gauge_float64.go

Documentation: github.com/rcrowley/go-metrics

     1  package metrics
     2  
     3  import (
     4  	"math"
     5  	"sync/atomic"
     6  )
     7  
     8  // GaugeFloat64s hold a float64 value that can be set arbitrarily.
     9  type GaugeFloat64 interface {
    10  	Snapshot() GaugeFloat64
    11  	Update(float64)
    12  	Value() float64
    13  }
    14  
    15  // GetOrRegisterGaugeFloat64 returns an existing GaugeFloat64 or constructs and registers a
    16  // new StandardGaugeFloat64.
    17  func GetOrRegisterGaugeFloat64(name string, r Registry) GaugeFloat64 {
    18  	if nil == r {
    19  		r = DefaultRegistry
    20  	}
    21  	return r.GetOrRegister(name, NewGaugeFloat64()).(GaugeFloat64)
    22  }
    23  
    24  // NewGaugeFloat64 constructs a new StandardGaugeFloat64.
    25  func NewGaugeFloat64() GaugeFloat64 {
    26  	if UseNilMetrics {
    27  		return NilGaugeFloat64{}
    28  	}
    29  	return &StandardGaugeFloat64{
    30  		value: 0.0,
    31  	}
    32  }
    33  
    34  // NewRegisteredGaugeFloat64 constructs and registers a new StandardGaugeFloat64.
    35  func NewRegisteredGaugeFloat64(name string, r Registry) GaugeFloat64 {
    36  	c := NewGaugeFloat64()
    37  	if nil == r {
    38  		r = DefaultRegistry
    39  	}
    40  	r.Register(name, c)
    41  	return c
    42  }
    43  
    44  // NewFunctionalGauge constructs a new FunctionalGauge.
    45  func NewFunctionalGaugeFloat64(f func() float64) GaugeFloat64 {
    46  	if UseNilMetrics {
    47  		return NilGaugeFloat64{}
    48  	}
    49  	return &FunctionalGaugeFloat64{value: f}
    50  }
    51  
    52  // NewRegisteredFunctionalGauge constructs and registers a new StandardGauge.
    53  func NewRegisteredFunctionalGaugeFloat64(name string, r Registry, f func() float64) GaugeFloat64 {
    54  	c := NewFunctionalGaugeFloat64(f)
    55  	if nil == r {
    56  		r = DefaultRegistry
    57  	}
    58  	r.Register(name, c)
    59  	return c
    60  }
    61  
    62  // GaugeFloat64Snapshot is a read-only copy of another GaugeFloat64.
    63  type GaugeFloat64Snapshot float64
    64  
    65  // Snapshot returns the snapshot.
    66  func (g GaugeFloat64Snapshot) Snapshot() GaugeFloat64 { return g }
    67  
    68  // Update panics.
    69  func (GaugeFloat64Snapshot) Update(float64) {
    70  	panic("Update called on a GaugeFloat64Snapshot")
    71  }
    72  
    73  // Value returns the value at the time the snapshot was taken.
    74  func (g GaugeFloat64Snapshot) Value() float64 { return float64(g) }
    75  
    76  // NilGauge is a no-op Gauge.
    77  type NilGaugeFloat64 struct{}
    78  
    79  // Snapshot is a no-op.
    80  func (NilGaugeFloat64) Snapshot() GaugeFloat64 { return NilGaugeFloat64{} }
    81  
    82  // Update is a no-op.
    83  func (NilGaugeFloat64) Update(v float64) {}
    84  
    85  // Value is a no-op.
    86  func (NilGaugeFloat64) Value() float64 { return 0.0 }
    87  
    88  // StandardGaugeFloat64 is the standard implementation of a GaugeFloat64 and uses
    89  // sync.Mutex to manage a single float64 value.
    90  type StandardGaugeFloat64 struct {
    91  	value uint64
    92  }
    93  
    94  // Snapshot returns a read-only copy of the gauge.
    95  func (g *StandardGaugeFloat64) Snapshot() GaugeFloat64 {
    96  	return GaugeFloat64Snapshot(g.Value())
    97  }
    98  
    99  // Update updates the gauge's value.
   100  func (g *StandardGaugeFloat64) Update(v float64) {
   101  	atomic.StoreUint64(&g.value, math.Float64bits(v))
   102  }
   103  
   104  // Value returns the gauge's current value.
   105  func (g *StandardGaugeFloat64) Value() float64 {
   106  	return math.Float64frombits(atomic.LoadUint64(&g.value))
   107  }
   108  
   109  // FunctionalGaugeFloat64 returns value from given function
   110  type FunctionalGaugeFloat64 struct {
   111  	value func() float64
   112  }
   113  
   114  // Value returns the gauge's current value.
   115  func (g FunctionalGaugeFloat64) Value() float64 {
   116  	return g.value()
   117  }
   118  
   119  // Snapshot returns the snapshot.
   120  func (g FunctionalGaugeFloat64) Snapshot() GaugeFloat64 { return GaugeFloat64Snapshot(g.Value()) }
   121  
   122  // Update panics.
   123  func (FunctionalGaugeFloat64) Update(float64) {
   124  	panic("Update called on a FunctionalGaugeFloat64")
   125  }
   126
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