79 lines
1.6 KiB
Go
79 lines
1.6 KiB
Go
package util
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import (
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"sync"
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"time"
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"github.com/evcc-io/evcc/api"
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)
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// Monitor monitors values for regular updates
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type Monitor[T any] struct {
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val T
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mu sync.RWMutex
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once sync.Once
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done chan struct{}
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updated time.Time
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timeout time.Duration
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}
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// NewMonitor created a new monitor with given timeout
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func NewMonitor[T any](timeout time.Duration) *Monitor[T] {
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return &Monitor[T]{
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done: make(chan struct{}),
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timeout: timeout,
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}
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}
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// Set updates the current value and timestamp
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func (m *Monitor[T]) Set(val T) {
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m.SetFunc(func(_ T) T { return val })
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}
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// SetFunc updates the current value and timestamp while holding the lock
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func (m *Monitor[T]) SetFunc(set func(T) T) {
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m.mu.Lock()
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defer m.mu.Unlock()
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m.val = set(m.val)
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m.updated = time.Now()
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m.once.Do(func() { close(m.done) })
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}
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// Get returns the current value or ErrOutdated if timeout exceeded
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func (m *Monitor[T]) Get() (T, error) {
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var res T
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err := m.GetFunc(func(v T) {
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res = v
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})
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return res, err
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}
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// GetFunc returns the current value or ErrOutdated if timeout exceeded while holding the lock
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func (m *Monitor[T]) GetFunc(get func(T)) error {
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m.mu.RLock()
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defer m.mu.RUnlock()
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// without timeout set, error if not yet received
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if m.timeout == 0 {
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select {
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case <-m.done:
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get(m.val)
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return nil
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default:
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return api.ErrOutdated
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}
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} else if time.Since(m.updated) > m.timeout {
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get(m.val)
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return api.ErrOutdated
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}
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get(m.val)
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return nil
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}
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// Done signals if monitor has been updated at least once
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func (m *Monitor[T]) Done() <-chan struct{} {
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return m.done
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}
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