82 lines
1.7 KiB
Go
82 lines
1.7 KiB
Go
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package settings
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import (
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"errors"
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"fmt"
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"log"
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"sync"
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)
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type ValueMonitorParseFunc[T any] func(string) (T, error)
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type ValueMonitor[T any] struct {
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mutex sync.RWMutex
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parent *Settings
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updates <-chan string
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key string
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parserFunc ValueMonitorParseFunc[T]
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value T
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}
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func (v *ValueMonitor[T]) GetValue() T {
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v.mutex.RLock()
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defer v.mutex.RUnlock()
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return v.value
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}
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func (v *ValueMonitor[T]) maintenanceThread() {
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ctx := v.parent.context
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for {
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select {
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case <-ctx.Done():
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return
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case s, ok := <-v.updates:
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if !ok {
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return
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}
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t, err := v.parserFunc(s)
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if err != nil {
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log.Printf("ValueMonitor error parsing key %q value %q from channel: %v\n", v.key, s, err)
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continue
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}
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func() {
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v.mutex.RLock()
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defer v.mutex.RUnlock()
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v.value = t
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}()
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}
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}
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}
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func NewValueMonitor[T any](settings *Settings, key string, parserFunc ValueMonitorParseFunc[T]) (*ValueMonitor[T], error) {
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monitorChannel := make(chan string, 1)
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err := settings.RegisterKeyToMonitor(key, monitorChannel)
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if err != nil {
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close(monitorChannel)
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return nil, fmt.Errorf("error registering ValueMonitor %w", err)
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}
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initialString, ok := <-monitorChannel
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if !ok {
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close(monitorChannel)
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return nil, errors.New("channel closed before reading initial value")
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}
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parsed, err := parserFunc(initialString)
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if err != nil {
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close(monitorChannel)
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return nil, fmt.Errorf("error parsing initial value from %q: %v", initialString, err)
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}
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go func() {
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<-settings.context.Done()
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close(monitorChannel)
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}()
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results := &ValueMonitor[T]{
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parent: settings,
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updates: monitorChannel,
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key: key,
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parserFunc: parserFunc,
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value: parsed,
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}
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go results.maintenanceThread()
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return results, nil
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}
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