Move runtime to core/runtime

Signed-off-by: Derek McGowan <derek@mcg.dev>

core/runtime/monitor.go

@@ -0,0 +1,71 @@
+/*
+   Copyright The containerd Authors.
+
+   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 runtime
+
+// TaskMonitor provides an interface for monitoring of containers within containerd
+type TaskMonitor interface {
+	// Monitor adds the provided container to the monitor.
+	// Labels are optional (can be nil) key value pairs to be added to the metrics namespace.
+	Monitor(task Task, labels map[string]string) error
+	// Stop stops and removes the provided container from the monitor
+	Stop(task Task) error
+}
+
+// NewMultiTaskMonitor returns a new TaskMonitor broadcasting to the provided monitors
+func NewMultiTaskMonitor(monitors ...TaskMonitor) TaskMonitor {
+	return &multiTaskMonitor{
+		monitors: monitors,
+	}
+}
+
+// NewNoopMonitor is a task monitor that does nothing
+func NewNoopMonitor() TaskMonitor {
+	return &noopTaskMonitor{}
+}
+
+type noopTaskMonitor struct {
+}
+
+func (mm *noopTaskMonitor) Monitor(c Task, labels map[string]string) error {
+	return nil
+}
+
+func (mm *noopTaskMonitor) Stop(c Task) error {
+	return nil
+}
+
+type multiTaskMonitor struct {
+	monitors []TaskMonitor
+}
+
+func (mm *multiTaskMonitor) Monitor(task Task, labels map[string]string) error {
+	for _, m := range mm.monitors {
+		if err := m.Monitor(task, labels); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (mm *multiTaskMonitor) Stop(c Task) error {
+	for _, m := range mm.monitors {
+		if err := m.Stop(c); err != nil {
+			return err
+		}
+	}
+	return nil
+}