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 fd)
  46 {
  47     wxUnusedVar(fd); // unused if wxLogTrace() disabled
  48
  49     uint32_t ep = 0;
  50
  51     if ( flags & wxFDIO_INPUT )
  52     {
  53         ep |= EPOLLIN;
  54         wxLogTrace(wxEpollDispatcher_Trace,
  55                    _T("Registered fd %d for input events"), fd);
  56     }
  57
  58     if ( flags & wxFDIO_OUTPUT )
  59     {
  60         ep |= EPOLLOUT;
  61         wxLogTrace(wxEpollDispatcher_Trace,
  62                    _T("Registered fd %d for output events"), fd);
  63     }
  64
  65     if ( flags & wxFDIO_EXCEPTION )
  66     {
  67         ep |= EPOLLERR | EPOLLHUP;
  68         wxLogTrace(wxEpollDispatcher_Trace,
  69                    _T("Registered fd %d for exceptional events"), fd);
  70     }
  71
  72     return ep;
  73 }
  74
  75 // ----------------------------------------------------------------------------
  76 // wxEpollDispatcher
  77 // ----------------------------------------------------------------------------
  78
  79 /* static */
  80 wxEpollDispatcher *wxEpollDispatcher::Create()
  81 {
  82     int epollDescriptor = epoll_create(1024);
  83     if ( epollDescriptor == -1 )
  84     {
  85         wxLogSysError(_("Failed to create epoll descriptor"));
  86         return NULL;
  87     }
  88     wxLogTrace(wxEpollDispatcher_Trace,
  89                    _T("Epoll fd %d created"), epollDescriptor);
  90     return new wxEpollDispatcher(epollDescriptor);
  91 }
  92
  93 wxEpollDispatcher::wxEpollDispatcher(int epollDescriptor)
  94 {
  95     wxASSERT_MSG( epollDescriptor != -1, _T("invalid descriptor") );
  96
  97     m_epollDescriptor = epollDescriptor;
  98 }
  99
 100 wxEpollDispatcher::~wxEpollDispatcher()
 101 {
 102     if ( close(m_epollDescriptor) != 0 )
 103     {
 104         wxLogSysError(_("Error closing epoll descriptor"));
 105     }
 106 }
 107
 108 bool wxEpollDispatcher::RegisterFD(int fd, wxFDIOHandler* handler, int flags)
 109 {
 110     epoll_event ev;
 111     ev.events = GetEpollMask(flags, fd);
 112     ev.data.ptr = handler;
 113
 114     const int ret = epoll_ctl(m_epollDescriptor, EPOLL_CTL_ADD, fd, &ev);
 115     if ( ret != 0 )
 116     {
 117         wxLogSysError(_("Failed to add descriptor %d to epoll descriptor %d"),
 118                       fd, m_epollDescriptor);
 119
 120         return false;
 121     }
 122     wxLogTrace(wxEpollDispatcher_Trace,
 123                _T("Added fd %d (handler %p) to epoll %d"), fd, handler, m_epollDescriptor);
 124
 125     return true;
 126 }
 127
 128 bool wxEpollDispatcher::ModifyFD(int fd, wxFDIOHandler* handler, int flags)
 129 {
 130     epoll_event ev;
 131     ev.events = GetEpollMask(flags, fd);
 132     ev.data.ptr = handler;
 133
 134     const int ret = epoll_ctl(m_epollDescriptor, EPOLL_CTL_MOD, fd, &ev);
 135     if ( ret != 0 )
 136     {
 137         wxLogSysError(_("Failed to modify descriptor %d in epoll descriptor %d"),
 138                       fd, m_epollDescriptor);
 139
 140         return false;
 141     }
 142
 143     wxLogTrace(wxEpollDispatcher_Trace,
 144                 _T("Modified fd %d (handler: %p) on epoll %d"), fd, handler, m_epollDescriptor);
 145     return true;
 146 }
 147
 148 bool wxEpollDispatcher::UnregisterFD(int fd)
 149 {
 150     epoll_event ev;
 151     ev.events = 0;
 152     ev.data.ptr = NULL;
 153
 154     if ( epoll_ctl(m_epollDescriptor, EPOLL_CTL_DEL, fd, &ev) != 0 )
 155     {
 156         wxLogSysError(_("Failed to unregister descriptor %d from epoll descriptor %d"),
 157                       fd, m_epollDescriptor);
 158     }
 159     wxLogTrace(wxEpollDispatcher_Trace,
 160                 _T("removed fd %d from %d"), fd, m_epollDescriptor);
 161     return true;
 162 }
 163
 164 int
 165 wxEpollDispatcher::DoPoll(epoll_event *events, int numEvents, int timeout) const
 166 {
 167     // the code below relies on TIMEOUT_INFINITE being -1 so that we can pass
 168     // timeout value directly to epoll_wait() which interprets -1 as meaning to
 169     // wait forever and would need to be changed if the value of
 170     // TIMEOUT_INFINITE ever changes
 171     wxCOMPILE_TIME_ASSERT( TIMEOUT_INFINITE == -1, UpdateThisCode );
 172
 173     wxMilliClock_t timeEnd;
 174     if ( timeout > 0 )
 175         timeEnd = wxGetLocalTimeMillis();
 176
 177     int rc;
 178     for ( ;; )
 179     {
 180         rc = epoll_wait(m_epollDescriptor, events, numEvents, timeout);
 181         if ( rc != -1 || errno != EINTR )
 182             break;
 183
 184         // we got interrupted, update the timeout and restart
 185         if ( timeout > 0 )
 186         {
 187             timeout = wxMilliClockToLong(timeEnd - wxGetLocalTimeMillis());
 188             if ( timeout < 0 )
 189                 return 0;
 190         }
 191     }
 192
 193     return rc;
 194 }
 195
 196 bool wxEpollDispatcher::HasPending() const
 197 {
 198     epoll_event event;
 199
 200     // NB: it's not really clear if epoll_wait() can return a number greater
 201     //     than the number of events passed to it but just in case it can, use
 202     //     >= instead of == here, see #10397
 203     return DoPoll(&event, 1, 0) >= 1;
 204 }
 205
 206 int wxEpollDispatcher::Dispatch(int timeout)
 207 {
 208     epoll_event events[16];
 209
 210     const int rc = DoPoll(events, WXSIZEOF(events), timeout);
 211
 212     if ( rc == -1 )
 213     {
 214         wxLogSysError(_("Waiting for IO on epoll descriptor %d failed"),
 215                       m_epollDescriptor);
 216         return -1;
 217     }
 218
 219     int numEvents = 0;
 220     for ( epoll_event *p = events; p < events + rc; p++ )
 221     {
 222         wxFDIOHandler * const handler = (wxFDIOHandler *)(p->data.ptr);
 223         if ( !handler )
 224         {
 225             wxFAIL_MSG( _T("NULL handler in epoll_event?") );
 226             continue;
 227         }
 228
 229         // note that for compatibility with wxSelectDispatcher we call
 230         // OnReadWaiting() on EPOLLHUP as this is what epoll_wait() returns
 231         // when the write end of a pipe is closed while with select() the
 232         // remaining pipe end becomes ready for reading when this happens
 233         if ( p->events & (EPOLLIN | EPOLLHUP) )
 234             handler->OnReadWaiting();
 235         else if ( p->events & EPOLLOUT )
 236             handler->OnWriteWaiting();
 237         else if ( p->events & EPOLLERR )
 238             handler->OnExceptionWaiting();
 239         else
 240             continue;
 241
 242         numEvents++;
 243     }
 244
 245     return numEvents;
 246 }
 247
 248 #endif // wxUSE_EPOLL_DISPATCHER