poller.go

Documentation: github.com/rs/zerolog/diode/internal/diodes

     1  package diodes
     2  
     3  import (
     4  	"context"
     5  	"time"
     6  )
     7  
     8  // Diode is any implementation of a diode.
     9  type Diode interface {
    10  	Set(GenericDataType)
    11  	TryNext() (GenericDataType, bool)
    12  }
    13  
    14  // Poller will poll a diode until a value is available.
    15  type Poller struct {
    16  	Diode
    17  	interval time.Duration
    18  	ctx      context.Context
    19  }
    20  
    21  // PollerConfigOption can be used to setup the poller.
    22  type PollerConfigOption func(*Poller)
    23  
    24  // WithPollingInterval sets the interval at which the diode is queried
    25  // for new data. The default is 10ms.
    26  func WithPollingInterval(interval time.Duration) PollerConfigOption {
    27  	return func(c *Poller) {
    28  		c.interval = interval
    29  	}
    30  }
    31  
    32  // WithPollingContext sets the context to cancel any retrieval (Next()). It
    33  // will not change any results for adding data (Set()). Default is
    34  // context.Background().
    35  func WithPollingContext(ctx context.Context) PollerConfigOption {
    36  	return func(c *Poller) {
    37  		c.ctx = ctx
    38  	}
    39  }
    40  
    41  // NewPoller returns a new Poller that wraps the given diode.
    42  func NewPoller(d Diode, opts ...PollerConfigOption) *Poller {
    43  	p := &Poller{
    44  		Diode:    d,
    45  		interval: 10 * time.Millisecond,
    46  		ctx:      context.Background(),
    47  	}
    48  
    49  	for _, o := range opts {
    50  		o(p)
    51  	}
    52  
    53  	return p
    54  }
    55  
    56  // Next polls the diode until data is available or until the context is done.
    57  // If the context is done, then nil will be returned.
    58  func (p *Poller) Next() GenericDataType {
    59  	for {
    60  		data, ok := p.Diode.TryNext()
    61  		if !ok {
    62  			if p.isDone() {
    63  				return nil
    64  			}
    65  
    66  			time.Sleep(p.interval)
    67  			continue
    68  		}
    69  		return data
    70  	}
    71  }
    72  
    73  func (p *Poller) isDone() bool {
    74  	select {
    75  	case <-p.ctx.Done():
    76  		return true
    77  	default:
    78  		return false
    79  	}
    80  }
    81
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