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memory.go
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memory.go
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// Copyright 2023 Linka Cloud All rights reserved.
//
// 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pending
import (
"bytes"
"sort"
"github.com/dgraph-io/badger/v3"
"github.com/dgraph-io/badger/v3/y"
)
const bitDelete byte = 1 << 0 // Set if the key has been deleted.
func newMem(addReadKey func(key []byte)) *mem {
return &mem{
m: make(map[string]*badger.Entry),
addReadKey: addReadKey,
}
}
type mem struct {
m map[string]*badger.Entry
addReadKey func(key []byte)
}
func (m *mem) Iterator(prefix []byte, readTs uint64, reversed bool) Iterator {
if m.empty() {
return &memIterator{
prefix: prefix,
readTs: readTs,
reversed: reversed,
addReadKey: m.addReadKey,
}
}
entries := m.slice()
// Number of pending writes per transaction shouldn't be too big in general.
sort.Slice(entries, func(i, j int) bool {
cmp := bytes.Compare(entries[i].Key, entries[j].Key)
if !reversed {
return cmp < 0
}
return cmp > 0
})
return &memIterator{
prefix: prefix,
readTs: readTs,
entries: entries,
reversed: reversed,
addReadKey: m.addReadKey,
}
}
func (p *mem) Set(e *badger.Entry) {
p.m[string(e.Key)] = e
}
func (p *mem) Delete(key []byte) {
p.m[string(key)] = &badger.Entry{
Key: key,
UserMeta: bitDelete,
}
}
func (p *mem) Replay(fn func(e *badger.Entry) error) error {
for _, e := range p.m {
if err := fn(e); err != nil {
return err
}
}
return nil
}
func (p *mem) Close() error {
return nil
}
func (p *mem) slice() []*badger.Entry {
entries := make([]*badger.Entry, 0, len(p.m))
for _, e := range p.m {
entries = append(entries, e)
}
return entries
}
func (p *mem) empty() bool {
return len(p.m) == 0
}
type memIterator struct {
prefix []byte
entries []*badger.Entry
nextIdx int
readTs uint64
reversed bool
addReadKey func(key []byte)
}
func (i *memIterator) Next() {
i.nextIdx++
}
func (i *memIterator) skip() bool {
return i.entries[i.nextIdx].UserMeta&bitDelete != 0 || !bytes.HasPrefix(i.entries[i.nextIdx].Key, i.prefix)
}
func (i *memIterator) Rewind() {
i.nextIdx = 0
}
func (i *memIterator) Seek(key []byte) {
i.addReadKey(key)
i.nextIdx = sort.Search(len(i.entries), func(idx int) bool {
cmp := bytes.Compare(i.entries[idx].Key, key)
if !i.reversed {
return cmp >= 0
}
return cmp <= 0
})
}
func (i *memIterator) Key() []byte {
y.AssertTrue(i.Valid())
return i.entries[i.nextIdx].Key
}
func (i *memIterator) Item() Item {
y.AssertTrue(i.Valid())
entry := i.entries[i.nextIdx]
i.addReadKey(entry.Key)
return &item{
readTs: i.readTs,
e: &badger.Entry{
Key: entry.Key,
Value: entry.Value,
ExpiresAt: entry.ExpiresAt,
UserMeta: entry.UserMeta,
},
}
}
func (i *memIterator) Valid() bool {
return i.nextIdx < len(i.entries)
}
func (i *memIterator) Close() {}