feat(cache-store): add deep copy function

CHANGELOG.md

@@ -62,6 +62,7 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 * (client) [#19870](https://github.com/cosmos/cosmos-sdk/pull/19870) Add new query command `wait-tx`. Alias `event-query-tx-for` to `wait-tx` for backward compatibility.
 * (crypto/keyring) [#20212](https://github.com/cosmos/cosmos-sdk/pull/20212) Expose the db keyring used in the keystore.
 * (genutil) [#19971](https://github.com/cosmos/cosmos-sdk/pull/19971) Allow manually setting the consensus key type in genesis
+* (store) [#20862](https://github.com/cosmos/cosmos-sdk/pull/20862) Add `Copy()` method for `CacheMultiStore` and `cachekv.Store`.
 
 ### Improvements
 

store/cachekv/store.go

@@ -161,6 +161,38 @@
 	}
 }
 
+// Copy creates a deep copy of the Store object
+func (store *Store) Copy() types.CacheKVStore {
+	store.mtx.Lock()
+	defer store.mtx.Unlock()
+
+	// Copy cache
+	cacheCopy := make(map[string]*cValue, len(store.cache))
+	for key, val := range store.cache {
+		newVal := *val // Create a copy of the cValue
+		cacheCopy[key] = &newVal
+	}
+
+	// Copy unsortedCache
+	unsortedCacheCopy := make(map[string]struct{}, len(store.unsortedCache))
+	for key := range store.unsortedCache {
+		unsortedCacheCopy[key] = struct{}{}
+	}
+
+	// Copy sortedCache
+	sortedCacheCopy := store.sortedCache.Copy()
+
+	// Create new Store with copied values
+	newStore := &Store{
+		cache:         cacheCopy,
+		unsortedCache: unsortedCacheCopy,
+		sortedCache:   sortedCacheCopy,
+		parent:        store.parent,
+	}
+
+	return newStore
+}
+
 // CacheWrap implements CacheWrapper.
 func (store *Store) CacheWrap() types.CacheWrap {
 	return NewStore(store)

store/cachemulti/store.go

@@ -127,6 +127,32 @@
 	}
 }
 
+// Copy creates a deep copy of the Store object
+func (cms Store) Copy() types.CacheMultiStore {
+	// Deep copy the db field
+	newDB := cms.db.Copy()
+
+	// Deep copy the cachekv stores map
+	newStores := make(map[types.StoreKey]types.CacheWrap, len(cms.stores))
+	for key, store := range cms.stores {
+		store, ok := store.(*cachekv.Store)
+		if ok {
+			newStores[key] = store.Copy()
+		}
+	}
+
+	// Create new Store with copied values
+	newStore := Store{
+		db:           newDB,
+		stores:       newStores,
+		keys:         cms.keys,
+		traceWriter:  cms.traceWriter,
+		traceContext: cms.traceContext,
+	}
+
+	return newStore
+}
+
 // Implements CacheWrapper.
 func (cms Store) CacheWrap() types.CacheWrap {
 	return cms.CacheMultiStore().(types.CacheWrap)

store/types/store.go

@@ -165,7 +165,8 @@ type MultiStore interface {
 // From MultiStore.CacheMultiStore()....
 type CacheMultiStore interface {
 	MultiStore
-	Write() // Writes operations to underlying KVStore
+	Write()                // Writes operations to underlying KVStore
+	Copy() CacheMultiStore // Returns a deep copy of the CacheMultiStore
 }
 
 // CommitMultiStore is an interface for a MultiStore without cache capabilities.
@@ -284,6 +285,8 @@ type CacheKVStore interface {
 
 	// Writes operations to underlying KVStore
 	Write()
+	// Copy creates a deep copy of the Store object
+	Copy() CacheKVStore
 }
 
 // CommitKVStore is an interface for MultiStore.