prometheus/storage/metric/operation.go

559 lines
13 KiB
Go

// Copyright 2013 Prometheus Team
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package metric
import (
"fmt"
"github.com/prometheus/prometheus/model"
"math"
"sort"
"time"
)
// Encapsulates a primitive query operation.
type op interface {
// The time at which this operation starts.
StartsAt() time.Time
// Extract samples from stream of values and advance operation time.
ExtractSamples(in []model.SamplePair) (out []model.SamplePair)
// Get current operation time or nil if no subsequent work associated with
// this operator remains.
CurrentTime() *time.Time
}
// Provides a sortable collection of operations.
type ops []op
func (o ops) Len() int {
return len(o)
}
func (o ops) Less(i, j int) bool {
return o[i].StartsAt().Before(o[j].StartsAt())
}
func (o ops) Swap(i, j int) {
o[i], o[j] = o[j], o[i]
}
// Encapsulates getting values at or adjacent to a specific time.
type getValuesAtTimeOp struct {
time time.Time
consumed bool
}
func (o getValuesAtTimeOp) String() string {
return fmt.Sprintf("getValuesAtTimeOp at %s", o.time)
}
func (g getValuesAtTimeOp) StartsAt() time.Time {
return g.time
}
func (g *getValuesAtTimeOp) ExtractSamples(in []model.SamplePair) (out []model.SamplePair) {
if len(in) == 0 {
return
}
out = extractValuesAroundTime(g.time, in)
g.consumed = true
return
}
func extractValuesAroundTime(t time.Time, in []model.SamplePair) (out []model.SamplePair) {
i := sort.Search(len(in), func(i int) bool {
return !in[i].Timestamp.Before(t)
})
fmt.Printf("I: %d\n", i)
switch i {
case len(in):
out = in[len(in)-1:]
case 0:
out = append(out, in[0:1]...)
default:
out = append(out, in[i-1:i+1]...)
}
return
}
func (g getValuesAtTimeOp) CurrentTime() (currentTime *time.Time) {
if !g.consumed {
currentTime = &g.time
}
return
}
// Encapsulates getting values at a given interval over a duration.
type getValuesAtIntervalOp struct {
from time.Time
through time.Time
interval time.Duration
}
func (o getValuesAtIntervalOp) String() string {
return fmt.Sprintf("getValuesAtIntervalOp from %s each %s through %s", o.from, o.interval, o.through)
}
func (g getValuesAtIntervalOp) StartsAt() time.Time {
return g.from
}
func (g getValuesAtIntervalOp) Through() time.Time {
return g.through
}
func (g *getValuesAtIntervalOp) ExtractSamples(in []model.SamplePair) (out []model.SamplePair) {
if len(in) == 0 {
return
}
lastChunkTime := in[len(in)-1].Timestamp
for {
out = extractValuesAroundTime(g.from, in)
g.from = g.from.Add(g.interval)
if g.from.After(lastChunkTime) {
break
}
if g.from.After(g.through) {
break
}
}
return
}
func (g getValuesAtIntervalOp) CurrentTime() (currentTime *time.Time) {
if g.from.After(g.through) {
return
}
return &g.from
}
type getValuesAlongRangeOp struct {
from time.Time
through time.Time
}
func (o getValuesAlongRangeOp) String() string {
return fmt.Sprintf("getValuesAlongRangeOp from %s through %s", o.from, o.through)
}
func (g getValuesAlongRangeOp) StartsAt() time.Time {
return g.from
}
func (g getValuesAlongRangeOp) Through() time.Time {
return g.through
}
func (g *getValuesAlongRangeOp) ExtractSamples(in []model.SamplePair) (out []model.SamplePair) {
if len(in) == 0 {
return
}
// Find the first sample where time >= g.from.
firstIdx := sort.Search(len(in), func(i int) bool {
return !in[i].Timestamp.Before(g.from)
})
if firstIdx == len(in) {
// No samples at or after operator start time.
return
}
// Find the first sample where time > g.through.
lastIdx := sort.Search(len(in), func(i int) bool {
return in[i].Timestamp.After(g.through)
})
if lastIdx == firstIdx {
return
}
lastSampleTime := in[lastIdx-1].Timestamp
g.from = lastSampleTime.Add(time.Duration(1))
return in[firstIdx:lastIdx]
}
func (g getValuesAlongRangeOp) CurrentTime() (currentTime *time.Time) {
if g.from.After(g.through) {
return
}
return &g.from
}
// Provides a collection of getMetricRangeOperation.
type getMetricRangeOperations []*getValuesAlongRangeOp
func (s getMetricRangeOperations) Len() int {
return len(s)
}
func (s getMetricRangeOperations) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
// Sorts getMetricRangeOperation according to duration in descending order.
type rangeDurationSorter struct {
getMetricRangeOperations
}
func (s rangeDurationSorter) Less(i, j int) bool {
l := s.getMetricRangeOperations[i]
r := s.getMetricRangeOperations[j]
return !l.through.Before(r.through)
}
// Encapsulates a general operation that occurs over a duration.
type durationOperator interface {
op
Through() time.Time
}
// Sorts durationOperator by the operation's duration in ascending order.
type durationOperators []durationOperator
func (o durationOperators) Len() int {
return len(o)
}
func (o durationOperators) Less(i, j int) bool {
return o[i].Through().Before(o[j].Through())
}
func (o durationOperators) Swap(i, j int) {
o[i], o[j] = o[j], o[i]
}
// Contains getValuesAtIntervalOp operations.
type getValuesAtIntervalOps []*getValuesAtIntervalOp
func (s getValuesAtIntervalOps) Len() int {
return len(s)
}
func (s getValuesAtIntervalOps) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
// Sorts durationOperator by the operation's duration in descending order.
type intervalDurationSorter struct {
getValuesAtIntervalOps
}
func (s intervalDurationSorter) Less(i, j int) bool {
l := s.getValuesAtIntervalOps[i]
r := s.getValuesAtIntervalOps[j]
return !l.through.Before(r.through)
}
// Sorts getValuesAtIntervalOp operations in ascending order by their
// frequency.
type frequencySorter struct {
getValuesAtIntervalOps
}
func (s frequencySorter) Less(i, j int) bool {
l := s.getValuesAtIntervalOps[i]
r := s.getValuesAtIntervalOps[j]
return l.interval < r.interval
}
// Selects and returns all operations that are getValuesAtIntervalOps operations.
func collectIntervals(ops ops) (intervals map[time.Duration]getValuesAtIntervalOps) {
intervals = make(map[time.Duration]getValuesAtIntervalOps)
for _, operation := range ops {
switch t := operation.(type) {
case *getValuesAtIntervalOp:
operations, _ := intervals[t.interval]
operations = append(operations, t)
intervals[t.interval] = operations
}
}
for _, operations := range intervals {
sort.Sort(intervalDurationSorter{operations})
}
return
}
// Selects and returns all operations that are getValuesAlongRangeOp operations.
func collectRanges(ops ops) (ranges getMetricRangeOperations) {
for _, operation := range ops {
switch t := operation.(type) {
case *getValuesAlongRangeOp:
ranges = append(ranges, t)
}
}
sort.Sort(rangeDurationSorter{ranges})
return
}
// optimizeForward iteratively scans operations and peeks ahead to subsequent
// ones to find candidates that can either be removed or truncated through
// simplification. For instance, if a range query happens to overlap a get-a-
// value-at-a-certain-point-request, the range query should flatten and subsume
// the other.
func optimizeForward(pending ops) (out ops) {
if len(pending) == 0 {
return
}
var (
firstOperation = pending[0]
)
pending = pending[1:len(pending)]
switch t := firstOperation.(type) {
case *getValuesAtTimeOp:
out = ops{firstOperation}
tail := optimizeForward(pending)
return append(out, tail...)
case *getValuesAtIntervalOp:
// If the last value was a scan at a given frequency along an interval,
// several optimizations may exist.
for _, peekOperation := range pending {
if peekOperation.StartsAt().After(t.Through()) {
break
}
// If the type is not a range request, we can't do anything.
switch next := peekOperation.(type) {
case *getValuesAlongRangeOp:
if !next.Through().After(t.Through()) {
var (
before = getValuesAtIntervalOp(*t)
after = getValuesAtIntervalOp(*t)
)
before.through = next.from
// Truncate the get value at interval request if a range request cuts
// it off somewhere.
var (
from = next.from
)
for {
from = from.Add(t.interval)
if from.After(next.through) {
after.from = from
break
}
}
pending = append(ops{&before, &after}, pending...)
sort.Sort(pending)
return optimizeForward(pending)
}
}
}
case *getValuesAlongRangeOp:
for _, peekOperation := range pending {
if peekOperation.StartsAt().After(t.Through()) {
break
}
switch next := peekOperation.(type) {
// All values at a specific time may be elided into the range query.
case *getValuesAtTimeOp:
pending = pending[1:len(pending)]
continue
case *getValuesAlongRangeOp:
// Range queries should be concatenated if they overlap.
pending = pending[1:len(pending)]
if next.Through().After(t.Through()) {
t.through = next.through
var (
head = ops{t}
tail = pending
)
pending = append(head, tail...)
return optimizeForward(pending)
}
case *getValuesAtIntervalOp:
pending = pending[1:len(pending)]
if next.through.After(t.Through()) {
var (
t = next.from
)
for {
t = t.Add(next.interval)
if t.After(next.through) {
next.from = t
pending = append(ops{next}, pending...)
return optimizeForward(pending)
}
}
}
default:
panic("unknown operation type")
}
}
default:
panic("unknown operation type")
}
// Strictly needed?
sort.Sort(pending)
tail := optimizeForward(pending)
return append(ops{firstOperation}, tail...)
}
func selectQueriesForTime(time time.Time, queries ops) (out ops) {
if len(queries) == 0 {
return
}
if !queries[0].StartsAt().Equal(time) {
return
}
out = append(out, queries[0])
tail := selectQueriesForTime(time, queries[1:len(queries)])
return append(out, tail...)
}
// Flattens queries that occur at the same time according to duration and level
// of greed.
func optimizeTimeGroup(group ops) (out ops) {
var (
rangeOperations = collectRanges(group)
intervalOperations = collectIntervals(group)
greediestRange durationOperator
greediestIntervals map[time.Duration]durationOperator
)
if len(rangeOperations) > 0 {
operations := durationOperators{}
for i := 0; i < len(rangeOperations); i++ {
operations = append(operations, rangeOperations[i])
}
// intervaledOperations sorts on the basis of the length of the window.
sort.Sort(operations)
greediestRange = operations[len(operations)-1 : len(operations)][0]
}
if len(intervalOperations) > 0 {
greediestIntervals = make(map[time.Duration]durationOperator)
for i, ops := range intervalOperations {
operations := durationOperators{}
for j := 0; j < len(ops); j++ {
operations = append(operations, ops[j])
}
// intervaledOperations sorts on the basis of the length of the window.
sort.Sort(operations)
greediestIntervals[i] = operations[len(operations)-1 : len(operations)][0]
}
}
var (
containsRange = greediestRange != nil
containsInterval = len(greediestIntervals) > 0
)
if containsRange && !containsInterval {
out = append(out, greediestRange)
} else if !containsRange && containsInterval {
intervalOperations := getValuesAtIntervalOps{}
for _, o := range greediestIntervals {
intervalOperations = append(intervalOperations, o.(*getValuesAtIntervalOp))
}
sort.Sort(frequencySorter{intervalOperations})
for _, o := range intervalOperations {
out = append(out, o)
}
} else if containsRange && containsInterval {
out = append(out, greediestRange)
for _, op := range greediestIntervals {
if !op.Through().After(greediestRange.Through()) {
continue
}
// The range operation does not exceed interval. Leave a snippet of
// interval.
var (
truncated = op.(*getValuesAtIntervalOp)
newIntervalOperation getValuesAtIntervalOp
// Refactor
remainingSlice = greediestRange.Through().Sub(greediestRange.StartsAt()) / time.Second
nextIntervalPoint = time.Duration(math.Ceil(float64(remainingSlice)/float64(truncated.interval)) * float64(truncated.interval/time.Second))
nextStart = greediestRange.Through().Add(nextIntervalPoint)
)
newIntervalOperation.from = nextStart
newIntervalOperation.interval = truncated.interval
newIntervalOperation.through = truncated.Through()
// Added back to the pending because additional curation could be
// necessary.
out = append(out, &newIntervalOperation)
}
} else {
// Operation is OK as-is.
out = append(out, group[0])
}
return
}
// Flattens all groups of time according to greed.
func optimizeTimeGroups(pending ops) (out ops) {
if len(pending) == 0 {
return
}
sort.Sort(pending)
nextOperation := pending[0]
groupedQueries := selectQueriesForTime(nextOperation.StartsAt(), pending)
out = optimizeTimeGroup(groupedQueries)
pending = pending[len(groupedQueries):len(pending)]
tail := optimizeTimeGroups(pending)
return append(out, tail...)
}
func optimize(pending ops) (out ops) {
return optimizeForward(optimizeTimeGroups(pending))
}