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d5d4ab7819
This change is an implementation of the signal runtime and os/signal package on Plan 9. Contrary to Unix, on Plan 9 a signal is called a note and is represented by a string. For this reason, the sigsend and signal_recv functions had to be reimplemented specifically for Plan 9. In order to reuse most of the code and internal interface of the os/signal package, the note strings are mapped to integers. Thanks to Russ Cox for the early review. Change-Id: I95836645efe21942bb1939f43f87fb3c0eaaef1a Reviewed-on: https://go-review.googlesource.com/2164 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Rob Pike <r@golang.org>
116 lines
2.0 KiB
Go
116 lines
2.0 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file implements runtime support for signal handling.
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package runtime
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const qsize = 64
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var sig struct {
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q noteQueue
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inuse bool
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lock mutex
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note note
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sleeping bool
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}
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type noteQueue struct {
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lock mutex
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data [qsize]*byte
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ri int
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wi int
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full bool
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}
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func (q *noteQueue) push(item *byte) bool {
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lock(&q.lock)
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if q.full {
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unlock(&q.lock)
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return false
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}
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q.data[q.wi] = item
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q.wi++
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if q.wi == qsize {
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q.wi = 0
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}
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if q.wi == q.ri {
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q.full = true
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}
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unlock(&q.lock)
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return true
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}
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func (q *noteQueue) pop() *byte {
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lock(&q.lock)
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q.full = false
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if q.ri == q.wi {
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unlock(&q.lock)
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return nil
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}
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item := q.data[q.ri]
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q.ri++
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if q.ri == qsize {
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q.ri = 0
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}
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unlock(&q.lock)
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return item
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}
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// Called from sighandler to send a signal back out of the signal handling thread.
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// Reports whether the signal was sent. If not, the caller typically crashes the program.
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func sendNote(s *byte) bool {
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if !sig.inuse {
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return false
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}
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// Add signal to outgoing queue.
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if !sig.q.push(s) {
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return false
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}
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lock(&sig.lock)
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if sig.sleeping {
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sig.sleeping = false
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notewakeup(&sig.note)
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}
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unlock(&sig.lock)
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return true
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}
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// Called to receive the next queued signal.
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// Must only be called from a single goroutine at a time.
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func signal_recv() string {
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for {
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note := sig.q.pop()
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if note != nil {
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return gostring(note)
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}
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lock(&sig.lock)
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sig.sleeping = true
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noteclear(&sig.note)
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unlock(&sig.lock)
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notetsleepg(&sig.note, -1)
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}
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}
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// Must only be called from a single goroutine at a time.
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func signal_enable(s uint32) {
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if !sig.inuse {
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// The first call to signal_enable is for us
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// to use for initialization. It does not pass
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// signal information in m.
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sig.inuse = true // enable reception of signals; cannot disable
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noteclear(&sig.note)
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return
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}
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}
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// Must only be called from a single goroutine at a time.
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func signal_disable(s uint32) {
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}
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