118 lines
2.1 KiB
Go
118 lines
2.1 KiB
Go
package cache
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import (
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"encoding/json"
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"fmt"
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"log/slog"
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"os"
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"path/filepath"
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"time"
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"go.uber.org/fx"
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)
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type CacheEntry struct {
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Expire time.Time `json:"e"`
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Value string `json:"v"`
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}
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type CacheResult struct {
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fx.Out
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Cache *Cache
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}
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type Cache struct {
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Root string
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Log *slog.Logger
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}
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type CacheParams struct {
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fx.In
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Log *slog.Logger
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}
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func NewCache(p CacheParams) CacheResult {
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c := &Cache{
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Root: filepath.Join(os.TempDir(), "gspot.cache"),
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Log: p.Log,
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}
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return CacheResult{
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Cache: c,
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}
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}
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func (c *Cache) load() (map[string]CacheEntry, error) {
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out := map[string]CacheEntry{}
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cache, err := os.Open(c.Root)
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if err != nil {
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return nil, err
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}
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if err := json.NewDecoder(cache).Decode(&out); err != nil {
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return nil, err
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}
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return out, nil
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}
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func (c *Cache) save(m map[string]CacheEntry) error {
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payload, err := json.Marshal(m)
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if err != nil {
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return err
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}
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slog.Debug("CACHE", "saving", string(payload))
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err = os.WriteFile(c.Root, payload, 0o600)
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if err != nil {
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return err
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}
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return nil
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}
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func (c *Cache) GetOrDo(key string, do func() (string, error), ttl time.Duration) (string, error) {
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conf, err := c.load()
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if err != nil {
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slog.Debug("CACHE", "failed read", err)
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return c.Do(key, do, ttl)
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}
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val, ok := conf[key]
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if !ok {
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return c.Do(key, do, ttl)
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}
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if time.Now().After(val.Expire) {
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return c.Do(key, do, ttl)
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}
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return val.Value, nil
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}
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func (c *Cache) Do(key string, do func() (string, error), ttl time.Duration) (string, error) {
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if do == nil {
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return "", nil
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}
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res, err := do()
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if err != nil {
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return "", err
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}
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return c.Put(key, res, ttl)
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}
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func (c *Cache) Put(key string, value string, ttl time.Duration) (string, error) {
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conf, err := c.load()
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if err != nil {
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conf = map[string]CacheEntry{}
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}
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conf[key] = CacheEntry{
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Expire: time.Now().Add(ttl),
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Value: value,
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}
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slog.Debug("CACHE", "new item", fmt.Sprintf("%s: %s", key, value))
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err = c.save(conf)
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if err != nil {
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slog.Debug("CACHE", "failed to save", err)
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}
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return value, nil
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}
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func (c *Cache) Clear() error {
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return os.Remove(c.Root)
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}
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