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package cache
import (
"errors"
"io"
"os"
"sync"
"time"
"github.com/rogpeppe/go-internal/lockedfile"
"github.com/vmihailenco/msgpack/v5"
)
type db struct {
File io.WriteSeeker
Store store
Stop chan struct{}
wg sync.WaitGroup
}
type Option func(*db) error
func openFile(filename string, options ...Option) (*db, error) {
ret, err := openMem(options...)
if err != nil {
return nil, err
}
file, err := lockedfile.OpenFile(filename, os.O_RDWR|os.O_CREATE, 0666)
if err != nil {
return nil, err
}
fileInfo, err := file.Stat()
if err != nil {
return nil, err
}
if fileInfo.Size() == 0 {
ret.File = file
ret.Flush()
} else {
err := ret.Store.LoadSnapshot(file)
if err != nil {
return nil, err
}
ret.File = file
}
return ret, nil
}
func openMem(options ...Option) (*db, error) {
ret := &db{}
ret.Store.Init()
ret.SetConfig(options...)
return ret, nil
}
func (d *db) Start() {
d.Stop = make(chan struct{})
d.wg.Add(1)
go d.backgroundWorker()
}
func (d *db) SetConfig(options ...Option) error {
d.Store.mu.Lock()
defer d.Store.mu.Unlock()
for _, opt := range options {
if err := opt(d); err != nil {
return err
}
}
return nil
}
func WithPolicy(e EvictionPolicyType) Option {
return func(d *db) error {
return d.Store.Policy.SetPolicy(e)
}
}
func WithMaxCost(maxCost uint64) Option {
return func(d *db) error {
d.Store.MaxCost = maxCost
return nil
}
}
func SetSnapshotTime(t time.Duration) Option {
return func(d *db) error {
d.Store.SnapshotTicker.Reset(t)
return nil
}
}
func SetCleanupTime(t time.Duration) Option {
return func(d *db) error {
d.Store.CleanupTicker.Reset(t)
return nil
}
}
func (d *db) backgroundWorker() {
defer d.wg.Done()
d.Store.SnapshotTicker.Resume()
defer d.Store.SnapshotTicker.Stop()
d.Store.CleanupTicker.Resume()
defer d.Store.CleanupTicker.Stop()
for {
select {
case <-d.Stop:
return
case <-d.Store.SnapshotTicker.C:
d.Flush()
case <-d.Store.CleanupTicker.C:
cleanup(&d.Store)
evict(&d.Store)
}
}
}
func (d *db) Close() {
close(d.Stop)
d.wg.Wait()
d.Flush()
d.Clear()
if d.File != nil {
closer, ok := d.File.(io.Closer)
if ok {
closer.Close()
}
}
}
func (d *db) Flush() error {
if d.File != nil {
return d.Store.Snapshot(d.File)
}
return nil
}
func (d *db) Clear() {
d.Store.Clear()
}
var ErrKeyNotFound = errors.New("key not found")
// The Cache database. Can be initialized by either OpenFile or OpenMem. Uses per DB Locks.
type DB[K any, V any] struct {
*db
}
func OpenFile[K any, V any](filename string, options ...Option) (DB[K, V], error) {
ret, err := openFile(filename, options...)
if err != nil {
return zero[DB[K, V]](), err
}
ret.Start()
return DB[K, V]{db: ret}, nil
}
func OpenMem[K any, V any](filename string, options ...Option) (DB[K, V], error) {
ret, err := openMem(options...)
if err != nil {
return zero[DB[K, V]](), err
}
ret.Start()
return DB[K, V]{db: ret}, nil
}
func (h *DB[K, V]) Get(key K, value V) (V, time.Duration, error) {
keyData, err := msgpack.Marshal(key)
if err != nil {
return value, 0, err
}
v, ttl, ok := h.Store.Get(keyData)
if !ok {
return value, 0, ErrKeyNotFound
}
if err = msgpack.Unmarshal(v, value); err != nil {
return value, 0, err
}
return value, ttl, err
}
func (h *DB[K, V]) GetValue(key K) (V, time.Duration, error) {
return h.Get(key, zero[V]())
}
func (h *DB[K, V]) Set(key K, value V, ttl time.Duration) error {
keyData, err := msgpack.Marshal(key)
if err != nil {
return err
}
valueData, err := msgpack.Marshal(value)
if err != nil {
return err
}
h.Store.Set(keyData, valueData, ttl)
return nil
}
func (h *DB[K, V]) Delete(key K) error {
keyData, err := msgpack.Marshal(key)
if err != nil {
return err
}
ok := h.Store.Delete(keyData)
if !ok {
return ErrKeyNotFound
}
return nil
}
|
