkpointed
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}
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func (m *SDK) collectRecords(ctx context.Context) int {
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checkpointed := 0
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m.current.Range(func(key interface{}, value interface{}) bool {
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inuse := value.(*record)
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unmapped := inuse.refMapped.tryUnmap()
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// If able to unmap then remove the record from the current Map.
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if unmapped {
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m.current.Delete(inuse.mapkey())
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}
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// Always report the values if a reference to the Record is active,
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// this is to keep the previous behavior.
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// TODO: Reconsider this logic.
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if inuse.refMapped.inUse() || atomic.LoadInt64(&inuse.modified) != 0 {
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atomic.StoreInt64(&inuse.modified, 0)
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checkpointed += m.checkpointRecord(ctx, inuse)
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}
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// Always continue to iterate over the entire map.
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return true
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})
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return checkpointed
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}
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func (m *SDK) collectAsync(ctx context.Context) int {
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checkpointed := 0
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m.asyncInstruments.Range(func(key, value interface{}) bool {
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a := key.(*asyncInstrument)
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a.callback(a.observe)
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checkpointed += m.checkpointAsync(ctx, a)
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return true
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})
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return checkpointed
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}
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func (m *SDK) checkpointRecord(ctx context.Context, r *record) int {
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return m.checkpoint(ctx, &r.inst.descriptor, r.recorder, r.labels)
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}
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func (m *SDK) checkpointAsync(ctx context.Context, a *asyncInstrument) int {
|
|
if len(a.recorders) == 0 {
|
|
return 0
|
|
}
|
|
checkpointed := 0
|
|
for encodedLabels, lrec := range a.recorders {
|
|
epochDiff := m.currentEpoch - lrec.modifiedEpoch
|
|
if epochDiff == 0 {
|
|
checkpointed += m.checkpoint(ctx, &a.descriptor, lrec.recorder, lrec.labels)
|
|
} else if epochDiff > 1 {
|
|
// This is second collection cycle with no
|
|
// observations for this labelset. Remove the
|
|
// recorder.
|
|
delete(a.recorders, encodedLabels)
|
|
}
|
|
}
|
|
if len(a.recorders) == 0 {
|
|
a.recorders = nil
|
|
}
|
|
return checkpointed
|
|
}
|
|
|
|
func (m *SDK) checkpoint(ctx context.Context, descriptor *metric.Descriptor, recorder export.Aggregator, labels *labels) int {
|
|
if recorder == nil {
|
|
return 0
|
|
}
|
|
recorder.Checkpoint(ctx, descriptor)
|
|
|
|
labels.ensureEncoded(m.labelEncoder)
|
|
exportLabels := export.NewLabels(labels, labels.cachedEncoded, m.labelEncoder)
|
|
exportRecord := export.NewRecord(descriptor, exportLabels, recorder)
|
|
err := m.batcher.Process(ctx, exportRecord)
|
|
if err != nil {
|
|
m.errorHandler(err)
|
|
}
|
|
return 1
|
|
}
|
|
|
|
// Resource returns the Resource this SDK was created with describing the
|
|
// entity for which it creates instruments for.
|
|
//
|
|
// Resource means that the SDK implements the Resourcer interface and
|
|
// therefore all metric instruments it creates will inherit its
|
|
// Resource by default unless explicitly overwritten.
|
|
func (m *SDK) Resource() resource.Resource {
|
|
return m.resource
|
|
}
|
|
|
|
// RecordBatch enters a batch of metric events.
|
|
func (m *SDK) RecordBatch(ctx context.Context, ls api.LabelSet, measurements ...api.Measurement) {
|
|
for _, meas := range measurements {
|
|
meas.SyncImpl().RecordOne(ctx, meas.Number(), ls)
|
|
}
|
|
}
|
|
|
|
func (r *record) RecordOne(ctx context.Context, number core.Number) {
|
|
if r.recorder == nil {
|
|
// The instrument is disabled according to the AggregationSelector.
|
|
return
|
|
}
|
|
if err := aggregator.RangeTest(number, &r.inst.descriptor); err != nil {
|
|
r.labels.meter.errorHandler(err)
|
|
return
|
|
}
|
|
if err := r.recorder.Update(ctx, number, &r.inst.descriptor); err != nil {
|
|
r.labels.meter.errorHandler(err)
|
|
return
|
|
}
|
|
}
|
|
|
|
func (r *record) Unbind() {
|
|
// Record was modified, inform the Collect() that things need to be collected.
|
|
// TODO: Reconsider if we should marked as modified when an Update happens and
|
|
// collect only when updates happened even for Bounds.
|
|
atomic.StoreInt64(&r.modified, 1)
|
|
r.refMapped.unref()
|
|
}
|
|
|
|
func (r *record) mapkey() mapkey {
|
|
return mapkey{
|
|
descriptor: &r.inst.descriptor,
|
|
ordered: r.labels.ordered,
|
|
}
|
|
}
|