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pipeline.go
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pipeline.go
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package log
import (
"github.com/prometheus/prometheus/pkg/labels"
)
// Pipeline transform and filter log lines and labels.
type Pipeline interface {
Process(line []byte, lbs labels.Labels) ([]byte, labels.Labels, bool)
}
// Stage is a single step of a Pipeline.
type Stage interface {
Process(line []byte, lbs *LabelsBuilder) ([]byte, bool)
}
var (
NoopPipeline Pipeline = &noopPipeline{}
NoopStage Stage = &noopStage{}
)
type noopPipeline struct{}
func (noopPipeline) Process(line []byte, lbs labels.Labels) ([]byte, labels.Labels, bool) {
return line, lbs, true
}
type noopStage struct{}
func (noopStage) Process(line []byte, lbs *LabelsBuilder) ([]byte, bool) {
return line, true
}
type StageFunc func(line []byte, lbs *LabelsBuilder) ([]byte, bool)
func (fn StageFunc) Process(line []byte, lbs *LabelsBuilder) ([]byte, bool) {
return fn(line, lbs)
}
// pipeline is a combinations of multiple stages.
// It can also be reduced into a single stage for convenience.
type pipeline struct {
stages []Stage
builder *LabelsBuilder
}
func NewPipeline(stages []Stage) Pipeline {
return &pipeline{
stages: stages,
builder: NewLabelsBuilder(),
}
}
func (p *pipeline) Process(line []byte, lbs labels.Labels) ([]byte, labels.Labels, bool) {
var ok bool
if len(p.stages) == 0 {
return line, lbs, true
}
p.builder.Reset(lbs)
for _, s := range p.stages {
line, ok = s.Process(line, p.builder)
if !ok {
return nil, nil, false
}
}
return line, p.builder.Labels(), true
}
// ReduceStages reduces multiple stages into one.
func ReduceStages(stages []Stage) Stage {
if len(stages) == 0 {
return NoopStage
}
return StageFunc(func(line []byte, lbs *LabelsBuilder) ([]byte, bool) {
var ok bool
for _, p := range stages {
line, ok = p.Process(line, lbs)
if !ok {
return nil, false
}
}
return line, true
})
}