gotosocial/internal/timeline/indexeditems.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"
"context"
"errors"
)
type indexedItems struct {
data *list.List
skipInsert SkipInsertFunction
}
type indexedItemsEntry struct {
itemID string
boostOfID string
accountID string
boostOfAccountID string
}
func (i *indexedItems) insertIndexed(ctx context.Context, newEntry *indexedItemsEntry) (bool, error) {
if i.data == nil {
i.data = &list.List{}
}
// if we have no entries yet, this is both the newest and oldest entry, so just put it in the front
if i.data.Len() == 0 {
i.data.PushFront(newEntry)
return true, nil
}
var insertMark *list.Element
var position int
// We need to iterate through the index to make sure we put this item in the appropriate place according to when it was created.
// We also need to make sure we're not inserting a duplicate item -- this can happen sometimes and it's not nice UX (*shudder*).
for e := i.data.Front(); e != nil; e = e.Next() {
position++
entry, ok := e.Value.(*indexedItemsEntry)
if !ok {
return false, errors.New("insertIndexed: could not parse e as an indexedItemsEntry")
}
skip, err := i.skipInsert(ctx, newEntry.itemID, newEntry.accountID, newEntry.boostOfID, newEntry.boostOfAccountID, entry.itemID, entry.accountID, entry.boostOfID, entry.boostOfAccountID, position)
if err != nil {
return false, err
}
if skip {
return false, nil
}
// if the item to index is newer than e, insert it before e in the list
if insertMark == nil {
if newEntry.itemID > entry.itemID {
insertMark = e
}
}
}
if insertMark != nil {
i.data.InsertBefore(newEntry, insertMark)
return true, nil
}
// if we reach this point it's the oldest item we've seen so put it at the back
i.data.PushBack(newEntry)
return true, nil
}