| // 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. |
| |
| //go:build linux |
| |
| package runtime |
| |
| import ( |
| "runtime/internal/atomic" |
| "runtime/internal/syscall" |
| "unsafe" |
| ) |
| |
| var ( |
| epfd int32 = -1 // epoll descriptor |
| |
| netpollBreakRd, netpollBreakWr uintptr // for netpollBreak |
| |
| netpollWakeSig atomic.Uint32 // used to avoid duplicate calls of netpollBreak |
| ) |
| |
| func netpollinit() { |
| var errno uintptr |
| epfd, errno = syscall.EpollCreate1(syscall.EPOLL_CLOEXEC) |
| if errno != 0 { |
| println("runtime: epollcreate failed with", errno) |
| throw("runtime: netpollinit failed") |
| } |
| r, w, errpipe := nonblockingPipe() |
| if errpipe != 0 { |
| println("runtime: pipe failed with", -errpipe) |
| throw("runtime: pipe failed") |
| } |
| ev := syscall.EpollEvent{ |
| Events: syscall.EPOLLIN, |
| } |
| *(**uintptr)(unsafe.Pointer(&ev.Data)) = &netpollBreakRd |
| errno = syscall.EpollCtl(epfd, syscall.EPOLL_CTL_ADD, r, &ev) |
| if errno != 0 { |
| println("runtime: epollctl failed with", errno) |
| throw("runtime: epollctl failed") |
| } |
| netpollBreakRd = uintptr(r) |
| netpollBreakWr = uintptr(w) |
| } |
| |
| func netpollIsPollDescriptor(fd uintptr) bool { |
| return fd == uintptr(epfd) || fd == netpollBreakRd || fd == netpollBreakWr |
| } |
| |
| func netpollopen(fd uintptr, pd *pollDesc) uintptr { |
| var ev syscall.EpollEvent |
| ev.Events = syscall.EPOLLIN | syscall.EPOLLOUT | syscall.EPOLLRDHUP | syscall.EPOLLET |
| tp := taggedPointerPack(unsafe.Pointer(pd), pd.fdseq.Load()) |
| *(*taggedPointer)(unsafe.Pointer(&ev.Data)) = tp |
| return syscall.EpollCtl(epfd, syscall.EPOLL_CTL_ADD, int32(fd), &ev) |
| } |
| |
| func netpollclose(fd uintptr) uintptr { |
| var ev syscall.EpollEvent |
| return syscall.EpollCtl(epfd, syscall.EPOLL_CTL_DEL, int32(fd), &ev) |
| } |
| |
| func netpollarm(pd *pollDesc, mode int) { |
| throw("runtime: unused") |
| } |
| |
| // netpollBreak interrupts an epollwait. |
| func netpollBreak() { |
| // Failing to cas indicates there is an in-flight wakeup, so we're done here. |
| if !netpollWakeSig.CompareAndSwap(0, 1) { |
| return |
| } |
| |
| for { |
| var b byte |
| n := write(netpollBreakWr, unsafe.Pointer(&b), 1) |
| if n == 1 { |
| break |
| } |
| if n == -_EINTR { |
| continue |
| } |
| if n == -_EAGAIN { |
| return |
| } |
| println("runtime: netpollBreak write failed with", -n) |
| throw("runtime: netpollBreak write failed") |
| } |
| } |
| |
| // netpoll checks for ready network connections. |
| // Returns list of goroutines that become runnable. |
| // delay < 0: blocks indefinitely |
| // delay == 0: does not block, just polls |
| // delay > 0: block for up to that many nanoseconds |
| func netpoll(delay int64) gList { |
| if epfd == -1 { |
| return gList{} |
| } |
| var waitms int32 |
| if delay < 0 { |
| waitms = -1 |
| } else if delay == 0 { |
| waitms = 0 |
| } else if delay < 1e6 { |
| waitms = 1 |
| } else if delay < 1e15 { |
| waitms = int32(delay / 1e6) |
| } else { |
| // An arbitrary cap on how long to wait for a timer. |
| // 1e9 ms == ~11.5 days. |
| waitms = 1e9 |
| } |
| var events [128]syscall.EpollEvent |
| retry: |
| n, errno := syscall.EpollWait(epfd, events[:], int32(len(events)), waitms) |
| if errno != 0 { |
| if errno != _EINTR { |
| println("runtime: epollwait on fd", epfd, "failed with", errno) |
| throw("runtime: netpoll failed") |
| } |
| // If a timed sleep was interrupted, just return to |
| // recalculate how long we should sleep now. |
| if waitms > 0 { |
| return gList{} |
| } |
| goto retry |
| } |
| var toRun gList |
| for i := int32(0); i < n; i++ { |
| ev := events[i] |
| if ev.Events == 0 { |
| continue |
| } |
| |
| if *(**uintptr)(unsafe.Pointer(&ev.Data)) == &netpollBreakRd { |
| if ev.Events != syscall.EPOLLIN { |
| println("runtime: netpoll: break fd ready for", ev.Events) |
| throw("runtime: netpoll: break fd ready for something unexpected") |
| } |
| if delay != 0 { |
| // netpollBreak could be picked up by a |
| // nonblocking poll. Only read the byte |
| // if blocking. |
| var tmp [16]byte |
| read(int32(netpollBreakRd), noescape(unsafe.Pointer(&tmp[0])), int32(len(tmp))) |
| netpollWakeSig.Store(0) |
| } |
| continue |
| } |
| |
| var mode int32 |
| if ev.Events&(syscall.EPOLLIN|syscall.EPOLLRDHUP|syscall.EPOLLHUP|syscall.EPOLLERR) != 0 { |
| mode += 'r' |
| } |
| if ev.Events&(syscall.EPOLLOUT|syscall.EPOLLHUP|syscall.EPOLLERR) != 0 { |
| mode += 'w' |
| } |
| if mode != 0 { |
| tp := *(*taggedPointer)(unsafe.Pointer(&ev.Data)) |
| pd := (*pollDesc)(tp.pointer()) |
| tag := tp.tag() |
| if pd.fdseq.Load() == tag { |
| pd.setEventErr(ev.Events == syscall.EPOLLERR, tag) |
| netpollready(&toRun, pd, mode) |
| } |
| } |
| } |
| return toRun |
| } |