From c3e907af7d58607d134ff667ddd316b65e8f5efe Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 24 Jul 2024 20:14:31 +0200
Subject: [PATCH] Warn if the download buffer is full

(cherry picked from commit f6a9a71b38b25d6c9fb0b9a7fbf0eccf99fa5520)
---
 src/libstore/filetransfer.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index ccae7e45b..18eb64573 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -859,6 +859,8 @@ void FileTransfer::download(
            sender.) */
         if (state->data.size() > fileTransferSettings.downloadBufferSize) {
             debug("download buffer is full; going to sleep");
+            static bool haveWarned = false;
+            warnOnce(haveWarned, "download buffer is full; consider increasing the 'download-buffer-size' setting");
             state.wait_for(state->request, std::chrono::seconds(10));
         }