Revert "Revert 'multi: implement wait using winsock events'"

This reverts commit 2260e0ebe6d45529495231b3e37a0c58fb92a6a2,
also restoring previous follow up changes which were reverted.

Authored-by: rcombs on github
Authored-by: Marc Hörsken
Reviewed-by: Jay Satiro
Reviewed-by: Marcel Raad

Restores #5634
Reverts #6281
Part of #6245

2 files changed, 153 insertions, 3 deletions

diff --git a/lib/multi.c b/lib/multi.c
index 99600a3ba..aa2eb52e3 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -381,6 +381,11 @@ struct Curl_multi *Curl_multi_handle(int hashsize, /* socket hash */
   multi->max_concurrent_streams = 100;
   multi->ipv6_works = Curl_ipv6works(NULL);
 
+#ifdef USE_WINSOCK
+  multi->wsa_event = WSACreateEvent();
+  if(multi->wsa_event == WSA_INVALID_EVENT)
+    goto error;
+#else
 #ifdef ENABLE_WAKEUP
   if(Curl_socketpair(AF_UNIX, SOCK_STREAM, 0, multi->wakeup_pair) < 0) {
     multi->wakeup_pair[0] = CURL_SOCKET_BAD;
@@ -394,6 +399,7 @@ struct Curl_multi *Curl_multi_handle(int hashsize, /* socket hash */
     multi->wakeup_pair[1] = CURL_SOCKET_BAD;
   }
 #endif
+#endif
 
   return multi;
 
@@ -1080,9 +1086,15 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
   unsigned int curlfds;
   long timeout_internal;
   int retcode = 0;
+#ifndef USE_WINSOCK
   struct pollfd a_few_on_stack[NUM_POLLS_ON_STACK];
   struct pollfd *ufds = &a_few_on_stack[0];
   bool ufds_malloc = FALSE;
+#else
+  struct pollfd pre_poll;
+  WSANETWORKEVENTS wsa_events;
+  DEBUGASSERT(multi->wsa_event != WSA_INVALID_EVENT);
+#endif
 
   if(!GOOD_MULTI_HANDLE(multi))
     return CURLM_BAD_HANDLE;
@@ -1128,11 +1140,16 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
   nfds += extra_nfds; /* add the externally provided ones */
 
 #ifdef ENABLE_WAKEUP
+#ifdef USE_WINSOCK
+  if(use_wakeup) {
+#else
   if(use_wakeup && multi->wakeup_pair[0] != CURL_SOCKET_BAD) {
+#endif
     ++nfds;
   }
 #endif
 
+#ifndef USE_WINSOCK
   if(nfds > NUM_POLLS_ON_STACK) {
     /* 'nfds' is a 32 bit value and 'struct pollfd' is typically 8 bytes
        big, so at 2^29 sockets this value might wrap. When a process gets
@@ -1143,7 +1160,9 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
       return CURLM_OUT_OF_MEMORY;
     ufds_malloc = TRUE;
   }
+
   nfds = 0;
+#endif
 
   /* only do the second loop if we found descriptors in the first stage run
      above */
@@ -1156,22 +1175,40 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
 
       for(i = 0; i < MAX_SOCKSPEREASYHANDLE; i++) {
         curl_socket_t s = CURL_SOCKET_BAD;
-
+#ifdef USE_WINSOCK
+        long mask = 0;
+#endif
         if(bitmap & GETSOCK_READSOCK(i)) {
+#ifdef USE_WINSOCK
+          if(timeout_ms && SOCKET_READABLE(sockbunch[i], 0) > 0)
+            timeout_ms = 0;
+          mask |= FD_READ|FD_ACCEPT|FD_CLOSE;
+#else
           ufds[nfds].fd = sockbunch[i];
           ufds[nfds].events = POLLIN;
           ++nfds;
+#endif
           s = sockbunch[i];
         }
         if(bitmap & GETSOCK_WRITESOCK(i)) {
+#ifdef USE_WINSOCK
+          if(timeout_ms && SOCKET_WRITABLE(sockbunch[i], 0) > 0)
+            timeout_ms = 0;
+          mask |= FD_WRITE|FD_CONNECT|FD_CLOSE;
+#else
           ufds[nfds].fd = sockbunch[i];
           ufds[nfds].events = POLLOUT;
           ++nfds;
+#endif
           s = sockbunch[i];
         }
         if(s == CURL_SOCKET_BAD) {
           break;
         }
+#ifdef USE_WINSOCK
+        if(WSAEventSelect(s, multi->wsa_event, mask) != 0)
+          return CURLM_INTERNAL_ERROR;
+#endif
       }
 
       data = data->next; /* check next handle */
@@ -1180,6 +1217,37 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
 
   /* Add external file descriptions from poll-like struct curl_waitfd */
   for(i = 0; i < extra_nfds; i++) {
+#ifdef USE_WINSOCK
+    long mask = 0;
+    extra_fds[i].revents = 0;
+    pre_poll.fd = extra_fds[i].fd;
+    pre_poll.events = 0;
+    pre_poll.revents = 0;
+    if(extra_fds[i].events & CURL_WAIT_POLLIN) {
+      mask |= FD_READ|FD_ACCEPT|FD_CLOSE;
+      pre_poll.events |= POLLIN;
+    }
+    if(extra_fds[i].events & CURL_WAIT_POLLPRI) {
+      mask |= FD_OOB;
+      pre_poll.events |= POLLPRI;
+    }
+    if(extra_fds[i].events & CURL_WAIT_POLLOUT) {
+      mask |= FD_WRITE|FD_CONNECT|FD_CLOSE;
+      pre_poll.events |= POLLOUT;
+    }
+    if(Curl_poll(&pre_poll, 1, 0) > 0) {
+      if(pre_poll.revents & POLLIN)
+        extra_fds[i].revents |= CURL_WAIT_POLLIN;
+      if(pre_poll.revents & POLLPRI)
+        extra_fds[i].revents |= CURL_WAIT_POLLPRI;
+      if(pre_poll.revents & POLLOUT)
+        extra_fds[i].revents |= CURL_WAIT_POLLOUT;
+      if(extra_fds[i].revents)
+        timeout_ms = 0;
+    }
+    if(WSAEventSelect(extra_fds[i].fd, multi->wsa_event, mask) != 0)
+      return CURLM_INTERNAL_ERROR;
+#else
     ufds[nfds].fd = extra_fds[i].fd;
     ufds[nfds].events = 0;
     if(extra_fds[i].events & CURL_WAIT_POLLIN)
@@ -1189,26 +1257,57 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
     if(extra_fds[i].events & CURL_WAIT_POLLOUT)
       ufds[nfds].events |= POLLOUT;
     ++nfds;
+#endif
   }
 
 #ifdef ENABLE_WAKEUP
+#ifndef USE_WINSOCK
   if(use_wakeup && multi->wakeup_pair[0] != CURL_SOCKET_BAD) {
     ufds[nfds].fd = multi->wakeup_pair[0];
     ufds[nfds].events = POLLIN;
     ++nfds;
   }
 #endif
+#endif
 
   if(nfds) {
     /* wait... */
+#ifdef USE_WINSOCK
+    WSAWaitForMultipleEvents(1, &multi->wsa_event, FALSE, timeout_ms, FALSE);
+#else
     int pollrc = Curl_poll(ufds, nfds, timeout_ms);
+#endif
+
+#ifdef USE_WINSOCK
+    /* With Winsock, we have to run this unconditionally to call
+       WSAEventSelect(fd, event, 0) on all the sockets */
+    {
+      retcode = 0;
+#else
     if(pollrc > 0) {
       retcode = pollrc;
+#endif
       /* copy revents results from the poll to the curl_multi_wait poll
          struct, the bit values of the actual underlying poll() implementation
          may not be the same as the ones in the public libcurl API! */
       for(i = 0; i < extra_nfds; i++) {
         unsigned short mask = 0;
+#ifdef USE_WINSOCK
+        wsa_events.lNetworkEvents = 0;
+        mask = extra_fds[i].revents;
+        if(WSAEnumNetworkEvents(extra_fds[i].fd, multi->wsa_event,
+                                &wsa_events) == 0) {
+          if(wsa_events.lNetworkEvents & (FD_READ|FD_ACCEPT|FD_CLOSE))
+            mask |= CURL_WAIT_POLLIN;
+          if(wsa_events.lNetworkEvents & (FD_WRITE|FD_CONNECT|FD_CLOSE))
+            mask |= CURL_WAIT_POLLOUT;
+          if(wsa_events.lNetworkEvents & FD_OOB)
+            mask |= CURL_WAIT_POLLPRI;
+          if(ret && wsa_events.lNetworkEvents != 0)
+            retcode++;
+        }
+        WSAEventSelect(extra_fds[i].fd, multi->wsa_event, 0);
+#else
         unsigned r = ufds[curlfds + i].revents;
 
         if(r & POLLIN)
@@ -1217,9 +1316,46 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
           mask |= CURL_WAIT_POLLOUT;
         if(r & POLLPRI)
           mask |= CURL_WAIT_POLLPRI;
+#endif
         extra_fds[i].revents = mask;
       }
 
+#ifdef USE_WINSOCK
+      /* Count up all our own sockets that had activity,
+         and remove them from the event. */
+      if(curlfds) {
+        data = multi->easyp;
+        while(data) {
+          bitmap = multi_getsock(data, sockbunch);
+
+          for(i = 0; i < MAX_SOCKSPEREASYHANDLE; i++) {
+            if(bitmap & (GETSOCK_READSOCK(i) | GETSOCK_WRITESOCK(i))) {
+              wsa_events.lNetworkEvents = 0;
+              if(WSAEnumNetworkEvents(sockbunch[i], multi->wsa_event,
+                                      &wsa_events) == 0) {
+                if(ret && wsa_events.lNetworkEvents != 0)
+                  retcode++;
+              }
+              if(ret && !timeout_ms && wsa_events.lNetworkEvents == 0) {
+                if((bitmap & GETSOCK_READSOCK(i)) &&
+                   SOCKET_READABLE(sockbunch[i], 0) > 0)
+                  retcode++;
+                else if((bitmap & GETSOCK_WRITESOCK(i)) &&
+                   SOCKET_WRITABLE(sockbunch[i], 0) > 0)
+                  retcode++;
+              }
+              WSAEventSelect(sockbunch[i], multi->wsa_event, 0);
+            }
+            else
+              break;
+          }
+
+          data = data->next;
+        }
+      }
+
+      WSAResetEvent(multi->wsa_event);
+#else
 #ifdef ENABLE_WAKEUP
       if(use_wakeup && multi->wakeup_pair[0] != CURL_SOCKET_BAD) {
         if(ufds[curlfds + extra_nfds].revents & POLLIN) {
@@ -1232,10 +1368,8 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
                when there is no more data, breaking the loop. */
             nread = sread(multi->wakeup_pair[0], buf, sizeof(buf));
             if(nread <= 0) {
-#ifndef USE_WINSOCK
               if(nread < 0 && EINTR == SOCKERRNO)
                 continue;
-#endif
               break;
             }
           }
@@ -1244,11 +1378,14 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
         }
       }
 #endif
+#endif
     }
   }
 
+#ifndef USE_WINSOCK
   if(ufds_malloc)
     free(ufds);
+#endif
   if(ret)
     *ret = retcode;
   if(!extrawait || nfds)
@@ -1303,6 +1440,10 @@ CURLMcode curl_multi_wakeup(struct Curl_multi *multi)
     return CURLM_BAD_HANDLE;
 
 #ifdef ENABLE_WAKEUP
+#ifdef USE_WINSOCK
+  if(WSASetEvent(multi->wsa_event))
+    return CURLM_OK;
+#else
   /* the wakeup_pair variable is only written during init and cleanup,
      making it safe to access from another thread after the init part
      and before cleanup */
@@ -1336,6 +1477,7 @@ CURLMcode curl_multi_wakeup(struct Curl_multi *multi)
     }
   }
 #endif
+#endif
   return CURLM_WAKEUP_FAILURE;
 }
 
@@ -2478,10 +2620,14 @@ CURLMcode curl_multi_cleanup(struct Curl_multi *multi)
     Curl_hash_destroy(&multi->hostcache);
     Curl_psl_destroy(&multi->psl);
 
+#ifdef USE_WINSOCK
+    WSACloseEvent(multi->wsa_event);
+#else
 #ifdef ENABLE_WAKEUP
     sclose(multi->wakeup_pair[0]);
     sclose(multi->wakeup_pair[1]);
 #endif
+#endif
     free(multi);
 
     return CURLM_OK;
diff --git a/lib/multihandle.h b/lib/multihandle.h
index edf790132..96b84749f 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -140,10 +140,14 @@ struct Curl_multi {
                                     previous callback */
   unsigned int max_concurrent_streams;
 
+#ifdef USE_WINSOCK
+  WSAEVENT wsa_event; /* winsock event used for waits */
+#else
 #ifdef ENABLE_WAKEUP
   curl_socket_t wakeup_pair[2]; /* socketpair() used for wakeup
                                    0 is used for read, 1 is used for write */
 #endif
+#endif
   /* multiplexing wanted */
   bool multiplexing;
   bool recheckstate; /* see Curl_multi_connchanged */