Awesome

cgo-channels

A quick program to explore the idea of sending data to a Go channel from C.

The program uses select across two channels:

stringChannel: this channel passes strings from C to Go.

messageChannel: passes Message data structures.

The publishMessage takes a C Message (as defined in message.h) and turns it into a Go Message, then sends it over the messageChannel.

This program makes use of cgo.

Usage

Fetch the repo:

% go get github.com/matiasinsaurralde/cgo-channels

Chdir somewhere (~ in this case) and build the program:

% cd ~
% go build github.com/matiasinsaurralde/cgo-channels

Run the program:

% ./cgo-channels
messageChannel receives: {[1 2 3]}
messageChannel receives: {[104 101 108 108 111 0 0 0]}
stringChannel receives: Hello from C
stringChannel receives: From Go!
stringChannel receives: Hello from C
stringChannel receives: From Go!

OpenMP support

I have included a very simple C program that uses OpenMP to parallelize the communication with Go channels, this has been tested under Linux and OSX.

There's a build tag that will include the right flags for each platform:

Linux

This command will include the OpenMP sample and -fopenmp flag:

% go build github.com/matiasinsaurralde/cgo-channels -tags 'openmp'

Expected output:

% ./cgo-channels
stringChannel receives: Hello from C
messageChannel receives: {[1 2 3]}
stringChannel receives: From Go!
messageChannel receives: {[104 101 108 108 111 0 0 0]}
stringChannel receives: Hello from thread 0, nthreads 8
stringChannel receives: Hello from thread 3, nthreads 8
stringChannel receives: Hello from thread 6, nthreads 8
stringChannel receives: Hello from thread 4, nthreads 8
stringChannel receives: Hello from thread 7, nthreads 8
stringChannel receives: Hello from thread 2, nthreads 8
stringChannel receives: Hello from thread 5, nthreads 8
stringChannel receives: Hello from thread 1, nthreads 8

OSX

clang-omp is a requirement, I installed it with:

% brew install clang-omp

You may find more details in its website.

We will need to override the default C compiler. To use clang-omp and the openmp build tag (for Go), run:

CC='clang-omp' go build -tags 'openmp'