aquatic/README.md
Joakim Frostegård 67c4c02bbd
aquatic_ws: mio: replace native_tls with rustls, rewrite connection state logic completely (#38)
* ws: mio: use rustls, rewrite Connection logic

* ws: mio: improve poll register/deregister handling

* ws: mio: work on type-level poll registry safety

* ws: mio: use stronger poll registry type-level guarantees

* ws: mio: fix stream reading

* ws: clean up, run fmt

* ws: mio: don't require registered connection for writing, improve docs

* ws: mio: add Connection::get_meta(), make Connection::meta private

* ws: mio: add ConnectionMap struct; remove utils.rs

* ws: mio: move token counter into ConnectionMap, improve docs

* ws: mio: connection: move Connection struct above state structs

* Update TODO

* ws: fix build errors

* ws: upgrade to tungstenite 0.16

* ws load test: don't panic on Close message; print shorter errors

* ws: fix socket worker bugs, add log statements

* ws: mio: wait for write availability if would block for ws messages

* Update README

* ws: mio: limit channels & queues; read 1 message only; other fixes

* ws: mio: send local responses each event; decrease channel size

* Update TODO

* ws: mio: limit ws send queue, fixing memory leak; limit pending messages

Also change some log output levels and run rustfmt

* Update TODO

* Update TODO
2021-12-16 16:09:36 +01:00

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Markdown

# aquatic
[![CargoBuildAndTest](https://github.com/greatest-ape/aquatic/actions/workflows/cargo-build-and-test.yml/badge.svg)](https://github.com/greatest-ape/aquatic/actions/workflows/cargo-build-and-test.yml) [![Test HTTP, UDP and WSS file transfer](https://github.com/greatest-ape/aquatic/actions/workflows/test-transfer.yml/badge.svg)](https://github.com/greatest-ape/aquatic/actions/workflows/test-transfer.yml)
Blazingly fast, multi-threaded BitTorrent tracker written in Rust, consisting
of sub-implementations for different protocols:
[BitTorrent over UDP]: https://libtorrent.org/udp_tracker_protocol.html
[BitTorrent over HTTP]: https://wiki.theory.org/index.php/BitTorrentSpecification#Tracker_HTTP.2FHTTPS_Protocol
[WebTorrent]: https://github.com/webtorrent
[rustls]: https://github.com/rustls/rustls
[native-tls]: https://github.com/sfackler/rust-native-tls
[mio]: https://github.com/tokio-rs/mio
[glommio]: https://github.com/DataDog/glommio
| Name | Protocol | OS requirements |
|--------------|--------------------------------------------|------------------------------------------------------------|
| aquatic_udp | [BitTorrent over UDP] | Unix-like |
| aquatic_http | [BitTorrent over HTTP] with TLS ([rustls]) | Linux 5.8+ |
| aquatic_ws | [WebTorrent] over TLS ([rustls]) | Unix-like with [mio] (default) / Linux 5.8+ with [glommio] |
## Usage
### Prerequisites
- Install Rust with [rustup](https://rustup.rs/) (stable is recommended)
- Install cmake with your package manager (e.g., `apt-get install cmake`)
- Unless you're planning to only run the cross-platform mio based
implementations, make sure locked memory limits are sufficient.
You can do this by adding the following lines to `/etc/security/limits.conf`,
and then logging out and back in:
```
* hard memlock 512
* soft memlock 512
```
- Clone this git repository and enter it
### Compiling
Compile the implementations that you are interested in:
```sh
# Tell Rust to enable support for all CPU extensions present on current CPU
# except for those relating to AVX-512. This is necessary for aquatic_ws and
# recommended for the other implementations.
. ./scripts/env-native-cpu-without-avx-512
cargo build --release -p aquatic_udp
cargo build --release -p aquatic_http
cargo build --release -p aquatic_ws
cargo build --release -p aquatic_ws --features "with-glommio" --no-default-features
```
### Running
Begin by generating configuration files. They differ between protocols.
```sh
./target/release/aquatic_udp -p > "aquatic-udp-config.toml"
./target/release/aquatic_http -p > "aquatic-http-config.toml"
./target/release/aquatic_ws -p > "aquatic-ws-config.toml"
```
Make adjustments to the files. You will likely want to adjust `address`
(listening address) under the `network` section.
`aquatic_http` requires configuring a TLS certificate file as well as a
private key file to run. More information is available in the
corresponding subsection of this document.
Once done, run the tracker:
```sh
./target/release/aquatic_udp -c "aquatic-udp-config.toml"
./target/release/aquatic_http -c "aquatic-http-config.toml"
./target/release/aquatic_ws -c "aquatic-ws-config.toml"
```
### Configuration values
Starting a lot more socket workers than request workers is recommended. All
implementations are heavily IO-bound and spend most of their time reading from
and writing to sockets. This part is handled by the `socket_workers`, which
also do parsing, serialisation and access control. They pass announce and
scrape requests to the `request_workers`, which update internal tracker state
and pass back responses.
#### Access control
Access control by info hash is supported for all protocols. The relevant part
of configuration is:
```toml
[access_list]
mode = 'off' # Change to 'black' (blacklist) or 'white' (whitelist)
path = '' # Path to text file with newline-delimited hex-encoded info hashes
```
The file is read on start and when the program receives `SIGUSR1`. If initial
parsing fails, the program exits. Later failures result in in emitting of
an error-level log message, while successful updates of the access list result
in emitting of an info-level log message.
#### More information
More documentation of the various configuration options might be available
under `src/config.rs` in directories `aquatic_udp`, `aquatic_http` and
`aquatic_ws`.
## Details on implementations
### aquatic_udp: UDP BitTorrent tracker
Aims to implements the
[UDP BitTorrent protocol](https://libtorrent.org/udp_tracker_protocol.html),
except that it:
* Doesn't care about IP addresses sent in announce requests. The packet
source IP is always used.
* Doesn't track of the number of torrent downloads (0 is always sent).
Supports IPv4 and IPv6.
#### Performance
![UDP BitTorrent tracker throughput comparison](./documents/aquatic-udp-load-test-illustration-2021-11-28.png)
More details are available [here](./documents/aquatic-udp-load-test-2021-11-28.pdf).
#### Optimisation attempts that didn't work out
* Using glommio
* Using io-uring
* Using zerocopy + vectored sends for responses
### aquatic_http: HTTP BitTorrent tracker
[HTTP BitTorrent protocol]: https://wiki.theory.org/index.php/BitTorrentSpecification#Tracker_HTTP.2FHTTPS_Protocol
Aims for compatibility with the [HTTP BitTorrent protocol], with some exceptions:
* Only runs over TLS
* Doesn't track of the number of torrent downloads (0 is always sent)
* Doesn't allow full scrapes, i.e. of all registered info hashes
`aquatic_http` has not been tested as much as `aquatic_udp` but likely works
fine.
#### TLS
A TLS certificate file (DER-encoded X.509) and a corresponding private key file
(DER-encoded ASN.1 in either PKCS#8 or PKCS#1 format) are required. Set their
paths in the configuration file, e.g.:
```toml
[network]
address = '0.0.0.0:3000'
tls_certificate_path = './cert.pem'
tls_private_key_path = './key.pem'
```
### aquatic_ws: WebTorrent tracker
Aims for compatibility with [WebTorrent](https://github.com/webtorrent)
clients, with some exceptions:
* Only runs over TLS
* Doesn't track of the number of torrent downloads (0 is always sent).
* Doesn't allow full scrapes, i.e. of all registered info hashes
For TLS setup instructions, please see `aquatic_http` TLS section above.
#### Benchmarks
[wt-tracker]: https://github.com/Novage/wt-tracker
[bittorrent-tracker]: https://github.com/webtorrent/bittorrent-tracker
The following benchmark is not very realistic, as it simulates a small number
of clients, each sending a large number of requests. Nonetheless, I think that
it gives a useful indication of relative performance.
Server responses per second, best result in bold:
| workers | aquatic | [wt-tracker] | [bittorrent-tracker] |
|---------|------------|--------------|----------------------|
| 1 | n/a | __117k__ | 45k |
| 2 | __225k__ | n/a | n/a |
| 4 | __627k__ | n/a | n/a |
| 6 | __831k__* | n/a | n/a |
| 8 | __1209k__* | n/a | n/a |
| 10 | __1455k__* | n/a | n/a |
| 12 | __1650k__* | n/a | n/a |
| 14 | __1804k__* | n/a | n/a |
| 16 | __1789k__* | n/a | n/a |
\* Using a VPS with 32 vCPUs. The other measurements were made using a 16 vCPU VPS.
Please refer to `documents/aquatic-ws-load-test-2021-08-18.pdf` for more details.
__Note__: these benchmarks were made with the mio-based implementation.
## Load testing
There are load test binaries for all protocols. They use a CLI structure
similar to the trackers and support generation and loading of configuration
files.
To run, first start the tracker that you want to test. Then run the
corresponding load test binary:
```sh
./scripts/run-load-test-udp.sh
./scripts/run-load-test-http.sh
./scripts/run-load-test-ws.sh
```
To fairly compare HTTP performance to opentracker, set keepalive to false in
`aquatic_http` settings.
## Copyright and license
Copyright (c) 2020-2021 Joakim Frostegård
Distributed under Apache 2.0 license (details in `LICENSE` file.)
## Trivia
The tracker is called aquatic because it thrives under a torrent of bits ;-)