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package kv
import (
"codeberg.org/gruf/go-errors"
"codeberg.org/gruf/go-store/storage"
)
var ErrIteratorClosed = errors.New("store/kv: iterator closed")
// KVIterator provides a read-only iterator to all the key-value
// pairs in a KVStore. While the iterator is open the store is read
// locked, you MUST release the iterator when you are finished with
// it.
//
// Please note:
// - individual iterators are NOT concurrency safe, though it is safe to
// have multiple iterators running concurrently
type KVIterator struct {
store *KVStore // store is the linked KVStore
entries []storage.StorageEntry
index int
key string
onClose func()
}
// Next attempts to set the next key-value pair, the
// return value is if there was another pair remaining
func (i *KVIterator) Next() bool {
next := i.index + 1
if next >= len(i.entries) {
i.key = ""
return false
}
i.key = i.entries[next].Key()
i.index = next
return true
}
// Key returns the next key from the store
func (i *KVIterator) Key() string {
return i.key
}
// Release releases the KVIterator and KVStore's read lock
func (i *KVIterator) Release() {
// Reset key, path, entries
i.store = nil
i.key = ""
i.entries = nil
// Perform requested callback
i.onClose()
}
// Value returns the next value from the KVStore
func (i *KVIterator) Value() ([]byte, error) {
// Check store isn't closed
if i.store == nil {
return nil, ErrIteratorClosed
}
// Attempt to fetch from store
return i.store.get(i.key)
}
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