ghc/rts/win32/IOManager.c

   1 /* IOManager.c
   2  *
   3  * Non-blocking / asynchronous I/O for Win32.
   4  *
   5  * (c) sof, 2002-2003.
   6  */
   7 #include "IOManager.h"
   8 #include "WorkQueue.h"
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <io.h>
  12 #include <winsock.h>
  13 #include <process.h>
  14
  15 /*
  16  * Internal state maintained by the IO manager.
  17  */
  18 typedef struct IOManagerState {
  19   CritSection      manLock;
  20   WorkQueue*       workQueue;
  21   int              numWorkers;
  22   int              workersIdle;
  23   HANDLE           hExitEvent;
  24   unsigned int     requestID;
  25 } IOManagerState;
  26
  27 /* ToDo: wrap up this state via a IOManager handle instead? */
  28 static IOManagerState* ioMan;
  29
  30 /*
  31  * The routine executed by each worker thread.
  32  */
  33 static
  34 unsigned
  35 WINAPI
  36 IOWorkerProc(PVOID param)
  37 {
  38   HANDLE  hWaits[2];
  39   DWORD   rc;
  40   IOManagerState* iom = (IOManagerState*)param;
  41   WorkQueue* pq = iom->workQueue;
  42   WorkItem*  work;
  43   int        len;
  44   DWORD      errCode;
  45
  46   hWaits[0] = (HANDLE)iom->hExitEvent;
  47   hWaits[1] = GetWorkQueueHandle(pq);
  48
  49   while (1) {
  50     /* The error code is communicated back on completion of request; reset. */
  51     errCode = 0;
  52
  53     EnterCriticalSection(&iom->manLock);
  54     iom->workersIdle++;
  55     LeaveCriticalSection(&iom->manLock);
  56
  57     rc = WaitForMultipleObjects( 2, hWaits, FALSE, INFINITE );
  58
  59     EnterCriticalSection(&iom->manLock);
  60     iom->workersIdle--;
  61     LeaveCriticalSection(&iom->manLock);
  62
  63     if ( WAIT_OBJECT_0 == rc ) {
  64       /* shutdown */
  65 #if 0
  66       fprintf(stderr, "shutting down...\n"); fflush(stderr);
  67 #endif
  68       return 0;
  69     } else if ( (WAIT_OBJECT_0 + 1) == rc ) {
  70       /* work item available, fetch it. */
  71 #if 0
  72       fprintf(stderr, "work available...\n"); fflush(stderr);
  73 #endif
  74       if (FetchWork(pq,(void**)&work)) {
  75         if ( work->workKind & WORKER_READ ) {
  76           if ( work->workKind & WORKER_FOR_SOCKET ) {
  77             len = recv(work->fd, work->buf, work->len, 0);
  78             if (len == SOCKET_ERROR) {
  79               errCode = WSAGetLastError();
  80             }
  81           } else {
  82             len = read(work->fd, work->buf, work->len);
  83             if (len == -1) { errCode = errno; }
  84           }
  85         } else if ( work->workKind & WORKER_WRITE ) {
  86           if ( work->workKind & WORKER_FOR_SOCKET ) {
  87             len = send(work->fd, work->buf, work->len, 0);
  88             if (len == SOCKET_ERROR) {
  89               errCode = WSAGetLastError();
  90             }
  91           } else {
  92             len = write(work->fd,work->buf, work->len);
  93             if (len == -1) { errCode = errno; }
  94           }
  95         } else if ( work->workKind & WORKER_DELAY ) {
  96           /* very approximate implementation of threadDelay */
  97           Sleep(work->len);
  98           len = work->len;
  99           errCode = 0;
 100         } else {
 101           fprintf(stderr, "unknown work request type (%d) , ignoring.\n", work->workKind);
 102           fflush(stderr);
 103           continue;
 104         }
 105         work->onCompletion(work->requestID,
 106                            work->param,
 107                            work->fd,
 108                            len,
 109                            work->buf,
 110                            errCode);
 111         /* Free the WorkItem */
 112         free(work);
 113       } else {
 114           fprintf(stderr, "unable to fetch work; fatal.\n"); fflush(stderr);
 115           return 1;
 116       }
 117     } else {
 118           fprintf(stderr, "waiting failed; fatal.\n"); fflush(stderr);
 119           return 1;
 120     }
 121   }
 122   return 0;
 123 }
 124
 125 static
 126 BOOL
 127 NewIOWorkerThread(IOManagerState* iom)
 128 {
 129   return ( 0 != _beginthreadex(NULL,
 130                                0,
 131                                IOWorkerProc,
 132                                (LPVOID)iom,
 133                                0,
 134                                NULL) );
 135 }
 136
 137 BOOL
 138 StartIOManager(void)
 139 {
 140   HANDLE hExit;
 141   WorkQueue* wq;
 142
 143   wq = NewWorkQueue();
 144   if ( !wq ) return FALSE;
 145
 146   ioMan = (IOManagerState*)malloc(sizeof(IOManagerState));
 147
 148   if (!ioMan) {
 149     FreeWorkQueue(wq);
 150     return FALSE;
 151   }
 152
 153   /* A manual-reset event */
 154   hExit = CreateEvent ( NULL, TRUE, FALSE, NULL );
 155   if ( !hExit ) {
 156     FreeWorkQueue(wq);
 157     free(ioMan);
 158     return FALSE;
 159   }
 160
 161   ioMan->hExitEvent = hExit;
 162   InitializeCriticalSection(&ioMan->manLock);
 163   ioMan->workQueue   = wq;
 164   ioMan->numWorkers  = 0;
 165   ioMan->workersIdle = 0;
 166   ioMan->requestID   = 1;
 167
 168   return TRUE;
 169 }
 170
 171 /*
 172  * Function: AddIORequest()
 173  *
 174  * Conduit to underlying WorkQueue's SubmitWork(); adds IO
 175  * request to work queue, returning without blocking.
 176  */
 177 int
 178 AddIORequest ( int   fd,
 179                BOOL  forWriting,
 180                BOOL  isSocket,
 181                int   len,
 182                char* buffer,
 183                void* data,
 184                CompletionProc onCompletion)
 185 {
 186   WorkItem* wItem = (WorkItem*)malloc(sizeof(WorkItem));
 187   if (!ioMan || !wItem) return 0;
 188
 189   /* Fill in the blanks */
 190   wItem->fd           = fd;
 191   wItem->workKind     = ( isSocket   ? WORKER_FOR_SOCKET : 0 ) |
 192                         ( forWriting ? WORKER_WRITE : WORKER_READ );
 193   wItem->len          = len;
 194   wItem->buf          = buffer;
 195   wItem->param        = data;
 196   wItem->onCompletion = onCompletion;
 197   wItem->requestID    = ioMan->requestID++;
 198
 199   EnterCriticalSection(&ioMan->manLock);
 200   /* If there are no worker threads available, create one.
 201    *
 202    * If this turns out to be too aggressive a policy, refine.
 203    */
 204 #if 0
 205   fprintf(stderr, "AddIORequest: %d\n", ioMan->workersIdle); fflush(stderr);
 206 #endif
 207   if ( ioMan->workersIdle == 0 ) {
 208     ioMan->numWorkers++;
 209     NewIOWorkerThread(ioMan);
 210   }
 211   LeaveCriticalSection(&ioMan->manLock);
 212
 213   if (SubmitWork(ioMan->workQueue,wItem)) {
 214     return wItem->requestID;
 215   } else {
 216     return 0;
 217   }
 218 }
 219
 220 /*
 221  * Function: AddDelayRequest()
 222  *
 223  */
 224 BOOL
 225 AddDelayRequest ( unsigned int   msecs,
 226                   void*          data,
 227                   CompletionProc onCompletion)
 228 {
 229   WorkItem* wItem = (WorkItem*)malloc(sizeof(WorkItem));
 230   if (!ioMan || !wItem) return FALSE;
 231
 232   /* Fill in the blanks */
 233   wItem->fd           = 0;
 234   wItem->workKind     = WORKER_DELAY;
 235   wItem->len          = msecs;
 236   wItem->buf          = 0;
 237   wItem->param        = data;
 238   wItem->onCompletion = onCompletion;
 239   wItem->requestID    = ioMan->requestID++;
 240
 241   EnterCriticalSection(&ioMan->manLock);
 242   if ( ioMan->workersIdle == 0 ) {
 243     ioMan->numWorkers++;
 244     NewIOWorkerThread(ioMan);
 245   }
 246   LeaveCriticalSection(&ioMan->manLock);
 247
 248   if (SubmitWork(ioMan->workQueue,wItem)) {
 249     return wItem->requestID;
 250   } else {
 251     return 0;
 252   }
 253 }
 254
 255 void ShutdownIOManager()
 256 {
 257   SetEvent(ioMan->hExitEvent);
 258   free(ioMan);
 259   ioMan = NULL;
 260 }