zmq.hpp

/*
    Copyright (c) 2016-2017 ZeroMQ community
    Copyright (c) 2009-2011 250bpm s.r.o.
    Copyright (c) 2011 Botond Ballo
    Copyright (c) 2007-2009 iMatix Corporation

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to
    deal in the Software without restriction, including without limitation the
    rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
    sell copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
    IN THE SOFTWARE.
*/

#ifndef __ZMQ_HPP_INCLUDED__
#define __ZMQ_HPP_INCLUDED__

#if (__cplusplus >= 201402L)
#define ZMQ_DEPRECATED(msg) [[deprecated(msg)]]
#elif defined(_MSC_VER)
#define ZMQ_DEPRECATED(msg) __declspec(deprecated(msg))
#elif defined(__GNUC__)
#define ZMQ_DEPRECATED(msg) __attribute__((deprecated(msg)))
#endif

#if (__cplusplus >= 201103L) || (defined(_MSC_VER) && (_MSC_VER >= 1900))
#define ZMQ_CPP11
#define ZMQ_NOTHROW noexcept
#define ZMQ_EXPLICIT explicit
#define ZMQ_OVERRIDE override
#else
#define ZMQ_CPP03
#define ZMQ_NOTHROW
#define ZMQ_EXPLICIT
#define ZMQ_OVERRIDE
#endif

#include <zmq.h>

#include <cassert>
#include <cstring>

#include <algorithm>
#include <exception>
#include <iomanip>
#include <iterator>
#include <sstream>
#include <string>
#include <vector>

/*  Version macros for compile-time API version detection                     */
#define CPPZMQ_VERSION_MAJOR 4
#define CPPZMQ_VERSION_MINOR 3 
#define CPPZMQ_VERSION_PATCH 1 

#define CPPZMQ_VERSION                                                              \
    ZMQ_MAKE_VERSION(CPPZMQ_VERSION_MAJOR, CPPZMQ_VERSION_MINOR,                    \
                     CPPZMQ_VERSION_PATCH)

#ifdef ZMQ_CPP11
#include <chrono>
#include <tuple>
#include <functional>
#include <unordered_map>
#include <memory>
#endif

//  Detect whether the compiler supports C++11 rvalue references.
#if (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 2))   \
     && defined(__GXX_EXPERIMENTAL_CXX0X__))
#define ZMQ_HAS_RVALUE_REFS
#define ZMQ_DELETED_FUNCTION = delete
#elif defined(__clang__)
#if __has_feature(cxx_rvalue_references)
#define ZMQ_HAS_RVALUE_REFS
#endif

#if __has_feature(cxx_deleted_functions)
#define ZMQ_DELETED_FUNCTION = delete
#else
#define ZMQ_DELETED_FUNCTION
#endif
#elif defined(_MSC_VER) && (_MSC_VER >= 1900)
#define ZMQ_HAS_RVALUE_REFS
#define ZMQ_DELETED_FUNCTION = delete
#elif defined(_MSC_VER) && (_MSC_VER >= 1600)
#define ZMQ_HAS_RVALUE_REFS
#define ZMQ_DELETED_FUNCTION
#else
#define ZMQ_DELETED_FUNCTION
#endif

#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(3, 3, 0)
#define ZMQ_NEW_MONITOR_EVENT_LAYOUT
#endif

#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 1, 0)
#define ZMQ_HAS_PROXY_STEERABLE
/*  Socket event data  */
typedef struct
{
    uint16_t event; // id of the event as bitfield
    int32_t value;  // value is either error code, fd or reconnect interval
} zmq_event_t;
#endif

// Avoid using deprecated message receive function when possible
#if ZMQ_VERSION < ZMQ_MAKE_VERSION(3, 2, 0)
#define zmq_msg_recv(msg, socket, flags) zmq_recvmsg(socket, msg, flags)
#endif


// In order to prevent unused variable warnings when building in non-debug
// mode use this macro to make assertions.
#ifndef NDEBUG
#define ZMQ_ASSERT(expression) assert(expression)
#else
#define ZMQ_ASSERT(expression) (void) (expression)
#endif

namespace zmq
{
typedef zmq_free_fn free_fn;
typedef zmq_pollitem_t pollitem_t;

class error_t : public std::exception
{
  public:
    error_t() : errnum(zmq_errno()) {}
#ifdef ZMQ_CPP11
    virtual const char *what() const noexcept { return zmq_strerror(errnum); }
#else
    virtual const char *what() const throw() { return zmq_strerror(errnum); }
#endif
    int num() const { return errnum; }

  private:
    int errnum;
};

inline int poll(zmq_pollitem_t const *items_, size_t nitems_, long timeout_ = -1)
{
    int rc = zmq_poll(const_cast<zmq_pollitem_t *>(items_),
                      static_cast<int>(nitems_), timeout_);
    if (rc < 0)
        throw error_t();
    return rc;
}

#ifdef ZMQ_CPP11
inline int
poll(zmq_pollitem_t const *items, size_t nitems, std::chrono::milliseconds timeout)
{
    return poll(items, nitems, static_cast<long>(timeout.count()));
}

inline int poll(std::vector<zmq_pollitem_t> const &items,
                std::chrono::milliseconds timeout)
{
    return poll(items.data(), items.size(), static_cast<long>(timeout.count()));
}

inline int poll(std::vector<zmq_pollitem_t> const &items, long timeout_ = -1)
{
    return poll(items.data(), items.size(), timeout_);
}
#endif


inline void proxy(void *frontend, void *backend, void *capture)
{
    int rc = zmq_proxy(frontend, backend, capture);
    if (rc != 0)
        throw error_t();
}

#ifdef ZMQ_HAS_PROXY_STEERABLE
inline void
proxy_steerable(void *frontend, void *backend, void *capture, void *control)
{
    int rc = zmq_proxy_steerable(frontend, backend, capture, control);
    if (rc != 0)
        throw error_t();
}
#endif

inline void version(int *major_, int *minor_, int *patch_)
{
    zmq_version(major_, minor_, patch_);
}

#ifdef ZMQ_CPP11
inline std::tuple<int, int, int> version()
{
    std::tuple<int, int, int> v;
    zmq_version(&std::get<0>(v), &std::get<1>(v), &std::get<2>(v));
    return v;
}
#endif

class message_t
{
    friend class socket_t;

  public:
    inline message_t()
    {
        int rc = zmq_msg_init(&msg);
        if (rc != 0)
            throw error_t();
    }

    inline explicit message_t(size_t size_)
    {
        int rc = zmq_msg_init_size(&msg, size_);
        if (rc != 0)
            throw error_t();
    }

    template<typename T> message_t(T first, T last) : msg()
    {
        typedef typename std::iterator_traits<T>::difference_type size_type;
        typedef typename std::iterator_traits<T>::value_type value_t;

        size_type const size_ = std::distance(first, last) * sizeof(value_t);
        int const rc = zmq_msg_init_size(&msg, size_);
        if (rc != 0)
            throw error_t();
        value_t *dest = data<value_t>();
        while (first != last) {
            *dest = *first;
            ++dest;
            ++first;
        }
    }

    inline message_t(const void *data_, size_t size_)
    {
        int rc = zmq_msg_init_size(&msg, size_);
        if (rc != 0)
            throw error_t();
        memcpy(data(), data_, size_);
    }

    inline message_t(void *data_, size_t size_, free_fn *ffn_, void *hint_ = NULL)
    {
        int rc = zmq_msg_init_data(&msg, data_, size_, ffn_, hint_);
        if (rc != 0)
            throw error_t();
    }

#if defined(ZMQ_BUILD_DRAFT_API) && defined(ZMQ_CPP11)
    template<typename T>
    explicit message_t(const T &msg_) : message_t(std::begin(msg_), std::end(msg_))
    {
    }
#endif

#ifdef ZMQ_HAS_RVALUE_REFS
    inline message_t(message_t &&rhs) : msg(rhs.msg)
    {
        int rc = zmq_msg_init(&rhs.msg);
        if (rc != 0)
            throw error_t();
    }

    inline message_t &operator=(message_t &&rhs) ZMQ_NOTHROW
    {
        std::swap(msg, rhs.msg);
        return *this;
    }
#endif

    inline ~message_t() ZMQ_NOTHROW
    {
        int rc = zmq_msg_close(&msg);
        ZMQ_ASSERT(rc == 0);
    }

    inline void rebuild()
    {
        int rc = zmq_msg_close(&msg);
        if (rc != 0)
            throw error_t();
        rc = zmq_msg_init(&msg);
        if (rc != 0)
            throw error_t();
    }

    inline void rebuild(size_t size_)
    {
        int rc = zmq_msg_close(&msg);
        if (rc != 0)
            throw error_t();
        rc = zmq_msg_init_size(&msg, size_);
        if (rc != 0)
            throw error_t();
    }

    inline void rebuild(const void *data_, size_t size_)
    {
        int rc = zmq_msg_close(&msg);
        if (rc != 0)
            throw error_t();
        rc = zmq_msg_init_size(&msg, size_);
        if (rc != 0)
            throw error_t();
        memcpy(data(), data_, size_);
    }

    inline void rebuild(void *data_, size_t size_, free_fn *ffn_, void *hint_ = NULL)
    {
        int rc = zmq_msg_close(&msg);
        if (rc != 0)
            throw error_t();
        rc = zmq_msg_init_data(&msg, data_, size_, ffn_, hint_);
        if (rc != 0)
            throw error_t();
    }

    inline void move(message_t const *msg_)
    {
        int rc = zmq_msg_move(&msg, const_cast<zmq_msg_t *>(&(msg_->msg)));
        if (rc != 0)
            throw error_t();
    }

    inline void copy(message_t const *msg_)
    {
        int rc = zmq_msg_copy(&msg, const_cast<zmq_msg_t *>(&(msg_->msg)));
        if (rc != 0)
            throw error_t();
    }

    inline bool more() const ZMQ_NOTHROW
    {
        int rc = zmq_msg_more(const_cast<zmq_msg_t *>(&msg));
        return rc != 0;
    }

    inline void *data() ZMQ_NOTHROW { return zmq_msg_data(&msg); }

    inline const void *data() const ZMQ_NOTHROW
    {
        return zmq_msg_data(const_cast<zmq_msg_t *>(&msg));
    }

    inline size_t size() const ZMQ_NOTHROW
    {
        return zmq_msg_size(const_cast<zmq_msg_t *>(&msg));
    }

    template<typename T> T *data() ZMQ_NOTHROW { return static_cast<T *>(data()); }

    template<typename T> T const *data() const ZMQ_NOTHROW
    {
        return static_cast<T const *>(data());
    }

    ZMQ_DEPRECATED("from 4.3.0, use operator== instead")
    inline bool equal(const message_t *other) const ZMQ_NOTHROW
    {
        return *this == *other;
    }

    inline bool operator==(const message_t &other) const ZMQ_NOTHROW
    {
        const size_t my_size = size();
        return my_size == other.size() && 0 == memcmp(data(), other.data(), my_size);
    }

    inline bool operator!=(const message_t &other) const ZMQ_NOTHROW
    {
        return !(*this == other);
    }

#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 1, 0)
    inline const char *gets(const char *property_)
    {
        const char *value = zmq_msg_gets(&msg, property_);
        if (value == NULL)
            throw error_t();
        return value;
    }
#endif

#if defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 0)
    inline uint32_t routing_id() const
    {
        return zmq_msg_routing_id(const_cast<zmq_msg_t*>(&msg));
    }

    inline void set_routing_id(uint32_t routing_id)
    {
        int rc = zmq_msg_set_routing_id(&msg, routing_id);
        if (rc != 0)
            throw error_t();
    }

    inline const char* group() const
    {
        return zmq_msg_group(const_cast<zmq_msg_t*>(&msg));
    }

    inline void set_group(const char* group)
    {
        int rc = zmq_msg_set_group(&msg, group);
        if (rc != 0)
            throw error_t();
    }
#endif

    /** Dump content to string. Ascii chars are readable, the rest is printed as hex.
         *  Probably ridiculously slow.
         */
    inline std::string str() const
    {
        // Partly mutuated from the same method in zmq::multipart_t
        std::stringstream os;

        const unsigned char *msg_data = this->data<unsigned char>();
        unsigned char byte;
        size_t size = this->size();
        int is_ascii[2] = {0, 0};

        os << "zmq::message_t [size " << std::dec << std::setw(3)
           << std::setfill('0') << size << "] (";
        // Totally arbitrary
        if (size >= 1000) {
            os << "... too big to print)";
        } else {
            while (size--) {
                byte = *msg_data++;

                is_ascii[1] = (byte >= 33 && byte < 127);
                if (is_ascii[1] != is_ascii[0])
                    os << " "; // Separate text/non text

                if (is_ascii[1]) {
                    os << byte;
                } else {
                    os << std::hex << std::uppercase << std::setw(2)
                       << std::setfill('0') << static_cast<short>(byte);
                }
                is_ascii[0] = is_ascii[1];
            }
            os << ")";
        }
        return os.str();
    }

  private:
    //  The underlying message
    zmq_msg_t msg;

    //  Disable implicit message copying, so that users won't use shared
    //  messages (less efficient) without being aware of the fact.
    message_t(const message_t &) ZMQ_DELETED_FUNCTION;
    void operator=(const message_t &) ZMQ_DELETED_FUNCTION;
};

class context_t
{
    friend class socket_t;

  public:
    inline context_t()
    {
        ptr = zmq_ctx_new();
        if (ptr == NULL)
            throw error_t();
    }


    inline explicit context_t(int io_threads_,
                              int max_sockets_ = ZMQ_MAX_SOCKETS_DFLT)
    {
        ptr = zmq_ctx_new();
        if (ptr == NULL)
            throw error_t();

        int rc = zmq_ctx_set(ptr, ZMQ_IO_THREADS, io_threads_);
        ZMQ_ASSERT(rc == 0);

        rc = zmq_ctx_set(ptr, ZMQ_MAX_SOCKETS, max_sockets_);
        ZMQ_ASSERT(rc == 0);
    }

#ifdef ZMQ_HAS_RVALUE_REFS
    inline context_t(context_t &&rhs) ZMQ_NOTHROW : ptr(rhs.ptr) { rhs.ptr = NULL; }
    inline context_t &operator=(context_t &&rhs) ZMQ_NOTHROW
    {
        std::swap(ptr, rhs.ptr);
        return *this;
    }
#endif

    inline int setctxopt(int option_, int optval_)
    {
        int rc = zmq_ctx_set(ptr, option_, optval_);
        ZMQ_ASSERT(rc == 0);
        return rc;
    }

    inline int getctxopt(int option_) { return zmq_ctx_get(ptr, option_); }

    inline ~context_t() ZMQ_NOTHROW { close(); }

    inline void close() ZMQ_NOTHROW
    {
        if (ptr == NULL)
            return;

        int rc;
        do {
            rc = zmq_ctx_destroy(ptr);
        } while (rc == -1 && errno == EINTR);

        ZMQ_ASSERT(rc == 0);
        ptr = NULL;
    }

    //  Be careful with this, it's probably only useful for
    //  using the C api together with an existing C++ api.
    //  Normally you should never need to use this.
    inline ZMQ_EXPLICIT operator void *() ZMQ_NOTHROW { return ptr; }

    inline ZMQ_EXPLICIT operator void const *() const ZMQ_NOTHROW { return ptr; }

    inline operator bool() const ZMQ_NOTHROW { return ptr != NULL; }

  private:
    void *ptr;

    context_t(const context_t &) ZMQ_DELETED_FUNCTION;
    void operator=(const context_t &) ZMQ_DELETED_FUNCTION;
};

#ifdef ZMQ_CPP11
enum class socket_type : int
{
    req = ZMQ_REQ,
    rep = ZMQ_REP,
    dealer = ZMQ_DEALER,
    router = ZMQ_ROUTER,
    pub = ZMQ_PUB,
    sub = ZMQ_SUB,
    xpub = ZMQ_XPUB,
    xsub = ZMQ_XSUB,
    push = ZMQ_PUSH,
    pull = ZMQ_PULL,
#if defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 0)
    server = ZMQ_SERVER,
    client = ZMQ_CLIENT,
    radio = ZMQ_RADIO,
    dish = ZMQ_DISH,
#endif
#if ZMQ_VERSION_MAJOR >= 4
    stream = ZMQ_STREAM,
#endif
    pair = ZMQ_PAIR
};
#endif

class socket_t
{
    friend class monitor_t;

  public:
    inline socket_t(context_t &context_, int type_) { init(context_, type_); }

#ifdef ZMQ_CPP11
    inline socket_t(context_t &context_, socket_type type_)
    {
        init(context_, static_cast<int>(type_));
    }
#endif

#ifdef ZMQ_HAS_RVALUE_REFS
    inline socket_t(socket_t &&rhs) ZMQ_NOTHROW : ptr(rhs.ptr), ctxptr(rhs.ctxptr)
    {
        rhs.ptr = NULL;
        rhs.ctxptr = NULL;
    }
    inline socket_t &operator=(socket_t &&rhs) ZMQ_NOTHROW
    {
        std::swap(ptr, rhs.ptr);
        return *this;
    }
#endif

    inline ~socket_t() ZMQ_NOTHROW { close(); }

    inline operator void *() ZMQ_NOTHROW { return ptr; }

    inline operator void const *() const ZMQ_NOTHROW { return ptr; }

    inline void close() ZMQ_NOTHROW
    {
        if (ptr == NULL)
            // already closed
            return;
        int rc = zmq_close(ptr);
        ZMQ_ASSERT(rc == 0);
        ptr = 0;
    }

    template<typename T> void setsockopt(int option_, T const &optval)
    {
        setsockopt(option_, &optval, sizeof(T));
    }

    inline void setsockopt(int option_, const void *optval_, size_t optvallen_)
    {
        int rc = zmq_setsockopt(ptr, option_, optval_, optvallen_);
        if (rc != 0)
            throw error_t();
    }

    inline void getsockopt(int option_, void *optval_, size_t *optvallen_) const
    {
        int rc = zmq_getsockopt(ptr, option_, optval_, optvallen_);
        if (rc != 0)
            throw error_t();
    }

    template<typename T> T getsockopt(int option_) const
    {
        T optval;
        size_t optlen = sizeof(T);
        getsockopt(option_, &optval, &optlen);
        return optval;
    }

    inline void bind(std::string const &addr) { bind(addr.c_str()); }

    inline void bind(const char *addr_)
    {
        int rc = zmq_bind(ptr, addr_);
        if (rc != 0)
            throw error_t();
    }

    inline void unbind(std::string const &addr) { unbind(addr.c_str()); }

    inline void unbind(const char *addr_)
    {
        int rc = zmq_unbind(ptr, addr_);
        if (rc != 0)
            throw error_t();
    }

    inline void connect(std::string const &addr) { connect(addr.c_str()); }

    inline void connect(const char *addr_)
    {
        int rc = zmq_connect(ptr, addr_);
        if (rc != 0)
            throw error_t();
    }

    inline void disconnect(std::string const &addr) { disconnect(addr.c_str()); }

    inline void disconnect(const char *addr_)
    {
        int rc = zmq_disconnect(ptr, addr_);
        if (rc != 0)
            throw error_t();
    }

    inline bool connected() const ZMQ_NOTHROW { return (ptr != NULL); }

    inline size_t send(const void *buf_, size_t len_, int flags_ = 0)
    {
        int nbytes = zmq_send(ptr, buf_, len_, flags_);
        if (nbytes >= 0)
            return (size_t) nbytes;
        if (zmq_errno() == EAGAIN)
            return 0;
        throw error_t();
    }

    inline bool send(message_t &msg_, int flags_ = 0)
    {
        int nbytes = zmq_msg_send(&(msg_.msg), ptr, flags_);
        if (nbytes >= 0)
            return true;
        if (zmq_errno() == EAGAIN)
            return false;
        throw error_t();
    }

    template<typename T> bool send(T first, T last, int flags_ = 0)
    {
        zmq::message_t msg(first, last);
        return send(msg, flags_);
    }

#ifdef ZMQ_HAS_RVALUE_REFS
    inline bool send(message_t &&msg_, int flags_ = 0) { return send(msg_, flags_); }
#endif

    inline size_t recv(void *buf_, size_t len_, int flags_ = 0)
    {
        int nbytes = zmq_recv(ptr, buf_, len_, flags_);
        if (nbytes >= 0)
            return (size_t) nbytes;
        if (zmq_errno() == EAGAIN)
            return 0;
        throw error_t();
    }

    inline bool recv(message_t *msg_, int flags_ = 0)
    {
        int nbytes = zmq_msg_recv(&(msg_->msg), ptr, flags_);
        if (nbytes >= 0)
            return true;
        if (zmq_errno() == EAGAIN)
            return false;
        throw error_t();
    }

#if defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 0)
    inline void join(const char* group)
    {
        int rc = zmq_join(ptr, group);
        if (rc != 0)
            throw error_t();
    }

    inline void leave(const char* group)
    {
        int rc = zmq_leave(ptr, group);
        if (rc != 0)
            throw error_t();
    }
#endif

  private:
    inline void init(context_t &context_, int type_)
    {
        ctxptr = context_.ptr;
        ptr = zmq_socket(context_.ptr, type_);
        if (ptr == NULL)
            throw error_t();
    }

    void *ptr;
    void *ctxptr;

    socket_t(const socket_t &) ZMQ_DELETED_FUNCTION;
    void operator=(const socket_t &) ZMQ_DELETED_FUNCTION;
};

class monitor_t
{
  public:
    monitor_t() : socketPtr(NULL), monitor_socket(NULL) {}

    virtual ~monitor_t()
    {
        if (socketPtr)
            zmq_socket_monitor(socketPtr, NULL, 0);

        if (monitor_socket)
            zmq_close(monitor_socket);
    }


#ifdef ZMQ_HAS_RVALUE_REFS
    monitor_t(monitor_t &&rhs) ZMQ_NOTHROW : socketPtr(rhs.socketPtr),
                                             monitor_socket(rhs.monitor_socket)
    {
        rhs.socketPtr = NULL;
        rhs.monitor_socket = NULL;
    }

    socket_t &operator=(socket_t &&rhs) ZMQ_DELETED_FUNCTION;
#endif


    void
    monitor(socket_t &socket, std::string const &addr, int events = ZMQ_EVENT_ALL)
    {
        monitor(socket, addr.c_str(), events);
    }

    void monitor(socket_t &socket, const char *addr_, int events = ZMQ_EVENT_ALL)
    {
        init(socket, addr_, events);
        while (true) {
            check_event(-1);
        }
    }

    void init(socket_t &socket, std::string const &addr, int events = ZMQ_EVENT_ALL)
    {
        init(socket, addr.c_str(), events);
    }

    void init(socket_t &socket, const char *addr_, int events = ZMQ_EVENT_ALL)
    {
        int rc = zmq_socket_monitor(socket.ptr, addr_, events);
        if (rc != 0)
            throw error_t();

        socketPtr = socket.ptr;
        monitor_socket = zmq_socket(socket.ctxptr, ZMQ_PAIR);
        assert(monitor_socket);

        rc = zmq_connect(monitor_socket, addr_);
        assert(rc == 0);

        on_monitor_started();
    }

    bool check_event(int timeout = 0)
    {
        assert(monitor_socket);

        zmq_msg_t eventMsg;
        zmq_msg_init(&eventMsg);

        zmq::pollitem_t items[] = {
          {monitor_socket, 0, ZMQ_POLLIN, 0},
        };

        zmq::poll(&items[0], 1, timeout);

        if (items[0].revents & ZMQ_POLLIN) {
            int rc = zmq_msg_recv(&eventMsg, monitor_socket, 0);
            if (rc == -1 && zmq_errno() == ETERM)
                return false;
            assert(rc != -1);

        } else {
            zmq_msg_close(&eventMsg);
            return false;
        }

#if ZMQ_VERSION_MAJOR >= 4
        const char *data = static_cast<const char *>(zmq_msg_data(&eventMsg));
        zmq_event_t msgEvent;
        memcpy(&msgEvent.event, data, sizeof(uint16_t));
        data += sizeof(uint16_t);
        memcpy(&msgEvent.value, data, sizeof(int32_t));
        zmq_event_t *event = &msgEvent;
#else
        zmq_event_t *event = static_cast<zmq_event_t *>(zmq_msg_data(&eventMsg));
#endif

#ifdef ZMQ_NEW_MONITOR_EVENT_LAYOUT
        zmq_msg_t addrMsg;
        zmq_msg_init(&addrMsg);
        int rc = zmq_msg_recv(&addrMsg, monitor_socket, 0);
        if (rc == -1 && zmq_errno() == ETERM) {
            zmq_msg_close(&eventMsg);
            return false;
        }

        assert(rc != -1);
        const char *str = static_cast<const char *>(zmq_msg_data(&addrMsg));
        std::string address(str, str + zmq_msg_size(&addrMsg));
        zmq_msg_close(&addrMsg);
#else
        // Bit of a hack, but all events in the zmq_event_t union have the same layout so this will work for all event types.
        std::string address = event->data.connected.addr;
#endif

#ifdef ZMQ_EVENT_MONITOR_STOPPED
        if (event->event == ZMQ_EVENT_MONITOR_STOPPED) {
            zmq_msg_close(&eventMsg);
            return false;
        }

#endif

        switch (event->event) {
            case ZMQ_EVENT_CONNECTED:
                on_event_connected(*event, address.c_str());
                break;
            case ZMQ_EVENT_CONNECT_DELAYED:
                on_event_connect_delayed(*event, address.c_str());
                break;
            case ZMQ_EVENT_CONNECT_RETRIED:
                on_event_connect_retried(*event, address.c_str());
                break;
            case ZMQ_EVENT_LISTENING:
                on_event_listening(*event, address.c_str());
                break;
            case ZMQ_EVENT_BIND_FAILED:
                on_event_bind_failed(*event, address.c_str());
                break;
            case ZMQ_EVENT_ACCEPTED:
                on_event_accepted(*event, address.c_str());
                break;
            case ZMQ_EVENT_ACCEPT_FAILED:
                on_event_accept_failed(*event, address.c_str());
                break;
            case ZMQ_EVENT_CLOSED:
                on_event_closed(*event, address.c_str());
                break;
            case ZMQ_EVENT_CLOSE_FAILED:
                on_event_close_failed(*event, address.c_str());
                break;
            case ZMQ_EVENT_DISCONNECTED:
                on_event_disconnected(*event, address.c_str());
                break;
#ifdef ZMQ_BUILD_DRAFT_API
#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 3)
            case ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL:
                on_event_handshake_failed_no_detail(*event, address.c_str());
                break;
            case ZMQ_EVENT_HANDSHAKE_FAILED_PROTOCOL:
                on_event_handshake_failed_protocol(*event, address.c_str());
                break;
            case ZMQ_EVENT_HANDSHAKE_FAILED_AUTH:
                on_event_handshake_failed_auth(*event, address.c_str());
                break;
            case ZMQ_EVENT_HANDSHAKE_SUCCEEDED:
                on_event_handshake_succeeded(*event, address.c_str());
                break;
#elif ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 1)
            case ZMQ_EVENT_HANDSHAKE_FAILED:
                on_event_handshake_failed(*event, address.c_str());
                break;
            case ZMQ_EVENT_HANDSHAKE_SUCCEED:
                on_event_handshake_succeed(*event, address.c_str());
                break;
#endif
#endif
            default:
                on_event_unknown(*event, address.c_str());
                break;
        }
        zmq_msg_close(&eventMsg);

        return true;
    }

#ifdef ZMQ_EVENT_MONITOR_STOPPED
    void abort()
    {
        if (socketPtr)
            zmq_socket_monitor(socketPtr, NULL, 0);

        socketPtr = NULL;
    }
#endif
    virtual void on_monitor_started() {}
    virtual void on_event_connected(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_connect_delayed(const zmq_event_t &event_,
                                          const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_connect_retried(const zmq_event_t &event_,
                                          const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_listening(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_bind_failed(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_accepted(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_accept_failed(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_closed(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_close_failed(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_disconnected(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 3)
    virtual void on_event_handshake_failed_no_detail(const zmq_event_t &event_,
                                                     const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_handshake_failed_protocol(const zmq_event_t &event_,
                                                    const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_handshake_failed_auth(const zmq_event_t &event_,
                                                const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_handshake_succeeded(const zmq_event_t &event_,
                                              const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
#elif ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 1)
    virtual void on_event_handshake_failed(const zmq_event_t &event_,
                                           const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
    virtual void on_event_handshake_succeed(const zmq_event_t &event_,
                                            const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }
#endif
    virtual void on_event_unknown(const zmq_event_t &event_, const char *addr_)
    {
        (void) event_;
        (void) addr_;
    }

  private:
    monitor_t(const monitor_t &) ZMQ_DELETED_FUNCTION;
    void operator=(const monitor_t &) ZMQ_DELETED_FUNCTION;

    void *socketPtr;
    void *monitor_socket;
};

#if defined(ZMQ_BUILD_DRAFT_API) && defined(ZMQ_CPP11) && defined(ZMQ_HAVE_POLLER)
template<typename T = void> class poller_t
{
  public:
    void add(zmq::socket_t &socket, short events, T *user_data)
    {
        if (0
            != zmq_poller_add(poller_ptr.get(), static_cast<void *>(socket),
                              user_data, events)) {
            throw error_t();
        }
    }

    void remove(zmq::socket_t &socket)
    {
        if (0 != zmq_poller_remove(poller_ptr.get(), static_cast<void *>(socket))) {
            throw error_t();
        }
    }

    void modify(zmq::socket_t &socket, short events)
    {
        if (0
            != zmq_poller_modify(poller_ptr.get(), static_cast<void *>(socket),
                                 events)) {
            throw error_t();
        }
    }

    size_t wait_all(std::vector<zmq_poller_event_t> &poller_events,
                    const std::chrono::microseconds timeout)
    {
        int rc = zmq_poller_wait_all(poller_ptr.get(), poller_events.data(),
                                     static_cast<int>(poller_events.size()),
                                     static_cast<long>(timeout.count()));
        if (rc > 0)
            return static_cast<size_t>(rc);

#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 3)
        if (zmq_errno() == EAGAIN)
#else
        if (zmq_errno() == ETIMEDOUT)
#endif
            return 0;

        throw error_t();
    }

  private:
    std::unique_ptr<void, std::function<void(void *)>> poller_ptr{
      []() {
          auto poller_new = zmq_poller_new();
          if (poller_new)
              return poller_new;
          throw error_t();
      }(),
      [](void *ptr) {
          int rc = zmq_poller_destroy(&ptr);
          ZMQ_ASSERT(rc == 0);
      }};
};
#endif //  defined(ZMQ_BUILD_DRAFT_API) && defined(ZMQ_CPP11) && defined(ZMQ_HAVE_POLLER)

inline std::ostream &operator<<(std::ostream &os, const message_t &msg)
{
    return os << msg.str();
}

} // namespace zmq

#endif // __ZMQ_HPP_INCLUDED__