Threads and channels

A thread is the basic execution entity. A scheduler controls the execution of threads.

A simple thread that waits for an event from another thread.

#include "simba.h"

struct event_t event;

void *my_thread_main(void *arg_p)
{
    uint32_t mask;

    while (1) {
        mask = 0x1;
        event_read(&event, &mask, sizeof(mask));

        std_printf(FSTR("Event received!\r\n"));
    }

    return (NULL);
}

Threads usually communicates over channels. There are many kinds of channels; queue, socket and event, to mention a few. All three implementing the same abstract channel interface (see src/sync/chan.h). This abstraction makes channel very powerful as a synchronization primitive. They can be seen as limited functionality file descriptors in linux.

The most common channel is the queue — Queue channel. It can be either synchronous or semi-asynchronous. In the synchronous version the writing thread will block until all written data has been read by the reader. In the semi-asynchronous version the writer writes to a buffer within the queue, and only blocks all data does not fit in the buffer. The buffer size is selected by the application.