Move cri server packages under pkg/cri

Organizes the cri related server packages under pkg/cri

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

pkg/cri/server/snapshots.go

@@ -0,0 +1,120 @@
+/*
+   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 server
+
+import (
+	"context"
+	"time"
+
+	"github.com/containerd/containerd/errdefs"
+	snapshot "github.com/containerd/containerd/snapshots"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+
+	ctrdutil "github.com/containerd/containerd/pkg/containerd/util"
+	snapshotstore "github.com/containerd/containerd/pkg/cri/store/snapshot"
+)
+
+// snapshotsSyncer syncs snapshot stats periodically. imagefs info and container stats
+// should both use cached result here.
+// TODO(random-liu): Benchmark with high workload. We may need a statsSyncer instead if
+// benchmark result shows that container cpu/memory stats also need to be cached.
+type snapshotsSyncer struct {
+	store       *snapshotstore.Store
+	snapshotter snapshot.Snapshotter
+	syncPeriod  time.Duration
+}
+
+// newSnapshotsSyncer creates a snapshot syncer.
+func newSnapshotsSyncer(store *snapshotstore.Store, snapshotter snapshot.Snapshotter,
+	period time.Duration) *snapshotsSyncer {
+	return &snapshotsSyncer{
+		store:       store,
+		snapshotter: snapshotter,
+		syncPeriod:  period,
+	}
+}
+
+// start starts the snapshots syncer. No stop function is needed because
+// the syncer doesn't update any persistent states, it's fine to let it
+// exit with the process.
+func (s *snapshotsSyncer) start() {
+	tick := time.NewTicker(s.syncPeriod)
+	go func() {
+		defer tick.Stop()
+		// TODO(random-liu): This is expensive. We should do benchmark to
+		// check the resource usage and optimize this.
+		for {
+			if err := s.sync(); err != nil {
+				logrus.WithError(err).Error("Failed to sync snapshot stats")
+			}
+			<-tick.C
+		}
+	}()
+}
+
+// sync updates all snapshots stats.
+func (s *snapshotsSyncer) sync() error {
+	ctx := ctrdutil.NamespacedContext()
+	start := time.Now().UnixNano()
+	var snapshots []snapshot.Info
+	// Do not call `Usage` directly in collect function, because
+	// `Usage` takes time, we don't want `Walk` to hold read lock
+	// of snapshot metadata store for too long time.
+	// TODO(random-liu): Set timeout for the following 2 contexts.
+	if err := s.snapshotter.Walk(ctx, func(ctx context.Context, info snapshot.Info) error {
+		snapshots = append(snapshots, info)
+		return nil
+	}); err != nil {
+		return errors.Wrap(err, "walk all snapshots failed")
+	}
+	for _, info := range snapshots {
+		sn, err := s.store.Get(info.Name)
+		if err == nil {
+			// Only update timestamp for non-active snapshot.
+			if sn.Kind == info.Kind && sn.Kind != snapshot.KindActive {
+				sn.Timestamp = time.Now().UnixNano()
+				s.store.Add(sn)
+				continue
+			}
+		}
+		// Get newest stats if the snapshot is new or active.
+		sn = snapshotstore.Snapshot{
+			Key:       info.Name,
+			Kind:      info.Kind,
+			Timestamp: time.Now().UnixNano(),
+		}
+		usage, err := s.snapshotter.Usage(ctx, info.Name)
+		if err != nil {
+			if !errdefs.IsNotFound(err) {
+				logrus.WithError(err).Errorf("Failed to get usage for snapshot %q", info.Name)
+			}
+			continue
+		}
+		sn.Size = uint64(usage.Size)
+		sn.Inodes = uint64(usage.Inodes)
+		s.store.Add(sn)
+	}
+	for _, sn := range s.store.List() {
+		if sn.Timestamp >= start {
+			continue
+		}
+		// Delete the snapshot stats if it's not updated this time.
+		s.store.Delete(sn.Key)
+	}
+	return nil
+}