ssize_t wait_for_events()

in io/iouring-wrapper.cpp [330:374]

• 41 lines of code
• 10 McCabe index (conditional complexity)

    ssize_t wait_for_events(void** data, size_t count, Timeout timeout) override {
        // Use master engine to wait for self event fd
        int ret = ::photon::wait_for_fd_readable(m_eventfd, timeout);
        if (ret < 0) {
            return errno == ETIMEDOUT ? 0 : -1;
        }
        uint64_t value;
        eventfd_read(m_eventfd, &value);

        // Reap events
        size_t num = 0;
        io_uring_cqe* cqe = nullptr;
        uint32_t head = 0;
        unsigned i = 0;
        io_uring_for_each_cqe(m_ring, head, cqe) {
            ++i;
            auto ctx = (ioCtx*) io_uring_cqe_get_data(cqe);
            if (!ctx) {
                // rm_interest didn't set user data
                continue;
            }
            ctx->res = cqe->res;
            if (cqe->flags & IORING_CQE_F_MORE && cqe->res & POLLERR) {
                LOG_ERROR_RETURN(0, -1, "iouring: multi-shot poll got POLLERR");
            }
            if (!ctx->is_event) {
                LOG_ERROR_RETURN(0, -1, "iouring: cascading engine only needs to handle event. Must be a bug...")
            }
            eventCtx* event_ctx = container_of(ctx, eventCtx, io_ctx);
            fdInterest fd_interest{event_ctx->event.fd, (uint32_t)evmap.translate_bitwisely(event_ctx->event.interests)};
            if (ctx->res == -ECANCELED) {
                m_event_contexts.erase(fd_interest);
            } else if (event_ctx->one_shot) {
                data[num++] = event_ctx->event.data;
                m_event_contexts.erase(fd_interest);
            } else {
                data[num++] = event_ctx->event.data;
            }
            if (num >= count) {
                break;
            }
        }
        io_uring_cq_advance(m_ring, i);
        return num;
    }