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resolution.go
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resolution.go
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// Copyright (c) 2016 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package policy
import (
"errors"
"fmt"
"strings"
"time"
"github.com/m3db/m3/src/metrics/generated/proto/policypb"
xtime "github.com/m3db/m3x/time"
)
const (
windowPrecisionSeparator = "@"
)
var (
emptyResolution Resolution
errNilResolutionProto = errors.New("nil resolution proto message")
)
// Resolution is the sampling resolution for datapoints.
type Resolution struct {
// Window is the bucket size represented by the resolution.
Window time.Duration
// Precision is the precision of datapoints stored at this resoluion.
Precision xtime.Unit
}
// ToProto converts the resolution to a protobuf message in place.
func (r Resolution) ToProto(pb *policypb.Resolution) error {
precision, err := r.Precision.Value()
if err != nil {
return err
}
pb.WindowSize = r.Window.Nanoseconds()
pb.Precision = precision.Nanoseconds()
return nil
}
// FromProto converts the protobuf message to a resolution in place.
func (r *Resolution) FromProto(pb *policypb.Resolution) error {
if pb == nil {
return errNilResolutionProto
}
precision, err := xtime.UnitFromDuration(time.Duration(pb.Precision))
if err != nil {
return err
}
r.Window = time.Duration(pb.WindowSize)
r.Precision = precision
return nil
}
// String is the string representation of a resolution.
func (r Resolution) String() string {
_, maxUnit := xtime.MaxUnitForDuration(r.Window)
if maxUnit == r.Precision {
// If the precision is the default value, do not write it for better readability.
return xtime.ToExtendedString(r.Window)
}
return fmt.Sprintf("%s%s1%s", xtime.ToExtendedString(r.Window), windowPrecisionSeparator, r.Precision.String())
}
// ParseResolution parses a resolution.
func ParseResolution(str string) (Resolution, error) {
separatorIdx := strings.Index(str, windowPrecisionSeparator)
// If there is no separator, the precision unit is the maximum time unit
// for which the window size is a multiple of.
if separatorIdx == -1 {
windowSize, err := xtime.ParseExtendedDuration(str)
if err != nil {
return emptyResolution, err
}
_, precision := xtime.MaxUnitForDuration(windowSize)
return Resolution{Window: windowSize, Precision: precision}, nil
}
// Otherwise the window and the precision are determined by the input.
windowSize, err := xtime.ParseExtendedDuration(str[:separatorIdx])
if err != nil {
return emptyResolution, err
}
precisionDuration, err := xtime.ParseExtendedDuration(str[separatorIdx+1:])
if err != nil {
return emptyResolution, err
}
precision, err := xtime.UnitFromDuration(precisionDuration)
if err != nil {
return emptyResolution, err
}
return Resolution{Window: windowSize, Precision: precision}, nil
}
// MustParseResolution parses a resolution in the form of window@precision,
// and panics if the input string is invalid.
func MustParseResolution(str string) Resolution {
resolution, err := ParseResolution(str)
if err != nil {
panic(fmt.Errorf("invalid resolution string %s: %v", str, err))
}
return resolution
}
// ResolutionValue is the resolution value.
type ResolutionValue int
// List of known resolution values.
const (
UnknownResolutionValue ResolutionValue = iota
OneSecond
TenSeconds
OneMinute
FiveMinutes
TenMinutes
)
var (
errUnknownResolution = errors.New("unknown resolution")
errUnknownResolutionValue = errors.New("unknown resolution value")
// EmptyResolution is an empty resolution.
EmptyResolution Resolution
)
// Resolution returns the resolution associated with a value.
func (v ResolutionValue) Resolution() (Resolution, error) {
resolution, exists := valuesToResolution[v]
if !exists {
return EmptyResolution, errUnknownResolutionValue
}
return resolution, nil
}
// IsValid returns whether the resolution value is valid.
func (v ResolutionValue) IsValid() bool {
_, valid := valuesToResolution[v]
return valid
}
// ValueFromResolution returns the value given a resolution.
func ValueFromResolution(resolution Resolution) (ResolutionValue, error) {
value, exists := resolutionToValues[resolution]
if exists {
return value, nil
}
return UnknownResolutionValue, errUnknownResolution
}
var (
valuesToResolution = map[ResolutionValue]Resolution{
OneSecond: Resolution{Window: time.Second, Precision: xtime.Second},
TenSeconds: Resolution{Window: 10 * time.Second, Precision: xtime.Second},
OneMinute: Resolution{Window: time.Minute, Precision: xtime.Minute},
FiveMinutes: Resolution{Window: 5 * time.Minute, Precision: xtime.Minute},
TenMinutes: Resolution{Window: 10 * time.Minute, Precision: xtime.Minute},
}
resolutionToValues = make(map[Resolution]ResolutionValue)
)
func init() {
for value, resolution := range valuesToResolution {
resolutionToValues[resolution] = value
}
}