future.c

Single file, header-only library implementing a future-type for C11.

Usage

typedef ftr_of(int) int_future_t;

int run_async_task(void* arg) {
    int_future_t* fut = arg;
    thrd_sleep(&(struct timespec){.tv_sec=8}, NULL);
    int err = ftr_complete(fut, 42);
    if (err) {
        fprintf(stderr, "error completing future: %s\n", ftr_errorstr(err));
        return 1;
    }
    return 0;
}

void f() {
    int_future_t* fut = ftr_new(int_future_t);

    thrd_t thread = {0};
    thrd_create(&thread, run_async_task, fut);

    int result;
    int err = ftr_get(fut, 10 * 1000, &result);
    if (err) {
        fprintf(stderr, "error waiting future: %s\n", ftr_errorstr(err));
        thrd_join(thread, NULL);
        ftr_delete(fut);
        return;
    }

    thrd_join(thread, NULL);
    ftr_delete(fut);
    return;
}

Docs

ftr_of(Type)

Macro to create a struct type that will hold a value of Type. It's meant to be used as typedef ftr_of(Type) FutureType.

FutureType* ftr_new(FutureType)

Allocate and initialize a future of type FutureType, that is, the type you typedef'ed with ftr_of.

int ftr_get(FutureType* future, int32_t timeout_ms, Type* dest)

Get the value of the future and place it in dest, or waits up to timeout_ms milliseconds if not ready yet. Returns 0 on success or one of the Error codes.

int ftr_wait(FutureType* future, int32_t timeout_ms)

Waits up to timeout_ms milliseconds for the future to be complete. Returns 0 on success or one of the Error codes.

int ftr_complete(FutureType* future, Type value)

Completes the future with the given value. If there's a thread waiting on ftr_get that thread is signaled and the value is received there. Returns 0 on success or one of the Error codes.

void ftr_delete(FutureType* future)

Release a future object that was created with ftr_new.

const char* ftr_errorstr(int err)

Returns a description for one of the Error codes.

Error codes

• ftr_success -> Code returned on success.
• ftr_invalid -> The future object is in a invalid state.
• ftr_timedout -> The operation timed out.
• ftr_nomem -> No memory available.
• ftr_destsize -> The size of the dest parameter in ftr_get is not enough to hold the future's value.
• ftr_error -> Other unknown error ocurred.

LICENSE

Public domain.