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added changes based on PR comments to the proposal

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caffix
2017-11-15 17:59:48 -05:00
parent 8b7649b90c
commit a724ffab25
3 changed files with 86 additions and 91 deletions
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32
docs/architecture/adr-006-trust-metric.md
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@ -38,7 +38,7 @@ where *R*[*i*] denotes the raw trust value at time interval *i* (where *i* == 0
`H[i] = ` ![formula1](img/formula1.png "Weighted Sum Formula")
The weights can be chosen either optimistically or pessimistically. With the history value available, we can now finish calculating the integral value:
The weights can be chosen either optimistically or pessimistically. An optimistic weight creates larger weights for newer history data values, while the the pessimistic weight creates larger weights for time intervals with lower scores. The default weights used during the calculation of the history value are optimistic and calculated as *Wk* = 0.8^*k*, for time interval *k*. With the history value available, we can now finish calculating the integral value:
```math
(2) Integral Value = b * H[i]
@ -49,13 +49,13 @@ Where *H*[*i*] denotes the history value at time interval *i* and *b* is the wei
```math
D[i] = R[i] – H[i]
(3) Derivative Value = (c * D[i]) * D[i]
(3) Derivative Value = c(D[i]) * D[i]
```
Where the value of *c* is selected based on the *D*[*i*] value relative to zero. With the three components brought together, our trust value equation is calculated as follows:
Where the value of *c* is selected based on the *D*[*i*] value relative to zero. The default selection process makes *c* equal to 0 unless *D*[*i*] is a negative value, in which case c is equal to 1. The result is that the maximum penalty is applied when current behavior is lower than previously experienced behavior. If the current behavior is better than the previously experienced behavior, then the Derivative Value has no impact on the trust value. With the three components brought together, our trust value equation is calculated as follows:
```math
TrustValue[i] = a * R[i] + b * H[i] + (c * D[i]) * D[i]
TrustValue[i] = a * R[i] + b * H[i] + c(D[i]) * D[i]
```
As a performance optimization that will keep the amount of raw interval data being saved to a reasonable size of *m*, while allowing us to represent 2^*m* - 1 history intervals, we can employ the fading memories technique that will trade space and time complexity for the precision of the history data values by summarizing larger quantities of less recent values. While our equation above attempts to access up to *maxH* (which can be 2^*m* - 1), we will map those requests down to *m* values using equation 4 below:
@ -99,17 +99,11 @@ func (tm *TrustMetric) Pause() {}
// Stop tells the metric to stop recording data over time intervals
func (tm *TrustMetric) Stop() {}
// BadEvent indicates that an undesirable event took place
func (tm *TrustMetric) BadEvent() {}
// BadEvents indicates that an undesirable event(s) took place
func (tm *TrustMetric) BadEvents(num int) {}
// AddBadEvents acknowledges multiple undesirable events
func (tm *TrustMetric) AddBadEvents(num int) {}
// GoodEvent indicates that a desirable event took place
func (tm *TrustMetric) GoodEvent() {}
// AddGoodEvents acknowledges multiple desirable events
func (tm *TrustMetric) AddGoodEvents(num int) {}
// GoodEvents indicates that a desirable event(s) took place
func (tm *TrustMetric) GoodEvents(num int) {}
// TrustValue gets the dependable trust value; always between 0 and 1
func (tm *TrustMetric) TrustValue() float64 {}
@ -125,7 +119,7 @@ func NewMetric() *TrustMetric {}
tm := NewMetric()
tm.BadEvent()
tm.BadEvents(1)
score := tm.TrustScore()
tm.Stop()
@ -170,9 +164,9 @@ config := TrustMetricConfig{
tm := NewMetricWithConfig(config)
tm.AddBadEvents(10)
tm.BadEvents(10)
tm.Pause()
tm.GoodEvent() // becomes active again
tm.GoodEvents(1) // becomes active again
```
@ -217,7 +211,7 @@ db := dbm.NewDB("trusthistory", "goleveldb", dirPathStr)
tms := NewTrustMetricStore(db, DefaultConfig())
tm := tms.GetPeerTrustMetric(key)
tm.BadEvent()
tm.BadEvents(1)
tms.PeerDisconnected(key)
@ -225,7 +219,7 @@ tms.PeerDisconnected(key)
## Status
Proposed.
Approved.
## Consequences