mirror of
https://github.com/wabbajack-tools/wabbajack.git
synced 2024-08-30 18:42:17 +00:00
42 lines
1.7 KiB
Markdown
42 lines
1.7 KiB
Markdown
### Overview of CSP (Communicating Sequential Processes) for the C# programmer
|
|
|
|
#### What is CSP?
|
|
Communicating Sequential processes is a programming model invented in 1978 by Tony Hoare, who described a process
|
|
of computation where hundreds or thousands of small processes communicate via channels. Think of this process like
|
|
a assembly line. Each worker in the factory is a process, and the conveyor belts are the channels. The workers don't need
|
|
to know where a part came from, or where it's going, they simply take one item off the belt, perform an operation and pass
|
|
the item on to another belt. This analogy works quite well, and the following observations about a factory also apply to
|
|
CSP:
|
|
|
|
* Multiple workers can pull from the same belt (channel/queue)
|
|
* Multiple workers can put work onto the belt
|
|
* Belts can buffer items, for slow consumers, but at some point they backup and block the writer
|
|
* A worker can pull/push to multiple belts.
|
|
|
|
|
|
#### What does this look like in C#?
|
|
|
|
The basic unit of CSP in this library is the channel:
|
|
|
|
```
|
|
var chan = Channel.Create()
|
|
```
|
|
|
|
Without any other parameters this creates a channel with a size of 0, so every pending put must be matched
|
|
1:1 with a take. This creates a syncronization point. Channels are fully async and thread-safe:
|
|
|
|
```
|
|
public async Task TestTakePutBlocking()
|
|
{
|
|
var channel = Channel.Create<int>();
|
|
// Channel size is 0, so we can't await, because we'd never complete
|
|
var ptask = channel.Put(1);
|
|
|
|
// Now the put is dispatched to the scheduler because we've taken the value
|
|
var (open, val) = await channel.Take();
|
|
|
|
Assert.AreEqual(1, val);
|
|
Assert.IsTrue(open);
|
|
Assert.IsTrue(await ptask);
|
|
}
|
|
``` |