melt-umn / ablec-goconcurrency

An implementation in silver to add channels and goroutine equivalents from Go to ableC

Go Concurrency for C

This extension will allow for concurrency similar to that found in the language go into ableC for use in C programs. Concurrent goroutines can be called from functions. It will also allow for the creation of the channel data type in order to pass data to and from this concurrent processes.

Creating Channels

Data is passed back and forth between concurrent functions using channels, exactly as it is in go. Channels are defined using the new keyword chan as

Channel<int> *ch = open_chan<int>()

for an integer channel. Multiple channels are defined similarly as

Channel<int> *ch1 = open_chan<int>()
Channel<int> *ch2 = open_chan<int>()
Channel<int> *ch3 = open_chan<int>()

Channels can be passed into functions like any other data type.

int printTwice (chan int ch2) {}

The operator <- is used to pass data into a channel or to read from one.

int foo;
ch1 <- 4;
foo <- ch2;

Spawing Concurrent Functions

We call functions to run concurrently using the keyword spawn. These concurrent calls work similarly to the goroutines in go and spawn is analogous to go's go keyword. spawn works for calling defined functions:

int example (chan int ch2) {
  ch2 <- 1;
  return 0;
}

int main (int argc, char **argv) {
  Channel<int> *ch = open chan;
  spawn example(ch);
  <-ch;
  return 0; 
}

In both of these cases <-ch' is used so main()waits for the concurrent function to push some data to the channel before returning. Without this,main` would return and end execution before the concurrent functions are able to do anything.

For more examples see the examples directory.

Select blocks

One can make a select statement that waits for one of any number of channel operations to happen, or on default proceeds on without blocking.

select {
  case ch <- 2:
  case v = <-ch:
  case <-ch:
  default:
}

Select statements are not randomized as in Go. In Go, if more than one channel operation could happen when a select block is reached, it will pick one at random. Our extension will always pick the first available statement in order, top-down.

Status

Full functionality for non-buffered channels, non-closures.

MDA and MDFA pass.

Some errors could be made to be nicer strings, some additional error checking could be added with more failure cases.