You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
105 lines
2.7 KiB
105 lines
2.7 KiB
// Copyright 2020 PingCAP, Inc.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package memdb
|
|
|
|
import (
|
|
"unsafe"
|
|
)
|
|
|
|
// Iterator iterates the entries in the DB.
|
|
type Iterator struct {
|
|
sb *Sandbox
|
|
curr *node
|
|
key []byte
|
|
val []byte
|
|
}
|
|
|
|
// NewIterator returns a new Iterator for the lock store.
|
|
func (sb *Sandbox) NewIterator() Iterator {
|
|
return Iterator{
|
|
sb: sb,
|
|
}
|
|
}
|
|
|
|
// Valid returns true if the iterator is positioned at a valid node.
|
|
func (it *Iterator) Valid() bool { return it.curr != nil }
|
|
|
|
// Key returns the key at the current position.
|
|
func (it *Iterator) Key() []byte {
|
|
return it.key
|
|
}
|
|
|
|
// Value returns value.
|
|
func (it *Iterator) Value() []byte {
|
|
return it.val
|
|
}
|
|
|
|
// Next moves the iterator to the next entry.
|
|
func (it *Iterator) Next() {
|
|
it.changeToAddr(it.curr.nexts(0))
|
|
}
|
|
|
|
// Prev moves the iterator to the previous entry.
|
|
func (it *Iterator) Prev() {
|
|
it.changeToAddr(it.curr.prev)
|
|
}
|
|
|
|
// Seek locates the iterator to the first entry with a key >= seekKey.
|
|
func (it *Iterator) Seek(seekKey []byte) {
|
|
node, nodeData, _ := it.sb.findGreaterEqual(seekKey) // find >=.
|
|
it.updateState(node, nodeData)
|
|
}
|
|
|
|
// SeekForPrev locates the iterator to the last entry with key <= target.
|
|
func (it *Iterator) SeekForPrev(target []byte) {
|
|
node, nodeData, _ := it.sb.findLess(target, true) // find <=.
|
|
it.updateState(node, nodeData)
|
|
}
|
|
|
|
// SeekForExclusivePrev locates the iterator to the last entry with key < target.
|
|
func (it *Iterator) SeekForExclusivePrev(target []byte) {
|
|
node, nodeData, _ := it.sb.findLess(target, false)
|
|
it.updateState(node, nodeData)
|
|
}
|
|
|
|
// SeekToFirst locates the iterator to the first entry.
|
|
func (it *Iterator) SeekToFirst() {
|
|
head := it.sb.getHead()
|
|
node, nodeData := head.getNext(it.sb.arena, 0)
|
|
it.updateState(node, nodeData)
|
|
}
|
|
|
|
// SeekToLast locates the iterator to the last entry.
|
|
func (it *Iterator) SeekToLast() {
|
|
node, nodeData := it.sb.findLast()
|
|
it.updateState(node, nodeData)
|
|
}
|
|
|
|
func (it *Iterator) updateState(node *node, nodeData []byte) {
|
|
it.curr = node
|
|
if node != nil {
|
|
it.key = node.getKey(nodeData)
|
|
it.val = node.getValue(nodeData)
|
|
}
|
|
}
|
|
|
|
func (it *Iterator) changeToAddr(addr arenaAddr) {
|
|
var data []byte
|
|
var n *node
|
|
if !addr.isNull() {
|
|
data = it.sb.arena.getFrom(addr)
|
|
n = (*node)(unsafe.Pointer(&data[0]))
|
|
}
|
|
it.updateState(n, data)
|
|
}
|
|
|