Adding upstream version 1.34.4.

Signed-off-by: Daniel Baumann <daniel@debian.org>

plugins/common/parallel/ordered.go

@@ -0,0 +1,84 @@
+package parallel
+
+import (
+	"sync"
+
+	"github.com/influxdata/telegraf"
+)
+
+type Ordered struct {
+	wg sync.WaitGroup
+	fn func(telegraf.Metric) []telegraf.Metric
+
+	// queue of jobs coming in. Workers pick jobs off this queue for processing
+	workerQueue chan job
+
+	// queue of ordered metrics going out
+	queue chan futureMetric
+}
+
+func NewOrdered(acc telegraf.Accumulator, fn func(telegraf.Metric) []telegraf.Metric, orderedQueueSize, workerCount int) *Ordered {
+	p := &Ordered{
+		fn:          fn,
+		workerQueue: make(chan job, workerCount),
+		queue:       make(chan futureMetric, orderedQueueSize),
+	}
+	p.startWorkers(workerCount)
+	p.wg.Add(1)
+	go func() {
+		p.readQueue(acc)
+		p.wg.Done()
+	}()
+	return p
+}
+
+func (p *Ordered) Enqueue(metric telegraf.Metric) {
+	future := make(futureMetric)
+	p.queue <- future
+
+	// write the future to the worker pool. Order doesn't matter now because the
+	// outgoing p.queue will enforce order regardless of the order the jobs are
+	// completed in
+	p.workerQueue <- job{
+		future: future,
+		metric: metric,
+	}
+}
+
+func (p *Ordered) readQueue(acc telegraf.Accumulator) {
+	// wait for the response from each worker in order
+	for mCh := range p.queue {
+		// allow each worker to write out multiple metrics
+		for metrics := range mCh {
+			for _, m := range metrics {
+				acc.AddMetric(m)
+			}
+		}
+	}
+}
+
+func (p *Ordered) startWorkers(count int) {
+	p.wg.Add(count)
+	for i := 0; i < count; i++ {
+		go func() {
+			for job := range p.workerQueue {
+				job.future <- p.fn(job.metric)
+				close(job.future)
+			}
+			p.wg.Done()
+		}()
+	}
+}
+
+func (p *Ordered) Stop() {
+	close(p.queue)
+	close(p.workerQueue)
+	p.wg.Wait()
+}
+
+type futureMetric chan []telegraf.Metric
+
+type job struct {
+	future futureMetric
+	metric telegraf.Metric
+}