From 533054b8a0221e746e34682fdbd245da3db32f17 Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Sun, 16 Apr 2023 23:11:44 +0300
Subject: [PATCH] Add option to disable backfilling in big guilds

---
 config/bridge.go    | 1 +
 config/upgrade.go   | 1 +
 example-config.yaml | 5 +++++
 user.go             | 4 +++-
 4 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/config/bridge.go b/config/bridge.go
index 44ef74c..495dd3b 100644
--- a/config/bridge.go
+++ b/config/bridge.go
@@ -71,6 +71,7 @@ type BridgeConfig struct {
 			Initial BackfillLimitPart `yaml:"initial"`
 			Missed  BackfillLimitPart `yaml:"missed"`
 		} `yaml:"forward_limits"`
+		MaxGuildMembers int `yaml:"max_guild_members"`
 	} `yaml:"backfill"`
 
 	Encryption bridgeconfig.EncryptionConfig `yaml:"encryption"`
diff --git a/config/upgrade.go b/config/upgrade.go
index 8b10beb..b4034da 100644
--- a/config/upgrade.go
+++ b/config/upgrade.go
@@ -72,6 +72,7 @@ func DoUpgrade(helper *up.Helper) {
 	helper.Copy(up.Int, "bridge", "backfill", "forward_limits", "initial", "channel")
 	helper.Copy(up.Int, "bridge", "backfill", "forward_limits", "missed", "dm")
 	helper.Copy(up.Int, "bridge", "backfill", "forward_limits", "missed", "channel")
+	helper.Copy(up.Int, "bridge", "backfill", "max_guild_members")
 	helper.Copy(up.Bool, "bridge", "encryption", "allow")
 	helper.Copy(up.Bool, "bridge", "encryption", "default")
 	helper.Copy(up.Bool, "bridge", "encryption", "require")
diff --git a/example-config.yaml b/example-config.yaml
index 8ce1a8e..d6e0028 100644
--- a/example-config.yaml
+++ b/example-config.yaml
@@ -186,6 +186,7 @@ bridge:
         # Optional extra text sent when joining a management room.
         additional_help: ""
 
+    # Settings for backfilling messages.
     backfill:
         # Limits for forward backfilling.
         forward_limits:
@@ -202,6 +203,10 @@ bridge:
             missed:
                 dm: 0
                 channel: 0
+        # Maximum members in a guild to enable backfilling. Set to -1 to disable limit.
+        # This can be used as a rough heuristic to disable backfilling in channels that are too active.
+        # Currently only applies to missed message backfill.
+        max_guild_members: -1
 
     # End-to-bridge encryption support options.
     #
diff --git a/user.go b/user.go
index f5fa83e..e6ea825 100644
--- a/user.go
+++ b/user.go
@@ -843,7 +843,9 @@ func (user *User) handleGuild(meta *discordgo.Guild, timestamp time.Time, isInSp
 				}
 			} else {
 				portal.UpdateInfo(user, ch)
-				portal.ForwardBackfillMissed(user, ch)
+				if user.bridge.Config.Bridge.Backfill.MaxGuildMembers < 0 || meta.MemberCount < user.bridge.Config.Bridge.Backfill.MaxGuildMembers {
+					portal.ForwardBackfillMissed(user, ch)
+				}
 			}
 		}
 	}