src/unix/epolldispatcher.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/epolldispatcher.cpp
   3 // Purpose:     implements dispatcher for epoll_wait() call
   4 // Author:      Lukasz Michalski
   5 // Created:     April 2007
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 2007 Lukasz Michalski
   8 // License:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // for compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #if wxUSE_EPOLL_DISPATCHER
  23
  24 #include "wx/unix/private/epolldispatcher.h"
  25 #include "wx/unix/private.h"
  26 #include "wx/stopwatch.h"
  27
  28 #ifndef WX_PRECOMP
  29     #include "wx/log.h"
  30     #include "wx/intl.h"
  31 #endif
  32
  33 #include <sys/epoll.h>
  34 #include <errno.h>
  35 #include <unistd.h>
  36
  37 #define wxEpollDispatcher_Trace wxT("epolldispatcher")
  38
  39 // ============================================================================
  40 // implementation
  41 // ============================================================================
  42
  43 // helper: return EPOLLxxx mask corresponding to the given flags (and also log
  44 // debugging messages about it)
  45 static uint32_t GetEpollMask(int flags, int WXUNUSED_UNLESS_DEBUG(fd))
  46 {
  47     uint32_t ep = 0;
  48
  49     if ( flags & wxFDIO_INPUT )
  50     {
  51         ep |= EPOLLIN;
  52         wxLogTrace(wxEpollDispatcher_Trace,
  53                    _T("Registered fd %d for input events"), fd);
  54     }
  55
  56     if ( flags & wxFDIO_OUTPUT )
  57     {
  58         ep |= EPOLLOUT;
  59         wxLogTrace(wxEpollDispatcher_Trace,
  60                    _T("Registered fd %d for output events"), fd);
  61     }
  62
  63     if ( flags & wxFDIO_EXCEPTION )
  64     {
  65         ep |= EPOLLERR | EPOLLHUP;
  66         wxLogTrace(wxEpollDispatcher_Trace,
  67                    _T("Registered fd %d for exceptional events"), fd);
  68     }
  69
  70     return ep;
  71 }
  72
  73 // ----------------------------------------------------------------------------
  74 // wxEpollDispatcher
  75 // ----------------------------------------------------------------------------
  76
  77 /* static */
  78 wxEpollDispatcher *wxEpollDispatcher::Create()
  79 {
  80     int epollDescriptor = epoll_create(1024);
  81     if ( epollDescriptor == -1 )
  82     {
  83         wxLogSysError(_("Failed to create epoll descriptor"));
  84         return NULL;
  85     }
  86     wxLogTrace(wxEpollDispatcher_Trace,
  87                    _T("Epoll fd %d created"), epollDescriptor);
  88     return new wxEpollDispatcher(epollDescriptor);
  89 }
  90
  91 wxEpollDispatcher::wxEpollDispatcher(int epollDescriptor)
  92 {
  93     wxASSERT_MSG( epollDescriptor != -1, _T("invalid descriptor") );
  94
  95     m_epollDescriptor = epollDescriptor;
  96 }
  97
  98 wxEpollDispatcher::~wxEpollDispatcher()
  99 {
 100     if ( close(m_epollDescriptor) != 0 )
 101     {
 102         wxLogSysError(_("Error closing epoll descriptor"));
 103     }
 104 }
 105
 106 bool wxEpollDispatcher::RegisterFD(int fd, wxFDIOHandler* handler, int flags)
 107 {
 108     epoll_event ev;
 109     ev.events = GetEpollMask(flags, fd);
 110     ev.data.ptr = handler;
 111
 112     const int ret = epoll_ctl(m_epollDescriptor, EPOLL_CTL_ADD, fd, &ev);
 113     if ( ret != 0 )
 114     {
 115         wxLogSysError(_("Failed to add descriptor %d to epoll descriptor %d"),
 116                       fd, m_epollDescriptor);
 117
 118         return false;
 119     }
 120     wxLogTrace(wxEpollDispatcher_Trace,
 121                _T("Added fd %d (handler %p) to epoll %d"), fd, handler, m_epollDescriptor);
 122
 123     return true;
 124 }
 125
 126 bool wxEpollDispatcher::ModifyFD(int fd, wxFDIOHandler* handler, int flags)
 127 {
 128     epoll_event ev;
 129     ev.events = GetEpollMask(flags, fd);
 130     ev.data.ptr = handler;
 131
 132     const int ret = epoll_ctl(m_epollDescriptor, EPOLL_CTL_MOD, fd, &ev);
 133     if ( ret != 0 )
 134     {
 135         wxLogSysError(_("Failed to modify descriptor %d in epoll descriptor %d"),
 136                       fd, m_epollDescriptor);
 137
 138         return false;
 139     }
 140
 141     wxLogTrace(wxEpollDispatcher_Trace,
 142                 _T("Modified fd %d (handler: %p) on epoll %d"), fd, handler, m_epollDescriptor);
 143     return true;
 144 }
 145
 146 bool wxEpollDispatcher::UnregisterFD(int fd)
 147 {
 148     epoll_event ev;
 149     ev.events = 0;
 150     ev.data.ptr = NULL;
 151
 152     if ( epoll_ctl(m_epollDescriptor, EPOLL_CTL_DEL, fd, &ev) != 0 )
 153     {
 154         wxLogSysError(_("Failed to unregister descriptor %d from epoll descriptor %d"),
 155                       fd, m_epollDescriptor);
 156     }
 157     wxLogTrace(wxEpollDispatcher_Trace,
 158                 _T("removed fd %d from %d"), fd, m_epollDescriptor);
 159     return true;
 160 }
 161
 162 int
 163 wxEpollDispatcher::DoPoll(epoll_event *events, int numEvents, int timeout) const
 164 {
 165     // the code below relies on TIMEOUT_INFINITE being -1 so that we can pass
 166     // timeout value directly to epoll_wait() which interprets -1 as meaning to
 167     // wait forever and would need to be changed if the value of
 168     // TIMEOUT_INFINITE ever changes
 169     wxCOMPILE_TIME_ASSERT( TIMEOUT_INFINITE == -1, UpdateThisCode );
 170
 171     wxMilliClock_t timeEnd;
 172     if ( timeout > 0 )
 173         timeEnd = wxGetLocalTimeMillis();
 174
 175     int rc;
 176     for ( ;; )
 177     {
 178         rc = epoll_wait(m_epollDescriptor, events, numEvents, timeout);
 179         if ( rc != -1 || errno != EINTR )
 180             break;
 181
 182         // we got interrupted, update the timeout and restart
 183         if ( timeout > 0 )
 184         {
 185             timeout = wxMilliClockToLong(timeEnd - wxGetLocalTimeMillis());
 186             if ( timeout < 0 )
 187                 return 0;
 188         }
 189     }
 190
 191     return rc;
 192 }
 193
 194 bool wxEpollDispatcher::HasPending() const
 195 {
 196     epoll_event event;
 197
 198     // NB: it's not really clear if epoll_wait() can return a number greater
 199     //     than the number of events passed to it but just in case it can, use
 200     //     >= instead of == here, see #10397
 201     return DoPoll(&event, 1, 0) >= 1;
 202 }
 203
 204 int wxEpollDispatcher::Dispatch(int timeout)
 205 {
 206     epoll_event events[16];
 207
 208     const int rc = DoPoll(events, WXSIZEOF(events), timeout);
 209
 210     if ( rc == -1 )
 211     {
 212         wxLogSysError(_("Waiting for IO on epoll descriptor %d failed"),
 213                       m_epollDescriptor);
 214         return -1;
 215     }
 216
 217     int numEvents = 0;
 218     for ( epoll_event *p = events; p < events + rc; p++ )
 219     {
 220         wxFDIOHandler * const handler = (wxFDIOHandler *)(p->data.ptr);
 221         if ( !handler )
 222         {
 223             wxFAIL_MSG( _T("NULL handler in epoll_event?") );
 224             continue;
 225         }
 226
 227         // note that for compatibility with wxSelectDispatcher we call
 228         // OnReadWaiting() on EPOLLHUP as this is what epoll_wait() returns
 229         // when the write end of a pipe is closed while with select() the
 230         // remaining pipe end becomes ready for reading when this happens
 231         if ( p->events & (EPOLLIN | EPOLLHUP) )
 232             handler->OnReadWaiting();
 233         else if ( p->events & EPOLLOUT )
 234             handler->OnWriteWaiting();
 235         else if ( p->events & EPOLLERR )
 236             handler->OnExceptionWaiting();
 237         else
 238             continue;
 239
 240         numEvents++;
 241     }
 242
 243     return numEvents;
 244 }
 245
 246 #endif // wxUSE_EPOLL_DISPATCHER