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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 headerfilter
import (
"fmt"
"net/http"
"sync/atomic"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/headerfilter"
)
// Cache provides a means of caching headerfilter.Filters in
// memory to reduce load on an underlying storage mechanism.
type Cache struct {
// current cached header filters slice.
ptr atomic.Pointer[headerfilter.Filters]
}
// RegularMatch performs .RegularMatch() on cached headerfilter.Filters, loading using callback if necessary.
func (c *Cache) RegularMatch(h http.Header, load func() ([]*gtsmodel.HeaderFilter, error)) (string, string, error) {
// Load ptr value.
ptr := c.ptr.Load()
if ptr == nil {
// Cache is not hydrated.
// Load filters from callback.
filters, err := loadFilters(load)
if err != nil {
return "", "", err
}
// Store the new
// header filters.
ptr = &filters
c.ptr.Store(ptr)
}
// Deref and perform match.
return ptr.RegularMatch(h)
}
// InverseMatch performs .InverseMatch() on cached headerfilter.Filters, loading using callback if necessary.
func (c *Cache) InverseMatch(h http.Header, load func() ([]*gtsmodel.HeaderFilter, error)) (string, string, error) {
// Load ptr value.
ptr := c.ptr.Load()
if ptr == nil {
// Cache is not hydrated.
// Load filters from callback.
filters, err := loadFilters(load)
if err != nil {
return "", "", err
}
// Store the new
// header filters.
ptr = &filters
c.ptr.Store(ptr)
}
// Deref and perform match.
return ptr.InverseMatch(h)
}
// Clear will drop the currently loaded filters,
// triggering a reload on next call to ._Match().
func (c *Cache) Clear() { c.ptr.Store(nil) }
// loadFilters will load filters from given load callback, creating and parsing raw filters.
func loadFilters(load func() ([]*gtsmodel.HeaderFilter, error)) (headerfilter.Filters, error) {
// Load filters from callback.
hdrFilters, err := load()
if err != nil {
return nil, fmt.Errorf("error reloading cache: %w", err)
}
// Allocate new header filter slice to store expressions.
filters := make(headerfilter.Filters, 0, len(hdrFilters))
// Add all raw expression to filter slice.
for _, filter := range hdrFilters {
if err := filters.Append(filter.Header, filter.Regex); err != nil {
return nil, fmt.Errorf("error appending exprs: %w", err)
}
}
return filters, nil
}
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