stream.hpp

#pragma once


#include <algorithm>
#include <iterator>
#include <cstddef>
#include <utility>
#include <memory>
#include <uv.h>
#include "request.hpp"
#include "handle.hpp"
#include "loop.hpp"


namespace uvw {


struct ConnectEvent {};


struct EndEvent {};


struct ListenEvent {};


struct ShutdownEvent {};


struct WriteEvent {};


struct DataEvent {
    explicit DataEvent(std::unique_ptr<char[]> buf, std::size_t len) noexcept
        : data{std::move(buf)}, length{len}
    {}

    std::unique_ptr<char[]> data; 
    std::size_t length; 
};


namespace details {


struct ConnectReq final: public Request<ConnectReq, uv_connect_t> {
    using Request::Request;

    template<typename F, typename... Args>
    void connect(F &&f, Args&&... args) {
        invoke(std::forward<F>(f), get(), std::forward<Args>(args)..., &defaultCallback<ConnectEvent>);
    }
};


struct ShutdownReq final: public Request<ShutdownReq, uv_shutdown_t> {
    using Request::Request;

    void shutdown(uv_stream_t *handle) {
        invoke(&uv_shutdown, get(), handle, &defaultCallback<ShutdownEvent>);
    }
};


class WriteReq final: public Request<WriteReq, uv_write_t> {
public:
    using Deleter = void(*)(char *);

    WriteReq(ConstructorAccess ca, std::shared_ptr<Loop> loop, std::unique_ptr<char[], Deleter> dt, unsigned int len)
        : Request<WriteReq, uv_write_t>{ca, std::move(loop)},
          data{std::move(dt)},
          buf{uv_buf_init(data.get(), len)}
    {}

    void write(uv_stream_t *handle) {
        invoke(&uv_write, get(), handle, &buf, 1, &defaultCallback<WriteEvent>);
    }

    void write(uv_stream_t *handle, uv_stream_t *send) {
        invoke(&uv_write2, get(), handle, &buf, 1, send, &defaultCallback<WriteEvent>);
    }

private:
    std::unique_ptr<char[], Deleter> data;
    uv_buf_t buf;
};


}


template<typename T, typename U>
class StreamHandle: public Handle<T, U> {
    static constexpr unsigned int DEFAULT_BACKLOG = 128;

    static void readCallback(uv_stream_t *handle, ssize_t nread, const uv_buf_t *buf) {
        T &ref = *(static_cast<T*>(handle->data));
        // data will be destroyed no matter of what the value of nread is
        std::unique_ptr<char[]> data{buf->base};

        // nread == 0 is ignored (see http://docs.libuv.org/en/v1.x/stream.html)
        // equivalent to EAGAIN/EWOULDBLOCK, it shouldn't be treated as an error
        // for we don't have data to emit though, it's fine to suppress it

        if(nread == UV_EOF) {
            // end of stream
            ref.publish(EndEvent{});
        } else if(nread > 0) {
            // data available
            ref.publish(DataEvent{std::move(data), static_cast<std::size_t>(nread)});
        } else if(nread < 0) {
            // transmission error
            ref.publish(ErrorEvent(nread));
        }
    }

    static void listenCallback(uv_stream_t *handle, int status) {
        T &ref = *(static_cast<T*>(handle->data));
        if(status) { ref.publish(ErrorEvent{status}); }
        else { ref.publish(ListenEvent{}); }
    }

public:
#ifdef _MSC_VER
    StreamHandle(ConstructorAccess ca, std::shared_ptr<Loop> ref)
        : Handle{ca, std::move(ref)}
    {}
#else
    using Handle<T, U>::Handle;
#endif

    void shutdown() {
        auto listener = [ptr = this->shared_from_this()](const auto &event, const auto &) {
            ptr->publish(event);
        };

        auto shutdown = this->loop().template resource<details::ShutdownReq>();
        shutdown->template once<ErrorEvent>(listener);
        shutdown->template once<ShutdownEvent>(listener);
        shutdown->shutdown(this->template get<uv_stream_t>());
    }

    void listen(int backlog = DEFAULT_BACKLOG) {
        this->invoke(&uv_listen, this->template get<uv_stream_t>(), backlog, &listenCallback);
    }

    template<typename S>
    void accept(S &ref) {
        this->invoke(&uv_accept, this->template get<uv_stream_t>(), ref.template get<uv_stream_t>());
    }

    void read() {
        this->invoke(&uv_read_start, this->template get<uv_stream_t>(), &this->allocCallback, &readCallback);
    }

    void stop() {
        this->invoke(&uv_read_stop, this->template get<uv_stream_t>());
    }

    void write(std::unique_ptr<char[]> data, unsigned int len) {
        auto req = this->loop().template resource<details::WriteReq>(
                    std::unique_ptr<char[], details::WriteReq::Deleter>{
                        data.release(), [](char *ptr) { delete[] ptr; }
                    }, len);

        auto listener = [ptr = this->shared_from_this()](const auto &event, const auto &) {
            ptr->publish(event);
        };

        req->template once<ErrorEvent>(listener);
        req->template once<WriteEvent>(listener);
        req->write(this->template get<uv_stream_t>());
    }

    void write(char *data, unsigned int len) {
        auto req = this->loop().template resource<details::WriteReq>(
                    std::unique_ptr<char[], details::WriteReq::Deleter>{
                        data, [](char *) {}
                    }, len);

        auto listener = [ptr = this->shared_from_this()](const auto &event, const auto &) {
            ptr->publish(event);
        };

        req->template once<ErrorEvent>(listener);
        req->template once<WriteEvent>(listener);
        req->write(this->template get<uv_stream_t>());
    }

    template<typename S>
    void write(S &send, std::unique_ptr<char[]> data, unsigned int len) {
        auto req = this->loop().template resource<details::WriteReq>(
                    std::unique_ptr<char[], details::WriteReq::Deleter>{
                        data.release(), [](char *ptr) { delete[] ptr; }
                    }, len);

        auto listener = [ptr = this->shared_from_this()](const auto &event, const auto &) {
            ptr->publish(event);
        };

        req->template once<ErrorEvent>(listener);
        req->template once<WriteEvent>(listener);
        req->write(this->template get<uv_stream_t>(), send.template get<uv_stream_t>());
    }

    template<typename S>
    void write(S &send, char *data, unsigned int len) {
        auto req = this->loop().template resource<details::WriteReq>(
                    std::unique_ptr<char[], details::WriteReq::Deleter>{
                        data, [](char *) {}
                    }, len);

        auto listener = [ptr = this->shared_from_this()](const auto &event, const auto &) {
            ptr->publish(event);
        };

        req->template once<ErrorEvent>(listener);
        req->template once<WriteEvent>(listener);
        req->write(this->template get<uv_stream_t>(), send.template get<uv_stream_t>());
    }

    int tryWrite(std::unique_ptr<char[]> data, unsigned int len) {
        uv_buf_t bufs[] = { uv_buf_init(data.get(), len) };
        auto bw = uv_try_write(this->template get<uv_stream_t>(), bufs, 1);

        if(bw < 0) {
            this->publish(ErrorEvent{bw});
            bw = 0;
        }

        return bw;
    }

    int tryWrite(char *data, unsigned int len) {
        uv_buf_t bufs[] = { uv_buf_init(data, len) };
        auto bw = uv_try_write(this->template get<uv_stream_t>(), bufs, 1);

        if(bw < 0) {
            this->publish(ErrorEvent{bw});
            bw = 0;
        }

        return bw;
    }

    bool readable() const noexcept {
        return (uv_is_readable(this->template get<uv_stream_t>()) == 1);
    }

    bool writable() const noexcept {
        return (uv_is_writable(this->template get<uv_stream_t>()) == 1);
    }

    bool blocking(bool enable = false) {
        return (0 == uv_stream_set_blocking(this->template get<uv_stream_t>(), enable));
    }
};


}