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author | Harrison Healey <harrisonmhealey@gmail.com> | 2018-01-16 12:03:31 -0500 |
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committer | GitHub <noreply@github.com> | 2018-01-16 12:03:31 -0500 |
commit | 2fa7c464f019f67c5c0494aaf5ac0f5ecc1ee7a7 (patch) | |
tree | e08ff912e1924c06939f314168c3362d6f1ec0de /vendor/github.com/miekg/dns/vendor/golang.org/x/net/internal/timeseries/timeseries.go | |
parent | f5c8a71698d0a7a16c68be220e49fe64bfee7f5c (diff) | |
download | chat-2fa7c464f019f67c5c0494aaf5ac0f5ecc1ee7a7.tar.gz chat-2fa7c464f019f67c5c0494aaf5ac0f5ecc1ee7a7.tar.bz2 chat-2fa7c464f019f67c5c0494aaf5ac0f5ecc1ee7a7.zip |
Updated dependencies and added avct/uasurfer (#8089)
* Updated dependencies and added avct/uasurfer
* Added uasurfer to NOTICE.txt
Diffstat (limited to 'vendor/github.com/miekg/dns/vendor/golang.org/x/net/internal/timeseries/timeseries.go')
-rw-r--r-- | vendor/github.com/miekg/dns/vendor/golang.org/x/net/internal/timeseries/timeseries.go | 525 |
1 files changed, 525 insertions, 0 deletions
diff --git a/vendor/github.com/miekg/dns/vendor/golang.org/x/net/internal/timeseries/timeseries.go b/vendor/github.com/miekg/dns/vendor/golang.org/x/net/internal/timeseries/timeseries.go new file mode 100644 index 000000000..685f0e7ea --- /dev/null +++ b/vendor/github.com/miekg/dns/vendor/golang.org/x/net/internal/timeseries/timeseries.go @@ -0,0 +1,525 @@ +// Copyright 2015 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package timeseries implements a time series structure for stats collection. +package timeseries // import "golang.org/x/net/internal/timeseries" + +import ( + "fmt" + "log" + "time" +) + +const ( + timeSeriesNumBuckets = 64 + minuteHourSeriesNumBuckets = 60 +) + +var timeSeriesResolutions = []time.Duration{ + 1 * time.Second, + 10 * time.Second, + 1 * time.Minute, + 10 * time.Minute, + 1 * time.Hour, + 6 * time.Hour, + 24 * time.Hour, // 1 day + 7 * 24 * time.Hour, // 1 week + 4 * 7 * 24 * time.Hour, // 4 weeks + 16 * 7 * 24 * time.Hour, // 16 weeks +} + +var minuteHourSeriesResolutions = []time.Duration{ + 1 * time.Second, + 1 * time.Minute, +} + +// An Observable is a kind of data that can be aggregated in a time series. +type Observable interface { + Multiply(ratio float64) // Multiplies the data in self by a given ratio + Add(other Observable) // Adds the data from a different observation to self + Clear() // Clears the observation so it can be reused. + CopyFrom(other Observable) // Copies the contents of a given observation to self +} + +// Float attaches the methods of Observable to a float64. +type Float float64 + +// NewFloat returns a Float. +func NewFloat() Observable { + f := Float(0) + return &f +} + +// String returns the float as a string. +func (f *Float) String() string { return fmt.Sprintf("%g", f.Value()) } + +// Value returns the float's value. +func (f *Float) Value() float64 { return float64(*f) } + +func (f *Float) Multiply(ratio float64) { *f *= Float(ratio) } + +func (f *Float) Add(other Observable) { + o := other.(*Float) + *f += *o +} + +func (f *Float) Clear() { *f = 0 } + +func (f *Float) CopyFrom(other Observable) { + o := other.(*Float) + *f = *o +} + +// A Clock tells the current time. +type Clock interface { + Time() time.Time +} + +type defaultClock int + +var defaultClockInstance defaultClock + +func (defaultClock) Time() time.Time { return time.Now() } + +// Information kept per level. Each level consists of a circular list of +// observations. The start of the level may be derived from end and the +// len(buckets) * sizeInMillis. +type tsLevel struct { + oldest int // index to oldest bucketed Observable + newest int // index to newest bucketed Observable + end time.Time // end timestamp for this level + size time.Duration // duration of the bucketed Observable + buckets []Observable // collections of observations + provider func() Observable // used for creating new Observable +} + +func (l *tsLevel) Clear() { + l.oldest = 0 + l.newest = len(l.buckets) - 1 + l.end = time.Time{} + for i := range l.buckets { + if l.buckets[i] != nil { + l.buckets[i].Clear() + l.buckets[i] = nil + } + } +} + +func (l *tsLevel) InitLevel(size time.Duration, numBuckets int, f func() Observable) { + l.size = size + l.provider = f + l.buckets = make([]Observable, numBuckets) +} + +// Keeps a sequence of levels. Each level is responsible for storing data at +// a given resolution. For example, the first level stores data at a one +// minute resolution while the second level stores data at a one hour +// resolution. + +// Each level is represented by a sequence of buckets. Each bucket spans an +// interval equal to the resolution of the level. New observations are added +// to the last bucket. +type timeSeries struct { + provider func() Observable // make more Observable + numBuckets int // number of buckets in each level + levels []*tsLevel // levels of bucketed Observable + lastAdd time.Time // time of last Observable tracked + total Observable // convenient aggregation of all Observable + clock Clock // Clock for getting current time + pending Observable // observations not yet bucketed + pendingTime time.Time // what time are we keeping in pending + dirty bool // if there are pending observations +} + +// init initializes a level according to the supplied criteria. +func (ts *timeSeries) init(resolutions []time.Duration, f func() Observable, numBuckets int, clock Clock) { + ts.provider = f + ts.numBuckets = numBuckets + ts.clock = clock + ts.levels = make([]*tsLevel, len(resolutions)) + + for i := range resolutions { + if i > 0 && resolutions[i-1] >= resolutions[i] { + log.Print("timeseries: resolutions must be monotonically increasing") + break + } + newLevel := new(tsLevel) + newLevel.InitLevel(resolutions[i], ts.numBuckets, ts.provider) + ts.levels[i] = newLevel + } + + ts.Clear() +} + +// Clear removes all observations from the time series. +func (ts *timeSeries) Clear() { + ts.lastAdd = time.Time{} + ts.total = ts.resetObservation(ts.total) + ts.pending = ts.resetObservation(ts.pending) + ts.pendingTime = time.Time{} + ts.dirty = false + + for i := range ts.levels { + ts.levels[i].Clear() + } +} + +// Add records an observation at the current time. +func (ts *timeSeries) Add(observation Observable) { + ts.AddWithTime(observation, ts.clock.Time()) +} + +// AddWithTime records an observation at the specified time. +func (ts *timeSeries) AddWithTime(observation Observable, t time.Time) { + + smallBucketDuration := ts.levels[0].size + + if t.After(ts.lastAdd) { + ts.lastAdd = t + } + + if t.After(ts.pendingTime) { + ts.advance(t) + ts.mergePendingUpdates() + ts.pendingTime = ts.levels[0].end + ts.pending.CopyFrom(observation) + ts.dirty = true + } else if t.After(ts.pendingTime.Add(-1 * smallBucketDuration)) { + // The observation is close enough to go into the pending bucket. + // This compensates for clock skewing and small scheduling delays + // by letting the update stay in the fast path. + ts.pending.Add(observation) + ts.dirty = true + } else { + ts.mergeValue(observation, t) + } +} + +// mergeValue inserts the observation at the specified time in the past into all levels. +func (ts *timeSeries) mergeValue(observation Observable, t time.Time) { + for _, level := range ts.levels { + index := (ts.numBuckets - 1) - int(level.end.Sub(t)/level.size) + if 0 <= index && index < ts.numBuckets { + bucketNumber := (level.oldest + index) % ts.numBuckets + if level.buckets[bucketNumber] == nil { + level.buckets[bucketNumber] = level.provider() + } + level.buckets[bucketNumber].Add(observation) + } + } + ts.total.Add(observation) +} + +// mergePendingUpdates applies the pending updates into all levels. +func (ts *timeSeries) mergePendingUpdates() { + if ts.dirty { + ts.mergeValue(ts.pending, ts.pendingTime) + ts.pending = ts.resetObservation(ts.pending) + ts.dirty = false + } +} + +// advance cycles the buckets at each level until the latest bucket in +// each level can hold the time specified. +func (ts *timeSeries) advance(t time.Time) { + if !t.After(ts.levels[0].end) { + return + } + for i := 0; i < len(ts.levels); i++ { + level := ts.levels[i] + if !level.end.Before(t) { + break + } + + // If the time is sufficiently far, just clear the level and advance + // directly. + if !t.Before(level.end.Add(level.size * time.Duration(ts.numBuckets))) { + for _, b := range level.buckets { + ts.resetObservation(b) + } + level.end = time.Unix(0, (t.UnixNano()/level.size.Nanoseconds())*level.size.Nanoseconds()) + } + + for t.After(level.end) { + level.end = level.end.Add(level.size) + level.newest = level.oldest + level.oldest = (level.oldest + 1) % ts.numBuckets + ts.resetObservation(level.buckets[level.newest]) + } + + t = level.end + } +} + +// Latest returns the sum of the num latest buckets from the level. +func (ts *timeSeries) Latest(level, num int) Observable { + now := ts.clock.Time() + if ts.levels[0].end.Before(now) { + ts.advance(now) + } + + ts.mergePendingUpdates() + + result := ts.provider() + l := ts.levels[level] + index := l.newest + + for i := 0; i < num; i++ { + if l.buckets[index] != nil { + result.Add(l.buckets[index]) + } + if index == 0 { + index = ts.numBuckets + } + index-- + } + + return result +} + +// LatestBuckets returns a copy of the num latest buckets from level. +func (ts *timeSeries) LatestBuckets(level, num int) []Observable { + if level < 0 || level > len(ts.levels) { + log.Print("timeseries: bad level argument: ", level) + return nil + } + if num < 0 || num >= ts.numBuckets { + log.Print("timeseries: bad num argument: ", num) + return nil + } + + results := make([]Observable, num) + now := ts.clock.Time() + if ts.levels[0].end.Before(now) { + ts.advance(now) + } + + ts.mergePendingUpdates() + + l := ts.levels[level] + index := l.newest + + for i := 0; i < num; i++ { + result := ts.provider() + results[i] = result + if l.buckets[index] != nil { + result.CopyFrom(l.buckets[index]) + } + + if index == 0 { + index = ts.numBuckets + } + index -= 1 + } + return results +} + +// ScaleBy updates observations by scaling by factor. +func (ts *timeSeries) ScaleBy(factor float64) { + for _, l := range ts.levels { + for i := 0; i < ts.numBuckets; i++ { + l.buckets[i].Multiply(factor) + } + } + + ts.total.Multiply(factor) + ts.pending.Multiply(factor) +} + +// Range returns the sum of observations added over the specified time range. +// If start or finish times don't fall on bucket boundaries of the same +// level, then return values are approximate answers. +func (ts *timeSeries) Range(start, finish time.Time) Observable { + return ts.ComputeRange(start, finish, 1)[0] +} + +// Recent returns the sum of observations from the last delta. +func (ts *timeSeries) Recent(delta time.Duration) Observable { + now := ts.clock.Time() + return ts.Range(now.Add(-delta), now) +} + +// Total returns the total of all observations. +func (ts *timeSeries) Total() Observable { + ts.mergePendingUpdates() + return ts.total +} + +// ComputeRange computes a specified number of values into a slice using +// the observations recorded over the specified time period. The return +// values are approximate if the start or finish times don't fall on the +// bucket boundaries at the same level or if the number of buckets spanning +// the range is not an integral multiple of num. +func (ts *timeSeries) ComputeRange(start, finish time.Time, num int) []Observable { + if start.After(finish) { + log.Printf("timeseries: start > finish, %v>%v", start, finish) + return nil + } + + if num < 0 { + log.Printf("timeseries: num < 0, %v", num) + return nil + } + + results := make([]Observable, num) + + for _, l := range ts.levels { + if !start.Before(l.end.Add(-l.size * time.Duration(ts.numBuckets))) { + ts.extract(l, start, finish, num, results) + return results + } + } + + // Failed to find a level that covers the desired range. So just + // extract from the last level, even if it doesn't cover the entire + // desired range. + ts.extract(ts.levels[len(ts.levels)-1], start, finish, num, results) + + return results +} + +// RecentList returns the specified number of values in slice over the most +// recent time period of the specified range. +func (ts *timeSeries) RecentList(delta time.Duration, num int) []Observable { + if delta < 0 { + return nil + } + now := ts.clock.Time() + return ts.ComputeRange(now.Add(-delta), now, num) +} + +// extract returns a slice of specified number of observations from a given +// level over a given range. +func (ts *timeSeries) extract(l *tsLevel, start, finish time.Time, num int, results []Observable) { + ts.mergePendingUpdates() + + srcInterval := l.size + dstInterval := finish.Sub(start) / time.Duration(num) + dstStart := start + srcStart := l.end.Add(-srcInterval * time.Duration(ts.numBuckets)) + + srcIndex := 0 + + // Where should scanning start? + if dstStart.After(srcStart) { + advance := dstStart.Sub(srcStart) / srcInterval + srcIndex += int(advance) + srcStart = srcStart.Add(advance * srcInterval) + } + + // The i'th value is computed as show below. + // interval = (finish/start)/num + // i'th value = sum of observation in range + // [ start + i * interval, + // start + (i + 1) * interval ) + for i := 0; i < num; i++ { + results[i] = ts.resetObservation(results[i]) + dstEnd := dstStart.Add(dstInterval) + for srcIndex < ts.numBuckets && srcStart.Before(dstEnd) { + srcEnd := srcStart.Add(srcInterval) + if srcEnd.After(ts.lastAdd) { + srcEnd = ts.lastAdd + } + + if !srcEnd.Before(dstStart) { + srcValue := l.buckets[(srcIndex+l.oldest)%ts.numBuckets] + if !srcStart.Before(dstStart) && !srcEnd.After(dstEnd) { + // dst completely contains src. + if srcValue != nil { + results[i].Add(srcValue) + } + } else { + // dst partially overlaps src. + overlapStart := maxTime(srcStart, dstStart) + overlapEnd := minTime(srcEnd, dstEnd) + base := srcEnd.Sub(srcStart) + fraction := overlapEnd.Sub(overlapStart).Seconds() / base.Seconds() + + used := ts.provider() + if srcValue != nil { + used.CopyFrom(srcValue) + } + used.Multiply(fraction) + results[i].Add(used) + } + + if srcEnd.After(dstEnd) { + break + } + } + srcIndex++ + srcStart = srcStart.Add(srcInterval) + } + dstStart = dstStart.Add(dstInterval) + } +} + +// resetObservation clears the content so the struct may be reused. +func (ts *timeSeries) resetObservation(observation Observable) Observable { + if observation == nil { + observation = ts.provider() + } else { + observation.Clear() + } + return observation +} + +// TimeSeries tracks data at granularities from 1 second to 16 weeks. +type TimeSeries struct { + timeSeries +} + +// NewTimeSeries creates a new TimeSeries using the function provided for creating new Observable. +func NewTimeSeries(f func() Observable) *TimeSeries { + return NewTimeSeriesWithClock(f, defaultClockInstance) +} + +// NewTimeSeriesWithClock creates a new TimeSeries using the function provided for creating new Observable and the clock for +// assigning timestamps. +func NewTimeSeriesWithClock(f func() Observable, clock Clock) *TimeSeries { + ts := new(TimeSeries) + ts.timeSeries.init(timeSeriesResolutions, f, timeSeriesNumBuckets, clock) + return ts +} + +// MinuteHourSeries tracks data at granularities of 1 minute and 1 hour. +type MinuteHourSeries struct { + timeSeries +} + +// NewMinuteHourSeries creates a new MinuteHourSeries using the function provided for creating new Observable. +func NewMinuteHourSeries(f func() Observable) *MinuteHourSeries { + return NewMinuteHourSeriesWithClock(f, defaultClockInstance) +} + +// NewMinuteHourSeriesWithClock creates a new MinuteHourSeries using the function provided for creating new Observable and the clock for +// assigning timestamps. +func NewMinuteHourSeriesWithClock(f func() Observable, clock Clock) *MinuteHourSeries { + ts := new(MinuteHourSeries) + ts.timeSeries.init(minuteHourSeriesResolutions, f, + minuteHourSeriesNumBuckets, clock) + return ts +} + +func (ts *MinuteHourSeries) Minute() Observable { + return ts.timeSeries.Latest(0, 60) +} + +func (ts *MinuteHourSeries) Hour() Observable { + return ts.timeSeries.Latest(1, 60) +} + +func minTime(a, b time.Time) time.Time { + if a.Before(b) { + return a + } + return b +} + +func maxTime(a, b time.Time) time.Time { + if a.After(b) { + return a + } + return b +} |