GoToSocial/internal/timeline/indexeditems.go

120 lines
3.3 KiB
Go

// 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"
"fmt"
)
type indexedItems struct {
data *list.List
skipInsert SkipInsertFunction
}
type indexedItemsEntry struct {
itemID string
boostOfID string
accountID string
boostOfAccountID string
prepared Preparable
}
// WARNING: ONLY CALL THIS FUNCTION IF YOU ALREADY HAVE
// A LOCK ON THE TIMELINE CONTAINING THIS INDEXEDITEMS!
func (i *indexedItems) insertIndexed(ctx context.Context, newEntry *indexedItemsEntry) (bool, error) {
// Lazily init indexed items.
if i.data == nil {
i.data = &list.List{}
i.data.Init()
}
if i.data.Len() == 0 {
// We have no entries yet, meaning this is both the
// newest + oldest entry, so just put it in the front.
i.data.PushFront(newEntry)
return true, nil
}
var (
insertMark *list.Element
currentPosition int
)
// We need to iterate through the index to make sure we put
// this item in the appropriate place according to its id.
// We also need to make sure we're not inserting a duplicate
// item -- this can happen sometimes and it's sucky UX.
for e := i.data.Front(); e != nil; e = e.Next() {
currentPosition++
currentEntry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
// Check if we need to skip inserting this item based on
// the current item.
//
// For example, if the new item is a boost, and the current
// item is the original, we may not want to insert the boost
// if it would appear very shortly after the original.
if skip, err := i.skipInsert(
ctx,
newEntry.itemID,
newEntry.accountID,
newEntry.boostOfID,
newEntry.boostOfAccountID,
currentEntry.itemID,
currentEntry.accountID,
currentEntry.boostOfID,
currentEntry.boostOfAccountID,
currentPosition,
); err != nil {
return false, fmt.Errorf("insertIndexed: error calling skipInsert: %w", err)
} else if skip {
// We don't need to insert this at all,
// so we can safely bail.
return false, nil
}
if insertMark != nil {
// We already found our mark.
continue
}
if currentEntry.itemID > newEntry.itemID {
// We're still in items newer than
// the one we're trying to insert.
continue
}
// We found our spot!
insertMark = e
}
if insertMark == nil {
// We looked through the whole timeline and didn't find
// a mark, so the new item is the oldest item we've seen;
// insert it at the back.
i.data.PushBack(newEntry)
return true, nil
}
i.data.InsertBefore(newEntry, insertMark)
return true, nil
}