[#1248] placement: Decouple ContainerNodes() cache from the placement builder.

Also, write tests.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/services/object_manager/placement/cache.go

@@ -0,0 +1,69 @@
+package placement
+
+import (
+	"crypto/sha256"
+	"fmt"
+	"sync"
+
+	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
+	netmapSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
+	"github.com/hashicorp/golang-lru/v2/simplelru"
+)
+
+// ContainerNodesCache caches results of ContainerNodes() invocation between epochs.
+type ContainerNodesCache struct {
+	// mtx protects lastEpoch and containerCache fields.
+	mtx sync.Mutex
+	// lastEpoch contains network map epoch for all values in the container cache.
+	lastEpoch uint64
+	// containerCache caches container nodes by ID. It is used to skip `GetContainerNodes` invocation if
+	// neither netmap nor container has changed.
+	containerCache simplelru.LRUCache[cid.ID, [][]netmapSDK.NodeInfo]
+}
+
+// defaultContainerCacheSize is the default size for the container cache.
+const defaultContainerCacheSize = 10
+
+// NewContainerNodesCache creates new cache which saves the result of the ContainerNodes() invocations.
+// If size is <= 0, defaultContainerCacheSize (10) is used.
+func NewContainerNodesCache(size int) *ContainerNodesCache {
+	if size <= 0 {
+		size = defaultContainerCacheSize
+	}
+
+	cache, _ := simplelru.NewLRU[cid.ID, [][]netmapSDK.NodeInfo](size, nil) // no error
+	return &ContainerNodesCache{
+		containerCache: cache,
+	}
+}
+
+// ContainerNodes returns the result of nm.ContainerNodes(), possibly from the cache.
+func (c *ContainerNodesCache) ContainerNodes(nm *netmapSDK.NetMap, cnr cid.ID, p netmapSDK.PlacementPolicy) ([][]netmapSDK.NodeInfo, error) {
+	c.mtx.Lock()
+	if nm.Epoch() == c.lastEpoch {
+		raw, ok := c.containerCache.Get(cnr)
+		c.mtx.Unlock()
+		if ok {
+			return raw, nil
+		}
+	} else {
+		c.lastEpoch = nm.Epoch()
+		c.containerCache.Purge()
+		c.mtx.Unlock()
+	}
+
+	binCnr := make([]byte, sha256.Size)
+	cnr.Encode(binCnr)
+
+	cn, err := nm.ContainerNodes(p, binCnr)
+	if err != nil {
+		return nil, fmt.Errorf("could not get container nodes: %w", err)
+	}
+
+	c.mtx.Lock()
+	if c.lastEpoch == nm.Epoch() {
+		c.containerCache.Add(cnr, cn)
+	}
+	c.mtx.Unlock()
+	return cn, nil
+}

pkg/services/object_manager/placement/cache_test.go

@@ -0,0 +1,95 @@
+package placement_test
+
+import (
+	"strconv"
+	"testing"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
+	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
+	cidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id/test"
+	netmapSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
+	"github.com/stretchr/testify/require"
+)
+
+func TestContainerNodesCache(t *testing.T) {
+	const size = 3
+
+	nodes := [6]netmapSDK.NodeInfo{}
+	for i := range nodes {
+		nodes[i].SetAttribute("ATTR", strconv.Itoa(i))
+	}
+
+	nm := func(epoch uint64, nodes []netmapSDK.NodeInfo) *netmapSDK.NetMap {
+		var nm netmapSDK.NetMap
+		nm.SetEpoch(epoch)
+		nm.SetNodes(nodes)
+		return &nm
+	}
+
+	var pp netmapSDK.PlacementPolicy
+	require.NoError(t, pp.DecodeString("REP 1"))
+
+	t.Run("update netmap on the new epoch", func(t *testing.T) {
+		c := placement.NewContainerNodesCache(size)
+
+		cnr := cidtest.ID()
+		res, err := c.ContainerNodes(nm(1, nodes[0:1]), cnr, pp)
+		require.NoError(t, err)
+
+		// Use other nodes in the argument to ensure the result is taken from cache.
+		resCached, err := c.ContainerNodes(nm(1, nodes[1:2]), cnr, pp)
+		require.NoError(t, err)
+		require.Equal(t, res, resCached)
+
+		// Update epoch, netmap should be purged.
+		resCached, err = c.ContainerNodes(nm(2, nodes[2:3]), cnr, pp)
+		require.NoError(t, err)
+		require.NotEqual(t, res, resCached)
+	})
+	t.Run("cache uses container as a key", func(t *testing.T) {
+		c := placement.NewContainerNodesCache(size)
+
+		res1, err := c.ContainerNodes(nm(1, nodes[0:1]), cidtest.ID(), pp)
+		require.NoError(t, err)
+
+		res2, err := c.ContainerNodes(nm(1, nodes[1:2]), cidtest.ID(), pp)
+		require.NoError(t, err)
+
+		require.NotEqual(t, res1, res2)
+	})
+	t.Run("cache respects size parameter", func(t *testing.T) {
+		c := placement.NewContainerNodesCache(size)
+
+		nm1 := nm(1, nodes[0:1])
+		nm2 := nm(1, nodes[1:2])
+		cnr := [size * 2]cid.ID{}
+		res := [size * 2][][]netmapSDK.NodeInfo{}
+		for i := 0; i < size*2; i++ {
+			cnr[i] = cidtest.ID()
+
+			var err error
+			res[i], err = c.ContainerNodes(nm1, cnr[i], pp)
+			require.NoError(t, err)
+		}
+
+		for i := size; i < size*2; i++ {
+			r, err := c.ContainerNodes(nm2, cnr[i], pp)
+			require.NoError(t, err)
+			require.Equal(t, res[i], r)
+		}
+		for i := 0; i < size; i++ {
+			r, err := c.ContainerNodes(nm2, cnr[i], pp)
+			require.NoError(t, err)
+			require.NotEqual(t, res[i], r)
+		}
+	})
+	t.Run("the error is propagated", func(t *testing.T) {
+		var pp netmapSDK.PlacementPolicy
+		require.NoError(t, pp.DecodeString("REP 1 SELECT 1 FROM X FILTER ATTR EQ 42 AS X"))
+
+		c := placement.NewContainerNodesCache(size)
+		_, err := c.ContainerNodes(nm(1, nodes[0:1]), cidtest.ID(), pp)
+		require.Error(t, err)
+	})
+
+}

pkg/services/object_manager/placement/netmap.go

@@ -3,24 +3,16 @@ package placement
 import (
 	"crypto/sha256"
 	"fmt"
-	"sync"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
 	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
 	netmapSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
-	"github.com/hashicorp/golang-lru/v2/simplelru"
 )
 
 type netMapBuilder struct {
 	nmSrc          netmap.Source
-	// mtx protects lastEpoch and containerCache fields.
-	mtx sync.Mutex
-	// lastEpoch contains contains network map epoch for all values in the container cache.
-	lastEpoch uint64
-	// containerCache caches container nodes by ID. It is used to skip `GetContainerNodes` invocation if
-	// neither netmap nor container has changed.
-	containerCache simplelru.LRUCache[cid.ID, [][]netmapSDK.NodeInfo]
+	containerCache *ContainerNodesCache
 }
 
 type netMapSrc struct {
@@ -29,22 +21,17 @@ type netMapSrc struct {
 	nm *netmapSDK.NetMap
 }
 
-// defaultContainerCacheSize is the default size for the container cache.
-const defaultContainerCacheSize = 10
-
 func NewNetworkMapBuilder(nm *netmapSDK.NetMap) Builder {
-	cache, _ := simplelru.NewLRU[cid.ID, [][]netmapSDK.NodeInfo](defaultContainerCacheSize, nil) // no error
 	return &netMapBuilder{
 		nmSrc:          &netMapSrc{nm: nm},
-		containerCache: cache,
+		containerCache: NewContainerNodesCache(0),
 	}
 }
 
 func NewNetworkMapSourceBuilder(nmSrc netmap.Source) Builder {
-	cache, _ := simplelru.NewLRU[cid.ID, [][]netmapSDK.NodeInfo](defaultContainerCacheSize, nil) // no error
 	return &netMapBuilder{
 		nmSrc:          nmSrc,
-		containerCache: cache,
+		containerCache: NewContainerNodesCache(0),
 	}
 }
 
@@ -58,33 +45,11 @@ func (b *netMapBuilder) BuildPlacement(cnr cid.ID, obj *oid.ID, p netmapSDK.Plac
 		return nil, fmt.Errorf("could not get network map: %w", err)
 	}
 
-	binCnr := make([]byte, sha256.Size)
-	cnr.Encode(binCnr)
-
-	b.mtx.Lock()
-	if nm.Epoch() == b.lastEpoch {
-		raw, ok := b.containerCache.Get(cnr)
-		b.mtx.Unlock()
-		if ok {
-			return BuildObjectPlacement(nm, raw, obj)
-		}
-	} else {
-		b.lastEpoch = nm.Epoch()
-		b.containerCache.Purge()
-		b.mtx.Unlock()
-	}
-
-	cn, err := nm.ContainerNodes(p, binCnr)
+	cn, err := b.containerCache.ContainerNodes(nm, cnr, p)
 	if err != nil {
-		return nil, fmt.Errorf("could not get container nodes: %w", err)
+		return nil, err
 	}
 
-	b.mtx.Lock()
-	if b.lastEpoch == nm.Epoch() {
-		b.containerCache.Add(cnr, cn)
-	}
-	b.mtx.Unlock()
-
 	return BuildObjectPlacement(nm, cn, obj)
 }