99 lines
2 KiB
Go
99 lines
2 KiB
Go
package plugin
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import (
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"context"
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"errors"
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"fmt"
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"sync"
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"time"
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"github.com/benbjohnson/clock"
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"github.com/evcc-io/evcc/util"
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)
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func init() {
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registry.AddCtx("cached", NewCachedFromConfig)
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}
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// cachedPlugin caches the wrapped reading for the configured duration
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type cachedPlugin struct {
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ctx context.Context
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clock clock.Clock
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cache time.Duration
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value Config
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}
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// NewCachedFromConfig creates cached provider
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func NewCachedFromConfig(ctx context.Context, other map[string]any) (Plugin, error) {
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var cc struct {
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Cache time.Duration
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Value Config
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}
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if err := util.DecodeOther(other, &cc); err != nil {
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return nil, err
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}
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if cc.Cache <= 0 {
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return nil, errors.New("cache duration is required")
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}
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return &cachedPlugin{
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ctx: ctx,
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clock: clock.New(),
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cache: cc.Cache,
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value: cc.Value,
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}, nil
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}
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func (o *cachedPlugin) cachedGetter[T any](valuer func(ctx context.Context) (func() (T, error), error)) (func() (T, error), error) {
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value, err := valuer(o.ctx)
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if err != nil {
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return nil, fmt.Errorf("cached: %w", err)
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}
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var mu sync.Mutex
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var updated time.Time
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var val T
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return func() (T, error) {
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mu.Lock()
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defer mu.Unlock()
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// refresh on first call and once the cache has expired; failures are not cached
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if updated.IsZero() || o.clock.Since(updated) > o.cache {
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v, err := value()
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if err != nil {
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return v, err
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}
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val = v
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updated = o.clock.Now()
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}
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return val, nil
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}, nil
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}
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var _ StringGetter = (*cachedPlugin)(nil)
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func (o *cachedPlugin) StringGetter() (func() (string, error), error) {
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return o.cachedGetter(o.value.StringGetter)
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}
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var _ FloatGetter = (*cachedPlugin)(nil)
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func (o *cachedPlugin) FloatGetter() (func() (float64, error), error) {
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return o.cachedGetter(o.value.FloatGetter)
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}
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var _ IntGetter = (*cachedPlugin)(nil)
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func (o *cachedPlugin) IntGetter() (func() (int64, error), error) {
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return o.cachedGetter(o.value.IntGetter)
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}
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var _ BoolGetter = (*cachedPlugin)(nil)
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func (o *cachedPlugin) BoolGetter() (func() (bool, error), error) {
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return o.cachedGetter(o.value.BoolGetter)
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}
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