gossamer_storage_tries_cached_total metric

dot/state/storage.go

@@ -43,7 +43,8 @@ type StorageState struct {
 
 // NewStorageState creates a new StorageState backed by the given trie and database located at basePath.
 func NewStorageState(db chaindb.Database, blockState *BlockState,
-	t *trie.Trie, onlinePruner pruner.Config) (*StorageState, error) {
+	t *trie.Trie, onlinePruner pruner.Config) (
+	*StorageState, error) {
 	if db == nil {
 		return nil, fmt.Errorf("cannot have nil database")
 	}
@@ -52,7 +53,10 @@ func NewStorageState(db chaindb.Database, blockState *BlockState,
 		return nil, fmt.Errorf("cannot have nil trie")
 	}
 
-	tries := newTries(t)
+	tries, err := newTries(t)
+	if err != nil {
+		return nil, fmt.Errorf("cannot create in-memory tries: %w", err)
+	}
 
 	storageTable := chaindb.NewTable(db, storagePrefix)
 

dot/state/tries.go

@@ -4,23 +4,38 @@
 package state
 
 import (
+	"errors"
+	"fmt"
 	"sync"
 
 	"github.com/ChainSafe/gossamer/lib/common"
 	"github.com/ChainSafe/gossamer/lib/trie"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 type tries struct {
 	rootToTrie map[common.Hash]*trie.Trie
 	mapMutex   sync.RWMutex
+	triesGauge prometheus.Gauge
 }
 
-func newTries(t *trie.Trie) *tries {
+func newTries(t *trie.Trie) (trs *tries, err error) {
+	triesGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "gossamer_storage",
+		Name:      "tries_cached_total",
+		Help:      "total number of tries cached in memory",
+	})
+	err = prometheus.Register(triesGauge)
+	if err != nil && !errors.As(err, &prometheus.AlreadyRegisteredError{}) {
+		return nil, fmt.Errorf("cannot register tries gauge: %w", err)
+	}
+
 	return &tries{
 		rootToTrie: map[common.Hash]*trie.Trie{
 			t.MustHash(): t,
 		},
-	}
+		triesGauge: triesGauge,
+	}, nil
 }
 
 // softSet sets the given trie at the given root hash
@@ -34,13 +49,15 @@ func (t *tries) softSet(root common.Hash, trie *trie.Trie) {
 		return
 	}
 
+	t.triesGauge.Inc()
 	t.rootToTrie[root] = trie
 }
 
 func (t *tries) delete(root common.Hash) {
 	t.mapMutex.Lock()
 	defer t.mapMutex.Unlock()
 	delete(t.rootToTrie, root)
+	t.triesGauge.Set(float64(len(t.rootToTrie)))
 }
 
 // get retrieves the trie corresponding to the root hash given