Signature mismatches

[faddat]

The method delete has one signature in the internal api testdb folder, and another in types.

[faddat]

• wasmvm/internal/api/iterator_test.go

  Line 75 in 6480176

  iter, _ = store.Iterator(nil, nil)

[chipshort]

I don't understand what you mean. The only delete method I see is this one:

wasmvm/internal/api/testdb/memdb.go

Line 122 in 6480176

func (db *MemDB) delete(key []byte) {

And what's with the Iterator method?

[faddat]

Ok, so if we look at the types/store.go

// KVStore copies a subset of types from cosmos-sdk
// We may wish to make this more generic sometime in the future, but not now
// https://github.com/cosmos/cosmos-sdk/blob/bef3689245bab591d7d169abd6bea52db97a70c7/store/types/store.go#L170
type KVStore interface {
	Get(key []byte) []byte
	Set(key, value []byte)
	Delete(key []byte)

	// Iterator over a domain of keys in ascending order. End is exclusive.
	// Start must be less than end, or the Iterator is invalid.
	// Iterator must be closed by caller.
	// To iterate over entire domain, use store.Iterator(nil, nil)
	Iterator(start, end []byte) Iterator

	// ReverseIterator iterator over a domain of keys in descending order. End is exclusive.
	// Start must be less than end, or the Iterator is invalid.
	// Iterator must be closed by caller.
	ReverseIterator(start, end []byte) Iterator
}

// Iterator represents an iterator over a domain of keys. Callers must call Close when done.
// No writes can happen to a domain while there exists an iterator over it, some backends may take
// out database locks to ensure this will not happen.
//
// Callers must make sure the iterator is valid before calling any methods on it, otherwise
// these methods will panic. This is in part caused by most backend databases using this convention.
//
// As with DB, keys and values should be considered read-only, and must be copied before they are
// modified.
//
// Typical usage:
//
// var itr Iterator = ...
// defer itr.Close()
//
//	for ; itr.Valid(); itr.Next() {
//	  k, v := itr.Key(); itr.Value()
//	  ...
//	}
//
//	if err := itr.Error(); err != nil {
//	  ...
//	}
//
// Copied from https://github.com/tendermint/tm-db/blob/v0.6.7/types.go#L121
type Iterator interface {
	// Domain returns the start (inclusive) and end (exclusive) limits of the iterator.
	// CONTRACT: start, end readonly []byte
	Domain() (start []byte, end []byte)

	// Valid returns whether the current iterator is valid. Once invalid, the Iterator remains
	// invalid forever.
	Valid() bool

	// Next moves the iterator to the next key in the database, as defined by order of iteration.
	// If Valid returns false, this method will panic.
	Next()

	// Key returns the key at the current position. Panics if the iterator is invalid.
	// CONTRACT: key readonly []byte
	Key() (key []byte)

	// Value returns the value at the current position. Panics if the iterator is invalid.
	// CONTRACT: value readonly []byte
	Value() (value []byte)

	// Error returns the last error encountered by the iterator, if any.
	Error() error

	// Close closes the iterator, releasing any allocated resources.
	Close() error
}

Then, we can compare to the testdb folder, where notably, calls can return errors:

package testdb

import (
	"bytes"
	"fmt"
	"sync"

	"github.com/google/btree"
)

const (
	// The approximate number of items and children per B-tree node. Tuned with benchmarks.
	bTreeDegree = 32
)

// item is a btree.Item with byte slices as keys and values.
type item struct {
	key   []byte
	value []byte
}

// Less implements btree.Item.
func (i *item) Less(other btree.Item) bool {
	// this considers nil == []byte{}, but that's ok since we handle nil endpoints
	// in iterators specially anyway
	return bytes.Compare(i.key, other.(*item).key) == -1
}

// newKey creates a new key item.
func newKey(key []byte) *item {
	return &item{key: key}
}

// newPair creates a new pair item.
func newPair(key, value []byte) *item {
	return &item{key: key, value: value}
}

// MemDB is an in-memory database backend using a B-tree for storage.
//
// For performance reasons, all given and returned keys and values are pointers to the in-memory
// database, so modifying them will cause the stored values to be modified as well. All DB methods
// already specify that keys and values should be considered read-only, but this is especially
// important with MemDB.
type MemDB struct {
	mtx   sync.RWMutex
	btree *btree.BTree
}

// NewMemDB creates a new in-memory database.
func NewMemDB() *MemDB {
	database := &MemDB{
		btree: btree.New(bTreeDegree),
	}
	return database
}

// Get implements DB.
func (db *MemDB) Get(key []byte) ([]byte, error) {
	if len(key) == 0 {
		return nil, errKeyEmpty
	}
	db.mtx.RLock()
	defer db.mtx.RUnlock()

	i := db.btree.Get(newKey(key))
	if i != nil {
		return i.(*item).value, nil
	}
	return nil, nil
}

// Has implements DB.
func (db *MemDB) Has(key []byte) (bool, error) {
	if len(key) == 0 {
		return false, errKeyEmpty
	}
	db.mtx.RLock()
	defer db.mtx.RUnlock()

	return db.btree.Has(newKey(key)), nil
}

// Set implements DB.
func (db *MemDB) Set(key []byte, value []byte) error {
	if len(key) == 0 {
		return errKeyEmpty
	}
	if value == nil {
		return errValueNil
	}
	db.mtx.Lock()
	defer db.mtx.Unlock()

	db.set(key, value)
	return nil
}

// set sets a value without locking the mutex.
func (db *MemDB) set(key []byte, value []byte) {
	db.btree.ReplaceOrInsert(newPair(key, value))
}

// SetSync implements DB.
func (db *MemDB) SetSync(key []byte, value []byte) error {
	return db.Set(key, value)
}

// Delete implements DB.
func (db *MemDB) Delete(key []byte) error {
	if len(key) == 0 {
		return errKeyEmpty
	}
	db.mtx.Lock()
	defer db.mtx.Unlock()

	db.delete(key)
	return nil
}

// delete deletes a key without locking the mutex.
func (db *MemDB) delete(key []byte) {
	db.btree.Delete(newKey(key))
}

// DeleteSync implements DB.
func (db *MemDB) DeleteSync(key []byte) error {
	return db.Delete(key)
}

// Close implements DB.
func (db *MemDB) Close() error {
	// Close is a noop since for an in-memory database, we don't have a destination to flush
	// contents to nor do we want any data loss on invoking Close().
	// See the discussion in https://github.com/tendermint/tendermint/libs/pull/56
	return nil
}

// Print implements DB.
func (db *MemDB) Print() error {
	db.mtx.RLock()
	defer db.mtx.RUnlock()

	db.btree.Ascend(func(i btree.Item) bool {
		item := i.(*item)
		fmt.Printf("[%X]:\t[%X]\n", item.key, item.value)
		return true
	})
	return nil
}

// Stats implements DB.
func (db *MemDB) Stats() map[string]string {
	db.mtx.RLock()
	defer db.mtx.RUnlock()

	stats := make(map[string]string)
	stats["database.type"] = "memDB"
	stats["database.size"] = fmt.Sprintf("%d", db.btree.Len())
	return stats
}

// Iterator implements DB.
// Takes out a read-lock on the database until the iterator is closed.
func (db *MemDB) Iterator(start, end []byte) (Iterator, error) {
	if (start != nil && len(start) == 0) || (end != nil && len(end) == 0) {
		return nil, errKeyEmpty
	}
	return newMemDBIterator(db, start, end, false), nil
}

// ReverseIterator implements DB.
// Takes out a read-lock on the database until the iterator is closed.
func (db *MemDB) ReverseIterator(start, end []byte) (Iterator, error) {
	if (start != nil && len(start) == 0) || (end != nil && len(end) == 0) {
		return nil, errKeyEmpty
	}
	return newMemDBIterator(db, start, end, true), nil
}

// IteratorNoMtx makes an iterator with no mutex.
func (db *MemDB) IteratorNoMtx(start, end []byte) (Iterator, error) {
	if (start != nil && len(start) == 0) || (end != nil && len(end) == 0) {
		return nil, errKeyEmpty
	}
	return newMemDBIteratorMtxChoice(db, start, end, false, false), nil
}

// ReverseIteratorNoMtx makes an iterator with no mutex.
func (db *MemDB) ReverseIteratorNoMtx(start, end []byte) (Iterator, error) {
	if (start != nil && len(start) == 0) || (end != nil && len(end) == 0) {
		return nil, errKeyEmpty
	}
	return newMemDBIteratorMtxChoice(db, start, end, true, false), nil
}