implement master server client, RPC part.

go/cmd/master/master.go

@@ -50,7 +50,6 @@ func main() {
 		panic("no valid datset specified.")
 	}
 
-	idx := 0
 	for _, path := range paths {
 		f, err := os.Open(path)
 		if err != nil {
@@ -66,7 +65,6 @@ func main() {
 		count := index.NumChunks()
 		for i := 0; i < count; i++ {
 			chunk := master.Chunk{
-				Idx:   idx,
 				Path:  path,
 				Index: *index.ChunkIndex(i),
 			}

go/connection/conn.go

@@ -21,6 +21,18 @@ func New() *Conn {
 	return c
 }
 
+// Close closes the connection.
+func (c *Conn) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.client == nil {
+		return nil
+	}
+
+	return c.client.Close()
+}
+
 // Connect connects the connection to a address.
 func (c *Conn) Connect(addr string) error {
 	c.mu.Lock()
@@ -56,6 +68,9 @@ func (c *Conn) Connect(addr string) error {
 	return nil
 }
 
+// TODO(helin): refactor Call to be able to perform given retry
+// policy.
+
 // Call make a RPC call.
 //
 // Call will be blocked until the connection to remote RPC service

go/master/client.go

@@ -0,0 +1,74 @@
+package master
+
+import (
+	"log"
+	"time"
+
+	"github.com/PaddlePaddle/Paddle/go/connection"
+)
+
+// Addresser provide the address of the master server.
+type Addresser interface {
+	Address() string
+}
+
+// Client is the client of the master server.
+type Client struct {
+	conn *connection.Conn
+}
+
+// NewClient creates a new Client.
+func NewClient(addr Addresser) *Client {
+	c := &Client{}
+	c.conn = connection.New()
+	go c.monitorMaster(addr)
+	return c
+}
+
+func (c *Client) monitorMaster(addr Addresser) {
+	lastMaster := ""
+	monitor := func() {
+		curMaster := addr.Address()
+		if curMaster != lastMaster {
+			if curMaster == "" {
+				err := c.conn.Close()
+				if err != nil {
+					log.Println(err)
+				}
+			} else {
+				err := c.conn.Connect(curMaster)
+				if err != nil {
+					log.Println(err)
+
+					// connect to addr failed, set
+					// to last known addr in order
+					// to retry next time.
+					curMaster = lastMaster
+				}
+
+			}
+		}
+
+		lastMaster = curMaster
+	}
+
+	monitor()
+	ticker := time.NewTicker(10 * time.Second)
+	for _ = range ticker.C {
+		monitor()
+	}
+}
+
+// GetTask gets a new task from the master server.
+func (c *Client) GetTask() (Task, error) {
+	var dummy int
+	var t Task
+	err := c.conn.Call("Service.GetTask", dummy, &t)
+	return t, err
+}
+
+// TaskFinished tells the master server a task is finished.
+func (c *Client) TaskFinished(taskID int) error {
+	var dummy int
+	return c.conn.Call("Service.TaskFinished", taskID, &dummy)
+}

go/master/client_test.go

@@ -0,0 +1,78 @@
+package master_test
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+	"net/rpc"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/PaddlePaddle/Paddle/go/master"
+)
+
+const (
+	totalTask    = 20
+	chunkPerTask = 10
+)
+
+var port int
+
+func init() {
+	l, err := net.Listen("tcp", ":0")
+	if err != nil {
+		panic(err)
+	}
+
+	ss := strings.Split(l.Addr().String(), ":")
+	p, err := strconv.Atoi(ss[len(ss)-1])
+	if err != nil {
+		panic(err)
+	}
+	port = p
+
+	go func(l net.Listener) {
+		chunks := make([]master.Chunk, totalTask)
+		s := master.NewService(chunks, chunkPerTask, time.Second, 1)
+		server := rpc.NewServer()
+		err := server.Register(s)
+		if err != nil {
+			panic(err)
+		}
+
+		mux := http.NewServeMux()
+		mux.Handle(rpc.DefaultRPCPath, server)
+		err = http.Serve(l, mux)
+		if err != nil {
+			panic(err)
+		}
+	}(l)
+}
+
+type addresser string
+
+func (a addresser) Address() string {
+	return string(a)
+}
+
+func TestClientFull(t *testing.T) {
+	c := master.NewClient(addresser(fmt.Sprintf(":%d", port)))
+
+	for i := 0; i < 5*totalTask/chunkPerTask; i++ {
+		task, err := c.GetTask()
+		if err != nil {
+			panic(err)
+		}
+
+		if len(task.Chunks) != chunkPerTask {
+			t.Fatal("wrong number of chunk per task", len(task.Chunks))
+		}
+
+		err = c.TaskFinished(task.ID)
+		if err != nil {
+			panic(err)
+		}
+	}
+}

go/master/service.go

@@ -75,9 +75,8 @@ func NewService(chunks []Chunk, chunksPerTask int, timeoutDur time.Duration, tim
 
 // Chunk is a chunk of data consisted of several data instances.
 type Chunk struct {
-	Idx   int // index of the chunk within the file
 	Path  string
-	Index recordio.Index // block index
+	Index recordio.Index // chunk index
 }
 
 // Task is the basic unit of data instances assigned to trainers.
@@ -123,6 +122,8 @@ func (s *Service) GetTask(dummy int, task *Task) error {
 		return err
 	}
 
+	*task = t.Task
+
 	time.AfterFunc(s.timeoutDur, func(taskID int, epoch int) func() {
 		return func() {
 			s.mu.Lock()
@@ -174,5 +175,11 @@ func (s *Service) TaskFinished(taskID int, dummy *int) error {
 	t.NumTimeout = 0
 	s.taskQueues.Done = append(s.taskQueues.Done, t)
 	delete(s.taskQueues.Pending, taskID)
+
+	if len(s.taskQueues.Todo) == 0 {
+		s.taskQueues.Todo = s.taskQueues.Done
+		s.taskQueues.Done = nil
+	}
+
 	return s.snapshot()
 }

go/pserver/client.go

@@ -47,7 +47,7 @@ func NewClient(l Lister, pserverNum int, sel Selector) *Client {
 // monitorPservers monitors pserver addresses, and updates connection
 // when the address changes.
 func (c *Client) monitorPservers(l Lister, pserverNum int) {
-	knownServers := make([]Server, pserverNum)
+	lastServers := make([]Server, pserverNum)
 	ticker := time.NewTicker(10 * time.Second)
 	monitor := func() {
 		curServers := make([]Server, pserverNum)
@@ -56,8 +56,17 @@ func (c *Client) monitorPservers(l Lister, pserverNum int) {
 			curServers[l.Index] = l
 		}
 
-		for i := range knownServers {
-			if knownServers[i].Addr != curServers[i].Addr {
+		for i := range lastServers {
+			if lastServers[i].Addr != curServers[i].Addr {
+				if curServers[i].Addr == "" {
+					err := c.pservers[i].Close()
+					if err != nil {
+						log.Println(err)
+					}
+
+					continue
+				}
+
 				err := c.pservers[i].Connect(curServers[i].Addr)
 				if err != nil {
 					log.Println(err)
@@ -65,12 +74,12 @@ func (c *Client) monitorPservers(l Lister, pserverNum int) {
 					// connect to addr failed, set
 					// to last known addr in order
 					// to retry next time.
-					curServers[i].Addr = knownServers[i].Addr
+					curServers[i].Addr = lastServers[i].Addr
 				}
 			}
 		}
 
-		knownServers = curServers
+		lastServers = curServers
 	}
 
 	monitor()