[feature] Read + Write tombstones for deleted Actors (#1005)

* [feature] Read + Write tombstones for deleted Actors

* copyTombstone

* update to use resultcache instead of old ttl cache

Signed-off-by: kim <grufwub@gmail.com>

* update go-cache library to fix result cache capacity / ordering bugs

Signed-off-by: kim <grufwub@gmail.com>

* bump go-cache/v3 to v3.1.6 to fix bugs

Signed-off-by: kim <grufwub@gmail.com>

* switch on status code

* better explain ErrGone reasoning

Signed-off-by: kim <grufwub@gmail.com>
Co-authored-by: kim <grufwub@gmail.com>

5 files changed, 206 insertions, 1 deletions

diff --git a/internal/db/bundb/bundb.go b/internal/db/bundb/bundb.go
index 02522e6f7..43e9a07c9 100644
--- a/internal/db/bundb/bundb.go
+++ b/internal/db/bundb/bundb.go
@@ -88,6 +88,7 @@ type DBService struct {
 	db.Status
 	db.Timeline
 	db.User
+	db.Tombstone
 	conn *DBConn
 }
 
@@ -181,12 +182,16 @@ func NewBunDBService(ctx context.Context) (db.DB, error) {
 	status := &statusDB{conn: conn, cache: cache.NewStatusCache()}
 	emoji := &emojiDB{conn: conn, cache: cache.NewEmojiCache()}
 	timeline := &timelineDB{conn: conn}
+	tombstone := &tombstoneDB{conn: conn}
 
 	// Setup DB cross-referencing
 	accounts.status = status
 	status.accounts = accounts
 	timeline.status = status
 
+	// Initialize db structs
+	tombstone.init()
+
 	ps := &DBService{
 		Account: accounts,
 		Admin: &adminDB{
@@ -228,7 +233,8 @@ func NewBunDBService(ctx context.Context) (db.DB, error) {
 			conn:  conn,
 			cache: userCache,
 		},
-		conn: conn,
+		Tombstone: tombstone,
+		conn:      conn,
 	}
 
 	// we can confidently return this useable service now
diff --git a/internal/db/bundb/migrations/20221108142419_create_account_tombstones.go b/internal/db/bundb/migrations/20221108142419_create_account_tombstones.go
new file mode 100644
index 000000000..9f0b7b8e9
--- /dev/null
+++ b/internal/db/bundb/migrations/20221108142419_create_account_tombstones.go
@@ -0,0 +1,57 @@
+/*
+   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 migrations
+
+import (
+	"context"
+
+	gtsmodel "github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/uptrace/bun"
+)
+
+func init() {
+	up := func(ctx context.Context, db *bun.DB) error {
+		return db.RunInTx(ctx, nil, func(ctx context.Context, tx bun.Tx) error {
+			if _, err := tx.NewCreateTable().Model(&gtsmodel.Tombstone{}).IfNotExists().Exec(ctx); err != nil {
+				return err
+			}
+
+			if _, err := tx.
+				NewCreateIndex().
+				Model(&gtsmodel.Tombstone{}).
+				Index("tombstone_uri_idx").
+				Column("uri").
+				Exec(ctx); err != nil {
+				return err
+			}
+
+			return nil
+		})
+	}
+
+	down := func(ctx context.Context, db *bun.DB) error {
+		return db.RunInTx(ctx, nil, func(ctx context.Context, tx bun.Tx) error {
+			return nil
+		})
+	}
+
+	if err := Migrations.Register(up, down); err != nil {
+		panic(err)
+	}
+}
diff --git a/internal/db/bundb/tombstone.go b/internal/db/bundb/tombstone.go
new file mode 100644
index 000000000..35032f43a
--- /dev/null
+++ b/internal/db/bundb/tombstone.go
@@ -0,0 +1,101 @@
+/*
+   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 bundb
+
+import (
+	"context"
+	"time"
+
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/uptrace/bun"
+
+	"codeberg.org/gruf/go-cache/v3/result"
+)
+
+type tombstoneDB struct {
+	conn  *DBConn
+	cache *result.Cache[*gtsmodel.Tombstone]
+}
+
+func (t *tombstoneDB) init() {
+	// Initialize tombstone result cache
+	t.cache = result.NewSized([]string{
+		"ID",
+		"URI",
+	}, func(t1 *gtsmodel.Tombstone) *gtsmodel.Tombstone {
+		t2 := new(gtsmodel.Tombstone)
+		*t2 = *t1
+		return t2
+	}, 1000)
+
+	// Set cache TTL and start sweep routine
+	t.cache.SetTTL(time.Minute*5, false)
+	t.cache.Start(time.Second * 10)
+}
+
+func (t *tombstoneDB) GetTombstoneByURI(ctx context.Context, uri string) (*gtsmodel.Tombstone, db.Error) {
+	return t.cache.Load("URI", func() (*gtsmodel.Tombstone, error) {
+		var tomb gtsmodel.Tombstone
+
+		q := t.conn.
+			NewSelect().
+			Model(&tomb).
+			Where("? = ?", bun.Ident("tombstone.uri"), uri)
+
+		if err := q.Scan(ctx); err != nil {
+			return nil, t.conn.ProcessError(err)
+		}
+
+		return &tomb, nil
+	}, uri)
+}
+
+func (t *tombstoneDB) TombstoneExistsWithURI(ctx context.Context, uri string) (bool, db.Error) {
+	tomb, err := t.GetTombstoneByURI(ctx, uri)
+	if err == db.ErrNoEntries {
+		err = nil
+	}
+	return (tomb != nil), err
+}
+
+func (t *tombstoneDB) PutTombstone(ctx context.Context, tombstone *gtsmodel.Tombstone) db.Error {
+	return t.cache.Store(tombstone, func() error {
+		_, err := t.conn.
+			NewInsert().
+			Model(tombstone).
+			Exec(ctx)
+		return t.conn.ProcessError(err)
+	})
+}
+
+func (t *tombstoneDB) DeleteTombstone(ctx context.Context, id string) db.Error {
+	if _, err := t.conn.
+		NewDelete().
+		TableExpr("? AS ?", bun.Ident("tombstones"), bun.Ident("tombstone")).
+		Where("? = ?", bun.Ident("tombstone.id"), id).
+		Exec(ctx); err != nil {
+		return t.conn.ProcessError(err)
+	}
+
+	// Invalidate from cache by ID
+	t.cache.Invalidate("ID", id)
+
+	return nil
+}
diff --git a/internal/db/db.go b/internal/db/db.go
index 52a76ecdb..8ec70d8b2 100644
--- a/internal/db/db.go
+++ b/internal/db/db.go
@@ -45,6 +45,7 @@ type DB interface {
 	Status
 	Timeline
 	User
+	Tombstone
 
 	/*
 		USEFUL CONVERSION FUNCTIONS
diff --git a/internal/db/tombstone.go b/internal/db/tombstone.go
new file mode 100644
index 000000000..e99632cb7
--- /dev/null
+++ b/internal/db/tombstone.go
@@ -0,0 +1,40 @@
+/*
+   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 db
+
+import (
+	"context"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// Tombstone contains functionality for storing + retrieving tombstones for remote AP Activities + Objects.
+type Tombstone interface {
+	// GetTombstoneByURI attempts to fetch a tombstone by the given URI.
+	GetTombstoneByURI(ctx context.Context, uri string) (*gtsmodel.Tombstone, Error)
+
+	// TombstoneExistsWithURI returns true if a tombstone with the given URI exists.
+	TombstoneExistsWithURI(ctx context.Context, uri string) (bool, Error)
+
+	// PutTombstone creates a new tombstone in the database.
+	PutTombstone(ctx context.Context, tombstone *gtsmodel.Tombstone) Error
+
+	// DeleteTombstone deletes a tombstone with the given ID.
+	DeleteTombstone(ctx context.Context, id string) Error
+}