gotosocial/internal/cache/slice.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package cache
import (
"codeberg.org/gruf/go-cache/v3/ttl"
"golang.org/x/exp/slices"
)
// SliceCache wraps a ttl.Cache to provide simple loader-callback
// functions for fetching + caching slices of objects (e.g. IDs).
type SliceCache[T any] struct {
*ttl.Cache[string, []T]
}
// Load will attempt to load an existing slice from the cache for the given key, else calling the provided load function and caching the result.
func (c *SliceCache[T]) Load(key string, load func() ([]T, error)) ([]T, error) {
// Look for follow IDs list in cache under this key.
data, ok := c.Get(key)
if !ok {
var err error
// Not cached, load!
data, err = load()
if err != nil {
return nil, err
}
// Store the data.
c.Set(key, data)
}
// Return data clone for safety.
return slices.Clone(data), nil
}
// LoadRange is functionally the same as .Load(), but will pass the result through provided reslice function before returning a cloned result.
func (c *SliceCache[T]) LoadRange(key string, load func() ([]T, error), reslice func([]T) []T) ([]T, error) {
// Look for follow IDs list in cache under this key.
data, ok := c.Get(key)
if !ok {
var err error
// Not cached, load!
data, err = load()
if err != nil {
return nil, err
}
// Store the data.
c.Set(key, data)
}
// Reslice to range.
slice := reslice(data)
// Return range clone for safety.
return slices.Clone(slice), nil
}