root/src/pkg/runtime/netpoll_epoll.c

DEFINITIONS

1. runtime·netpollinit
2. runtime·netpollopen
3. runtime·netpollclose
4. runtime·netpollarm
5. runtime·netpoll

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build linux

#include "runtime.h"
#include "defs_GOOS_GOARCH.h"

int32   runtime·epollcreate(int32 size);
int32   runtime·epollcreate1(int32 flags);
int32   runtime·epollctl(int32 epfd, int32 op, int32 fd, EpollEvent *ev);
int32   runtime·epollwait(int32 epfd, EpollEvent *ev, int32 nev, int32 timeout);
void    runtime·closeonexec(int32 fd);

static int32 epfd = -1;  // epoll descriptor

void
runtime·netpollinit(void)
{
        epfd = runtime·epollcreate1(EPOLL_CLOEXEC);
        if(epfd >= 0)
                return;
        epfd = runtime·epollcreate(1024);
        if(epfd >= 0) {
                runtime·closeonexec(epfd);
                return;
        }
        runtime·printf("netpollinit: failed to create descriptor (%d)\n", -epfd);
        runtime·throw("netpollinit: failed to create descriptor");
}

int32
runtime·netpollopen(uintptr fd, PollDesc *pd)
{
        EpollEvent ev;
        int32 res;

        ev.events = EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET;
        ev.data = (uint64)pd;
        res = runtime·epollctl(epfd, EPOLL_CTL_ADD, (int32)fd, &ev);
        return -res;
}

int32
runtime·netpollclose(uintptr fd)
{
        EpollEvent ev;
        int32 res;

        res = runtime·epollctl(epfd, EPOLL_CTL_DEL, (int32)fd, &ev);
        return -res;
}

void
runtime·netpollarm(PollDesc* pd, int32 mode)
{
        USED(pd, mode);
        runtime·throw("unused");
}

// polls for ready network connections
// returns list of goroutines that become runnable
G*
runtime·netpoll(bool block)
{
        static int32 lasterr;
        EpollEvent events[128], *ev;
        int32 n, i, waitms, mode;
        G *gp;

        if(epfd == -1)
                return nil;
        waitms = -1;
        if(!block)
                waitms = 0;
retry:
        n = runtime·epollwait(epfd, events, nelem(events), waitms);
        if(n < 0) {
                if(n != -EINTR && n != lasterr) {
                        lasterr = n;
                        runtime·printf("runtime: epollwait on fd %d failed with %d\n", epfd, -n);
                }
                goto retry;
        }
        gp = nil;
        for(i = 0; i < n; i++) {
                ev = &events[i];
                if(ev->events == 0)
                        continue;
                mode = 0;
                if(ev->events & (EPOLLIN|EPOLLRDHUP|EPOLLHUP|EPOLLERR))
                        mode += 'r';
                if(ev->events & (EPOLLOUT|EPOLLHUP|EPOLLERR))
                        mode += 'w';
                if(mode)
                        runtime·netpollready(&gp, (void*)ev->data, mode);
        }
        if(block && gp == nil)
                goto retry;
        return gp;
}