resmgr: remove old scattered bits of metrics polling.

Remove the old resmgr-triggered polling of policy metrics
and the old resmgr-level polling policy metrics collector.
Implement policy metrics collection in the policy package
itself.

Signed-off-by: Krisztian Litkey <[email protected]>

pkg/resmgr/events.go

@@ -17,42 +17,21 @@ package resmgr
 import (
 	logger "github.com/containers/nri-plugins/pkg/log"
 	"github.com/containers/nri-plugins/pkg/resmgr/cache"
-	"github.com/containers/nri-plugins/pkg/resmgr/metrics"
 )
 
 // Our logger instance for events.
 var evtlog = logger.NewLogger("events")
 
 // setupEventProcessing sets up event and metrics processing.
 func (m *resmgr) setupEventProcessing() error {
-	var err error
-
 	m.events = make(chan interface{}, 8)
 	m.stop = make(chan interface{})
-	options := metrics.Options{
-		PollInterval: opt.MetricsTimer,
-	}
-	if m.metrics, err = metrics.NewMetrics(options); err != nil {
-		return resmgrError("failed to create metrics (pre)processor: %v", err)
-	}
-
-	return nil
-}
-
-func (m *resmgr) startMetricsProcessing() error {
-	if err := m.metrics.Start(); err != nil {
-		return resmgrError("failed to start metrics (pre)processor: %v", err)
-	}
 
 	return nil
 }
 
 // startEventProcessing starts event and metrics processing.
 func (m *resmgr) startEventProcessing() error {
-	if err := m.startMetricsProcessing(); err != nil {
-		return resmgrError("failed to start metrics (pre)processor: %v", err)
-	}
-
 	stop := m.stop
 	go func() {
 		for {
@@ -73,7 +52,6 @@ func (m *resmgr) startEventProcessing() error {
 func (m *resmgr) stopEventProcessing() {
 	if m.stop != nil {
 		close(m.stop)
-		m.metrics.Stop()
 		m.stop = nil
 	}
 }

pkg/resmgr/policy/metrics.go

@@ -0,0 +1,68 @@
+// Copyright The NRI Plugins Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package policy
+
+import (
+	"sync"
+
+	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/containers/nri-plugins/pkg/metrics"
+)
+
+type Collector struct {
+	policy *policy
+	block  sync.Mutex
+}
+
+var _ prometheus.Collector = &Collector{}
+
+func (p *policy) registerCollector() error {
+	collector := &Collector{policy: p}
+	p.collector = collector
+
+	return metrics.Register(p.ActivePolicy(), collector, metrics.WithGroup("policy"))
+}
+
+func (c *Collector) Describe(ch chan<- *prometheus.Desc) {
+	log.Debug("describing metrics")
+	for _, d := range c.policy.active.DescribeMetrics() {
+		ch <- d
+	}
+}
+
+func (c *Collector) Collect(ch chan<- prometheus.Metric) {
+	c.Block()
+	log.Debug("collecting metrics")
+	polled := c.policy.active.PollMetrics()
+	c.Unblock()
+
+	pm, err := c.policy.active.CollectMetrics(polled)
+	if err != nil {
+		log.Error("failed to collect metrics: %v", err)
+		return
+	}
+	for _, m := range pm {
+		ch <- m
+	}
+}
+
+func (c *Collector) Block() {
+	c.block.Lock()
+}
+
+func (c *Collector) Unblock() {
+	c.block.Unlock()
+}