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stream.go
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/
stream.go
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package ingest
// An InStream is a runner that will pass data from the input channel down to future runners
type InStream struct {
in chan interface{}
name string
}
// NewInStream builds an input stream for the specified input channel
func NewInStream(name string, in chan interface{}) *InStream {
return &InStream{in, name}
}
// Name implements Runner for InStream
func (i *InStream) Name() string {
return i.name
}
// Run implements Runner for InStream
func (i *InStream) Run(stage *Stage) error {
for {
select {
case <-stage.Abort:
return nil
case rec, ok := <-i.in:
if !ok {
return nil
}
select {
case <-stage.Abort:
return nil
case stage.Out <- rec:
continue
}
}
}
}
// SkipAbortErr saves us having to send nil errors back on abort
func (i *InStream) SkipAbortErr() bool {
return true
}
// A TransformStream is a stream which will run a transform function
// on all entries before emitting them back out
type TransformStream struct {
name string
transformFn TransformFn
}
// A TransformFn is the function signature used by the TransformStream
type TransformFn func(rec interface{}) (res interface{}, err error)
// NewTransformStream builds an input stream for the specified input channel
func NewTransformStream(name string, transformFn TransformFn) *TransformStream {
return &TransformStream{
name: name,
transformFn: transformFn,
}
}
// Name implements Runner for TransformStream
func (t *TransformStream) Name() string {
return t.name
}
// Run implements Runner for TransformStream
func (t *TransformStream) Run(stage *Stage) error {
for {
select {
case <-stage.Abort:
return nil
case rec, ok := <-stage.In:
if !ok {
return nil
}
rec, err := t.transformFn(rec)
if err != nil {
return err
}
select {
case <-stage.Abort:
return nil
case stage.Out <- rec:
continue
}
}
}
}
// SkipAbortErr saves us having to send nil errors back on abort
func (t *TransformStream) SkipAbortErr() bool {
return true
}