source/io/windows/eventreader.cpp

   1 #include <windows.h>
   2 #include <algorithm>
   3 #include <msp/core/systemerror.h>
   4 #include "eventreader.h"
   5 #include "handle_private.h"
   6
   7 using namespace std;
   8
   9 namespace Msp {
  10 namespace IO {
  11
  12 struct EventReader::Private
  13 {
  14         OVERLAPPED *overlapped;
  15         Handle event;
  16         unsigned buf_size;
  17         char *buffer;
  18         unsigned buf_avail;
  19         char *buf_next;
  20 };
  21
  22
  23 EventReader::EventReader(Handle &h, unsigned size):
  24         handle(h),
  25         priv(new Private)
  26 {
  27         priv->overlapped = 0;
  28         *priv->event = CreateEvent(0, true, false, 0);
  29         priv->buf_size = size;
  30         priv->buffer = new char[priv->buf_size];
  31         priv->buf_avail = 0;
  32         priv->buf_next = priv->buffer;
  33 }
  34
  35 EventReader::~EventReader()
  36 {
  37         CloseHandle(*priv->event);
  38         delete priv->overlapped;
  39         delete[] priv->buffer;
  40         delete priv;
  41 }
  42
  43 const Handle &EventReader::get_event()
  44 {
  45         start();
  46         return priv->event;
  47 }
  48
  49 void EventReader::start()
  50 {
  51         if(priv->buf_avail || priv->overlapped)
  52                 return;
  53
  54         priv->overlapped = new OVERLAPPED;
  55         memset(priv->overlapped, 0, sizeof(OVERLAPPED));
  56         priv->overlapped->hEvent = *priv->event;
  57
  58         DWORD ret;
  59         priv->buf_next = priv->buffer;
  60         if(!ReadFile(*handle, priv->buffer, priv->buf_size, &ret, priv->overlapped))
  61         {
  62                 unsigned err = GetLastError();
  63                 if(err!=ERROR_IO_PENDING)
  64                         throw system_error("ReadFile");
  65         }
  66         else
  67         {
  68                 priv->buf_avail = ret;
  69                 delete priv->overlapped;
  70                 priv->overlapped = 0;
  71                 SetEvent(*priv->event);
  72         }
  73 }
  74
  75 void EventReader::wait()
  76 {
  77         if(!priv->overlapped)
  78                 return;
  79
  80         DWORD ret;
  81         if(!GetOverlappedResult(*handle, priv->overlapped, &ret, true))
  82                 throw system_error("GetOverlappedResult");
  83         else
  84         {
  85                 priv->buf_avail = ret;
  86                 delete priv->overlapped;
  87                 priv->overlapped = 0;
  88         }
  89 }
  90
  91 unsigned EventReader::read(char *buf, unsigned len)
  92 {
  93         if(!priv->buf_avail)
  94         {
  95                 // No data in buffer, try to get some
  96                 start();
  97                 wait();
  98         }
  99
 100         len = min(len, priv->buf_avail);
 101         memcpy(buf, priv->buf_next, len);
 102         priv->buf_next += len;
 103         priv->buf_avail -= len;
 104
 105         if(!priv->buf_avail)
 106         {
 107                 ResetEvent(*priv->event);
 108                 start();
 109         }
 110
 111         return len;
 112 }
 113
 114 } // namespace IO
 115 } // namespace Msp