From 0c85717f8fcc35dd0b3687bdf00d710c2cfea71b Mon Sep 17 00:00:00 2001
From: Evgeny Poberezkin <evgeny@poberezkin.com>
Date: Sun, 7 Sep 2025 09:04:17 +0100
Subject: [PATCH] smp server: faster export

---
 src/Simplex/Messaging/Server.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Simplex/Messaging/Server.hs b/src/Simplex/Messaging/Server.hs
index 23ce85035..fa6d17eee 100644
--- a/src/Simplex/Messaging/Server.hs
+++ b/src/Simplex/Messaging/Server.hs
@@ -2124,7 +2124,7 @@ exportMessages tty ms f drainMsgs = do
       msgs <-
         unsafeRunStore q "saveQueueMsgs" $
           getQueueMessages_ drainMsgs q =<< getMsgQueue ms q False
-      BLD.hPutBuilder h $ encodeMessages (recipientId q) msgs
+      unless (null msgs) $ BLD.hPutBuilder h $ encodeMessages (recipientId q) msgs
       pure $ Sum $ length msgs
     encodeMessages rId = mconcat . map (\msg -> BLD.byteString (strEncode $ MLRv3 rId msg) <> BLD.char8 '\n')