From: Marc Hoersken Date: Sun, 6 Dec 2020 16:28:26 +0000 (+0100) Subject: multi: reduce Win32 API calls to improve performance X-Git-Tag: curl-7_77_0~159 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e92998a3121ac0752d86fd90d9d6053af760048e;p=thirdparty%2Fcurl.git multi: reduce Win32 API calls to improve performance 1. Consolidate pre-checks into a single Curl_poll call: This is an attempt to restructure the code in Curl_multi_wait in such a way that less syscalls are made by removing individual calls to Curl_socket_check via SOCKET_READABLE/SOCKET_WRITABLE. 2. Avoid resetting the WinSock event multiple times: We finally call WSAResetEvent anyway, so specifying it as an optional parameter to WSAEnumNetworkEvents is redundant. 3. Wakeup directly in case no sockets are being monitoring: Fix the WinSock based implementation to skip extra waiting by not sleeping in case no sockets are to be waited on and just the WinSock event is being monitored for wakeup functionality. Assisted-by: Tommy Odom Reviewed-by: Jay Satiro Reviewed-by: Marcel Raad Bug: #6146 Closes #6245 --- diff --git a/lib/multi.c b/lib/multi.c index aa2eb52e31..38af89d0df 100644 --- a/lib/multi.c +++ b/lib/multi.c @@ -1086,12 +1086,10 @@ 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; +#ifdef USE_WINSOCK WSANETWORKEVENTS wsa_events; DEBUGASSERT(multi->wsa_event != WSA_INVALID_EVENT); #endif @@ -1149,7 +1147,6 @@ static CURLMcode multi_wait(struct Curl_multi *multi, } #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 @@ -1160,9 +1157,7 @@ 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 */ @@ -1180,34 +1175,31 @@ static CURLMcode multi_wait(struct Curl_multi *multi, #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 +#endif 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 +#endif 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) + if(WSAEventSelect(s, multi->wsa_event, mask) != 0) { + if(ufds_malloc) + free(ufds); return CURLM_INTERNAL_ERROR; + } #endif } @@ -1219,35 +1211,18 @@ static CURLMcode multi_wait(struct Curl_multi *multi, 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) { + 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) { + if(extra_fds[i].events & CURL_WAIT_POLLPRI) mask |= FD_OOB; - pre_poll.events |= POLLPRI; - } - if(extra_fds[i].events & CURL_WAIT_POLLOUT) { + 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) + if(WSAEventSelect(extra_fds[i].fd, multi->wsa_event, mask) != 0) { + if(ufds_malloc) + free(ufds); return CURLM_INTERNAL_ERROR; -#else + } +#endif ufds[nfds].fd = extra_fds[i].fd; ufds[nfds].events = 0; if(extra_fds[i].events & CURL_WAIT_POLLIN) @@ -1257,7 +1232,6 @@ 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 @@ -1270,53 +1244,59 @@ static CURLMcode multi_wait(struct Curl_multi *multi, #endif #endif +#if defined(ENABLE_WAKEUP) && defined(USE_WINSOCK) + if(nfds || use_wakeup) { +#else if(nfds) { - /* wait... */ +#endif + int pollrc; #ifdef USE_WINSOCK - WSAWaitForMultipleEvents(1, &multi->wsa_event, FALSE, timeout_ms, FALSE); + if(nfds) + pollrc = Curl_poll(ufds, nfds, 0); /* just pre-check with WinSock */ + else + pollrc = 0; + if(pollrc <= 0) /* now wait... if not ready during the pre-check above */ + WSAWaitForMultipleEvents(1, &multi->wsa_event, FALSE, timeout_ms, FALSE); #else - int pollrc = Curl_poll(ufds, nfds, timeout_ms); + pollrc = Curl_poll(ufds, nfds, timeout_ms); /* wait... */ #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; +#ifdef USE_WINSOCK + } + /* With WinSock, we have to run the following section unconditionally + to call WSAEventSelect(fd, event, 0) on all the sockets */ + { #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 r = ufds[curlfds + i].revents; 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(WSAEnumNetworkEvents(extra_fds[i].fd, NULL, &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) + if(ret && pollrc <= 0 && wsa_events.lNetworkEvents != 0) retcode++; } WSAEventSelect(extra_fds[i].fd, multi->wsa_event, 0); -#else - unsigned r = ufds[curlfds + i].revents; - + if(pollrc <= 0) + continue; +#endif if(r & POLLIN) mask |= CURL_WAIT_POLLIN; if(r & POLLOUT) mask |= CURL_WAIT_POLLOUT; if(r & POLLPRI) mask |= CURL_WAIT_POLLPRI; -#endif extra_fds[i].revents = mask; } @@ -1331,17 +1311,8 @@ static CURLMcode multi_wait(struct Curl_multi *multi, 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) + if(WSAEnumNetworkEvents(sockbunch[i], NULL, &wsa_events) == 0) { + if(ret && pollrc <= 0 && wsa_events.lNetworkEvents != 0) retcode++; } WSAEventSelect(sockbunch[i], multi->wsa_event, 0); @@ -1382,16 +1353,15 @@ static CURLMcode multi_wait(struct Curl_multi *multi, } } -#ifndef USE_WINSOCK if(ufds_malloc) free(ufds); -#endif if(ret) *ret = retcode; - if(!extrawait || nfds) - /* if any socket was checked */ - ; - else { +#if defined(ENABLE_WAKEUP) && defined(USE_WINSOCK) + if(extrawait && !nfds && !use_wakeup) { +#else + if(extrawait && !nfds) { +#endif long sleep_ms = 0; /* Avoid busy-looping when there's nothing particular to wait for */