telegraf/plugins/serializers/influx/reader.go

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package influx
import (
"bytes"
"fmt"
"io"
"log"
"github.com/influxdata/telegraf"
)
// reader is an io.Reader for line protocol.
type reader struct {
metrics []telegraf.Metric
serializer *Serializer
offset int
buf *bytes.Buffer
}
// NewReader creates a new reader over the given metrics.
func NewReader(metrics []telegraf.Metric, serializer *Serializer) io.Reader {
return &reader{
metrics: metrics,
serializer: serializer,
offset: 0,
buf: bytes.NewBuffer(make([]byte, 0, serializer.maxLineBytes)),
}
}
// SetMetrics changes the metrics to be read.
func (r *reader) SetMetrics(metrics []telegraf.Metric) {
r.metrics = metrics
r.offset = 0
r.buf.Reset()
}
// Read reads up to len(p) bytes of the current metric into p, each call will
// only serialize at most one metric so the number of bytes read may be less
// than p. Subsequent calls to Read will read the next metric until all are
// emitted. If a metric cannot be serialized, an error will be returned, you
// may resume with the next metric by calling Read again. When all metrics
// are emitted the err is io.EOF.
func (r *reader) Read(p []byte) (int, error) {
if r.buf.Len() > 0 {
return r.buf.Read(p)
}
if r.offset >= len(r.metrics) {
return 0, io.EOF
}
for _, metric := range r.metrics[r.offset:] {
_, err := r.serializer.Write(r.buf, metric)
r.offset += 1
if err != nil {
r.buf.Reset()
switch err.(type) {
case *MetricError:
// Since we are serializing an array of metrics, don't fail
// the entire batch just because of one unserializable metric.
log.Printf(
"D! [serializers.influx] could not serialize metric %q: %v; discarding metric",
metric.Name(), err)
continue
default:
fmt.Println(err)
return 0, err
}
}
break
}
return r.buf.Read(p)
}