138 lines
3.7 KiB
Go
138 lines
3.7 KiB
Go
// Copyright The OpenTelemetry Authors
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// SPDX-License-Identifier: Apache-2.0
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package metric // import "go.opentelemetry.io/otel/sdk/metric"
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import (
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"context"
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"fmt"
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"sync"
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"go.opentelemetry.io/otel/sdk/resource"
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)
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// config contains configuration options for a MeterProvider.
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type config struct {
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res *resource.Resource
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readers []Reader
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views []View
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}
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// readerSignals returns a force-flush and shutdown function for a
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// MeterProvider to call in their respective options. All Readers c contains
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// will have their force-flush and shutdown methods unified into returned
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// single functions.
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func (c config) readerSignals() (forceFlush, shutdown func(context.Context) error) {
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var fFuncs, sFuncs []func(context.Context) error
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for _, r := range c.readers {
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sFuncs = append(sFuncs, r.Shutdown)
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if f, ok := r.(interface{ ForceFlush(context.Context) error }); ok {
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fFuncs = append(fFuncs, f.ForceFlush)
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}
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}
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return unify(fFuncs), unifyShutdown(sFuncs)
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}
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// unify unifies calling all of funcs into a single function call. All errors
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// returned from calls to funcs will be unify into a single error return
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// value.
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func unify(funcs []func(context.Context) error) func(context.Context) error {
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return func(ctx context.Context) error {
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var errs []error
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for _, f := range funcs {
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if err := f(ctx); err != nil {
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errs = append(errs, err)
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}
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}
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return unifyErrors(errs)
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}
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}
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// unifyErrors combines multiple errors into a single error.
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func unifyErrors(errs []error) error {
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switch len(errs) {
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case 0:
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return nil
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case 1:
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return errs[0]
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default:
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return fmt.Errorf("%v", errs)
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}
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}
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// unifyShutdown unifies calling all of funcs once for a shutdown. If called
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// more than once, an ErrReaderShutdown error is returned.
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func unifyShutdown(funcs []func(context.Context) error) func(context.Context) error {
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f := unify(funcs)
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var once sync.Once
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return func(ctx context.Context) error {
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err := ErrReaderShutdown
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once.Do(func() { err = f(ctx) })
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return err
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}
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}
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// newConfig returns a config configured with options.
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func newConfig(options []Option) config {
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conf := config{res: resource.Default()}
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for _, o := range options {
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conf = o.apply(conf)
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}
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return conf
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}
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// Option applies a configuration option value to a MeterProvider.
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type Option interface {
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apply(config) config
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}
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// optionFunc applies a set of options to a config.
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type optionFunc func(config) config
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// apply returns a config with option(s) applied.
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func (o optionFunc) apply(conf config) config {
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return o(conf)
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}
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// WithResource associates a Resource with a MeterProvider. This Resource
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// represents the entity producing telemetry and is associated with all Meters
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// the MeterProvider will create.
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//
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// By default, if this Option is not used, the default Resource from the
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// go.opentelemetry.io/otel/sdk/resource package will be used.
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func WithResource(res *resource.Resource) Option {
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return optionFunc(func(conf config) config {
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conf.res = res
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return conf
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})
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}
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// WithReader associates Reader r with a MeterProvider.
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//
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// By default, if this option is not used, the MeterProvider will perform no
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// operations; no data will be exported without a Reader.
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func WithReader(r Reader) Option {
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return optionFunc(func(cfg config) config {
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if r == nil {
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return cfg
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}
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cfg.readers = append(cfg.readers, r)
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return cfg
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})
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}
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// WithView associates views with a MeterProvider.
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//
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// Views are appended to existing ones in a MeterProvider if this option is
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// used multiple times.
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//
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// By default, if this option is not used, the MeterProvider will use the
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// default view.
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func WithView(views ...View) Option {
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return optionFunc(func(cfg config) config {
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cfg.views = append(cfg.views, views...)
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return cfg
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})
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}
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