Merge pull request #588 from onflow/fxamacker/remove-old-function-FixLoadedBrokenReferences

Remove unused storage function FixLoadedBrokenReferences

Author: fxamacker

storage.go

@@ -20,7 +20,6 @@ package atree
 
 import (
 	"encoding/binary"
-	"errors"
 	"fmt"
 	"sort"
 	"strings"
@@ -1013,233 +1012,6 @@ func (s *PersistentSlabStorage) DeltasSizeWithoutTempAddresses() uint64 {
 	return size
 }
 
-// FixLoadedBrokenReferences traverses loaded slabs and fixes broken references in maps.
-// A broken reference is a SlabID referencing a non-existent slab.
-// To fix a map containing broken references, this function replaces broken map with
-// empty map having the same SlabID and also removes all slabs in the old map.
-// Limitations:
-// - only fix broken references in map
-// - only traverse loaded slabs in deltas and cache
-// NOTE: The intended use case is to enable migration programs in onflow/flow-go to
-// fix broken references.  As of April 2024, only 10 registers in testnet (not mainnet)
-// were found to have broken references and they seem to have resulted from a bug
-// that was fixed 2 years ago by https://github.com/onflow/cadence/pull/1565.
-func (s *PersistentSlabStorage) FixLoadedBrokenReferences(needToFix func(old Value) bool) (
-	fixedSlabIDs map[SlabID][]SlabID, // key: root slab ID, value: slab IDs containing broken refs
-	skippedSlabIDs map[SlabID][]SlabID, // key: root slab ID, value: slab IDs containing broken refs
-	err error,
-) {
-
-	// parentOf is used to find root slab from non-root slab.
-	// Broken reference can be in non-root slab, and we need SlabID of root slab
-	// to replace broken map by creating an empty new map with same SlabID.
-	parentOf := make(map[SlabID]SlabID)
-
-	getRootSlabID := func(id SlabID) SlabID {
-		for {
-			parentID, ok := parentOf[id]
-			if ok {
-				id = parentID
-			} else {
-				return id
-			}
-		}
-	}
-
-	hasBrokenReferenceInSlab := func(id SlabID, slab Slab) bool {
-		if slab == nil {
-			return false
-		}
-
-		switch slab.(type) {
-		case *ArrayMetaDataSlab, *MapMetaDataSlab: // metadata slabs
-			var foundBrokenRef bool
-
-			for _, childStorable := range slab.ChildStorables() {
-
-				if slabIDStorable, ok := childStorable.(SlabIDStorable); ok {
-
-					childID := SlabID(slabIDStorable)
-
-					// Track parent-child relationship of root slabs and non-root slabs.
-					parentOf[childID] = id
-
-					if !s.existIfLoaded(childID) {
-						foundBrokenRef = true
-					}
-
-					// Continue with remaining child storables to track parent-child relationship.
-				}
-			}
-
-			return foundBrokenRef
-
-		default: // data slabs
-			childStorables := slab.ChildStorables()
-
-			for len(childStorables) > 0 {
-
-				var nextChildStorables []Storable
-
-				for _, childStorable := range childStorables {
-
-					if slabIDStorable, ok := childStorable.(SlabIDStorable); ok {
-
-						if !s.existIfLoaded(SlabID(slabIDStorable)) {
-							return true
-						}
-
-						continue
-					}
-
-					// Append child storables of this childStorable to
-					// handle nested SlabIDStorable, such as Cadence SomeValue.
-					nextChildStorables = append(
-						nextChildStorables,
-						childStorable.ChildStorables()...,
-					)
-				}
-
-				childStorables = nextChildStorables
-			}
-
-			return false
-		}
-	}
-
-	var brokenSlabIDs []SlabID
-
-	// Iterate delta slabs.
-	for id, slab := range s.deltas {
-		if hasBrokenReferenceInSlab(id, slab) {
-			brokenSlabIDs = append(brokenSlabIDs, id)
-		}
-	}
-
-	// Iterate cache slabs.
-	for id, slab := range s.cache {
-		if _, ok := s.deltas[id]; ok {
-			continue
-		}
-		if hasBrokenReferenceInSlab(id, slab) {
-			brokenSlabIDs = append(brokenSlabIDs, id)
-		}
-	}
-
-	if len(brokenSlabIDs) == 0 {
-		return nil, nil, nil
-	}
-
-	rootSlabIDsWithBrokenData := make(map[SlabID][]SlabID)
-	var errs []error
-
-	// Find SlabIDs of root slab for slabs containing broken references.
-	for _, id := range brokenSlabIDs {
-		rootID := getRootSlabID(id)
-		if rootID == SlabIDUndefined {
-			errs = append(errs, fmt.Errorf("failed to get root slab id for slab %s", id))
-			continue
-		}
-		rootSlabIDsWithBrokenData[rootID] = append(rootSlabIDsWithBrokenData[rootID], id)
-	}
-
-	for rootSlabID, brokenSlabIDs := range rootSlabIDsWithBrokenData {
-		rootSlab := s.RetrieveIfLoaded(rootSlabID)
-		if rootSlab == nil {
-			errs = append(errs, fmt.Errorf("failed to retrieve loaded root slab %s", rootSlabID))
-			continue
-		}
-
-		switch rootSlab := rootSlab.(type) {
-		case MapSlab:
-			value, err := rootSlab.StoredValue(s)
-			if err != nil {
-				errs = append(errs, fmt.Errorf("failed to convert slab %s into value", rootSlab.SlabID()))
-				continue
-			}
-
-			if needToFix(value) {
-				err := s.fixBrokenReferencesInMap(rootSlab)
-				if err != nil {
-					errs = append(errs, err)
-					continue
-				}
-			} else {
-				if skippedSlabIDs == nil {
-					skippedSlabIDs = make(map[SlabID][]SlabID)
-				}
-				skippedSlabIDs[rootSlabID] = brokenSlabIDs
-			}
-
-		default:
-			// IMPORTANT: Only handle map slabs for now.  DO NOT silently fix currently unknown problems.
-			errs = append(errs, fmt.Errorf("failed to fix broken references in non-map slab %s (%T)", rootSlab.SlabID(), rootSlab))
-		}
-	}
-
-	for id := range skippedSlabIDs {
-		delete(rootSlabIDsWithBrokenData, id)
-	}
-
-	return rootSlabIDsWithBrokenData, skippedSlabIDs, errors.Join(errs...)
-}
-
-// fixBrokenReferencesInMap replaces replaces broken map with empty map
-// having the same SlabID and also removes all slabs in the old map.
-func (s *PersistentSlabStorage) fixBrokenReferencesInMap(old MapSlab) error {
-	id := old.SlabID()
-
-	oldExtraData := old.ExtraData()
-
-	// Create an empty map with the same StorgeID, type, and seed as the old map.
-	newMap := &MapDataSlab{
-		header: MapSlabHeader{
-			slabID: id,
-			size:   mapRootDataSlabPrefixSize + hkeyElementsPrefixSize,
-		},
-		extraData: &MapExtraData{
-			TypeInfo: oldExtraData.TypeInfo,
-			Seed:     oldExtraData.Seed,
-		},
-		elements: newHkeyElements(0),
-	}
-
-	// Store new empty map with the same SlabID.
-	err := s.Store(id, newMap)
-	if err != nil {
-		return err
-	}
-
-	// Remove all slabs and references in old map.
-	references, _, err := s.getAllChildReferences(old)
-	if err != nil {
-		return err
-	}
-
-	for _, childID := range references {
-		err = s.Remove(childID)
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func (s *PersistentSlabStorage) existIfLoaded(id SlabID) bool {
-	// Check deltas.
-	if slab, ok := s.deltas[id]; ok {
-		return slab != nil
-	}
-
-	// Check read cache.
-	if slab, ok := s.cache[id]; ok {
-		return slab != nil
-	}
-
-	return false
-}
-
 // GetAllChildReferences returns child references of given slab (all levels),
 // including nested container and theirs child references.
 func (s *PersistentSlabStorage) GetAllChildReferences(id SlabID) (