mirror of
https://github.com/c9s/bbgo.git
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59 lines
1.1 KiB
Go
59 lines
1.1 KiB
Go
package bbgo
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import (
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"encoding/json"
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"io/ioutil"
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"os"
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"path"
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"reflect"
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"github.com/pkg/errors"
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)
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type DataFetcher func() (interface{}, error)
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// WithCache let you use the cache with the given cache key, variable reference and your data fetcher,
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// The key must be an unique ID.
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// obj is the pointer of your local variable
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// fetcher is the closure that will fetch your remote data or some slow operation.
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func WithCache(key string, obj interface{}, fetcher DataFetcher) error {
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cacheDir := CacheDir()
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cacheFile := path.Join(cacheDir, key+".json")
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if _, err := os.Stat(cacheFile); os.IsNotExist(err) {
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data, err := fetcher()
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if err != nil {
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return err
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}
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out, err := json.Marshal(data)
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if err != nil {
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return err
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}
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if err := ioutil.WriteFile(cacheFile, out, 0666); err != nil {
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return err
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}
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rv := reflect.ValueOf(obj).Elem()
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if !rv.CanSet() {
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return errors.New("can not set cache object value")
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}
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rv.Set(reflect.ValueOf(data))
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} else {
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data, err := ioutil.ReadFile(cacheFile)
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if err != nil {
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return err
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}
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if err := json.Unmarshal(data, obj); err != nil {
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return err
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}
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}
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return nil
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}
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