GoToSocial/internal/timeline/prune.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 timeline
import (
"container/list"
)
func (t *timeline) Prune(desiredPreparedItemsLength int, desiredIndexedItemsLength int) int {
t.Lock()
defer t.Unlock()
l := t.items.data
if l == nil {
// Nothing to prune.
return 0
}
var (
position int
totalPruned int
toRemove *[]*list.Element
)
// Only initialize toRemove if we know we're
// going to need it, otherwise skiperino.
if toRemoveLen := t.items.data.Len() - desiredIndexedItemsLength; toRemoveLen > 0 {
toRemove = func() *[]*list.Element { tr := make([]*list.Element, 0, toRemoveLen); return &tr }()
}
// Work from the front of the list until we get
// to the point where we need to start pruning.
for e := l.Front(); e != nil; e = e.Next() {
position++
if position <= desiredPreparedItemsLength {
// We're still within our allotted
// prepped length, nothing to do yet.
continue
}
// We need to *at least* unprepare this entry.
// If we're beyond our indexed length already,
// we can just remove the item completely.
if position > desiredIndexedItemsLength {
*toRemove = append(*toRemove, e)
totalPruned++
continue
}
entry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
if entry.prepared == nil {
// It's already unprepared (mood).
continue
}
entry.prepared = nil // <- eat this up please garbage collector nom nom nom
totalPruned++
}
if toRemove != nil {
for _, e := range *toRemove {
l.Remove(e)
}
}
return totalPruned
}