[bugfix] fix possible infinite loops in media / emoji cleanup (#2590)

* update media / emoji cleaner funcs to use new paging package, check for same returned maxID

* fix other calls of getattachments and getmojis not using paging

* use alternative order-by function

8 files changed, 156 insertions, 117 deletions

diff --git a/cmd/gotosocial/action/admin/media/list.go b/cmd/gotosocial/action/admin/media/list.go
index 0a2e60ede..ed10c967a 100644
--- a/cmd/gotosocial/action/admin/media/list.go
+++ b/cmd/gotosocial/action/admin/media/list.go
@@ -31,14 +31,14 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/db/bundb"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 	"github.com/superseriousbusiness/gotosocial/internal/state"
 )
 
 type list struct {
 	dbService  db.DB
 	state      *state.State
-	maxID      string
-	limit      int
+	page       paging.Page
 	localOnly  bool
 	remoteOnly bool
 	out        *bufio.Writer
@@ -47,31 +47,32 @@ type list struct {
 // Get a list of attachment using a custom filter
 func (l *list) GetAllAttachmentPaths(ctx context.Context, filter func(*gtsmodel.MediaAttachment) string) ([]string, error) {
 	res := make([]string, 0, 100)
+
 	for {
-		attachments, err := l.dbService.GetAttachments(ctx, l.maxID, l.limit)
-		if err != nil {
+		// Get the next page of media attachments up to max ID.
+		attachments, err := l.dbService.GetAttachments(ctx, &l.page)
+		if err != nil && !errors.Is(err, db.ErrNoEntries) {
 			return nil, fmt.Errorf("failed to retrieve media metadata from database: %w", err)
 		}
 
+		// Get current max ID.
+		maxID := l.page.Max.Value
+
+		// If no attachments or the same group is returned, we reached the end.
+		if len(attachments) == 0 || maxID == attachments[len(attachments)-1].ID {
+			break
+		}
+
+		// Use last ID as the next 'maxID' value.
+		maxID = attachments[len(attachments)-1].ID
+		l.page.Max = paging.MaxID(maxID)
+
 		for _, a := range attachments {
 			v := filter(a)
 			if v != "" {
 				res = append(res, v)
 			}
 		}
-
-		// If we got less results than our limit, we've reached the
-		// last page to retrieve and we can break the loop. If the
-		// last batch happens to contain exactly the same amount of
-		// items as the limit we'll end up doing one extra query.
-		if len(attachments) < l.limit {
-			break
-		}
-
-		// Grab the last ID from the batch and set it as the maxID
-		// that'll be used in the next iteration so we don't get items
-		// we've already seen.
-		l.maxID = attachments[len(attachments)-1].ID
 	}
 	return res, nil
 }
@@ -80,30 +81,30 @@ func (l *list) GetAllAttachmentPaths(ctx context.Context, filter func(*gtsmodel.
 func (l *list) GetAllEmojisPaths(ctx context.Context, filter func(*gtsmodel.Emoji) string) ([]string, error) {
 	res := make([]string, 0, 100)
 	for {
-		attachments, err := l.dbService.GetEmojis(ctx, l.maxID, l.limit)
+		// Get the next page of emoji media up to max ID.
+		attachments, err := l.dbService.GetEmojis(ctx, &l.page)
 		if err != nil {
 			return nil, fmt.Errorf("failed to retrieve media metadata from database: %w", err)
 		}
 
+		// Get current max ID.
+		maxID := l.page.Max.Value
+
+		// If no attachments or the same group is returned, we reached the end.
+		if len(attachments) == 0 || maxID == attachments[len(attachments)-1].ID {
+			break
+		}
+
+		// Use last ID as the next 'maxID' value.
+		maxID = attachments[len(attachments)-1].ID
+		l.page.Max = paging.MaxID(maxID)
+
 		for _, a := range attachments {
 			v := filter(a)
 			if v != "" {
 				res = append(res, v)
 			}
 		}
-
-		// If we got less results than our limit, we've reached the
-		// last page to retrieve and we can break the loop. If the
-		// last batch happens to contain exactly the same amount of
-		// items as the limit we'll end up doing one extra query.
-		if len(attachments) < l.limit {
-			break
-		}
-
-		// Grab the last ID from the batch and set it as the maxID
-		// that'll be used in the next iteration so we don't get items
-		// we've already seen.
-		l.maxID = attachments[len(attachments)-1].ID
 	}
 	return res, nil
 }
@@ -137,8 +138,7 @@ func setupList(ctx context.Context) (*list, error) {
 	return &list{
 		dbService:  dbService,
 		state:      &state,
-		limit:      200,
-		maxID:      "",
+		page:       paging.Page{Limit: 200},
 		localOnly:  localOnly,
 		remoteOnly: remoteOnly,
 		out:        bufio.NewWriter(os.Stdout),
diff --git a/internal/cleaner/emoji.go b/internal/cleaner/emoji.go
index d2baec7e8..62ed0f012 100644
--- a/internal/cleaner/emoji.go
+++ b/internal/cleaner/emoji.go
@@ -27,6 +27,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 )
 
 // Emoji encompasses a set of
@@ -105,8 +106,9 @@ func (e *Emoji) UncacheRemote(ctx context.Context, olderThan time.Time) (int, er
 			return total, gtserror.Newf("error getting remote emoji: %w", err)
 		}
 
-		if len(emojis) == 0 {
-			// reached end.
+		// If no emojis / same group is returned, we reached the end.
+		if len(emojis) == 0 ||
+			olderThan.Equal(emojis[len(emojis)-1].CreatedAt) {
 			break
 		}
 
@@ -140,23 +142,30 @@ func (e *Emoji) UncacheRemote(ctx context.Context, olderThan time.Time) (int, er
 func (e *Emoji) FixBroken(ctx context.Context) (int, error) {
 	var (
 		total int
-		maxID string
+		page  paging.Page
 	)
 
+	// Set page select limit.
+	page.Limit = selectLimit
+
 	for {
-		// Fetch the next batch of emoji media up to next ID.
-		emojis, err := e.state.DB.GetEmojis(ctx, maxID, selectLimit)
+		// Fetch the next batch of emoji to next max ID.
+		emojis, err := e.state.DB.GetEmojis(ctx, &page)
 		if err != nil && !errors.Is(err, db.ErrNoEntries) {
 			return total, gtserror.Newf("error getting emojis: %w", err)
 		}
 
-		if len(emojis) == 0 {
-			// reached end.
+		// Get current max ID.
+		maxID := page.Max.Value
+
+		// If no emoji or the same group is returned, we reached end.
+		if len(emojis) == 0 || maxID == emojis[len(emojis)-1].ID {
 			break
 		}
 
-		// Use last as the next 'maxID' value.
+		// Use last ID as the next 'maxID'.
 		maxID = emojis[len(emojis)-1].ID
+		page.Max = paging.MaxID(maxID)
 
 		for _, emoji := range emojis {
 			// Check / fix missing broken emoji.
@@ -182,23 +191,30 @@ func (e *Emoji) FixBroken(ctx context.Context) (int, error) {
 func (e *Emoji) PruneUnused(ctx context.Context) (int, error) {
 	var (
 		total int
-		maxID string
+		page  paging.Page
 	)
 
+	// Set page select limit.
+	page.Limit = selectLimit
+
 	for {
-		// Fetch the next batch of emoji media up to next ID.
-		emojis, err := e.state.DB.GetRemoteEmojis(ctx, maxID, selectLimit)
+		// Fetch the next batch of emoji to next max ID.
+		emojis, err := e.state.DB.GetRemoteEmojis(ctx, &page)
 		if err != nil && !errors.Is(err, db.ErrNoEntries) {
 			return total, gtserror.Newf("error getting remote emojis: %w", err)
 		}
 
-		if len(emojis) == 0 {
-			// reached end.
+		// Get current max ID.
+		maxID := page.Max.Value
+
+		// If no emoji or the same group is returned, we reached end.
+		if len(emojis) == 0 || maxID == emojis[len(emojis)-1].ID {
 			break
 		}
 
-		// Use last as the next 'maxID' value.
+		// Use last ID as the next 'maxID'.
 		maxID = emojis[len(emojis)-1].ID
+		page.Max = paging.MaxID(maxID)
 
 		for _, emoji := range emojis {
 			// Check / prune unused emoji media.
@@ -224,23 +240,30 @@ func (e *Emoji) PruneUnused(ctx context.Context) (int, error) {
 func (e *Emoji) FixCacheStates(ctx context.Context) (int, error) {
 	var (
 		total int
-		maxID string
+		page  paging.Page
 	)
 
+	// Set page select limit.
+	page.Limit = selectLimit
+
 	for {
-		// Fetch the next batch of emoji media up to next ID.
-		emojis, err := e.state.DB.GetRemoteEmojis(ctx, maxID, selectLimit)
+		// Fetch the next batch of emoji to next max ID.
+		emojis, err := e.state.DB.GetRemoteEmojis(ctx, &page)
 		if err != nil && !errors.Is(err, db.ErrNoEntries) {
 			return total, gtserror.Newf("error getting remote emojis: %w", err)
 		}
 
-		if len(emojis) == 0 {
-			// reached end.
+		// Get current max ID.
+		maxID := page.Max.Value
+
+		// If no emoji or the same group is returned, we reached end.
+		if len(emojis) == 0 || maxID == emojis[len(emojis)-1].ID {
 			break
 		}
 
-		// Use last as the next 'maxID' value.
+		// Use last ID as the next 'maxID'.
 		maxID = emojis[len(emojis)-1].ID
+		page.Max = paging.MaxID(maxID)
 
 		for _, emoji := range emojis {
 			// Check / fix required emoji cache states.
diff --git a/internal/cleaner/media.go b/internal/cleaner/media.go
index 6db205d13..f3cda5d87 100644
--- a/internal/cleaner/media.go
+++ b/internal/cleaner/media.go
@@ -28,6 +28,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 	"github.com/superseriousbusiness/gotosocial/internal/media"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 	"github.com/superseriousbusiness/gotosocial/internal/regexes"
 	"github.com/superseriousbusiness/gotosocial/internal/uris"
 )
@@ -128,23 +129,30 @@ func (m *Media) PruneOrphaned(ctx context.Context) (int, error) {
 func (m *Media) PruneUnused(ctx context.Context) (int, error) {
 	var (
 		total int
-		maxID string
+		page  paging.Page
 	)
 
+	// Set page select limit.
+	page.Limit = selectLimit
+
 	for {
-		// Fetch the next batch of media attachments up to next max ID.
-		attachments, err := m.state.DB.GetAttachments(ctx, maxID, selectLimit)
+		// Fetch the next batch of media attachments to next maxID.
+		attachments, err := m.state.DB.GetAttachments(ctx, &page)
 		if err != nil && !errors.Is(err, db.ErrNoEntries) {
 			return total, gtserror.Newf("error getting attachments: %w", err)
 		}
 
-		if len(attachments) == 0 {
-			// reached end.
+		// Get current max ID.
+		maxID := page.Max.Value
+
+		// If no attachments or the same group is returned, we reached the end.
+		if len(attachments) == 0 || maxID == attachments[len(attachments)-1].ID {
 			break
 		}
 
 		// Use last ID as the next 'maxID' value.
 		maxID = attachments[len(attachments)-1].ID
+		page.Max = paging.MaxID(maxID)
 
 		for _, media := range attachments {
 			// Check / prune unused media attachment.
@@ -183,8 +191,9 @@ func (m *Media) UncacheRemote(ctx context.Context, olderThan time.Time) (int, er
 			return total, gtserror.Newf("error getting remote attachments: %w", err)
 		}
 
-		if len(attachments) == 0 {
-			// reached end.
+		// If no attachments / same group is returned, we reached the end.
+		if len(attachments) == 0 ||
+			olderThan.Equal(attachments[len(attachments)-1].CreatedAt) {
 			break
 		}
 
@@ -215,23 +224,29 @@ func (m *Media) UncacheRemote(ctx context.Context, olderThan time.Time) (int, er
 func (m *Media) FixCacheStates(ctx context.Context) (int, error) {
 	var (
 		total int
-		maxID string
+		page  paging.Page
 	)
 
+	// Set page select limit.
+	page.Limit = selectLimit
+
 	for {
 		// Fetch the next batch of media attachments up to next max ID.
-		attachments, err := m.state.DB.GetRemoteAttachments(ctx, maxID, selectLimit)
+		attachments, err := m.state.DB.GetRemoteAttachments(ctx, &page)
 		if err != nil && !errors.Is(err, db.ErrNoEntries) {
 			return total, gtserror.Newf("error getting remote attachments: %w", err)
 		}
+		// Get current max ID.
+		maxID := page.Max.Value
 
-		if len(attachments) == 0 {
-			// reached end.
+		// If no attachments or the same group is returned, we reached the end.
+		if len(attachments) == 0 || maxID == attachments[len(attachments)-1].ID {
 			break
 		}
 
 		// Use last ID as the next 'maxID' value.
 		maxID = attachments[len(attachments)-1].ID
+		page.Max = paging.MaxID(maxID)
 
 		for _, media := range attachments {
 			// Check / fix required media cache states.
diff --git a/internal/db/bundb/emoji.go b/internal/db/bundb/emoji.go
index d1cb9dfbd..608cb6417 100644
--- a/internal/db/bundb/emoji.go
+++ b/internal/db/bundb/emoji.go
@@ -30,6 +30,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 	"github.com/superseriousbusiness/gotosocial/internal/state"
 	"github.com/superseriousbusiness/gotosocial/internal/util"
 	"github.com/uptrace/bun"
@@ -326,8 +327,11 @@ func (e *emojiDB) GetEmojisBy(ctx context.Context, domain string, includeDisable
 	return e.GetEmojisByIDs(ctx, emojiIDs)
 }
 
-func (e *emojiDB) GetEmojis(ctx context.Context, maxID string, limit int) ([]*gtsmodel.Emoji, error) {
-	var emojiIDs []string
+func (e *emojiDB) GetEmojis(ctx context.Context, page *paging.Page) ([]*gtsmodel.Emoji, error) {
+	maxID := page.GetMax()
+	limit := page.GetLimit()
+
+	emojiIDs := make([]string, 0, limit)
 
 	q := e.db.NewSelect().
 		Table("emojis").
@@ -349,8 +353,11 @@ func (e *emojiDB) GetEmojis(ctx context.Context, maxID string, limit int) ([]*gt
 	return e.GetEmojisByIDs(ctx, emojiIDs)
 }
 
-func (e *emojiDB) GetRemoteEmojis(ctx context.Context, maxID string, limit int) ([]*gtsmodel.Emoji, error) {
-	var emojiIDs []string
+func (e *emojiDB) GetRemoteEmojis(ctx context.Context, page *paging.Page) ([]*gtsmodel.Emoji, error) {
+	maxID := page.GetMax()
+	limit := page.GetLimit()
+
+	emojiIDs := make([]string, 0, limit)
 
 	q := e.db.NewSelect().
 		Table("emojis").
diff --git a/internal/db/bundb/media.go b/internal/db/bundb/media.go
index ce3c90083..ced38a588 100644
--- a/internal/db/bundb/media.go
+++ b/internal/db/bundb/media.go
@@ -27,6 +27,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 	"github.com/superseriousbusiness/gotosocial/internal/state"
 	"github.com/superseriousbusiness/gotosocial/internal/util"
 	"github.com/uptrace/bun"
@@ -232,7 +233,10 @@ func (m *mediaDB) DeleteAttachment(ctx context.Context, id string) error {
 	return err
 }
 
-func (m *mediaDB) GetAttachments(ctx context.Context, maxID string, limit int) ([]*gtsmodel.MediaAttachment, error) {
+func (m *mediaDB) GetAttachments(ctx context.Context, page *paging.Page) ([]*gtsmodel.MediaAttachment, error) {
+	maxID := page.GetMax()
+	limit := page.GetLimit()
+
 	attachmentIDs := make([]string, 0, limit)
 
 	q := m.db.NewSelect().
@@ -255,7 +259,10 @@ func (m *mediaDB) GetAttachments(ctx context.Context, maxID string, limit int) (
 	return m.GetAttachmentsByIDs(ctx, attachmentIDs)
 }
 
-func (m *mediaDB) GetRemoteAttachments(ctx context.Context, maxID string, limit int) ([]*gtsmodel.MediaAttachment, error) {
+func (m *mediaDB) GetRemoteAttachments(ctx context.Context, page *paging.Page) ([]*gtsmodel.MediaAttachment, error) {
+	maxID := page.GetMax()
+	limit := page.GetLimit()
+
 	attachmentIDs := make([]string, 0, limit)
 
 	q := m.db.NewSelect().
diff --git a/internal/db/emoji.go b/internal/db/emoji.go
index fed956933..26a881dbc 100644
--- a/internal/db/emoji.go
+++ b/internal/db/emoji.go
@@ -22,6 +22,7 @@ import (
 	"time"
 
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 )
 
 // EmojiAllDomains can be used as the `domain` value in a GetEmojis
@@ -47,10 +48,10 @@ type Emoji interface {
 	GetUseableEmojis(ctx context.Context) ([]*gtsmodel.Emoji, error)
 
 	// GetEmojis fetches all emojis with IDs less than 'maxID', up to a maximum of 'limit' emojis.
-	GetEmojis(ctx context.Context, maxID string, limit int) ([]*gtsmodel.Emoji, error)
+	GetEmojis(ctx context.Context, page *paging.Page) ([]*gtsmodel.Emoji, error)
 
 	// GetRemoteEmojis fetches all remote emojis with IDs less than 'maxID', up to a maximum of 'limit' emojis.
-	GetRemoteEmojis(ctx context.Context, maxID string, limit int) ([]*gtsmodel.Emoji, error)
+	GetRemoteEmojis(ctx context.Context, page *paging.Page) ([]*gtsmodel.Emoji, error)
 
 	// GetCachedEmojisOlderThan fetches all cached remote emojis with 'updated_at' greater than 'olderThan', up to a maximum of 'limit' emojis.
 	GetCachedEmojisOlderThan(ctx context.Context, olderThan time.Time, limit int) ([]*gtsmodel.Emoji, error)
diff --git a/internal/db/media.go b/internal/db/media.go
index 0ef03226b..a41f8970a 100644
--- a/internal/db/media.go
+++ b/internal/db/media.go
@@ -22,6 +22,7 @@ import (
 	"time"
 
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 )
 
 // Media contains functions related to creating/getting/removing media attachments.
@@ -42,10 +43,10 @@ type Media interface {
 	DeleteAttachment(ctx context.Context, id string) error
 
 	// GetAttachments fetches media attachments up to a given max ID, and at most limit.
-	GetAttachments(ctx context.Context, maxID string, limit int) ([]*gtsmodel.MediaAttachment, error)
+	GetAttachments(ctx context.Context, page *paging.Page) ([]*gtsmodel.MediaAttachment, error)
 
 	// GetRemoteAttachments fetches media attachments with a non-empty domain, up to a given max ID, and at most limit.
-	GetRemoteAttachments(ctx context.Context, maxID string, limit int) ([]*gtsmodel.MediaAttachment, error)
+	GetRemoteAttachments(ctx context.Context, page *paging.Page) ([]*gtsmodel.MediaAttachment, error)
 
 	// GetCachedAttachmentsOlderThan gets limit n remote attachments (including avatars and headers) older than
 	// the given time. These will be returned in order of attachment.created_at descending (i.e. newest to oldest).
diff --git a/internal/util/slices.go b/internal/util/slices.go
index 51d560dbd..0505229e5 100644
--- a/internal/util/slices.go
+++ b/internal/util/slices.go
@@ -17,6 +17,8 @@
 
 package util
 
+import "slices"
+
 // Deduplicate deduplicates entries in the given slice.
 func Deduplicate[T comparable](in []T) []T {
 	var (
@@ -47,6 +49,10 @@ func DeduplicateFunc[T any, C comparable](in []T, key func(v T) C) []T {
 		deduped = make([]T, 0, inL)
 	)
 
+	if key == nil {
+		panic("nil func")
+	}
+
 	for _, v := range in {
 		k := key(v)
 
@@ -66,6 +72,10 @@ func DeduplicateFunc[T any, C comparable](in []T, key func(v T) C) []T {
 // passing each item to 'get' and deduplicating the end result.
 // Compared to Deduplicate() this returns []K, NOT input type []T.
 func Collate[T any, K comparable](in []T, get func(T) K) []K {
+	if get == nil {
+		panic("nil func")
+	}
+
 	ks := make([]K, 0, len(in))
 	km := make(map[K]struct{}, len(in))
 
@@ -86,50 +96,25 @@ func Collate[T any, K comparable](in []T, get func(T) K) []K {
 
 // OrderBy orders a slice of given type by the provided alternative slice of comparable type.
 func OrderBy[T any, K comparable](in []T, keys []K, key func(T) K) {
-	var (
-		start  int
-		offset int
-	)
-
-	for i := 0; i < len(keys); i++ {
-		var (
-			// key at index.
-			k = keys[i]
-
-			// sentinel
-			// idx value.
-			idx = -1
-		)
-
-		// Look for model with key in slice.
-		for j := start; j < len(in); j++ {
-			if key(in[j]) == k {
-				idx = j
-				break
-			}
-		}
-
-		if idx == -1 {
-			// model with key
-			// was not found.
-			offset++
-			continue
-		}
-
-		// Update
-		// start
-		start++
+	if key == nil {
+		panic("nil func")
+	}
 
-		// Expected ID index.
-		exp := i - offset
+	// Create lookup of keys->idx.
+	m := make(map[K]int, len(in))
+	for i, k := range keys {
+		m[k] = i
+	}
 
-		if idx == exp {
-			// Model is in expected
-			// location, keep going.
-			continue
+	// Sort according to the reverse lookup.
+	slices.SortFunc(in, func(a, b T) int {
+		ai := m[key(a)]
+		bi := m[key(b)]
+		if ai < bi {
+			return -1
+		} else if bi < ai {
+			return +1
 		}
-
-		// Swap models at current and expected.
-		in[idx], in[exp] = in[exp], in[idx]
-	}
+		return 0
+	})
 }