Files
mgmt/event/event.go
James Shubin 12fce52cd7 legal: Happy 2018 everyone...
Done with:

ack '2017+' -l | xargs sed -i -e 's/2017+/2018+/g'

Checked manually with:

git add -p

Hello to future James from 2019, and Happy Hacking!
2018-01-03 21:22:07 -05:00

120 lines
3.1 KiB
Go

// Mgmt
// Copyright (C) 2013-2018+ James Shubin and the project contributors
// Written by James Shubin <james@shubin.ca> and the project contributors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
// Package event provides some primitives that are used for message passing.
package event
import (
"fmt"
)
//go:generate stringer -type=Kind -output=kind_stringer.go
// Kind represents the type of event being passed.
type Kind int
// The different event kinds are used in different contexts.
const (
EventNil Kind = iota
EventExit
EventStart
EventPause
EventPoke
EventBackPoke
)
// Resp is a channel to be used for boolean responses. A nil represents an ACK,
// and a non-nil represents a NACK (false). This also lets us use custom errors.
type Resp chan error
// Event is the main struct that stores event information and responses.
type Event struct {
Kind Kind
Resp Resp // channel to send an ack response on, nil to skip
//Wg *sync.WaitGroup // receiver barrier to Wait() for everyone else on
Err error // store an error in our event
}
// ACK sends a single acknowledgement on the channel if one was requested.
func (event *Event) ACK() {
if event.Resp != nil { // if they've requested an ACK
event.Resp.ACK()
}
}
// NACK sends a negative acknowledgement message on the channel if one was requested.
func (event *Event) NACK() {
if event.Resp != nil { // if they've requested a NACK
event.Resp.NACK()
}
}
// ACKNACK sends a custom ACK or NACK message on the channel if one was requested.
func (event *Event) ACKNACK(err error) {
if event.Resp != nil { // if they've requested a NACK
event.Resp.ACKNACK(err)
}
}
// NewResp is just a helper to return the right type of response channel.
func NewResp() Resp {
resp := make(chan error)
return resp
}
// ACK sends a true value to resp.
func (resp Resp) ACK() {
if resp != nil {
resp <- nil // TODO: close instead?
}
}
// NACK sends a false value to resp.
func (resp Resp) NACK() {
if resp != nil {
resp <- fmt.Errorf("NACK")
}
}
// ACKNACK sends a custom ACK or NACK. The ACK value is always nil, the NACK can
// be any non-nil error value.
func (resp Resp) ACKNACK(err error) {
if resp != nil {
resp <- err
}
}
// Wait waits for any response from a Resp channel and returns it.
func (resp Resp) Wait() error {
return <-resp
}
// ACKWait waits for a +ive Ack from a Resp channel.
func (resp Resp) ACKWait() {
for {
// wait until true value
if resp.Wait() == nil {
return
}
}
}
// Error returns the stored error value.
func (event *Event) Error() error {
return event.Err
}