88 lines
1.7 KiB
Go
88 lines
1.7 KiB
Go
package state
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import (
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"context"
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"errors"
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"go.opentelemetry.io/otel/attribute"
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"go.opentelemetry.io/otel/codes"
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"go.opentelemetry.io/otel/trace"
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"gitea.libretechconsulting.com/rmcguire/ambient-local-exporter/pkg/weather"
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)
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// Returns last requested number of weather updates
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func (w *WeatherState) Get(ctx context.Context, last int) (
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[]*weather.WeatherUpdate, error,
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) {
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if last < 1 {
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last = 1
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}
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ctx, span := w.tracer.Start(ctx, "getWeatherState")
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span.SetAttributes(
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attribute.Int("last", last),
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attribute.Int("keep", w.keep),
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attribute.Int("currentSize", w.Count()),
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)
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defer span.End()
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updates, err := w.get(ctx, last)
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if err != nil {
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span.RecordError(err)
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span.SetStatus(codes.Error, err.Error())
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} else {
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span.SetStatus(codes.Ok, "")
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}
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return updates, err
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}
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func (w *WeatherState) get(ctx context.Context, last int) (
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[]*weather.WeatherUpdate, error,
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) {
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span := trace.SpanFromContext(ctx)
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w.RLock()
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defer w.Unlock()
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span.AddEvent("acquired lock on state cache")
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updates := w.updates
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if w.count() == 0 {
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err := errors.New("no state to get")
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span.RecordError(err)
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return nil, err
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} else if w.count() <= last {
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span.RecordError(errors.New("requested more state than exists"))
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} else {
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updates = updates[len(updates)-last:]
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}
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span.SetAttributes(attribute.Int("retrieved", len(updates)))
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span.SetStatus(codes.Ok, "")
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return updates, nil
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}
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// Returns count of retained weather updates
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func (w *WeatherState) Count() int {
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_, span := w.tracer.Start(w.ctx, "countWeatherState")
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defer span.End()
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count := w.count()
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span.SetAttributes(attribute.Int("count", count))
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span.SetStatus(codes.Ok, "")
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return count
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}
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func (w *WeatherState) count() int {
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w.RLock()
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defer w.RUnlock()
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return len(w.updates)
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}
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