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signal.go
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signal.go
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/*
* Copyright (c) 2017-2020 The qitmeer developers
*/
package main
import (
"os"
"os/signal"
"syscall"
)
// shutdownRequestChannel is used to initiate shutdown from one of the
// subsystems using the same code paths as when an interrupt signal is received.
var shutdownRequestChannel = make(chan struct{})
// interruptSignals defines the default signals to catch in order to do a proper
// shutdown. This may be modified during init depending on the platform.
var interruptSignals = []os.Signal{os.Interrupt, os.Kill, syscall.SIGINT, syscall.SIGTERM}
// interruptListener listens for OS Signals such as SIGINT (Ctrl+C) and shutdown
// requests from shutdownRequestChannel. It returns a channel that is closed
// when either signal is received.
func interruptListener() <-chan struct{} {
c := make(chan struct{})
go func() {
interruptChannel := make(chan os.Signal, 1)
signal.Notify(interruptChannel, interruptSignals...)
// Listen for initial shutdown signal and close the returned
// channel to notify the caller.
select {
case sig := <-interruptChannel:
log.Info("Shutting down...", "Received signal", sig)
case <-shutdownRequestChannel:
log.Info("Shutdown requested. Shutting down...")
}
close(c)
// Listen for repeated signals and display a message so the user
// knows the shutdown is in progress and the process is not
// hung.
for {
select {
case sig := <-interruptChannel:
log.Info("Already shutting down...", "Received signal", sig)
case <-shutdownRequestChannel:
log.Info("Shutdown requested. Already shutting down...")
}
}
}()
return c
}
// interruptRequested returns true when the channel returned by
// interruptListener was closed. This simplifies early shutdown slightly since
// the caller can just use an if statement instead of a select.
func interruptRequested(interrupted <-chan struct{}) bool {
select {
case <-interrupted:
return true
default:
}
return false
}