Win wsa select event (#342)

* Fix #323: Missing SelectInterrupt implementation for Windows

Using WSAEventSelect, WSAWaitForMultipleEvents and WSAEnumNetworkEvents to emulate poll() with an interrupt-event.

* Cleanup

* Fixed incomplete comment.

* Switched ifdefs to support other Unixes with pipe file descriptors

* Fixed: SelectInterrupt fallback code for getFd()==-1 && getEvent()==nullptr converted a PollResultType::Timeout into a ReadyForRead causing the HttpClient to fail because it uses a hard-coded "SelectInterrupt" instance that doesn't implement getFd() and getEvent().

* Fixed gcc compile errors

* - HttpClient now uses the SelectInterruptFactory
- Fixed wrong ix::poll result when using Windows WSA functions

* We must deselect the networkevents from the socket event. Otherwise the socket will report states that aren't there.

CMakeLists.txt

@@ -41,6 +41,7 @@ set( IXWEBSOCKET_SOURCES
     ixwebsocket/IXSelectInterrupt.cpp
     ixwebsocket/IXSelectInterruptFactory.cpp
     ixwebsocket/IXSelectInterruptPipe.cpp
+    ixwebsocket/IXSelectInterruptEvent.cpp
     ixwebsocket/IXSetThreadName.cpp
     ixwebsocket/IXSocket.cpp
     ixwebsocket/IXSocketConnect.cpp
@@ -80,6 +81,7 @@ set( IXWEBSOCKET_HEADERS
     ixwebsocket/IXSelectInterrupt.h
     ixwebsocket/IXSelectInterruptFactory.h
     ixwebsocket/IXSelectInterruptPipe.h
+    ixwebsocket/IXSelectInterruptEvent.h
     ixwebsocket/IXSetThreadName.h
     ixwebsocket/IXSocket.h
     ixwebsocket/IXSocketConnect.h

ixwebsocket/IXNetSystem.cpp

@@ -7,6 +7,9 @@
 #include "IXNetSystem.h"
 #include <cstdint>
 #include <cstdio>
+#ifdef _WIN32
+#include <vector>
+#endif
 
 namespace ix
 {
@@ -37,6 +40,51 @@ namespace ix
 #endif
     }
 
+#ifdef _WIN32
+    struct WSAEvent
+    {
+    public:
+        WSAEvent(struct pollfd* fd)
+            : _fd(fd)
+        {
+            _event = WSACreateEvent();
+        }
+
+        WSAEvent(WSAEvent&& source) noexcept
+        {
+            _event = source._event;
+            source._event = WSA_INVALID_EVENT; // invalidate the event in the source
+            _fd = source._fd;
+        }
+
+        ~WSAEvent()
+        {
+            if (_event != WSA_INVALID_EVENT)
+            {
+                // We must deselect the networkevents from the socket event. Otherwise the
+                // socket will report states that aren't there.
+                if (_fd != nullptr && _fd->fd != -1)
+                    WSAEventSelect(_fd->fd, _event, 0);
+                WSACloseEvent(_event);
+            }
+        }
+
+        operator HANDLE()
+        {
+            return _event;
+        }
+
+        operator struct pollfd*()
+        {
+            return _fd;
+        }
+
+    private:
+        HANDLE _event;
+        struct pollfd* _fd;
+    };
+#endif
+
     //
     // That function could 'return WSAPoll(pfd, nfds, timeout);'
     // but WSAPoll is said to have weird behaviors on the internet
@@ -44,9 +92,118 @@ namespace ix
     //
     // So we make it a select wrapper
     //
-    int poll(struct pollfd* fds, nfds_t nfds, int timeout)
+    // UPDATE: WSAPoll was fixed in Windows 10 Version 2004
+    //
+    // The optional "event" is set to nullptr if it wasn't signaled.
+    int poll(struct pollfd* fds, nfds_t nfds, int timeout, void** event)
     {
 #ifdef _WIN32
+
+        if (event && *event)
+        {
+            HANDLE interruptEvent = reinterpret_cast<HANDLE>(*event);
+            *event = nullptr; // the event wasn't signaled yet
+
+            if (nfds < 0 || nfds >= MAXIMUM_WAIT_OBJECTS - 1)
+            {
+                WSASetLastError(WSAEINVAL);
+                return SOCKET_ERROR;
+            }
+
+            std::vector<WSAEvent> socketEvents;
+            std::vector<HANDLE> handles;
+            // put the interrupt event as first element, making it highest priority
+            handles.push_back(interruptEvent);
+
+            // create the WSAEvents for the sockets
+            for (nfds_t i = 0; i < nfds; ++i)
+            {
+                struct pollfd* fd = &fds[i];
+                fd->revents = 0;
+                if (fd->fd >= 0)
+                {
+                    // create WSAEvent and add it to the vectors
+                    socketEvents.push_back(std::move(WSAEvent(fd)));
+                    HANDLE handle = socketEvents.back();
+                    if (handle == WSA_INVALID_EVENT)
+                    {
+                        WSASetLastError(WSAENOBUFS);
+                        return SOCKET_ERROR;
+                    }
+                    handles.push_back(handle);
+
+                    // mapping
+                    long networkEvents = 0;
+                    if (fd->events & (POLLIN                               )) networkEvents |= FD_READ  | FD_ACCEPT;
+                    if (fd->events & (POLLOUT /*| POLLWRNORM | POLLWRBAND*/)) networkEvents |= FD_WRITE | FD_CONNECT;
+                    //if (fd->events & (POLLPRI | POLLRDBAND               )) networkEvents |= FD_OOB;
+
+                    if (WSAEventSelect(fd->fd, handle, networkEvents) != 0)
+                    {
+                        fd->revents = POLLNVAL;
+                        socketEvents.pop_back();
+                        handles.pop_back();
+                    }
+                }
+            }
+
+            DWORD n = WSAWaitForMultipleEvents(handles.size(), handles.data(), FALSE, timeout != -1 ? static_cast<DWORD>(timeout) : WSA_INFINITE, FALSE);
+
+            if (n == WSA_WAIT_FAILED) return SOCKET_ERROR;
+            if (n == WSA_WAIT_TIMEOUT) return 0;
+            if (n == WSA_WAIT_EVENT_0)
+            {
+                // the interrupt event was signaled
+                *event = reinterpret_cast<void*>(interruptEvent);
+                return 1;
+            }
+
+            int handleIndex = n - WSA_WAIT_EVENT_0;
+            int socketIndex = handleIndex - 1;
+
+            WSANETWORKEVENTS netEvents;
+            int count = 0;
+            // WSAWaitForMultipleEvents returns the index of the first signaled event. And to emulate WSAPoll()
+            // all the signaled events must be processed.
+            while (socketIndex < socketEvents.size())
+            {
+                struct pollfd* fd = socketEvents[socketIndex];
+
+                memset(&netEvents, 0, sizeof(netEvents));
+                if (WSAEnumNetworkEvents(fd->fd, socketEvents[socketIndex], &netEvents) != 0)
+                {
+                    fd->revents = POLLERR;
+                }
+                else if (netEvents.lNetworkEvents != 0)
+                {
+                    // mapping
+                    if (netEvents.lNetworkEvents & (FD_READ  | FD_ACCEPT | FD_OOB)) fd->revents |= POLLIN;
+                    if (netEvents.lNetworkEvents & (FD_WRITE | FD_CONNECT        )) fd->revents |= POLLOUT;
+
+                    for (int i = 0; i < FD_MAX_EVENTS; ++i)
+                    {
+                        if (netEvents.iErrorCode[i] != 0)
+                        {
+                            fd->revents |= POLLERR;
+                            break;
+                        }
+                    }
+
+                    if (fd->revents != 0)
+                    {
+                        // only signaled sockets count
+                        count++;
+                    }
+                }
+                socketIndex++;
+            }
+
+            return count;
+        }
+        else
+        {
+            if (event && *event) *event = nullptr;
+
             socket_t maxfd = 0;
             fd_set readfds, writefds, errorfds;
             FD_ZERO(&readfds);
@@ -104,9 +261,11 @@ namespace ix
                     fd->revents |= POLLERR;
                 }
             }
-
             return ret;
+        }
 #else
+        if (event && *event) *event = nullptr;
+
         //
         // It was reported that on Android poll can fail and return -1 with
         // errno == EINTR, which should be a temp error and should typically

ixwebsocket/IXNetSystem.h

@@ -78,7 +78,7 @@ namespace ix
     bool initNetSystem();
     bool uninitNetSystem();
 
-    int poll(struct pollfd* fds, nfds_t nfds, int timeout);
+    int poll(struct pollfd* fds, nfds_t nfds, int timeout, void** event);
 
     const char* inet_ntop(int af, const void* src, char* dst, socklen_t size);
     int inet_pton(int af, const char* src, void* dst);

ixwebsocket/IXSelectInterrupt.cpp

@@ -45,4 +45,9 @@ namespace ix
     {
         return -1;
     }
+
+    void* SelectInterrupt::getEvent() const
+    {
+        return nullptr;
+    }
 } // namespace ix

ixwebsocket/IXSelectInterrupt.h

@@ -24,6 +24,7 @@ namespace ix
         virtual bool clear();
         virtual uint64_t read();
         virtual int getFd() const;
+        virtual void* getEvent() const;
 
         // Used as special codes for pipe communication
         static const uint64_t kSendRequest;

ixwebsocket/IXSelectInterruptEvent.cpp

@@ -0,0 +1,84 @@
+/*
+ *  IXSelectInterruptEvent.cpp
+ */
+
+//
+// On Windows we use a Windows Event to wake up ix::poll() (WSAWaitForMultipleEvents).
+// And on any other platform that doesn't support pipe file descriptors we
+// emulate the interrupt event by using a short timeout with ix::poll() and
+// read from the SelectInterrupt. (see Socket::poll() "Emulation mode")
+//
+#include "IXSelectInterruptEvent.h"
+
+namespace ix
+{
+    SelectInterruptEvent::SelectInterruptEvent()
+    {
+#ifdef _WIN32
+        _event = CreateEvent(NULL, TRUE, FALSE, NULL);
+#endif
+    }
+
+    SelectInterruptEvent::~SelectInterruptEvent()
+    {
+#ifdef _WIN32
+        CloseHandle(_event);
+#endif
+    }
+
+    bool SelectInterruptEvent::init(std::string& /*errorMsg*/)
+    {
+        return true;
+    }
+
+    bool SelectInterruptEvent::notify(uint64_t value)
+    {
+        std::lock_guard<std::mutex> lock(_valuesMutex);
+
+        // WebSocket implementation detail: We only need one of the values in the queue
+        if (std::find(_values.begin(), _values.end(), value) == _values.end())
+            _values.push_back(value);
+#ifdef _WIN32
+        SetEvent(_event); // wake up
+#endif
+        return true;
+    }
+
+    uint64_t SelectInterruptEvent::read()
+    {
+        std::lock_guard<std::mutex> lock(_valuesMutex);
+
+        if (_values.size() > 0)
+        {
+            uint64_t value = _values.front();
+            _values.pop_front();
+#ifdef _WIN32
+            // signal the event if there is still data in the queue
+            if (_values.size() == 0)
+                ResetEvent(_event);
+#endif
+            return value;
+        }
+        return 0;
+    }
+
+    bool SelectInterruptEvent::clear()
+    {
+        std::lock_guard<std::mutex> lock(_valuesMutex);
+        _values.clear();
+#ifdef _WIN32
+        ResetEvent(_event);
+#endif
+        return true;
+    }
+
+    void* SelectInterruptEvent::getEvent() const
+    {
+#ifdef _WIN32
+        return reinterpret_cast<void*>(_event);
+#else
+        return nullptr;
+#endif
+    }
+
+} // namespace ix

ixwebsocket/IXSelectInterruptEvent.h

@@ -0,0 +1,39 @@
+/*
+ *  IXSelectInterruptEvent.h
+ */
+
+#pragma once
+
+#include "IXSelectInterrupt.h"
+#include <mutex>
+#include <stdint.h>
+#include <string>
+#include <deque>
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+namespace ix
+{
+    class SelectInterruptEvent final : public SelectInterrupt
+    {
+    public:
+        SelectInterruptEvent();
+        virtual ~SelectInterruptEvent();
+
+        bool init(std::string& /*errorMsg*/) final;
+
+        bool notify(uint64_t value) final;
+        bool clear() final;
+        uint64_t read() final;
+        void* getEvent() const final;
+    private:
+        // contains every value only once, new values are inserted at the begin, nu
+        std::deque<uint64_t> _values;
+        std::mutex _valuesMutex;
+#ifdef _WIN32
+        // Windows Event to wake up the socket poll
+        HANDLE _event;
+#endif
+    };
+} // namespace ix

ixwebsocket/IXSelectInterruptFactory.cpp

@@ -7,20 +7,20 @@
 #include "IXSelectInterruptFactory.h"
 
 #include "IXUniquePtr.h"
-#if defined(__linux__) || defined(__APPLE__)
+#if _WIN32
-#include "IXSelectInterruptPipe.h"
+#include "IXSelectInterruptEvent.h"
 #else
-#include "IXSelectInterrupt.h"
+#include "IXSelectInterruptPipe.h"
 #endif
 
 namespace ix
 {
     SelectInterruptPtr createSelectInterrupt()
     {
-#if defined(__linux__) || defined(__APPLE__)
+#ifdef _WIN32
-        return ix::make_unique<SelectInterruptPipe>();
+        return ix::make_unique<SelectInterruptEvent>();
 #else
-        return ix::make_unique<SelectInterrupt>();
+        return ix::make_unique<SelectInterruptPipe>();
 #endif
     }
 } // namespace ix

ixwebsocket/IXSocket.cpp

@@ -47,6 +47,8 @@ namespace ix
                                 int sockfd,
                                 const SelectInterruptPtr& selectInterrupt)
     {
+        PollResultType pollResult = PollResultType::ReadyForRead;
+
         //
         // We used to use ::select to poll but on Android 9 we get large fds out of
         // ::connect which crash in FD_SET as they are larger than FD_SETSIZE. Switching
@@ -68,9 +70,11 @@ namespace ix
 
         // File descriptor used to interrupt select when needed
         int interruptFd = -1;
+        void* interruptEvent = nullptr;
         if (selectInterrupt)
         {
             interruptFd = selectInterrupt->getFd();
+            interruptEvent = selectInterrupt->getEvent();
 
             if (interruptFd != -1)
             {
@@ -78,11 +82,21 @@ namespace ix
                 fds[1].fd = interruptFd;
                 fds[1].events = POLLIN;
             }
+            else if (interruptEvent == nullptr)
+            {
+                // Emulation mode: SelectInterrupt neither supports file descriptors nor events
+
+                // Check the selectInterrupt for requests before doing the poll().
+                if (readSelectInterruptRequest(selectInterrupt, &pollResult))
+                {
+                    return pollResult;
+                }
+            }
         }
 
-        int ret = ix::poll(fds, nfds, timeoutMs);
+        void* event = interruptEvent; // ix::poll will set event to nullptr if it wasn't signaled
+        int ret = ix::poll(fds, nfds, timeoutMs, &event);
 
-        PollResultType pollResult = PollResultType::ReadyForRead;
         if (ret < 0)
         {
             pollResult = PollResultType::Error;
@@ -90,19 +104,18 @@ namespace ix
         else if (ret == 0)
         {
             pollResult = PollResultType::Timeout;
-        }
+            if (selectInterrupt && interruptFd == -1 && interruptEvent == nullptr)
-        else if (interruptFd != -1 && fds[1].revents & POLLIN)
             {
-            uint64_t value = selectInterrupt->read();
+                // Emulation mode: SelectInterrupt neither supports fd nor events
 
-            if (value == SelectInterrupt::kSendRequest)
+                // Check the selectInterrupt for requests
-            {
+                readSelectInterruptRequest(selectInterrupt, &pollResult);
-                pollResult = PollResultType::SendRequest;
             }
-            else if (value == SelectInterrupt::kCloseRequest)
-            {
-                pollResult = PollResultType::CloseRequest;
         }
+        else if ((interruptFd != -1 && fds[1].revents & POLLIN) || (interruptEvent != nullptr && event != nullptr))
+        {
+            // The InterruptEvent was signaled
+            readSelectInterruptRequest(selectInterrupt, &pollResult);
         }
         else if (sockfd != -1 && readyToRead && fds[0].revents & POLLIN)
         {
@@ -143,6 +156,25 @@ namespace ix
         return pollResult;
     }
 
+    bool Socket::readSelectInterruptRequest(const SelectInterruptPtr& selectInterrupt,
+                                            PollResultType* pollResult)
+    {
+        uint64_t value = selectInterrupt->read();
+
+        if (value == SelectInterrupt::kSendRequest)
+        {
+            *pollResult = PollResultType::SendRequest;
+            return true;
+        }
+        else if (value == SelectInterrupt::kCloseRequest)
+        {
+            *pollResult = PollResultType::CloseRequest;
+            return true;
+        }
+
+        return false;
+    }
+
     PollResultType Socket::isReadyToRead(int timeoutMs)
     {
         if (_sockfd == -1)
@@ -171,6 +203,11 @@ namespace ix
         return _selectInterrupt->notify(wakeUpCode);
     }
 
+    bool Socket::isWakeUpFromPollSupported()
+    {
+        return _selectInterrupt->getFd() != -1 || _selectInterrupt->getEvent() != nullptr;
+    }
+
     bool Socket::accept(std::string& errMsg)
     {
         if (_sockfd == -1)

ixwebsocket/IXSocket.h

@@ -43,6 +43,7 @@ namespace ix
         // Functions to check whether there is activity on the socket
         PollResultType poll(int timeoutMs = kDefaultPollTimeout);
         bool wakeUpFromPoll(uint64_t wakeUpCode);
+        bool isWakeUpFromPollSupported();
 
         PollResultType isReadyToWrite(int timeoutMs);
         PollResultType isReadyToRead(int timeoutMs);
@@ -83,6 +84,9 @@ namespace ix
         std::atomic<int> _sockfd;
         std::mutex _socketMutex;
 
+        static bool readSelectInterruptRequest(const SelectInterruptPtr& selectInterrupt,
+                                               PollResultType* pollResult);
+
     private:
         static const int kDefaultPollTimeout;
         static const int kDefaultPollNoTimeout;

ixwebsocket/IXSocketConnect.cpp

@@ -20,6 +20,7 @@
 #include <linux/in.h>
 #include <linux/tcp.h>
 #endif
+#include <ixwebsocket/IXSelectInterruptFactory.h>
 
 namespace ix
 {
@@ -66,7 +67,7 @@ namespace ix
 
             int timeoutMs = 10;
             bool readyToRead = false;
-            auto selectInterrupt = ix::make_unique<SelectInterrupt>();
+            SelectInterruptPtr selectInterrupt = ix::createSelectInterrupt();
             PollResultType pollResult = Socket::poll(readyToRead, timeoutMs, fd, selectInterrupt);
 
             if (pollResult == PollResultType::Timeout)

ixwebsocket/IXWebSocketTransport.cpp

@@ -297,13 +297,11 @@ namespace ix
             lastingTimeoutDelayInMs = (1000 * _pingIntervalSecs) - timeSinceLastPingMs;
         }
 
-#ifdef _WIN32
+        // The platform may not have select interrupt capabilities, so wait with a small timeout
-        // Windows does not have select interrupt capabilities, so wait with a small timeout
+        if (lastingTimeoutDelayInMs <= 0 && !_socket->isWakeUpFromPollSupported())
-        if (lastingTimeoutDelayInMs <= 0)
         {
             lastingTimeoutDelayInMs = 20;
         }
-#endif
 
         // If we are requesting a cancellation, pass in a positive and small timeout
         // to never poll forever without a timeout.