Created
February 25, 2013 00:26
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Playing around with the ideas from Hoare's "A model for communicating sequential processes" (specifically section 10). Doesn't gracefully quit or do the print spooling thing. Run like: `go run multiprogrammed_batch_processing_system.go -readers 3 -printers 3 -processors 2 -job "3:3" -job "2" -job "1:1:1" -job "4:4:4:4:4:4" -job "5:5"`. See -h fo…
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package main | |
import ( | |
"flag" | |
"fmt" | |
"math/rand" | |
"strings" | |
"time" | |
) | |
const ( | |
EOF = "-99" | |
) | |
var ( | |
NumCardReaders int | |
NumLinePrinters int | |
NumProcessors int | |
UserJobs Jobs | |
) | |
func Process(in chan string) chan string { | |
output := make(chan string) | |
go func() { | |
for { | |
input := <-in | |
time.Sleep(time.Duration(rand.Intn(100) * 1000000)) //Do stuff | |
if input == EOF { | |
break | |
} else { | |
output <- input + "!" | |
} | |
} | |
close(output) | |
}() | |
return output | |
} | |
type Processor struct { | |
Id int | |
Readers chan *CardReader | |
Printers chan *LinePrinter | |
} | |
func NewProcessor(id int, cardReaders chan *CardReader, linePrinters chan *LinePrinter) *Processor { | |
me := &Processor{ | |
Id: id, | |
Readers: cardReaders, | |
Printers: linePrinters, | |
} | |
go func() { | |
for { | |
var curCard string | |
var commandInput chan string | |
var commandOutput chan string | |
cardReader := <-me.Readers | |
linePrinter := <-me.Printers | |
curCard = <-cardReader.Output | |
if curCard == EOF { | |
cardReaders <- cardReader | |
linePrinters <- linePrinter | |
goto Cleanup //no work | |
} | |
commandInput = make(chan string) | |
commandOutput = Process(commandInput) | |
for { | |
select { | |
case output, ok := <-commandOutput: | |
if !ok { | |
cardReader.Finish <- true | |
goto Cleanup | |
} | |
linePrinter.Output <- fmt.Sprintf("P%d %s", me.Id, output) | |
case commandInput <- curCard: | |
curCard = <-cardReader.Output | |
} | |
} | |
Cleanup: | |
cardReaders <- cardReader | |
linePrinters <- linePrinter | |
} | |
}() | |
return me | |
} | |
type CardReader struct { | |
Id int | |
Cards chan string //This should really be a queue | |
Finish chan bool | |
Output chan string | |
} | |
func NewCardReader(id, buffer int) *CardReader { | |
me := &CardReader{ | |
Id: id, | |
Cards: make(chan string, buffer), | |
Finish: make(chan bool), | |
Output: make(chan string), | |
} | |
go func() { | |
curCard, open := <-me.Cards | |
for { | |
if !open { | |
me.Output <- EOF | |
} | |
if curCard != EOF { | |
curCard = fmt.Sprintf("R%d %s", me.Id, curCard) | |
} | |
select { | |
case me.Output <- curCard: | |
if curCard != EOF { | |
curCard, open = <-me.Cards | |
} | |
case <-me.Finish: | |
curCard, open = <-me.Cards | |
} | |
} | |
}() | |
return me | |
} | |
type LinePrinter struct { | |
Id int | |
Output chan string | |
} | |
func NewLinePrinter(id int) *LinePrinter { | |
me := &LinePrinter{ | |
Id: id, | |
Output: make(chan string), | |
} | |
go func() { | |
for { | |
fmt.Printf("L%d %s\n", me.Id, <-me.Output) | |
} | |
}() | |
return me | |
} | |
type Job struct { | |
Cards []string | |
} | |
type Jobs []*Job | |
func (me *Jobs) String() string { | |
return "" | |
} | |
func (me *Jobs) Set(value string) error { | |
parts := strings.Split(value, ":") | |
job := &Job{ | |
Cards: parts, | |
} | |
*me = append(*me, job) | |
return nil | |
} | |
func init() { | |
flag.IntVar(&NumCardReaders, "readers", 1, "Number of card readers") | |
flag.IntVar(&NumLinePrinters, "printers", 1, "Number of line printers") | |
flag.IntVar(&NumProcessors, "processors", 1, "Number of processors") | |
flag.Var(&UserJobs, "job", "Job specified as list of : seperated values (don't use -99 ;) )") | |
flag.Parse() | |
} | |
func main() { | |
cardReaders := make(chan *CardReader, NumCardReaders) | |
linePrinters := make(chan *LinePrinter, NumLinePrinters) | |
processors := make([]*Processor, NumProcessors) | |
quit := make(chan int) | |
for i := 0; i < NumCardReaders; i++ { | |
cardReaders <- NewCardReader(i, 10000) | |
} | |
//Place cards in card reader | |
for _, job := range UserJobs { | |
cardReader := <-cardReaders | |
for _, card := range job.Cards { | |
cardReader.Cards <- card | |
} | |
cardReader.Cards <- EOF | |
cardReaders <- cardReader | |
} | |
//Close card reader queues | |
for i := 0; i < NumCardReaders; i++ { | |
cardReader := <-cardReaders | |
close(cardReader.Cards) | |
cardReaders <- cardReader | |
} | |
for i := 0; i < cap(linePrinters); i++ { | |
linePrinters <- NewLinePrinter(i) | |
} | |
for i := 0; i < len(processors); i++ { | |
processors[i] = NewProcessor(i, cardReaders, linePrinters) | |
} | |
<-quit | |
} |
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It's a dumb little detail, but now that this has broken out of the playground it could likely use a![:trollface: :trollface:](https://github.githubassets.com/images/icons/emoji/trollface.png)
rand.Seed(...)