ddidderr
0f10108438
Centralize the bulk-transfer sizing in config.rs and bump the values used
on both ends of a QUIC connection:
- CHUNK_SIZE: 32 MiB -> 128 MiB
- QUIC_CONNECTION_DATA_WINDOW: 64 MiB -> 256 MiB
- QUIC_STREAM_DATA_WINDOW: 32 MiB -> 128 MiB
- QUIC_MAX_SEND_BUFFER_SIZE: 32 MiB -> 128 MiB
- QUIC_INITIAL_CONGESTION_WINDOW: 1 MiB -> 4 MiB
- FILE_TRANSFER_BUFFER_SIZE: 64 KiB -> 1 MiB (new constant)
The previous 32 MiB stream window was already comfortably above the
bandwidth-delay product of a sub-millisecond LAN at 2.5 GbE. The further
bump is deliberately generous: the goal is to push flow control and
per-syscall overhead far enough out of the way that they cannot be the
suspect when isolating the remaining LAN download bottleneck (disk, NIC,
or s2n-quic platform offload on the sending host). Memory pressure from
the larger windows is not observable on a desktop client moving GB-sized
games.
stream_file_bytes previously read the local file in 64 KiB chunks. At
multi-Gbit/s send rates that produced many thousands of disk reads per
second; bumping to 1 MiB keeps the per-file syscall load modest with no
measurable latency cost on streamed bulk transfers. The buffer size lives
in config.rs as FILE_TRANSFER_BUFFER_SIZE so it stays adjustable from one
place.
Also add a started/MiB-per-second log line at info level when a file
finishes streaming. This matches the S37 measurement methodology already
used in the peer-cli harness and makes per-file send throughput visible in
normal operation.
The peer-cli extended-scenarios harness uses CHUNK_SIZE as the tolerance
bound for chunk-boundary variance in its assertions, so its constant is
bumped to match. The multi-chunk planning unit test is rewritten to
reference CHUNK_SIZE symbolically (CHUNK_SIZE * 3 + CHUNK_SIZE / 2)
instead of a hardcoded 120 MiB; the previous literal would silently
degrade into a single-chunk test at the new chunk size and stop
exercising the spread-across-peers code path.
Test Plan:
- just fmt
- just clippy
- just test
- python3 crates/lanspread-peer-cli/scripts/run_extended_scenarios.py S37 \
--build-image
- python3 crates/lanspread-peer-cli/scripts/run_extended_scenarios.py S37
Refs: local LAN download performance investigation on 2026-05-20.
Depends-on: d7f7dc737e (QUIC UDP socket buffer sizing).
lanspread
Description
Peer-to-peer game library sharing for LAN parties.
- Peers let users browse and download games from each other
- they discover each other on the local network via mDNS
- they exchange library metadata over QUIC
Ships as a Tauri desktop app.
Development
Prerequisites
# install Tauri CLI
cargo install tauri-cli
# install Deno with a package manager or from https://deno.land/
Build or Run
# build
just build
# run
just run
# test
just test
Scripted peer harness
crates/lanspread-peer-cli runs the peer runtime without the GUI and speaks
JSONL on stdin/stdout. It is intended for automated multi-peer smoke tests.
just peer-cli-build
just peer-cli-image
just peer-cli-run alpha