agent: add 'system metrics' function

agent/system_metrics.go

@@ -0,0 +1,62 @@
+// Copyright 2017 CoreOS, Inc.
+//
+// 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 agent
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/gyuho/psn"
+)
+
+// collectMetrics starts collecting metrics.
+func collectMetrics(fs *flags, t *transporterServer) error {
+	if fs == nil || t == nil || t.cmd == nil {
+		return fmt.Errorf("cannot find process to track (%+v, %+v)", fs, t)
+	}
+	plog.Infof("starting collecting metrics [database %q | PID: %d | disk device: %q | network interface: %q]",
+		t.req.Database, t.pid, fs.diskDevice, fs.networkInterface)
+
+	if err := os.RemoveAll(fs.systemMetricsLog); err != nil {
+		return err
+	}
+
+	c := psn.NewCSV(fs.systemMetricsLog, t.pid, fs.diskDevice, fs.networkInterface)
+	if err := c.Add(); err != nil {
+		return err
+	}
+
+	go func() {
+		for {
+			select {
+			case <-time.After(time.Second):
+				if err := c.Add(); err != nil {
+					plog.Errorf("psn.CSV.Add error (%v)", err)
+					continue
+				}
+
+			case <-t.uploadSig:
+				plog.Info("upload signal received; returning")
+				return
+
+			case sig := <-notifier:
+				plog.Infof("signal received %q", sig.String())
+				return
+			}
+		}
+	}()
+	return nil
+}