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multi_cache_session_adapter.go
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/
multi_cache_session_adapter.go
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// Copyright 2023 Tryvium Travels LTD
//
// 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 multicacheadapters
import (
"encoding/json"
"reflect"
"sync"
"time"
"github.com/hashicorp/go-multierror"
cacheadapters "github.com/tryvium-travels/golang-cache-adapters"
)
// MultiCacheSessionAdapter is a cache adapter which uses multiple
// sub-adapters, following a priority given by the index of
// the adapter in the inner array of adapters.
type MultiCacheSessionAdapter struct {
subAdapters []cacheadapters.CacheSessionAdapter // The array of sub-adapters
showWarnings bool
wg sync.WaitGroup
}
// NewSession creates a new multi cache session adapter from an
// index-based priority array of cache adapters (called sub-adapters) and a
// flag instructing to show warning (non-fatal) errors.
//
// index-based means that the array at the first position(s) will
// have more priority than those at latter positions.
func NewSession(adapters ...cacheadapters.CacheSessionAdapter) (*MultiCacheSessionAdapter, error) {
finalAdapters := make([]cacheadapters.CacheSessionAdapter, 0, len(adapters))
for _, adapter := range adapters {
if value := reflect.ValueOf(adapter); adapter != nil && value.IsValid() && !value.IsNil() {
finalAdapters = append(finalAdapters, adapter)
}
}
if len(finalAdapters) == 0 {
return nil, ErrInvalidSubAdapters
}
return &MultiCacheSessionAdapter{finalAdapters, false, sync.WaitGroup{}}, nil
}
// EnableWarning enable the return of warning errors.
//
// If the error is a warning, you can continue standard execution as
// The operations concluded successfully. You can then log the warning
// using your favourite tool (like sentry).
//
// Warning errors, if shown need different handling from traditional
// errors. Use the helper IsWarning(error err) to check for warnings.
//
// Example of handling of warnings:
//
// err := adapter.Get("key", &objRef)
// if (cacheadapters.IsWarning(err)) {
// // log the error, but use objRef safely
// } else if err != nil {
// // log the error and handle a failure
// // you cannot use objRef safely here
// }
// // else use objRef safely without any error
func (mcsa *MultiCacheSessionAdapter) EnableWarnings() {
mcsa.showWarnings = true
}
// DisableWarning disables the return of warning errors.
//
// If the error is a warning, you can continue standard execution as
// The operations concluded successfully. You can then log the warning
// using your favourite tool (like sentry).
//
// Warning errors, if shown need different handling from traditional
// errors. Use the helper IsWarning(error err) to check for warnings.
//
// Example of handling of warnings:
//
// err := adapter.Get("key", &objRef)
// if (errors.Is(cacheadapter.ErrWarning)) {
// // log the error, but use objRef safely
// } else if err != nil {
// // log the error and handle a failure
// // you cannot use objRef safely here
// }
// // else use objRef safely without any error
func (mcsa *MultiCacheSessionAdapter) DisableWarnings() {
mcsa.showWarnings = false
}
// Get obtains a value from the cache using a key, then tries to unmarshal
// it into the object reference passed as parameter.
func (mcsa *MultiCacheSessionAdapter) Get(key string, objectRef interface{}) error {
errs := make([]error, 0, len(mcsa.subAdapters))
for _, adapter := range mcsa.subAdapters {
var temp json.RawMessage
err := adapter.Get(key, &temp)
if err != nil {
errs = append(errs, err)
continue
}
err = json.Unmarshal(temp, &objectRef)
if err != nil {
errs = append(errs, err)
continue
}
break
}
return mcsa.errorOrNil(errs)
}
// Set sets a value represented by the object parameter into the cache, with the specified key.
func (mcsa *MultiCacheSessionAdapter) Set(key string, object interface{}, TTL *time.Duration) error {
errs := make([]error, 0, len(mcsa.subAdapters))
for _, adapter := range mcsa.subAdapters {
err := adapter.Set(key, object, TTL)
if err != nil {
errs = append(errs, err)
}
}
return mcsa.errorOrNil(errs)
}
// SetTTL marks the specified key new expiration, deletes it via using
// cacheadapters.TTLExpired or negative duration.
func (mcsa *MultiCacheSessionAdapter) SetTTL(key string, newTTL time.Duration) error {
errs := make([]error, 0, len(mcsa.subAdapters))
for _, adapter := range mcsa.subAdapters {
err := adapter.SetTTL(key, newTTL)
if err != nil {
errs = append(errs, err)
}
}
return mcsa.errorOrNil(errs)
}
// Delete deletes a key from the cache.
func (mcsa *MultiCacheSessionAdapter) Delete(key string) error {
errs := make([]error, 0, len(mcsa.subAdapters))
for _, adapter := range mcsa.subAdapters {
err := adapter.Delete(key)
if err != nil {
errs = append(errs, err)
}
}
return mcsa.errorOrNil(errs)
}
// Close closes the Cache Sessions.
func (mcsa *MultiCacheSessionAdapter) Close() error {
errs := make([]error, 0, len(mcsa.subAdapters))
for _, adapter := range mcsa.subAdapters {
err := adapter.Close()
if err != nil {
errs = append(errs, err)
}
}
return mcsa.errorOrNil(errs)
}
// errorOrNil parses the accumulated errors into one final
// error, or returns nil if there are none.
func (mcsa *MultiCacheSessionAdapter) errorOrNil(errs []error) error {
err := multierror.Append(nil, errs...)
if len(errs) == len(mcsa.subAdapters) {
return err
}
if mcsa.showWarnings {
return multierror.Append(ErrMultiCacheWarning, err)
}
return nil
}