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// Copyright 2009 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.
// This file implements runtime support for signal handling.
package runtime
const qsize = 64
var sig struct {
q noteQueue
inuse bool
lock mutex
note note
sleeping bool
}
type noteQueue struct {
lock mutex
data [qsize]*byte
ri int
wi int
full bool
}
func (q *noteQueue) push(item *byte) bool {
lock(&q.lock)
if q.full {
unlock(&q.lock)
return false
}
q.data[q.wi] = item
q.wi++
if q.wi == qsize {
q.wi = 0
}
if q.wi == q.ri {
q.full = true
}
unlock(&q.lock)
return true
}
func (q *noteQueue) pop() *byte {
lock(&q.lock)
q.full = false
if q.ri == q.wi {
unlock(&q.lock)
return nil
}
item := q.data[q.ri]
q.ri++
if q.ri == qsize {
q.ri = 0
}
unlock(&q.lock)
return item
}
// Called from sighandler to send a signal back out of the signal handling thread.
// Reports whether the signal was sent. If not, the caller typically crashes the program.
func sendNote(s *byte) bool {
if !sig.inuse {
return false
}
// Add signal to outgoing queue.
if !sig.q.push(s) {
return false
}
lock(&sig.lock)
if sig.sleeping {
sig.sleeping = false
notewakeup(&sig.note)
}
unlock(&sig.lock)
return true
}
// Called to receive the next queued signal.
// Must only be called from a single goroutine at a time.
func signal_recv() string {
for {
note := sig.q.pop()
if note != nil {
return gostring(note)
}
lock(&sig.lock)
sig.sleeping = true
noteclear(&sig.note)
unlock(&sig.lock)
notetsleepg(&sig.note, -1)
}
}
// Must only be called from a single goroutine at a time.
func signal_enable(s uint32) {
if !sig.inuse {
// The first call to signal_enable is for us
// to use for initialization. It does not pass
// signal information in m.
sig.inuse = true // enable reception of signals; cannot disable
noteclear(&sig.note)
return
}
}
// Must only be called from a single goroutine at a time.
func signal_disable(s uint32) {
}
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