[#185] Update SDK to support new tree/pool version

Signed-off-by: Marina Biryukova <m.biryukova@yadro.com>

internal/service/frostfs/source.go

@@ -0,0 +1,69 @@
+package frostfs
+
+import (
+	"context"
+	"fmt"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/internal/cache"
+	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/internal/handler"
+	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/internal/logs"
+	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
+	"go.uber.org/zap"
+)
+
+type Source struct {
+	frostFS     *FrostFS
+	netmapCache *cache.NetmapCache
+	bucketCache *cache.BucketCache
+	log         *zap.Logger
+}
+
+func NewSource(frostFS *FrostFS, netmapCache *cache.NetmapCache, bucketCache *cache.BucketCache, log *zap.Logger) *Source {
+	return &Source{
+		frostFS:     frostFS,
+		netmapCache: netmapCache,
+		bucketCache: bucketCache,
+		log:         log,
+	}
+}
+
+func (s *Source) NetMapSnapshot(ctx context.Context) (netmap.NetMap, error) {
+	cachedNetmap := s.netmapCache.Get()
+	if cachedNetmap != nil {
+		return *cachedNetmap, nil
+	}
+
+	netmapSnapshot, err := s.frostFS.NetmapSnapshot(ctx)
+	if err != nil {
+		return netmap.NetMap{}, fmt.Errorf("get netmap: %w", err)
+	}
+
+	if err = s.netmapCache.Put(netmapSnapshot); err != nil {
+		s.log.Warn(logs.CouldntCacheNetmap, zap.Error(err))
+	}
+
+	return netmapSnapshot, nil
+}
+
+func (s *Source) PlacementPolicy(ctx context.Context, cnrID cid.ID) (netmap.PlacementPolicy, error) {
+	info := s.bucketCache.GetByCID(cnrID)
+	if info != nil {
+		return info.PlacementPolicy, nil
+	}
+
+	prm := handler.PrmContainer{
+		ContainerID: cnrID,
+	}
+	res, err := s.frostFS.Container(ctx, prm)
+	if err != nil {
+		return netmap.PlacementPolicy{}, fmt.Errorf("get container: %w", err)
+	}
+
+	// We don't put container back to the cache to keep cache
+	// coherent to the requests made by users. FrostFS Source
+	// is being used by SDK Tree Pool and it should not fill cache
+	// with possibly irrelevant container values.
+
+	return res.PlacementPolicy(), nil
+}