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fd_poll_runtime.go
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fd_poll_runtime.go
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// 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 unix || windows || wasip1
package poll
import (
"errors"
"sync"
"syscall"
"time"
_ "unsafe" // for go:linkname
)
// runtimeNano returns the current value of the runtime clock in nanoseconds.
//
//go:linkname runtimeNano runtime.nanotime
func runtimeNano() int64
func runtime_pollServerInit()
func runtime_pollOpen(fd uintptr) (uintptr, int)
func runtime_pollClose(ctx uintptr)
func runtime_pollWait(ctx uintptr, mode int) int
func runtime_pollWaitCanceled(ctx uintptr, mode int)
func runtime_pollReset(ctx uintptr, mode int) int
func runtime_pollSetDeadline(ctx uintptr, d int64, mode int)
func runtime_pollUnblock(ctx uintptr)
func runtime_isPollServerDescriptor(fd uintptr) bool
type pollDesc struct {
runtimeCtx uintptr
}
var serverInit sync.Once
func (pd *pollDesc) init(fd *FD) error {
serverInit.Do(runtime_pollServerInit)
ctx, errno := runtime_pollOpen(uintptr(fd.Sysfd))
if errno != 0 {
return errnoErr(syscall.Errno(errno))
}
pd.runtimeCtx = ctx
return nil
}
func (pd *pollDesc) close() {
if pd.runtimeCtx == 0 {
return
}
runtime_pollClose(pd.runtimeCtx)
pd.runtimeCtx = 0
}
// Evict evicts fd from the pending list, unblocking any I/O running on fd.
func (pd *pollDesc) evict() {
if pd.runtimeCtx == 0 {
return
}
runtime_pollUnblock(pd.runtimeCtx)
}
func (pd *pollDesc) prepare(mode int, isFile bool) error {
if pd.runtimeCtx == 0 {
return nil
}
res := runtime_pollReset(pd.runtimeCtx, mode)
return convertErr(res, isFile)
}
func (pd *pollDesc) prepareRead(isFile bool) error {
return pd.prepare('r', isFile)
}
func (pd *pollDesc) prepareWrite(isFile bool) error {
return pd.prepare('w', isFile)
}
func (pd *pollDesc) wait(mode int, isFile bool) error {
if pd.runtimeCtx == 0 {
return errors.New("waiting for unsupported file type")
}
res := runtime_pollWait(pd.runtimeCtx, mode)
return convertErr(res, isFile)
}
func (pd *pollDesc) waitRead(isFile bool) error {
return pd.wait('r', isFile)
}
func (pd *pollDesc) waitWrite(isFile bool) error {
return pd.wait('w', isFile)
}
func (pd *pollDesc) waitCanceled(mode int) {
if pd.runtimeCtx == 0 {
return
}
runtime_pollWaitCanceled(pd.runtimeCtx, mode)
}
func (pd *pollDesc) pollable() bool {
return pd.runtimeCtx != 0
}
// Error values returned by runtime_pollReset and runtime_pollWait.
// These must match the values in runtime/netpoll.go.
const (
pollNoError = 0
pollErrClosing = 1
pollErrTimeout = 2
pollErrNotPollable = 3
)
func convertErr(res int, isFile bool) error {
switch res {
case pollNoError:
return nil
case pollErrClosing:
return errClosing(isFile)
case pollErrTimeout:
return ErrDeadlineExceeded
case pollErrNotPollable:
return ErrNotPollable
}
println("unreachable: ", res)
panic("unreachable")
}
// SetDeadline sets the read and write deadlines associated with fd.
func (fd *FD) SetDeadline(t time.Time) error {
return setDeadlineImpl(fd, t, 'r'+'w')
}
// SetReadDeadline sets the read deadline associated with fd.
func (fd *FD) SetReadDeadline(t time.Time) error {
return setDeadlineImpl(fd, t, 'r')
}
// SetWriteDeadline sets the write deadline associated with fd.
func (fd *FD) SetWriteDeadline(t time.Time) error {
return setDeadlineImpl(fd, t, 'w')
}
func setDeadlineImpl(fd *FD, t time.Time, mode int) error {
var d int64
if !t.IsZero() {
d = int64(time.Until(t))
if d == 0 {
d = -1 // don't confuse deadline right now with no deadline
}
}
if err := fd.incref(); err != nil {
return err
}
defer fd.decref()
if fd.pd.runtimeCtx == 0 {
return ErrNoDeadline
}
runtime_pollSetDeadline(fd.pd.runtimeCtx, d, mode)
return nil
}
// IsPollDescriptor reports whether fd is the descriptor being used by the poller.
// This is only used for testing.
//
// IsPollDescriptor should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
// - github.com/opencontainers/runc
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname IsPollDescriptor
func IsPollDescriptor(fd uintptr) bool {
return runtime_isPollServerDescriptor(fd)
}