[feature] Prune timelines once per hour to plug memory leak (#1117)

* export highest/lowest ULIDs as proper const

* add stop + start to timeline manager, other small fixes

* unexport unused interface funcs + tidy up

* add LastGot func

* add timeline Prune function

* test prune

* update lastGot

internal/db/bundb/notification_test.go

@@ -91,7 +91,7 @@ func (suite *NotificationTestSuite) TestGetNotificationsWithSpam() {
 	suite.spamNotifs()
 	testAccount := suite.testAccounts["local_account_1"]
 	before := time.Now()
-	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", "00000000000000000000000000")
+	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, id.Highest, id.Lowest)
 	suite.NoError(err)
 	timeTaken := time.Since(before)
 	fmt.Printf("\n\n\n withSpam: got %d notifications in %s\n\n\n", len(notifications), timeTaken)
@@ -105,7 +105,7 @@ func (suite *NotificationTestSuite) TestGetNotificationsWithSpam() {
 func (suite *NotificationTestSuite) TestGetNotificationsWithoutSpam() {
 	testAccount := suite.testAccounts["local_account_1"]
 	before := time.Now()
-	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", "00000000000000000000000000")
+	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, id.Highest, id.Lowest)
 	suite.NoError(err)
 	timeTaken := time.Since(before)
 	fmt.Printf("\n\n\n withoutSpam: got %d notifications in %s\n\n\n", len(notifications), timeTaken)
@@ -122,7 +122,7 @@ func (suite *NotificationTestSuite) TestClearNotificationsWithSpam() {
 	err := suite.db.ClearNotifications(context.Background(), testAccount.ID)
 	suite.NoError(err)
 
-	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", "00000000000000000000000000")
+	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, id.Highest, id.Lowest)
 	suite.NoError(err)
 	suite.NotNil(notifications)
 	suite.Empty(notifications)
@@ -134,7 +134,7 @@ func (suite *NotificationTestSuite) TestClearNotificationsWithTwoAccounts() {
 	err := suite.db.ClearNotifications(context.Background(), testAccount.ID)
 	suite.NoError(err)
 
-	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", "00000000000000000000000000")
+	notifications, err := suite.db.GetNotifications(context.Background(), testAccount.ID, []string{}, 20, id.Highest, id.Lowest)
 	suite.NoError(err)
 	suite.NotNil(notifications)
 	suite.Empty(notifications)

internal/id/ulid.go

@@ -1,3 +1,21 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   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 id
 
 import (
@@ -8,7 +26,11 @@
 	"github.com/oklog/ulid"
 )
 
-const randomRange = 631152381 // ~20 years in seconds
+const (
+	Highest     = "ZZZZZZZZZZZZZZZZZZZZZZZZZZ" // Highest is the highest possible ULID
+	Lowest      = "00000000000000000000000000" // Lowest is the lowest possible ULID
+	randomRange = 631152381                    // ~20 years in seconds
+)
 
 // ULID represents a Universally Unique Lexicographically Sortable Identifier of 26 characters. See https://github.com/oklog/ulid
 type ULID string

internal/processing/processor.go

@@ -351,6 +351,11 @@ func (p *processor) Start() error {
 		return err
 	}
 
+	// Start status timelines
+	if err := p.statusTimelines.Start(); err != nil {
+		return err
+	}
+
 	return nil
 }
 
@@ -359,8 +364,14 @@ func (p *processor) Stop() error {
 	if err := p.clientWorker.Stop(); err != nil {
 		return err
 	}
+
 	if err := p.fedWorker.Stop(); err != nil {
 		return err
 	}
+
+	if err := p.statusTimelines.Stop(); err != nil {
+		return err
+	}
+
 	return nil
 }

internal/timeline/get.go

@@ -23,6 +23,7 @@
 	"context"
 	"errors"
 	"fmt"
+	"time"
 
 	"codeberg.org/gruf/go-kv"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
@@ -30,16 +31,27 @@
 
 const retries = 5
 
+func (t *timeline) LastGot() time.Time {
+	t.Lock()
+	defer t.Unlock()
+	return t.lastGot
+}
+
 func (t *timeline) Get(ctx context.Context, amount int, maxID string, sinceID string, minID string, prepareNext bool) ([]Preparable, error) {
 	l := log.WithFields(kv.Fields{
-
 		{"accountID", t.accountID},
 		{"amount", amount},
 		{"maxID", maxID},
 		{"sinceID", sinceID},
 		{"minID", minID},
 	}...)
-	l.Debug("entering get")
+	l.Debug("entering get and updating t.lastGot")
+
+	// regardless of what happens below, update the
+	// last time Get was called for this timeline
+	t.Lock()
+	t.lastGot = time.Now()
+	t.Unlock()
 
 	var items []Preparable
 	var err error
@@ -47,7 +59,7 @@ func (t *timeline) Get(ctx context.Context, amount int, maxID string, sinceID st
 	// no params are defined to just fetch from the top
 	// this is equivalent to a user asking for the top x items from their timeline
 	if maxID == "" && sinceID == "" && minID == "" {
-		items, err = t.GetXFromTop(ctx, amount)
+		items, err = t.getXFromTop(ctx, amount)
 		// aysnchronously prepare the next predicted query so it's ready when the user asks for it
 		if len(items) != 0 {
 			nextMaxID := items[len(items)-1].GetID()
@@ -67,7 +79,7 @@ func (t *timeline) Get(ctx context.Context, amount int, maxID string, sinceID st
 	// this is equivalent to a user asking for the next x items from their timeline, starting from maxID
 	if maxID != "" && sinceID == "" {
 		attempts := 0
-		items, err = t.GetXBehindID(ctx, amount, maxID, &attempts)
+		items, err = t.getXBehindID(ctx, amount, maxID, &attempts)
 		// aysnchronously prepare the next predicted query so it's ready when the user asks for it
 		if len(items) != 0 {
 			nextMaxID := items[len(items)-1].GetID()
@@ -86,25 +98,26 @@ func (t *timeline) Get(ctx context.Context, amount int, maxID string, sinceID st
 	// maxID is defined and sinceID || minID are as well, so take a slice between them
 	// this is equivalent to a user asking for items older than x but newer than y
 	if maxID != "" && sinceID != "" {
-		items, err = t.GetXBetweenID(ctx, amount, maxID, minID)
+		items, err = t.getXBetweenID(ctx, amount, maxID, minID)
 	}
 	if maxID != "" && minID != "" {
-		items, err = t.GetXBetweenID(ctx, amount, maxID, minID)
+		items, err = t.getXBetweenID(ctx, amount, maxID, minID)
 	}
 
 	// maxID isn't defined, but sinceID || minID are, so take x before
 	// this is equivalent to a user asking for items newer than x (eg., refreshing the top of their timeline)
 	if maxID == "" && sinceID != "" {
-		items, err = t.GetXBeforeID(ctx, amount, sinceID, true)
+		items, err = t.getXBeforeID(ctx, amount, sinceID, true)
 	}
 	if maxID == "" && minID != "" {
-		items, err = t.GetXBeforeID(ctx, amount, minID, true)
+		items, err = t.getXBeforeID(ctx, amount, minID, true)
 	}
 
 	return items, err
 }
 
-func (t *timeline) GetXFromTop(ctx context.Context, amount int) ([]Preparable, error) {
+// getXFromTop returns x amount of items from the top of the timeline, from newest to oldest.
+func (t *timeline) getXFromTop(ctx context.Context, amount int) ([]Preparable, error) {
 	// make a slice of preparedItems with the length we need to return
 	preparedItems := make([]Preparable, 0, amount)
 
@@ -124,7 +137,7 @@ func (t *timeline) GetXFromTop(ctx context.Context, amount int) ([]Preparable, e
 	for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
 		entry, ok := e.Value.(*preparedItemsEntry)
 		if !ok {
-			return nil, errors.New("GetXFromTop: could not parse e as a preparedItemsEntry")
+			return nil, errors.New("getXFromTop: could not parse e as a preparedItemsEntry")
 		}
 		preparedItems = append(preparedItems, entry.prepared)
 		served++
@@ -136,9 +149,12 @@ func (t *timeline) GetXFromTop(ctx context.Context, amount int) ([]Preparable, e
 	return preparedItems, nil
 }
 
-func (t *timeline) GetXBehindID(ctx context.Context, amount int, behindID string, attempts *int) ([]Preparable, error) {
+// getXBehindID returns x amount of items from the given id onwards, from newest to oldest.
+// This will NOT include the item with the given ID.
+//
+// This corresponds to an api call to /timelines/home?max_id=WHATEVER
+func (t *timeline) getXBehindID(ctx context.Context, amount int, behindID string, attempts *int) ([]Preparable, error) {
 	l := log.WithFields(kv.Fields{
-
 		{"amount", amount},
 		{"behindID", behindID},
 		{"attempts", attempts},
@@ -164,7 +180,7 @@ func (t *timeline) GetXBehindID(ctx context.Context, amount int, behindID string
 		position++
 		entry, ok := e.Value.(*preparedItemsEntry)
 		if !ok {
-			return nil, errors.New("GetXBehindID: could not parse e as a preparedPostsEntry")
+			return nil, errors.New("getXBehindID: could not parse e as a preparedPostsEntry")
 		}
 
 		if entry.itemID <= behindID {
@@ -177,10 +193,10 @@ func (t *timeline) GetXBehindID(ctx context.Context, amount int, behindID string
 	// we didn't find it, so we need to make sure it's indexed and prepared and then try again
 	// this can happen when a user asks for really old items
 	if behindIDMark == nil {
-		if err := t.PrepareBehind(ctx, behindID, amount); err != nil {
+		if err := t.prepareBehind(ctx, behindID, amount); err != nil {
-			return nil, fmt.Errorf("GetXBehindID: error preparing behind and including ID %s", behindID)
+			return nil, fmt.Errorf("getXBehindID: error preparing behind and including ID %s", behindID)
 		}
-		oldestID, err := t.OldestPreparedItemID(ctx)
+		oldestID, err := t.oldestPreparedItemID(ctx)
 		if err != nil {
 			return nil, err
 		}
@@ -196,13 +212,13 @@ func (t *timeline) GetXBehindID(ctx context.Context, amount int, behindID string
 			l.Tracef("exceeded retries looking for behindID %s", behindID)
 			return items, nil
 		}
-		l.Trace("trying GetXBehindID again")
+		l.Trace("trying getXBehindID again")
-		return t.GetXBehindID(ctx, amount, behindID, attempts)
+		return t.getXBehindID(ctx, amount, behindID, attempts)
 	}
 
 	// make sure we have enough items prepared behind it to return what we're being asked for
 	if t.preparedItems.data.Len() < amount+position {
-		if err := t.PrepareBehind(ctx, behindID, amount); err != nil {
+		if err := t.prepareBehind(ctx, behindID, amount); err != nil {
 			return nil, err
 		}
 	}
@@ -213,7 +229,7 @@ func (t *timeline) GetXBehindID(ctx context.Context, amount int, behindID string
 	for e := behindIDMark.Next(); e != nil; e = e.Next() {
 		entry, ok := e.Value.(*preparedItemsEntry)
 		if !ok {
-			return nil, errors.New("GetXBehindID: could not parse e as a preparedPostsEntry")
+			return nil, errors.New("getXBehindID: could not parse e as a preparedPostsEntry")
 		}
 
 		// serve up to the amount requested
@@ -227,7 +243,11 @@ func (t *timeline) GetXBehindID(ctx context.Context, amount int, behindID string
 	return items, nil
 }
 
-func (t *timeline) GetXBeforeID(ctx context.Context, amount int, beforeID string, startFromTop bool) ([]Preparable, error) {
+// getXBeforeID returns x amount of items up to the given id, from newest to oldest.
+// This will NOT include the item with the given ID.
+//
+// This corresponds to an api call to /timelines/home?since_id=WHATEVER
+func (t *timeline) getXBeforeID(ctx context.Context, amount int, beforeID string, startFromTop bool) ([]Preparable, error) {
 	// make a slice of items with the length we need to return
 	items := make([]Preparable, 0, amount)
 
@@ -241,7 +261,7 @@ func (t *timeline) GetXBeforeID(ctx context.Context, amount int, beforeID string
 	for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
 		entry, ok := e.Value.(*preparedItemsEntry)
 		if !ok {
-			return nil, errors.New("GetXBeforeID: could not parse e as a preparedPostsEntry")
+			return nil, errors.New("getXBeforeID: could not parse e as a preparedPostsEntry")
 		}
 
 		if entry.itemID >= beforeID {
@@ -263,7 +283,7 @@ func (t *timeline) GetXBeforeID(ctx context.Context, amount int, beforeID string
 		for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
 			entry, ok := e.Value.(*preparedItemsEntry)
 			if !ok {
-				return nil, errors.New("GetXBeforeID: could not parse e as a preparedPostsEntry")
+				return nil, errors.New("getXBeforeID: could not parse e as a preparedPostsEntry")
 			}
 
 			if entry.itemID == beforeID {
@@ -283,7 +303,7 @@ func (t *timeline) GetXBeforeID(ctx context.Context, amount int, beforeID string
 		for e := beforeIDMark.Prev(); e != nil; e = e.Prev() {
 			entry, ok := e.Value.(*preparedItemsEntry)
 			if !ok {
-				return nil, errors.New("GetXBeforeID: could not parse e as a preparedPostsEntry")
+				return nil, errors.New("getXBeforeID: could not parse e as a preparedPostsEntry")
 			}
 
 			// serve up to the amount requested
@@ -298,7 +318,11 @@ func (t *timeline) GetXBeforeID(ctx context.Context, amount int, beforeID string
 	return items, nil
 }
 
-func (t *timeline) GetXBetweenID(ctx context.Context, amount int, behindID string, beforeID string) ([]Preparable, error) {
+// getXBetweenID returns x amount of items from the given maxID, up to the given id, from newest to oldest.
+// This will NOT include the item with the given IDs.
+//
+// This corresponds to an api call to /timelines/home?since_id=WHATEVER&max_id=WHATEVER_ELSE
+func (t *timeline) getXBetweenID(ctx context.Context, amount int, behindID string, beforeID string) ([]Preparable, error) {
 	// make a slice of items with the length we need to return
 	items := make([]Preparable, 0, amount)
 
@@ -314,7 +338,7 @@ func (t *timeline) GetXBetweenID(ctx context.Context, amount int, behindID strin
 		position++
 		entry, ok := e.Value.(*preparedItemsEntry)
 		if !ok {
-			return nil, errors.New("GetXBetweenID: could not parse e as a preparedPostsEntry")
+			return nil, errors.New("getXBetweenID: could not parse e as a preparedPostsEntry")
 		}
 
 		if entry.itemID == behindID {
@@ -325,12 +349,12 @@ func (t *timeline) GetXBetweenID(ctx context.Context, amount int, behindID strin
 
 	// we didn't find it
 	if behindIDMark == nil {
-		return nil, fmt.Errorf("GetXBetweenID: couldn't find item with ID %s", behindID)
+		return nil, fmt.Errorf("getXBetweenID: couldn't find item with ID %s", behindID)
 	}
 
 	// make sure we have enough items prepared behind it to return what we're being asked for
 	if t.preparedItems.data.Len() < amount+position {
-		if err := t.PrepareBehind(ctx, behindID, amount); err != nil {
+		if err := t.prepareBehind(ctx, behindID, amount); err != nil {
 			return nil, err
 		}
 	}
@@ -341,7 +365,7 @@ func (t *timeline) GetXBetweenID(ctx context.Context, amount int, behindID strin
 	for e := behindIDMark.Next(); e != nil; e = e.Next() {
 		entry, ok := e.Value.(*preparedItemsEntry)
 		if !ok {
-			return nil, errors.New("GetXBetweenID: could not parse e as a preparedPostsEntry")
+			return nil, errors.New("getXBetweenID: could not parse e as a preparedPostsEntry")
 		}
 
 		if entry.itemID == beforeID {

internal/timeline/get_test.go

@@ -89,6 +89,9 @@ func (suite *GetTestSuite) TearDownTest() {
 }
 
 func (suite *GetTestSuite) TestGetDefault() {
+	// lastGot should be zero
+	suite.Zero(suite.timeline.LastGot())
+
 	// get 10 20 the top and don't prepare the next query
 	statuses, err := suite.timeline.Get(context.Background(), 20, "", "", "", false)
 	if err != nil {
@@ -108,6 +111,9 @@ func (suite *GetTestSuite) TestGetDefault() {
 			highest = s.GetID()
 		}
 	}
+
+	// lastGot should be up to date
+	suite.WithinDuration(time.Now(), suite.timeline.LastGot(), 1*time.Second)
 }
 
 func (suite *GetTestSuite) TestGetDefaultPrepareNext() {
@@ -297,165 +303,6 @@ func (suite *GetTestSuite) TestGetBetweenIDPrepareNext() {
 	time.Sleep(1 * time.Second)
 }
 
-func (suite *GetTestSuite) TestGetXFromTop() {
-	// get 5 from the top
-	statuses, err := suite.timeline.GetXFromTop(context.Background(), 5)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	suite.Len(statuses, 5)
-
-	// statuses should be sorted highest to lowest ID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-	}
-}
-
-func (suite *GetTestSuite) TestGetXBehindID() {
-	// get 3 behind the 'middle' id
-	var attempts *int
-	a := 0
-	attempts = &a
-	statuses, err := suite.timeline.GetXBehindID(context.Background(), 3, "01F8MHBQCBTDKN6X5VHGMMN4MA", attempts)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	suite.Len(statuses, 3)
-
-	// statuses should be sorted highest to lowest ID
-	// all status IDs should be less than the behindID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-		suite.Less(s.GetID(), "01F8MHBQCBTDKN6X5VHGMMN4MA")
-	}
-}
-
-func (suite *GetTestSuite) TestGetXBehindID0() {
-	// try to get behind 0, the lowest possible ID
-	var attempts *int
-	a := 0
-	attempts = &a
-	statuses, err := suite.timeline.GetXBehindID(context.Background(), 3, "0", attempts)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	// there's nothing beyond it so len should be 0
-	suite.Len(statuses, 0)
-}
-
-func (suite *GetTestSuite) TestGetXBehindNonexistentReasonableID() {
-	// try to get behind an id that doesn't exist, but is close to one that does so we should still get statuses back
-	var attempts *int
-	a := 0
-	attempts = &a
-	statuses, err := suite.timeline.GetXBehindID(context.Background(), 3, "01F8MHBQCBTDKN6X5VHGMMN4MB", attempts) // change the last A to a B
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-	suite.Len(statuses, 3)
-
-	// statuses should be sorted highest to lowest ID
-	// all status IDs should be less than the behindID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-		suite.Less(s.GetID(), "01F8MHBCN8120SYH7D5S050MGK")
-	}
-}
-
-func (suite *GetTestSuite) TestGetXBehindVeryHighID() {
-	// try to get behind an id that doesn't exist, and is higher than any other ID we could possibly have
-	var attempts *int
-	a := 0
-	attempts = &a
-	statuses, err := suite.timeline.GetXBehindID(context.Background(), 7, "9998MHBQCBTDKN6X5VHGMMN4MA", attempts)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	// we should get all 7 statuses we asked for because they all have lower IDs than the very high ID given in the query
-	suite.Len(statuses, 7)
-
-	// statuses should be sorted highest to lowest ID
-	// all status IDs should be less than the behindID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-		suite.Less(s.GetID(), "9998MHBQCBTDKN6X5VHGMMN4MA")
-	}
-}
-
-func (suite *GetTestSuite) TestGetXBeforeID() {
-	// get 3 before the 'middle' id
-	statuses, err := suite.timeline.GetXBeforeID(context.Background(), 3, "01F8MHBQCBTDKN6X5VHGMMN4MA", true)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	suite.Len(statuses, 3)
-
-	// statuses should be sorted highest to lowest ID
-	// all status IDs should be greater than the beforeID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-		suite.Greater(s.GetID(), "01F8MHBQCBTDKN6X5VHGMMN4MA")
-	}
-}
-
-func (suite *GetTestSuite) TestGetXBeforeIDNoStartFromTop() {
-	// get 3 before the 'middle' id
-	statuses, err := suite.timeline.GetXBeforeID(context.Background(), 3, "01F8MHBQCBTDKN6X5VHGMMN4MA", false)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	suite.Len(statuses, 3)
-
-	// statuses should be sorted lowest to highest ID
-	// all status IDs should be greater than the beforeID
-	var lowest string
-	for i, s := range statuses {
-		if i == 0 {
-			lowest = s.GetID()
-		} else {
-			suite.Greater(s.GetID(), lowest)
-			lowest = s.GetID()
-		}
-		suite.Greater(s.GetID(), "01F8MHBQCBTDKN6X5VHGMMN4MA")
-	}
-}
-
 func TestGetTestSuite(t *testing.T) {
 	suite.Run(t, new(GetTestSuite))
 }

internal/timeline/index.go

@@ -28,79 +28,80 @@
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
-func (t *timeline) IndexBefore(ctx context.Context, itemID string, amount int) error {
+func (t *timeline) ItemIndexLength(ctx context.Context) int {
-	l := log.WithFields(kv.Fields{
+	if t.indexedItems == nil || t.indexedItems.data == nil {
-
+		return 0
-		{"amount", amount},
-	}...)
-
-	// lazily initialize index if it hasn't been done already
-	if t.itemIndex.data == nil {
-		t.itemIndex.data = &list.List{}
-		t.itemIndex.data.Init()
 	}
-
+	return t.indexedItems.data.Len()
-	toIndex := []Timelineable{}
-	offsetID := itemID
-
-	l.Trace("entering grabloop")
-grabloop:
-	for i := 0; len(toIndex) < amount && i < 5; i++ { // try the grabloop 5 times only
-		// first grab items using the caller-provided grab function
-		l.Trace("grabbing...")
-		items, stop, err := t.grabFunction(ctx, t.accountID, "", "", offsetID, amount)
-		if err != nil {
-			return err
-		}
-		if stop {
-			break grabloop
-		}
-
-		l.Trace("filtering...")
-		// now filter each item using the caller-provided filter function
-		for _, item := range items {
-			shouldIndex, err := t.filterFunction(ctx, t.accountID, item)
-			if err != nil {
-				return err
-			}
-			if shouldIndex {
-				toIndex = append(toIndex, item)
-			}
-			offsetID = item.GetID()
-		}
-	}
-	l.Trace("left grabloop")
-
-	// index the items we got
-	for _, s := range toIndex {
-		if _, err := t.IndexOne(ctx, s.GetID(), s.GetBoostOfID(), s.GetAccountID(), s.GetBoostOfAccountID()); err != nil {
-			return fmt.Errorf("IndexBehind: error indexing item with id %s: %s", s.GetID(), err)
-		}
-	}
-
-	return nil
 }
 
-func (t *timeline) IndexBehind(ctx context.Context, itemID string, amount int) error {
+// func (t *timeline) indexBefore(ctx context.Context, itemID string, amount int) error {
-	l := log.WithFields(kv.Fields{
+// 	l := log.WithFields(kv.Fields{{"amount", amount}}...)
 
-		{"amount", amount},
+// 	// lazily initialize index if it hasn't been done already
-	}...)
+// 	if t.indexedItems.data == nil {
+// 		t.indexedItems.data = &list.List{}
+// 		t.indexedItems.data.Init()
+// 	}
+
+// 	toIndex := []Timelineable{}
+// 	offsetID := itemID
+
+// 	l.Trace("entering grabloop")
+// grabloop:
+// 	for i := 0; len(toIndex) < amount && i < 5; i++ { // try the grabloop 5 times only
+// 		// first grab items using the caller-provided grab function
+// 		l.Trace("grabbing...")
+// 		items, stop, err := t.grabFunction(ctx, t.accountID, "", "", offsetID, amount)
+// 		if err != nil {
+// 			return err
+// 		}
+// 		if stop {
+// 			break grabloop
+// 		}
+
+// 		l.Trace("filtering...")
+// 		// now filter each item using the caller-provided filter function
+// 		for _, item := range items {
+// 			shouldIndex, err := t.filterFunction(ctx, t.accountID, item)
+// 			if err != nil {
+// 				return err
+// 			}
+// 			if shouldIndex {
+// 				toIndex = append(toIndex, item)
+// 			}
+// 			offsetID = item.GetID()
+// 		}
+// 	}
+// 	l.Trace("left grabloop")
+
+// 	// index the items we got
+// 	for _, s := range toIndex {
+// 		if _, err := t.IndexOne(ctx, s.GetID(), s.GetBoostOfID(), s.GetAccountID(), s.GetBoostOfAccountID()); err != nil {
+// 			return fmt.Errorf("indexBefore: error indexing item with id %s: %s", s.GetID(), err)
+// 		}
+// 	}
+
+// 	return nil
+// }
+
+func (t *timeline) indexBehind(ctx context.Context, itemID string, amount int) error {
+	l := log.WithFields(kv.Fields{{"amount", amount}}...)
 
 	// lazily initialize index if it hasn't been done already
-	if t.itemIndex.data == nil {
+	if t.indexedItems.data == nil {
-		t.itemIndex.data = &list.List{}
+		t.indexedItems.data = &list.List{}
-		t.itemIndex.data.Init()
+		t.indexedItems.data.Init()
 	}
 
 	// If we're already indexedBehind given itemID by the required amount, we can return nil.
 	// First find position of itemID (or as near as possible).
 	var position int
 positionLoop:
-	for e := t.itemIndex.data.Front(); e != nil; e = e.Next() {
+	for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-		entry, ok := e.Value.(*itemIndexEntry)
+		entry, ok := e.Value.(*indexedItemsEntry)
 		if !ok {
-			return errors.New("IndexBehind: could not parse e as an itemIndexEntry")
+			return errors.New("indexBehind: could not parse e as an itemIndexEntry")
 		}
 
 		if entry.itemID <= itemID {
@@ -111,7 +112,7 @@ func (t *timeline) IndexBehind(ctx context.Context, itemID string, amount int) e
 	}
 
 	// now check if the length of indexed items exceeds the amount of items required (position of itemID, plus amount of posts requested after that)
-	if t.itemIndex.data.Len() > position+amount {
+	if t.indexedItems.data.Len() > position+amount {
 		// we have enough indexed behind already to satisfy amount, so don't need to make db calls
 		l.Trace("returning nil since we already have enough items indexed")
 		return nil
@@ -151,7 +152,7 @@ func (t *timeline) IndexBehind(ctx context.Context, itemID string, amount int) e
 	// index the items we got
 	for _, s := range toIndex {
 		if _, err := t.IndexOne(ctx, s.GetID(), s.GetBoostOfID(), s.GetAccountID(), s.GetBoostOfAccountID()); err != nil {
-			return fmt.Errorf("IndexBehind: error indexing item with id %s: %s", s.GetID(), err)
+			return fmt.Errorf("indexBehind: error indexing item with id %s: %s", s.GetID(), err)
 		}
 	}
 
@@ -162,28 +163,28 @@ func (t *timeline) IndexOne(ctx context.Context, itemID string, boostOfID string
 	t.Lock()
 	defer t.Unlock()
 
-	postIndexEntry := &itemIndexEntry{
+	postIndexEntry := &indexedItemsEntry{
 		itemID:           itemID,
 		boostOfID:        boostOfID,
 		accountID:        accountID,
 		boostOfAccountID: boostOfAccountID,
 	}
 
-	return t.itemIndex.insertIndexed(ctx, postIndexEntry)
+	return t.indexedItems.insertIndexed(ctx, postIndexEntry)
 }
 
 func (t *timeline) IndexAndPrepareOne(ctx context.Context, statusID string, boostOfID string, accountID string, boostOfAccountID string) (bool, error) {
 	t.Lock()
 	defer t.Unlock()
 
-	postIndexEntry := &itemIndexEntry{
+	postIndexEntry := &indexedItemsEntry{
 		itemID:           statusID,
 		boostOfID:        boostOfID,
 		accountID:        accountID,
 		boostOfAccountID: boostOfAccountID,
 	}
 
-	inserted, err := t.itemIndex.insertIndexed(ctx, postIndexEntry)
+	inserted, err := t.indexedItems.insertIndexed(ctx, postIndexEntry)
 	if err != nil {
 		return inserted, fmt.Errorf("IndexAndPrepareOne: error inserting indexed: %s", err)
 	}
@@ -199,13 +200,13 @@ func (t *timeline) IndexAndPrepareOne(ctx context.Context, statusID string, boos
 
 func (t *timeline) OldestIndexedItemID(ctx context.Context) (string, error) {
 	var id string
-	if t.itemIndex == nil || t.itemIndex.data == nil || t.itemIndex.data.Back() == nil {
+	if t.indexedItems == nil || t.indexedItems.data == nil || t.indexedItems.data.Back() == nil {
 		// return an empty string if postindex hasn't been initialized yet
 		return id, nil
 	}
 
-	e := t.itemIndex.data.Back()
+	e := t.indexedItems.data.Back()
-	entry, ok := e.Value.(*itemIndexEntry)
+	entry, ok := e.Value.(*indexedItemsEntry)
 	if !ok {
 		return id, errors.New("OldestIndexedItemID: could not parse e as itemIndexEntry")
 	}
@@ -214,13 +215,13 @@ func (t *timeline) OldestIndexedItemID(ctx context.Context) (string, error) {
 
 func (t *timeline) NewestIndexedItemID(ctx context.Context) (string, error) {
 	var id string
-	if t.itemIndex == nil || t.itemIndex.data == nil || t.itemIndex.data.Front() == nil {
+	if t.indexedItems == nil || t.indexedItems.data == nil || t.indexedItems.data.Front() == nil {
 		// return an empty string if postindex hasn't been initialized yet
 		return id, nil
 	}
 
-	e := t.itemIndex.data.Front()
+	e := t.indexedItems.data.Front()
-	entry, ok := e.Value.(*itemIndexEntry)
+	entry, ok := e.Value.(*indexedItemsEntry)
 	if !ok {
 		return id, errors.New("NewestIndexedItemID: could not parse e as itemIndexEntry")
 	}

internal/timeline/index_test.go

@@ -69,63 +69,6 @@ func (suite *IndexTestSuite) TearDownTest() {
 	testrig.StandardDBTeardown(suite.db)
 }
 
-func (suite *IndexTestSuite) TestIndexBeforeLowID() {
-	// index 10 before the lowest status ID possible
-	err := suite.timeline.IndexBefore(context.Background(), "00000000000000000000000000", 10)
-	suite.NoError(err)
-
-	postID, err := suite.timeline.OldestIndexedItemID(context.Background())
-	suite.NoError(err)
-	suite.Equal("01F8MHBQCBTDKN6X5VHGMMN4MA", postID)
-
-	indexLength := suite.timeline.ItemIndexLength(context.Background())
-	suite.Equal(10, indexLength)
-}
-
-func (suite *IndexTestSuite) TestIndexBeforeHighID() {
-	// index 10 before the highest status ID possible
-	err := suite.timeline.IndexBefore(context.Background(), "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", 10)
-	suite.NoError(err)
-
-	// the oldest indexed post should be empty
-	postID, err := suite.timeline.OldestIndexedItemID(context.Background())
-	suite.NoError(err)
-	suite.Empty(postID)
-
-	// indexLength should be 0
-	indexLength := suite.timeline.ItemIndexLength(context.Background())
-	suite.Equal(0, indexLength)
-}
-
-func (suite *IndexTestSuite) TestIndexBehindHighID() {
-	// index 10 behind the highest status ID possible
-	err := suite.timeline.IndexBehind(context.Background(), "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", 10)
-	suite.NoError(err)
-
-	// the newest indexed post should be the highest one we have in our testrig
-	postID, err := suite.timeline.NewestIndexedItemID(context.Background())
-	suite.NoError(err)
-	suite.Equal("01G36SF3V6Y6V5BF9P4R7PQG7G", postID)
-
-	indexLength := suite.timeline.ItemIndexLength(context.Background())
-	suite.Equal(10, indexLength)
-}
-
-func (suite *IndexTestSuite) TestIndexBehindLowID() {
-	// index 10 behind the lowest status ID possible
-	err := suite.timeline.IndexBehind(context.Background(), "00000000000000000000000000", 10)
-	suite.NoError(err)
-
-	// the newest indexed post should be empty
-	postID, err := suite.timeline.NewestIndexedItemID(context.Background())
-	suite.NoError(err)
-	suite.Empty(postID)
-
-	// indexLength should be 0
-	indexLength := suite.timeline.ItemIndexLength(context.Background())
-	suite.Equal(0, indexLength)
-}
-
 func (suite *IndexTestSuite) TestOldestIndexedItemIDEmpty() {
 	// the oldest indexed post should be an empty string since there's nothing indexed yet
 	postID, err := suite.timeline.OldestIndexedItemID(context.Background())
@@ -137,17 +80,6 @@ func (suite *IndexTestSuite) TestOldestIndexedItemIDEmpty() {
 	suite.Equal(0, indexLength)
 }
 
-func (suite *IndexTestSuite) TestNewestIndexedItemIDEmpty() {
-	// the newest indexed post should be an empty string since there's nothing indexed yet
-	postID, err := suite.timeline.NewestIndexedItemID(context.Background())
-	suite.NoError(err)
-	suite.Empty(postID)
-
-	// indexLength should be 0
-	indexLength := suite.timeline.ItemIndexLength(context.Background())
-	suite.Equal(0, indexLength)
-}
-
 func (suite *IndexTestSuite) TestIndexAlreadyIndexed() {
 	testStatus := suite.testStatuses["local_account_1_status_1"]
 

internal/timeline/indexeditems.go

@@ -24,26 +24,26 @@
 	"errors"
 )
 
-type itemIndex struct {
+type indexedItems struct {
 	data       *list.List
 	skipInsert SkipInsertFunction
 }
 
-type itemIndexEntry struct {
+type indexedItemsEntry struct {
 	itemID           string
 	boostOfID        string
 	accountID        string
 	boostOfAccountID string
 }
 
-func (p *itemIndex) insertIndexed(ctx context.Context, i *itemIndexEntry) (bool, error) {
+func (i *indexedItems) insertIndexed(ctx context.Context, newEntry *indexedItemsEntry) (bool, error) {
-	if p.data == nil {
+	if i.data == nil {
-		p.data = &list.List{}
+		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 p.data.Len() == 0 {
+	if i.data.Len() == 0 {
-		p.data.PushFront(i)
+		i.data.PushFront(newEntry)
 		return true, nil
 	}
 
@@ -51,15 +51,15 @@ func (p *itemIndex) insertIndexed(ctx context.Context, i *itemIndexEntry) (bool,
 	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 := p.data.Front(); e != nil; e = e.Next() {
+	for e := i.data.Front(); e != nil; e = e.Next() {
 		position++
 
-		entry, ok := e.Value.(*itemIndexEntry)
+		entry, ok := e.Value.(*indexedItemsEntry)
 		if !ok {
-			return false, errors.New("index: could not parse e as an itemIndexEntry")
+			return false, errors.New("insertIndexed: could not parse e as an indexedItemsEntry")
 		}
 
-		skip, err := p.skipInsert(ctx, i.itemID, i.accountID, i.boostOfID, i.boostOfAccountID, entry.itemID, entry.accountID, entry.boostOfID, entry.boostOfAccountID, position)
+		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
 		}
@@ -69,18 +69,18 @@ func (p *itemIndex) insertIndexed(ctx context.Context, i *itemIndexEntry) (bool,
 
 		// if the item to index is newer than e, insert it before e in the list
 		if insertMark == nil {
-			if i.itemID > entry.itemID {
+			if newEntry.itemID > entry.itemID {
 				insertMark = e
 			}
 		}
 	}
 
 	if insertMark != nil {
-		p.data.InsertBefore(i, insertMark)
+		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
-	p.data.PushBack(i)
+	i.data.PushBack(newEntry)
 	return true, nil
 }

internal/timeline/manager.go

@@ -23,15 +23,12 @@
 	"fmt"
 	"strings"
 	"sync"
+	"time"
 
 	"codeberg.org/gruf/go-kv"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
-const (
-	desiredPostIndexLength = 400
-)
-
 // Manager abstracts functions for creating timelines for multiple accounts, and adding, removing, and fetching entries from those timelines.
 //
 // By the time a timelineable hits the manager interface, it should already have been filtered and it should be established that the item indeed
@@ -65,8 +62,6 @@ type Manager interface {
 	GetTimeline(ctx context.Context, accountID string, maxID string, sinceID string, minID string, limit int, local bool) ([]Preparable, error)
 	// GetIndexedLength returns the amount of items that have been *indexed* for the given account ID.
 	GetIndexedLength(ctx context.Context, timelineAccountID string) int
-	// GetDesiredIndexLength returns the amount of items that we, ideally, index for each user.
-	GetDesiredIndexLength(ctx context.Context) int
 	// GetOldestIndexedID returns the id ID for the oldest item that we have indexed for the given account.
 	GetOldestIndexedID(ctx context.Context, timelineAccountID string) (string, error)
 	// PrepareXFromTop prepares limit n amount of items, based on their indexed representations, from the top of the index.
@@ -77,6 +72,10 @@ type Manager interface {
 	WipeItemFromAllTimelines(ctx context.Context, itemID string) error
 	// WipeStatusesFromAccountID removes all items by the given accountID from the timelineAccountID's timelines.
 	WipeItemsFromAccountID(ctx context.Context, timelineAccountID string, accountID string) error
+	// Start starts hourly cleanup jobs for this timeline manager.
+	Start() error
+	// Stop stops the timeline manager (currently a stub, doesn't do anything).
+	Stop() error
 }
 
 // NewManager returns a new timeline manager.
@@ -98,9 +97,44 @@ type manager struct {
 	skipInsertFunction SkipInsertFunction
 }
 
+func (m *manager) Start() error {
+	// range through all timelines in the sync map once per hour + prune as necessary
+	go func() {
+		for now := range time.NewTicker(1 * time.Hour).C {
+			m.accountTimelines.Range(func(key any, value any) bool {
+				timelineAccountID, ok := key.(string)
+				if !ok {
+					panic("couldn't parse timeline manager sync map key as string, this should never happen so panic")
+				}
+
+				t, ok := value.(Timeline)
+				if !ok {
+					panic("couldn't parse timeline manager sync map value as Timeline, this should never happen so panic")
+				}
+
+				anHourAgo := now.Add(-1 * time.Hour)
+				if lastGot := t.LastGot(); lastGot.Before(anHourAgo) {
+					amountPruned := t.Prune(defaultDesiredPreparedItemsLength, defaultDesiredIndexedItemsLength)
+					log.WithFields(kv.Fields{
+						{"timelineAccountID", timelineAccountID},
+						{"amountPruned", amountPruned},
+					}...).Info("pruned indexed and prepared items from timeline")
+				}
+
+				return true
+			})
+		}
+	}()
+
+	return nil
+}
+
+func (m *manager) Stop() error {
+	return nil
+}
+
 func (m *manager) Ingest(ctx context.Context, item Timelineable, timelineAccountID string) (bool, error) {
 	l := log.WithFields(kv.Fields{
-
 		{"timelineAccountID", timelineAccountID},
 		{"itemID", item.GetID()},
 	}...)
@@ -116,7 +150,6 @@ func (m *manager) Ingest(ctx context.Context, item Timelineable, timelineAccount
 
 func (m *manager) IngestAndPrepare(ctx context.Context, item Timelineable, timelineAccountID string) (bool, error) {
 	l := log.WithFields(kv.Fields{
-
 		{"timelineAccountID", timelineAccountID},
 		{"itemID", item.GetID()},
 	}...)
@@ -132,7 +165,6 @@ func (m *manager) IngestAndPrepare(ctx context.Context, item Timelineable, timel
 
 func (m *manager) Remove(ctx context.Context, timelineAccountID string, itemID string) (int, error) {
 	l := log.WithFields(kv.Fields{
-
 		{"timelineAccountID", timelineAccountID},
 		{"itemID", itemID},
 	}...)
@@ -147,10 +179,7 @@ func (m *manager) Remove(ctx context.Context, timelineAccountID string, itemID s
 }
 
 func (m *manager) GetTimeline(ctx context.Context, timelineAccountID string, maxID string, sinceID string, minID string, limit int, local bool) ([]Preparable, error) {
-	l := log.WithFields(kv.Fields{
+	l := log.WithFields(kv.Fields{{"timelineAccountID", timelineAccountID}}...)
-
-		{"timelineAccountID", timelineAccountID},
-	}...)
 
 	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
 	if err != nil {
@@ -173,10 +202,6 @@ func (m *manager) GetIndexedLength(ctx context.Context, timelineAccountID string
 	return t.ItemIndexLength(ctx)
 }
 
-func (m *manager) GetDesiredIndexLength(ctx context.Context) int {
-	return desiredPostIndexLength
-}
-
 func (m *manager) GetOldestIndexedID(ctx context.Context, timelineAccountID string) (string, error) {
 	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
 	if err != nil {

internal/timeline/prepare.go

@@ -26,154 +26,12 @@
 
 	"codeberg.org/gruf/go-kv"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
-func (t *timeline) prepareNextQuery(ctx context.Context, amount int, maxID string, sinceID string, minID string) error {
-	l := log.WithFields(kv.Fields{
-
-		{"amount", amount},
-		{"maxID", maxID},
-		{"sinceID", sinceID},
-		{"minID", minID},
-	}...)
-
-	var err error
-
-	// maxID is defined but sinceID isn't so take from behind
-	if maxID != "" && sinceID == "" {
-		l.Debug("preparing behind maxID")
-		err = t.PrepareBehind(ctx, maxID, amount)
-	}
-
-	// maxID isn't defined, but sinceID || minID are, so take x before
-	if maxID == "" && sinceID != "" {
-		l.Debug("preparing before sinceID")
-		err = t.PrepareBefore(ctx, sinceID, false, amount)
-	}
-	if maxID == "" && minID != "" {
-		l.Debug("preparing before minID")
-		err = t.PrepareBefore(ctx, minID, false, amount)
-	}
-
-	return err
-}
-
-func (t *timeline) PrepareBehind(ctx context.Context, itemID string, amount int) error {
-	// lazily initialize prepared items if it hasn't been done already
-	if t.preparedItems.data == nil {
-		t.preparedItems.data = &list.List{}
-		t.preparedItems.data.Init()
-	}
-
-	if err := t.IndexBehind(ctx, itemID, amount); err != nil {
-		return fmt.Errorf("PrepareBehind: error indexing behind id %s: %s", itemID, err)
-	}
-
-	// if the itemindex is nil, nothing has been indexed yet so there's nothing to prepare
-	if t.itemIndex.data == nil {
-		return nil
-	}
-
-	var prepared int
-	var preparing bool
-	t.Lock()
-	defer t.Unlock()
-prepareloop:
-	for e := t.itemIndex.data.Front(); e != nil; e = e.Next() {
-		entry, ok := e.Value.(*itemIndexEntry)
-		if !ok {
-			return errors.New("PrepareBehind: could not parse e as itemIndexEntry")
-		}
-
-		if !preparing {
-			// we haven't hit the position we need to prepare from yet
-			if entry.itemID == itemID {
-				preparing = true
-			}
-		}
-
-		if preparing {
-			if err := t.prepare(ctx, entry.itemID); err != nil {
-				// there's been an error
-				if err != db.ErrNoEntries {
-					// it's a real error
-					return fmt.Errorf("PrepareBehind: error preparing item with id %s: %s", entry.itemID, err)
-				}
-				// the status just doesn't exist (anymore) so continue to the next one
-				continue
-			}
-			if prepared == amount {
-				// we're done
-				break prepareloop
-			}
-			prepared++
-		}
-	}
-
-	return nil
-}
-
-func (t *timeline) PrepareBefore(ctx context.Context, statusID string, include bool, amount int) error {
-	t.Lock()
-	defer t.Unlock()
-
-	// lazily initialize prepared posts if it hasn't been done already
-	if t.preparedItems.data == nil {
-		t.preparedItems.data = &list.List{}
-		t.preparedItems.data.Init()
-	}
-
-	// if the postindex is nil, nothing has been indexed yet so there's nothing to prepare
-	if t.itemIndex.data == nil {
-		return nil
-	}
-
-	var prepared int
-	var preparing bool
-prepareloop:
-	for e := t.itemIndex.data.Back(); e != nil; e = e.Prev() {
-		entry, ok := e.Value.(*itemIndexEntry)
-		if !ok {
-			return errors.New("PrepareBefore: could not parse e as a postIndexEntry")
-		}
-
-		if !preparing {
-			// we haven't hit the position we need to prepare from yet
-			if entry.itemID == statusID {
-				preparing = true
-				if !include {
-					continue
-				}
-			}
-		}
-
-		if preparing {
-			if err := t.prepare(ctx, entry.itemID); err != nil {
-				// there's been an error
-				if err != db.ErrNoEntries {
-					// it's a real error
-					return fmt.Errorf("PrepareBefore: error preparing status with id %s: %s", entry.itemID, err)
-				}
-				// the status just doesn't exist (anymore) so continue to the next one
-				continue
-			}
-			if prepared == amount {
-				// we're done
-				break prepareloop
-			}
-			prepared++
-		}
-	}
-
-	return nil
-}
-
 func (t *timeline) PrepareFromTop(ctx context.Context, amount int) error {
-	l := log.WithFields(kv.Fields{
+	l := log.WithFields(kv.Fields{{"amount", amount}}...)
-
-		{"amount", amount},
-	}...)
 
 	// lazily initialize prepared posts if it hasn't been done already
 	if t.preparedItems.data == nil {
@@ -182,10 +40,10 @@ func (t *timeline) PrepareFromTop(ctx context.Context, amount int) error {
 	}
 
 	// if the postindex is nil, nothing has been indexed yet so index from the highest ID possible
-	if t.itemIndex.data == nil {
+	if t.indexedItems.data == nil {
 		l.Debug("postindex.data was nil, indexing behind highest possible ID")
-		if err := t.IndexBehind(ctx, "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", amount); err != nil {
+		if err := t.indexBehind(ctx, id.Highest, amount); err != nil {
-			return fmt.Errorf("PrepareFromTop: error indexing behind id %s: %s", "ZZZZZZZZZZZZZZZZZZZZZZZZZZ", err)
+			return fmt.Errorf("PrepareFromTop: error indexing behind id %s: %s", id.Highest, err)
 		}
 	}
 
@@ -194,12 +52,12 @@ func (t *timeline) PrepareFromTop(ctx context.Context, amount int) error {
 	defer t.Unlock()
 	var prepared int
 prepareloop:
-	for e := t.itemIndex.data.Front(); e != nil; e = e.Next() {
+	for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
 		if e == nil {
 			continue
 		}
 
-		entry, ok := e.Value.(*itemIndexEntry)
+		entry, ok := e.Value.(*indexedItemsEntry)
 		if !ok {
 			return errors.New("PrepareFromTop: could not parse e as a postIndexEntry")
 		}
@@ -226,6 +84,142 @@ func (t *timeline) PrepareFromTop(ctx context.Context, amount int) error {
 	return nil
 }
 
+func (t *timeline) prepareNextQuery(ctx context.Context, amount int, maxID string, sinceID string, minID string) error {
+	l := log.WithFields(kv.Fields{
+		{"amount", amount},
+		{"maxID", maxID},
+		{"sinceID", sinceID},
+		{"minID", minID},
+	}...)
+
+	var err error
+	switch {
+	case maxID != "" && sinceID == "":
+		l.Debug("preparing behind maxID")
+		err = t.prepareBehind(ctx, maxID, amount)
+	case maxID == "" && sinceID != "":
+		l.Debug("preparing before sinceID")
+		err = t.prepareBefore(ctx, sinceID, false, amount)
+	case maxID == "" && minID != "":
+		l.Debug("preparing before minID")
+		err = t.prepareBefore(ctx, minID, false, amount)
+	}
+
+	return err
+}
+
+// prepareBehind instructs the timeline to prepare the next amount of entries for serialization, from position onwards.
+// If include is true, then the given item ID will also be prepared, otherwise only entries behind it will be prepared.
+func (t *timeline) prepareBehind(ctx context.Context, itemID string, amount int) error {
+	// lazily initialize prepared items if it hasn't been done already
+	if t.preparedItems.data == nil {
+		t.preparedItems.data = &list.List{}
+		t.preparedItems.data.Init()
+	}
+
+	if err := t.indexBehind(ctx, itemID, amount); err != nil {
+		return fmt.Errorf("prepareBehind: error indexing behind id %s: %s", itemID, err)
+	}
+
+	// if the itemindex is nil, nothing has been indexed yet so there's nothing to prepare
+	if t.indexedItems.data == nil {
+		return nil
+	}
+
+	var prepared int
+	var preparing bool
+	t.Lock()
+	defer t.Unlock()
+prepareloop:
+	for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
+		entry, ok := e.Value.(*indexedItemsEntry)
+		if !ok {
+			return errors.New("prepareBehind: could not parse e as itemIndexEntry")
+		}
+
+		if !preparing {
+			// we haven't hit the position we need to prepare from yet
+			if entry.itemID == itemID {
+				preparing = true
+			}
+		}
+
+		if preparing {
+			if err := t.prepare(ctx, entry.itemID); err != nil {
+				// there's been an error
+				if err != db.ErrNoEntries {
+					// it's a real error
+					return fmt.Errorf("prepareBehind: error preparing item with id %s: %s", entry.itemID, err)
+				}
+				// the status just doesn't exist (anymore) so continue to the next one
+				continue
+			}
+			if prepared == amount {
+				// we're done
+				break prepareloop
+			}
+			prepared++
+		}
+	}
+
+	return nil
+}
+
+func (t *timeline) prepareBefore(ctx context.Context, statusID string, include bool, amount int) error {
+	t.Lock()
+	defer t.Unlock()
+
+	// lazily initialize prepared posts if it hasn't been done already
+	if t.preparedItems.data == nil {
+		t.preparedItems.data = &list.List{}
+		t.preparedItems.data.Init()
+	}
+
+	// if the postindex is nil, nothing has been indexed yet so there's nothing to prepare
+	if t.indexedItems.data == nil {
+		return nil
+	}
+
+	var prepared int
+	var preparing bool
+prepareloop:
+	for e := t.indexedItems.data.Back(); e != nil; e = e.Prev() {
+		entry, ok := e.Value.(*indexedItemsEntry)
+		if !ok {
+			return errors.New("prepareBefore: could not parse e as a postIndexEntry")
+		}
+
+		if !preparing {
+			// we haven't hit the position we need to prepare from yet
+			if entry.itemID == statusID {
+				preparing = true
+				if !include {
+					continue
+				}
+			}
+		}
+
+		if preparing {
+			if err := t.prepare(ctx, entry.itemID); err != nil {
+				// there's been an error
+				if err != db.ErrNoEntries {
+					// it's a real error
+					return fmt.Errorf("prepareBefore: error preparing status with id %s: %s", entry.itemID, err)
+				}
+				// the status just doesn't exist (anymore) so continue to the next one
+				continue
+			}
+			if prepared == amount {
+				// we're done
+				break prepareloop
+			}
+			prepared++
+		}
+	}
+
+	return nil
+}
+
 func (t *timeline) prepare(ctx context.Context, itemID string) error {
 	// trigger the caller-provided prepare function
 	prepared, err := t.prepareFunction(ctx, t.accountID, itemID)
@@ -245,7 +239,9 @@ func (t *timeline) prepare(ctx context.Context, itemID string) error {
 	return t.preparedItems.insertPrepared(ctx, preparedItemsEntry)
 }
 
-func (t *timeline) OldestPreparedItemID(ctx context.Context) (string, error) {
+// oldestPreparedItemID returns the id of the rearmost (ie., the oldest) prepared item, or an error if something goes wrong.
+// If nothing goes wrong but there's no oldest item, an empty string will be returned so make sure to check for this.
+func (t *timeline) oldestPreparedItemID(ctx context.Context) (string, error) {
 	var id string
 	if t.preparedItems == nil || t.preparedItems.data == nil {
 		// return an empty string if prepared items hasn't been initialized yet
@@ -260,7 +256,7 @@ func (t *timeline) OldestPreparedItemID(ctx context.Context) (string, error) {
 
 	entry, ok := e.Value.(*preparedItemsEntry)
 	if !ok {
-		return id, errors.New("OldestPreparedItemID: could not parse e as a preparedItemsEntry")
+		return id, errors.New("oldestPreparedItemID: could not parse e as a preparedItemsEntry")
 	}
 
 	return entry.itemID, nil

internal/timeline/prepareditems.go

@@ -37,30 +37,30 @@ type preparedItemsEntry struct {
 	prepared         Preparable
 }
 
-func (p *preparedItems) insertPrepared(ctx context.Context, i *preparedItemsEntry) error {
+func (p *preparedItems) insertPrepared(ctx context.Context, newEntry *preparedItemsEntry) error {
 	if p.data == nil {
 		p.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 p.data.Len() == 0 {
-		p.data.PushFront(i)
+		p.data.PushFront(newEntry)
 		return nil
 	}
 
 	var insertMark *list.Element
 	var position int
-	// We need to iterate through the index to make sure we put this post in the appropriate place according to when it was created.
+	// We need to iterate through the index to make sure we put this entry in the appropriate place according to when it was created.
-	// We also need to make sure we're not inserting a duplicate post -- this can happen sometimes and it's not nice UX (*shudder*).
+	// We also need to make sure we're not inserting a duplicate entry -- this can happen sometimes and it's not nice UX (*shudder*).
 	for e := p.data.Front(); e != nil; e = e.Next() {
 		position++
 
 		entry, ok := e.Value.(*preparedItemsEntry)
 		if !ok {
-			return errors.New("index: could not parse e as a preparedPostsEntry")
+			return errors.New("insertPrepared: could not parse e as a preparedItemsEntry")
 		}
 
-		skip, err := p.skipInsert(ctx, i.itemID, i.accountID, i.boostOfID, i.boostOfAccountID, entry.itemID, entry.accountID, entry.boostOfID, entry.boostOfAccountID, position)
+		skip, err := p.skipInsert(ctx, newEntry.itemID, newEntry.accountID, newEntry.boostOfID, newEntry.boostOfAccountID, entry.itemID, entry.accountID, entry.boostOfID, entry.boostOfAccountID, position)
 		if err != nil {
 			return err
 		}
@@ -68,25 +68,25 @@ func (p *preparedItems) insertPrepared(ctx context.Context, i *preparedItemsEntr
 			return nil
 		}
 
-		// if the post to index is newer than e, insert it before e in the list
+		// if the entry to index is newer than e, insert it before e in the list
 		if insertMark == nil {
-			if i.itemID > entry.itemID {
+			if newEntry.itemID > entry.itemID {
 				insertMark = e
 			}
 		}
 
 		// make sure we don't insert a duplicate
-		if entry.itemID == i.itemID {
+		if entry.itemID == newEntry.itemID {
 			return nil
 		}
 	}
 
 	if insertMark != nil {
-		p.data.InsertBefore(i, insertMark)
+		p.data.InsertBefore(newEntry, insertMark)
 		return nil
 	}
 
-	// if we reach this point it's the oldest post we've seen so put it at the back
+	// if we reach this point it's the oldest entry we've seen so put it at the back
-	p.data.PushBack(i)
+	p.data.PushBack(newEntry)
 	return nil
 }

internal/timeline/prune.go

@@ -0,0 +1,68 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   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"
+)
+
+const (
+	defaultDesiredIndexedItemsLength  = 400
+	defaultDesiredPreparedItemsLength = 50
+)
+
+func (t *timeline) Prune(desiredPreparedItemsLength int, desiredIndexedItemsLength int) int {
+	t.Lock()
+	defer t.Unlock()
+
+	pruneList := func(pruneTo int, listToPrune *list.List) int {
+		if listToPrune == nil {
+			// no need to prune
+			return 0
+		}
+
+		unprunedLength := listToPrune.Len()
+		if unprunedLength <= pruneTo {
+			// no need to prune
+			return 0
+		}
+
+		// work from the back + assemble a slice of entries that we will prune
+		amountStillToPrune := unprunedLength - pruneTo
+		itemsToPrune := make([]*list.Element, 0, amountStillToPrune)
+		for e := listToPrune.Back(); amountStillToPrune > 0; e = e.Prev() {
+			itemsToPrune = append(itemsToPrune, e)
+			amountStillToPrune--
+		}
+
+		// remove the entries we found
+		var totalPruned int
+		for _, e := range itemsToPrune {
+			listToPrune.Remove(e)
+			totalPruned++
+		}
+
+		return totalPruned
+	}
+
+	prunedPrepared := pruneList(desiredPreparedItemsLength, t.preparedItems.data)
+	prunedIndexed := pruneList(desiredIndexedItemsLength, t.indexedItems.data)
+
+	return prunedPrepared + prunedIndexed
+}

internal/timeline/prune_test.go

@@ -0,0 +1,110 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   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_test
+
+import (
+	"context"
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/processing"
+	"github.com/superseriousbusiness/gotosocial/internal/timeline"
+	"github.com/superseriousbusiness/gotosocial/internal/visibility"
+	"github.com/superseriousbusiness/gotosocial/testrig"
+)
+
+type PruneTestSuite struct {
+	TimelineStandardTestSuite
+}
+
+func (suite *PruneTestSuite) SetupSuite() {
+	suite.testAccounts = testrig.NewTestAccounts()
+	suite.testStatuses = testrig.NewTestStatuses()
+}
+
+func (suite *PruneTestSuite) SetupTest() {
+	testrig.InitTestLog()
+	testrig.InitTestConfig()
+
+	suite.db = testrig.NewTestDB()
+	suite.tc = testrig.NewTestTypeConverter(suite.db)
+	suite.filter = visibility.NewFilter(suite.db)
+
+	testrig.StandardDBSetup(suite.db, nil)
+
+	// let's take local_account_1 as the timeline owner
+	tl, err := timeline.NewTimeline(
+		context.Background(),
+		suite.testAccounts["local_account_1"].ID,
+		processing.StatusGrabFunction(suite.db),
+		processing.StatusFilterFunction(suite.db, suite.filter),
+		processing.StatusPrepareFunction(suite.db, suite.tc),
+		processing.StatusSkipInsertFunction(),
+	)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	// put the status IDs in a determinate order since we can't trust a map to keep its order
+	statuses := []*gtsmodel.Status{}
+	for _, s := range suite.testStatuses {
+		statuses = append(statuses, s)
+	}
+	sort.Slice(statuses, func(i, j int) bool {
+		return statuses[i].ID > statuses[j].ID
+	})
+
+	// prepare the timeline by just shoving all test statuses in it -- let's not be fussy about who sees what
+	for _, s := range statuses {
+		_, err := tl.IndexAndPrepareOne(context.Background(), s.GetID(), s.BoostOfID, s.AccountID, s.BoostOfAccountID)
+		if err != nil {
+			suite.FailNow(err.Error())
+		}
+	}
+
+	suite.timeline = tl
+}
+
+func (suite *PruneTestSuite) TearDownTest() {
+	testrig.StandardDBTeardown(suite.db)
+}
+
+func (suite *PruneTestSuite) TestPrune() {
+	// prune down to 5 prepared + 5 indexed
+	suite.Equal(24, suite.timeline.Prune(5, 5))
+	suite.Equal(5, suite.timeline.ItemIndexLength(context.Background()))
+}
+
+func (suite *PruneTestSuite) TestPruneTo0() {
+	// prune down to 0 prepared + 0 indexed
+	suite.Equal(34, suite.timeline.Prune(0, 0))
+	suite.Equal(0, suite.timeline.ItemIndexLength(context.Background()))
+}
+
+func (suite *PruneTestSuite) TestPruneToInfinityAndBeyond() {
+	// prune to 99999, this should result in no entries being pruned
+	suite.Equal(0, suite.timeline.Prune(99999, 99999))
+	suite.Equal(17, suite.timeline.ItemIndexLength(context.Background()))
+}
+
+func TestPruneTestSuite(t *testing.T) {
+	suite.Run(t, new(PruneTestSuite))
+}

internal/timeline/remove.go

@@ -29,7 +29,6 @@
 
 func (t *timeline) Remove(ctx context.Context, statusID string) (int, error) {
 	l := log.WithFields(kv.Fields{
-
 		{"accountTimeline", t.accountID},
 		{"statusID", statusID},
 	}...)
@@ -40,9 +39,9 @@ func (t *timeline) Remove(ctx context.Context, statusID string) (int, error) {
 
 	// remove entr(ies) from the post index
 	removeIndexes := []*list.Element{}
-	if t.itemIndex != nil && t.itemIndex.data != nil {
+	if t.indexedItems != nil && t.indexedItems.data != nil {
-		for e := t.itemIndex.data.Front(); e != nil; e = e.Next() {
+		for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-			entry, ok := e.Value.(*itemIndexEntry)
+			entry, ok := e.Value.(*indexedItemsEntry)
 			if !ok {
 				return removed, errors.New("Remove: could not parse e as a postIndexEntry")
 			}
@@ -53,7 +52,7 @@ func (t *timeline) Remove(ctx context.Context, statusID string) (int, error) {
 		}
 	}
 	for _, e := range removeIndexes {
-		t.itemIndex.data.Remove(e)
+		t.indexedItems.data.Remove(e)
 		removed++
 	}
 
@@ -82,19 +81,19 @@ func (t *timeline) Remove(ctx context.Context, statusID string) (int, error) {
 
 func (t *timeline) RemoveAllBy(ctx context.Context, accountID string) (int, error) {
 	l := log.WithFields(kv.Fields{
-
 		{"accountTimeline", t.accountID},
 		{"accountID", accountID},
 	}...)
+
 	t.Lock()
 	defer t.Unlock()
 	var removed int
 
 	// remove entr(ies) from the post index
 	removeIndexes := []*list.Element{}
-	if t.itemIndex != nil && t.itemIndex.data != nil {
+	if t.indexedItems != nil && t.indexedItems.data != nil {
-		for e := t.itemIndex.data.Front(); e != nil; e = e.Next() {
+		for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-			entry, ok := e.Value.(*itemIndexEntry)
+			entry, ok := e.Value.(*indexedItemsEntry)
 			if !ok {
 				return removed, errors.New("Remove: could not parse e as a postIndexEntry")
 			}
@@ -105,7 +104,7 @@ func (t *timeline) RemoveAllBy(ctx context.Context, accountID string) (int, erro
 		}
 	}
 	for _, e := range removeIndexes {
-		t.itemIndex.data.Remove(e)
+		t.indexedItems.data.Remove(e)
 		removed++
 	}
 

internal/timeline/timeline.go

@@ -21,6 +21,7 @@
 import (
 	"context"
 	"sync"
+	"time"
 )
 
 // GrabFunction is used by a Timeline to grab more items to index.
@@ -73,26 +74,9 @@ type Timeline interface {
 	// If prepareNext is true, then the next predicted query will be prepared already in a goroutine,
 	// to make the next call to Get faster.
 	Get(ctx context.Context, amount int, maxID string, sinceID string, minID string, prepareNext bool) ([]Preparable, error)
-	// GetXFromTop returns x amount of items from the top of the timeline, from newest to oldest.
-	GetXFromTop(ctx context.Context, amount int) ([]Preparable, error)
-	// GetXBehindID returns x amount of items from the given id onwards, from newest to oldest.
-	// This will NOT include the item with the given ID.
-	//
-	// This corresponds to an api call to /timelines/home?max_id=WHATEVER
-	GetXBehindID(ctx context.Context, amount int, fromID string, attempts *int) ([]Preparable, error)
-	// GetXBeforeID returns x amount of items up to the given id, from newest to oldest.
-	// This will NOT include the item with the given ID.
-	//
-	// This corresponds to an api call to /timelines/home?since_id=WHATEVER
-	GetXBeforeID(ctx context.Context, amount int, sinceID string, startFromTop bool) ([]Preparable, error)
-	// GetXBetweenID returns x amount of items from the given maxID, up to the given id, from newest to oldest.
-	// This will NOT include the item with the given IDs.
-	//
-	// This corresponds to an api call to /timelines/home?since_id=WHATEVER&max_id=WHATEVER_ELSE
-	GetXBetweenID(ctx context.Context, amount int, maxID string, sinceID string) ([]Preparable, error)
 
 	/*
-		INDEXING FUNCTIONS
+		INDEXING + PREPARATION FUNCTIONS
 	*/
 
 	// IndexOne puts a item into the timeline at the appropriate place according to its 'createdAt' property.
@@ -100,35 +84,14 @@ type Timeline interface {
 	// The returned bool indicates whether or not the item was actually inserted into the timeline. This will be false
 	// if the item is a boost and the original item or another boost of it already exists < boostReinsertionDepth back in the timeline.
 	IndexOne(ctx context.Context, itemID string, boostOfID string, accountID string, boostOfAccountID string) (bool, error)
-
+	// IndexAndPrepareOne puts a item into the timeline at the appropriate place according to its 'createdAt' property,
-	// OldestIndexedItemID returns the id of the rearmost (ie., the oldest) indexed item, or an error if something goes wrong.
-	// If nothing goes wrong but there's no oldest item, an empty string will be returned so make sure to check for this.
-	OldestIndexedItemID(ctx context.Context) (string, error)
-	// NewestIndexedItemID returns the id of the frontmost (ie., the newest) indexed item, or an error if something goes wrong.
-	// If nothing goes wrong but there's no newest item, an empty string will be returned so make sure to check for this.
-	NewestIndexedItemID(ctx context.Context) (string, error)
-
-	IndexBefore(ctx context.Context, itemID string, amount int) error
-	IndexBehind(ctx context.Context, itemID string, amount int) error
-
-	/*
-		PREPARATION FUNCTIONS
-	*/
-
-	// PrepareXFromTop instructs the timeline to prepare x amount of items from the top of the timeline.
-	PrepareFromTop(ctx context.Context, amount int) error
-	// PrepareBehind instructs the timeline to prepare the next amount of entries for serialization, from position onwards.
-	// If include is true, then the given item ID will also be prepared, otherwise only entries behind it will be prepared.
-	PrepareBehind(ctx context.Context, itemID string, amount int) error
-	// IndexOne puts a item into the timeline at the appropriate place according to its 'createdAt' property,
 	// and then immediately prepares it.
 	//
 	// The returned bool indicates whether or not the item was actually inserted into the timeline. This will be false
 	// if the item is a boost and the original item or another boost of it already exists < boostReinsertionDepth back in the timeline.
 	IndexAndPrepareOne(ctx context.Context, itemID string, boostOfID string, accountID string, boostOfAccountID string) (bool, error)
-	// OldestPreparedItemID returns the id of the rearmost (ie., the oldest) prepared item, or an error if something goes wrong.
+	// PrepareXFromTop instructs the timeline to prepare x amount of items from the top of the timeline, useful during init.
-	// If nothing goes wrong but there's no oldest item, an empty string will be returned so make sure to check for this.
+	PrepareFromTop(ctx context.Context, amount int) error
-	OldestPreparedItemID(ctx context.Context) (string, error)
 
 	/*
 		INFO FUNCTIONS
@@ -136,13 +99,24 @@ type Timeline interface {
 
 	// ActualPostIndexLength returns the actual length of the item index at this point in time.
 	ItemIndexLength(ctx context.Context) int
+	// OldestIndexedItemID returns the id of the rearmost (ie., the oldest) indexed item, or an error if something goes wrong.
+	// If nothing goes wrong but there's no oldest item, an empty string will be returned so make sure to check for this.
+	OldestIndexedItemID(ctx context.Context) (string, error)
+	// NewestIndexedItemID returns the id of the frontmost (ie., the newest) indexed item, or an error if something goes wrong.
+	// If nothing goes wrong but there's no newest item, an empty string will be returned so make sure to check for this.
+	NewestIndexedItemID(ctx context.Context) (string, error)
 
 	/*
 		UTILITY FUNCTIONS
 	*/
 
-	// Reset instructs the timeline to reset to its base state -- cache only the minimum amount of items.
+	// LastGot returns the time that Get was last called.
-	Reset() error
+	LastGot() time.Time
+	// Prune prunes preparedItems and indexedItems in this timeline to the desired lengths.
+	// This will be a no-op if the lengths are already < the desired values.
+	// Prune acquires a lock on the timeline before pruning.
+	// The return value is the combined total of items pruned from preparedItems and indexedItems.
+	Prune(desiredPreparedItemsLength int, desiredIndexedItemsLength int) int
 	// Remove removes a item from both the index and prepared items.
 	//
 	// If a item has multiple entries in a timeline, they will all be removed.
@@ -157,12 +131,13 @@ type Timeline interface {
 
 // timeline fulfils the Timeline interface
 type timeline struct {
-	itemIndex       *itemIndex
+	indexedItems    *indexedItems
 	preparedItems   *preparedItems
 	grabFunction    GrabFunction
 	filterFunction  FilterFunction
 	prepareFunction PrepareFunction
 	accountID       string
+	lastGot         time.Time
 	sync.Mutex
 }
 
@@ -175,7 +150,7 @@ func NewTimeline(
 	prepareFunction PrepareFunction,
 	skipInsertFunction SkipInsertFunction) (Timeline, error) {
 	return &timeline{
-		itemIndex: &itemIndex{
+		indexedItems: &indexedItems{
 			skipInsert: skipInsertFunction,
 		},
 		preparedItems: &preparedItems{
@@ -185,17 +160,6 @@ func NewTimeline(
 		filterFunction:  filterFunction,
 		prepareFunction: prepareFunction,
 		accountID:       timelineAccountID,
+		lastGot:         time.Time{},
 	}, nil
 }
-
-func (t *timeline) Reset() error {
-	return nil
-}
-
-func (t *timeline) ItemIndexLength(ctx context.Context) int {
-	if t.itemIndex == nil || t.itemIndex.data == nil {
-		return 0
-	}
-
-	return t.itemIndex.data.Len()
-}

internal/typeutils/internaltoas.go

@@ -34,13 +34,6 @@
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
-// const (
-// 	// highestID is the highest possible ULID
-// 	highestID = "ZZZZZZZZZZZZZZZZZZZZZZZZZZ"
-// 	// lowestID is the lowest possible ULID
-// 	lowestID = "00000000000000000000000000"
-// )
-
 // Converts a gts model account into an Activity Streams person type.
 func (c *converter) AccountToAS(ctx context.Context, a *gtsmodel.Account) (vocab.ActivityStreamsPerson, error) {
 	person := streams.NewActivityStreamsPerson()