# constrained-connection
Simulate constrained network connections.
Can be used to benchmark networking logic build on top of a stream oriented
connection (e.g. TCP). Create a connection by specifying its bandwidth as
well as its round trip time (delay). The connection will delay each bytes
chunk by the configured delay and allow at most [bandwidth-delay
product](https://en.wikipedia.org/wiki/Bandwidth-delay_product) number of
bytes on the *wire* enforcing backpressure.
```rust
let msg = vec![0; 10 * 1024 * 1024];
let msg_clone = msg.clone();
let start = Instant::now();
let mut pool = futures::executor::LocalPool::new();
let bandwidth = 1_000_000_000;
let rtt = Duration::from_micros(100);
let (mut a, mut b) = Connection::new_constrained(bandwidth, rtt);
pool.spawner().spawn_obj(async move {
a.write_all(&msg_clone).await.unwrap();
}.boxed().into()).unwrap();
pool.run_until(async {
let mut received_msg = Vec::new();
b.read_to_end(&mut received_msg).await.unwrap();
assert_eq!(msg, received_msg);
});
let duration = start.elapsed();
println!(
"Bandwidth {} KiB/s, RTT {:.5} s, Payload length {} KiB, duration {:.5} s",
bandwidth / 1024, rtt.as_secs_f64(), msg.len() / 1024, duration.as_secs_f64(),
);
```
For now, as the library is not properly optimized, you can not simulate high
speed networks. Execute the `examples/accuracy.rs` binary for details.
```bash
$ cargo run --example accuracy --release
Name Bandwidth RTT Payload Duration Acurracy
Satellite Network 500 KiB/s 0.90000 s 10240 KiB 164.49 s 1.00 %
Residential DSL 1953 KiB/s 0.05000 s 10240 KiB 42.97 s 1.02 %
Mobile HSDPA 5859 KiB/s 0.10000 s 10240 KiB 14.19 s 1.01 %
Residential ADSL2+ 19531 KiB/s 0.05000 s 10240 KiB 4.33 s 1.03 %
Residential Cable Internet 195312 KiB/s 0.02000 s 10240 KiB 0.46 s 1.07 %
GBit LAN 976562 KiB/s 0.00010 s 10240 KiB 0.26 s 3.16 %
High Speed Terrestiral Net 976562 KiB/s 0.00100 s 10240 KiB 0.13 s 1.56 %
Ultra High Speed LAN 97656250 KiB/s 0.00003 s 10240 KiB 0.01 s 16.08 %
```
License: Apache-2.0 OR MIT