# cogo
<img style="width: 100px;height: 100px;" width="100" height="100" src="docs/logo.png" />
Cogo is a high-performance library for programming stackful coroutines with which you can easily develop and maintain massive concurrent programs. It can be thought as the Rust version of the popular [Goroutine][go].
> Initial code frok from [May](https://github.com/Xudong-Huang/may) and we add Many improvements(Inspired by ```Golang``` [parking_lot](https://github.com/Amanieu/parking_lot) and [crossbeam](https://github.com/crossbeam-rs/crossbeam)) and [hyper](https://github.com/hyperium/hyper) and more...
## Performance
* platform(16CPU/32 thread AMD Ryzen 9 5950X,32GB mem,Os:Unbutu-20.04)
* [TechEmpowerBench fork project](https://github.com/zhuxiujia/FrameworkBenchmarks)
# cogo crates
> Cogo STD standard library
* ``` cogo/std/http/server ``` An HTTP server is available(Body parsing upcoming)
* ``` cogo/std/http/client ``` An HTTP Client(TODO) upcoming
* ``` cogo/std/queue ``` Basic queue data structures
* ``` cogo/std/sync ``` Includes ``` Mutex/RwLock/WaitGroup/Semphore/channel(Bounded, unbounded, chan!()) ```...and more..
* ``` cogo/std/defer ``` Defers evaluation of a block of code until the end of the scope.
* ``` cogo/std/map ``` Provides the same concurrency map as Golang, with ```SyncHashMap``` and ```SyncBtreeMap```.It is suitable for concurrent environments with too many reads and too few writes
> Crates based on cogo implementation
* [cdbc](https://github.com/co-rs/cdbc) Database Drivers include mysql, Postgres, AND SQLite
* [fast_log](https://github.com/co-rs/fast_log) High-performance log impl
* [cogo-redis](https://github.com/co-rs/cogo-redis) TODO: an redis client.
* [cogo-grpc](https://github.com/co-rs/cogo-grpc) TODO: an grpc server/client.
## Features
* The stackful coroutine implementation is based on [generator][generator];
* Support schedule on a configurable number of threads for multi-core systems;
* Support coroutine version of a local storage ([CLS][cls]);
* Support efficient asynchronous network I/O;
* Support efficient timer management;
* Support standard synchronization primitives, a semaphore, an MPMC channel, etc;
* Support cancellation of coroutines;
* Support graceful panic handling that will not affect other coroutines;
* Support scoped coroutine creation;
* Support general selection for all the coroutine API;
* All the coroutine API are compatible with the standard library semantics;
* All the coroutine API can be safely called in multi-threaded context;
* Both stable, beta, and nightly channels are supported;
* x86_64 GNU/Linux, x86_64 Windows, x86_64 Mac, aarch64 Linux OS are supported.
* Support High performance channel(2 times better performance, Support the buffer);
* Support WaitGroup Support
* Support defer!()
## Usage
A naive echo server implemented with Cogo:
```rust
#[macro_use]
extern crate cogo;
use cogo::net::TcpListener;
use std::io::{Read, Write};
fn main() {
let listener = TcpListener::bind("127.0.0.1:8000").unwrap();
while let Ok((mut stream, _)) = listener.accept() {
go!(move || {
let mut buf = vec![0; 1024 * 16]; // alloc in heap!
while let Ok(n) = stream.read(&mut buf) {
if n == 0 {
break;
}
stream.write_all(&buf[0..n]).unwrap();
}
});
}
}
```
## More examples
### The I/O heavy bound examples
* [An echo server](examples/src/echo.rs)
* [An echo client](examples/src/echo_client.rs)
* [simple HTTP](examples/src/http.rs)
* [simple HTTPS](examples/src/https.rs)
* [tiny HTTP](examples/src/http-tiny.rs)
* [WebSockets](examples/src/websocket.rs)
## Caveat
There is a detailed [document][caveat] that describes Cogo's main restrictions. In general, there are four things you should follow when writing programs that use coroutines:
* Don't call thread-blocking API (It will hurt the performance);
* Carefully use Thread Local Storage (access TLS in coroutine might trigger undefined behavior).
> It's considered **unsafe** with the following pattern:
> ```rust
> set_tls();
> // Or another coroutine API that would cause scheduling:
> coroutine::yield_now();
> use_tls();
> ```
> but it's **safe** if your code is not sensitive about the previous state of TLS. Or there is no coroutines scheduling between **set** TLS and **use** TLS.
* Don't run CPU bound tasks for long time, but it's ok if you don't care about fairness;
* Don't exceed the coroutine stack. There is a guard page for each coroutine stack. When stack overflow occurs, it will trigger segment fault error.
**Note:**
> The first three rules are common when using cooperative asynchronous libraries in Rust. Even using a futures-based system also have these limitations. So what you should really focus on is a coroutine stack size, make sure it's big enough for your applications.
## How to tune a stack size
```rust
cogo::config().set_stack_size(8*1024);//default is 4k=4*1024,Multiple of 4kb is recommended
```