160 lines
3 KiB
Go
160 lines
3 KiB
Go
// Skeleton to part 7 of the Whispering Gophers code lab.
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//
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// This program extends part 6 by adding a Peers type.
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// The rest of the code is left as-is, so functionally there is no change.
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//
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// However we have added a peers_test.go file, so that running
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// go test
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// from the package directory will test your implementation of the Peers type.
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//
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package main
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import (
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"bufio"
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"encoding/json"
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"flag"
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"fmt"
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"log"
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"net"
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"os"
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"sync"
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"code.google.com/p/whispering-gophers/util"
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)
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var (
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peerAddr = flag.String("peer", "", "peer host:port")
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self string
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)
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type Message struct {
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Addr string
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Body string
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}
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func main() {
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flag.Parse()
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l, err := util.Listen()
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if err != nil {
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log.Fatal(err)
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}
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self = l.Addr().String()
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log.Println("Listening on", self)
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go dial(*peerAddr)
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go readInput()
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for {
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c, err := l.Accept()
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if err != nil {
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log.Fatal(err)
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}
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go serve(c)
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}
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}
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type Peers struct {
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m map[string]chan<- Message
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mu sync.RWMutex
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}
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// Add creates and returns a new channel for the given peer address.
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// If an address already exists in the registry, it returns nil.
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func (p *Peers) Add(addr string) <-chan Message {
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// TODO: Take the write lock on p.mu. Unlock it before returning (using defer).
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defer p.mu.Unlock()
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p.mu.Lock()
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// TODO: Check if the address is already in the peers map under the key addr.
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if _, ok := p.m[addr] ; ok {
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// TODO: If it is, return nil.
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return nil
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}
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// TODO: Make a new channel of messages
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messages := make(chan Message)
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// TODO: Add it to the peers map
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p.m[addr] = messages
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// TODO: Return the newly created channel.
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return messages
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}
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// Remove deletes the specified peer from the registry.
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func (p *Peers) Remove(addr string) {
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// TODO: Take the write lock on p.mu. Unlock it before returning (using defer).
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defer p.mu.Unlock()
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p.mu.Lock()
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// TODO: Delete the peer from the peers map.
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delete(p.m, addr)
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}
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// List returns a slice of all active peer channels.
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func (p *Peers) List() []chan<- Message {
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// TODO: Take the read lock on p.mu. Unlock it before returning (using defer).
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defer p.mu.RUnlock()
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p.mu.RLock()
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// TODO: Declare a slice of chan<- Message.
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var s []chan <- Message
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/* TODO: Iterate over the map using range */
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for _, v := range p.m {
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// TODO: Append each channel into the slice.
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s = append(s, v)
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}
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// TODO: Return the slice.
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return s
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}
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func serve(c net.Conn) {
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defer c.Close()
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d := json.NewDecoder(c)
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for {
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var m Message
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err := d.Decode(&m)
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if err != nil {
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log.Println(err)
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return
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}
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fmt.Printf("%#v\n", m)
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}
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}
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var peer = make(chan Message)
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func readInput() {
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s := bufio.NewScanner(os.Stdin)
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for s.Scan() {
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m := Message{
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Addr: self,
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Body: s.Text(),
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}
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peer <- m
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}
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if err := s.Err(); err != nil {
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log.Fatal(err)
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}
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}
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func dial(addr string) {
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c, err := net.Dial("tcp", addr)
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if err != nil {
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log.Println(addr, err)
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return
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}
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defer c.Close()
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e := json.NewEncoder(c)
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for m := range peer {
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err := e.Encode(m)
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if err != nil {
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log.Println(addr, err)
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return
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}
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}
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}
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