libgo/runtime/netpoll_epoll.c

   1 // Copyright 2013 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build linux
   6
   7 #include <errno.h>
   8 #include <unistd.h>
   9 #include <fcntl.h>
  10 #include <sys/epoll.h>
  11
  12 #include "runtime.h"
  13 #include "defs.h"
  14
  15 #ifndef EPOLLRDHUP
  16 #define EPOLLRDHUP 0x2000
  17 #endif
  18
  19 #ifndef EPOLL_CLOEXEC
  20 #define EPOLL_CLOEXEC 02000000
  21 #endif
  22
  23 #ifndef HAVE_EPOLL_CREATE1
  24 extern int epoll_create1(int __flags);
  25 #endif
  26
  27 typedef struct epoll_event EpollEvent;
  28
  29 static int32
  30 runtime_epollcreate(int32 size)
  31 {
  32         int r;
  33
  34         r = epoll_create(size);
  35         if(r >= 0)
  36                 return r;
  37         return - errno;
  38 }
  39
  40 static int32
  41 runtime_epollcreate1(int32 flags)
  42 {
  43         int r;
  44
  45         r = epoll_create1(flags);
  46         if(r >= 0)
  47                 return r;
  48         return - errno;
  49 }
  50
  51 static int32
  52 runtime_epollctl(int32 epfd, int32 op, int32 fd, EpollEvent *ev)
  53 {
  54         int r;
  55
  56         r = epoll_ctl(epfd, op, fd, ev);
  57         if(r >= 0)
  58                 return r;
  59         return - errno;
  60 }
  61
  62 static int32
  63 runtime_epollwait(int32 epfd, EpollEvent *ev, int32 nev, int32 timeout)
  64 {
  65         int r;
  66
  67         r = epoll_wait(epfd, ev, nev, timeout);
  68         if(r >= 0)
  69                 return r;
  70         return - errno;
  71 }
  72
  73 static void
  74 runtime_closeonexec(int32 fd)
  75 {
  76         fcntl(fd, F_SETFD, FD_CLOEXEC);
  77 }
  78
  79 static int32 epfd = -1;  // epoll descriptor
  80
  81 void
  82 runtime_netpollinit(void)
  83 {
  84         epfd = runtime_epollcreate1(EPOLL_CLOEXEC);
  85         if(epfd >= 0)
  86                 return;
  87         epfd = runtime_epollcreate(1024);
  88         if(epfd >= 0) {
  89                 runtime_closeonexec(epfd);
  90                 return;
  91         }
  92         runtime_printf("netpollinit: failed to create descriptor (%d)\n", -epfd);
  93         runtime_throw("netpollinit: failed to create descriptor");
  94 }
  95
  96 int32
  97 runtime_netpollopen(int32 fd, PollDesc *pd)
  98 {
  99         EpollEvent ev;
 100         int32 res;
 101
 102         ev.events = EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET;
 103         ev.data.ptr = (void*)pd;
 104         res = runtime_epollctl(epfd, EPOLL_CTL_ADD, fd, &ev);
 105         return -res;
 106 }
 107
 108 int32
 109 runtime_netpollclose(int32 fd)
 110 {
 111         EpollEvent ev;
 112         int32 res;
 113
 114         res = runtime_epollctl(epfd, EPOLL_CTL_DEL, fd, &ev);
 115         return -res;
 116 }
 117
 118 // polls for ready network connections
 119 // returns list of goroutines that become runnable
 120 G*
 121 runtime_netpoll(bool block)
 122 {
 123         static int32 lasterr;
 124         EpollEvent events[128], *ev;
 125         int32 n, i, waitms, mode;
 126         G *gp;
 127
 128         if(epfd == -1)
 129                 return nil;
 130         waitms = -1;
 131         if(!block)
 132                 waitms = 0;
 133 retry:
 134         n = runtime_epollwait(epfd, events, nelem(events), waitms);
 135         if(n < 0) {
 136                 if(n != -EINTR && n != lasterr) {
 137                         lasterr = n;
 138                         runtime_printf("runtime: epollwait on fd %d failed with %d\n", epfd, -n);
 139                 }
 140                 goto retry;
 141         }
 142         gp = nil;
 143         for(i = 0; i < n; i++) {
 144                 ev = &events[i];
 145                 if(ev->events == 0)
 146                         continue;
 147                 mode = 0;
 148                 if(ev->events & (EPOLLIN|EPOLLRDHUP|EPOLLHUP|EPOLLERR))
 149                         mode += 'r';
 150                 if(ev->events & (EPOLLOUT|EPOLLHUP|EPOLLERR))
 151                         mode += 'w';
 152                 if(mode)
 153                         runtime_netpollready(&gp, (void*)ev->data.ptr, mode);
 154         }
 155         if(block && gp == nil)
 156                 goto retry;
 157         return gp;
 158 }