lab1 passed all tests

src/mr/coordinator.go

@@ -1,33 +1,186 @@
 package mr
 
-import "log"
+import (
-import "net"
+	"crypto/rand"
-import "os"
+	"errors"
-import "net/rpc"
+	"fmt"
-import "net/http"
+	"log"
+	"math/big"
+	"net"
+	"net/http"
+	"net/rpc"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
 
+const (
+	JOB_TIMEOUT_S    = 10 * time.Second
+	GET_TASK_TIMEOUT = 2 * time.Second
+	DEBUG            = false
+)
 
 type Coordinator struct {
-	// Your definitions here.
+	MapJobs    []Job
+	ReduceJobs []Job
+	NReduce    int
+	mu         sync.Mutex
+	mapWg      sync.WaitGroup
+	reduceWg   sync.WaitGroup
+}
 
+type Job struct {
+	WorkerId  string
+	Filenames []string
+	Status    bool
+	Active    bool
+	LastPing  time.Time
 }
 
 // Your code here -- RPC handlers for the worker to call.
-
-//
-// an example RPC handler.
 //
 // the RPC argument and reply types are defined in rpc.go.
-//
+func (c *Coordinator) GetTasks(args *RpcArgument, reply *RpcReply) error {
-func (c *Coordinator) Example(args *ExampleArgs, reply *ExampleReply) error {
+	c.mu.Lock()
-	reply.Y = args.X + 1
+	defer c.mu.Unlock()
+
+	done := make(chan struct{})
+
+	if args.Method != "request_task" {
+		return errors.New("argument .Method not valid for this procedure")
+	}
+	// check for any non-completed OR non-active map jobs
+	for i, mj := range c.MapJobs {
+		// assign job that not already done OR not actively being run by other workers
+		// status = false AND active = false
+		if !mj.Status && !mj.Active {
+			wId, err := genWorkerId()
+			if err != nil {
+				fmt.Println(err)
+			}
+			reply.NReduce = c.NReduce
+			reply.TaskType = "map"
+			reply.Filenames = mj.Filenames
+			reply.WorkerId = wId
+			// set job status, taken by a worke
+			c.MapJobs[i].WorkerId = wId
+			c.MapJobs[i].Active = true
+			c.MapJobs[i].LastPing = time.Now()
+			if DEBUG {
+				fmt.Printf("[Map Job Assigned] %s | file: %s | status: %t | active: %t |\n",
+					c.MapJobs[i].WorkerId,
+					c.MapJobs[i].Filenames[0],
+					c.MapJobs[i].Status, c.MapJobs[i].Active)
+			}
+			return nil
+		}
+	}
+	go func() {
+		c.mapWg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		if DEBUG {
+			fmt.Println("Wait done. Continuing...")
+		}
+	case <-time.After(GET_TASK_TIMEOUT):
+		return nil
+	}
+
+	done = make(chan struct{})
+
+	// check for reduce jobs
+	for i, rj := range c.ReduceJobs {
+		if !rj.Status && !rj.Active {
+			wId, err := genWorkerId()
+			if err != nil {
+				fmt.Println(err)
+			}
+			reply.WorkerId = wId
+			reply.NReduce = c.NReduce
+			reply.TaskType = "reduce"
+			reply.Filenames = rj.Filenames
+			// set job status, taken by a worker
+			c.ReduceJobs[i].WorkerId = wId
+			c.ReduceJobs[i].Active = true
+			c.ReduceJobs[i].LastPing = time.Now()
+			if DEBUG {
+				fmt.Printf("[Reduce Job Assigned] %s | status: %t | active: %t |\n",
+					c.ReduceJobs[i].WorkerId, c.ReduceJobs[i].Status, c.ReduceJobs[i].Active)
+			}
+			return nil
+		}
+	}
+	go func() {
+		c.reduceWg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		if DEBUG {
+			fmt.Println("Wait done. Continuing...")
+		}
+	case <-time.After(GET_TASK_TIMEOUT):
+		return nil
+	}
+
+	reply.TaskType = "done"
+	reply.NReduce = c.NReduce
+	reply.Filenames = []string{}
 	return nil
 }
 
+// Set task complete
+func (c *Coordinator) SetTaskDone(args *RpcArgument, reply *RpcReply) error {
+	if args.Method != "set_task_done" {
+		return errors.New("argument .Method not valid for this procedure")
+	}
+	if args.TaskType == "map" {
+		wId := args.WorkerId
+		for i, _ := range c.MapJobs {
+			if c.MapJobs[i].WorkerId == wId {
+				c.MapJobs[i].Status = true
+				c.MapJobs[i].Active = false
+				c.mapWg.Done()
+				if DEBUG {
+					fmt.Printf("[DONE] %s | file: %s | status: %t | active: %t\n",
+						c.MapJobs[i].WorkerId,
+						c.MapJobs[i].Filenames[0],
+						c.MapJobs[i].Status, c.MapJobs[i].Active)
+				}
+			}
+		}
+		// Check again
+		for _, ifn := range args.IntermediateFiles {
+			reduceJobIdx := strings.Split(ifn, "-")[2]
+			idx, err := strconv.Atoi(reduceJobIdx)
+			if err != nil {
+				fmt.Printf("Error converting string to integer: %v\n", err)
+			}
+			c.ReduceJobs[idx].Filenames = append(c.ReduceJobs[idx].Filenames, ifn)
+		}
+
+	} else if args.TaskType == "reduce" {
+		wId := args.WorkerId
+		for i, _ := range c.ReduceJobs {
+			if c.ReduceJobs[i].WorkerId == wId {
+				c.ReduceJobs[i].Status = true
+				c.ReduceJobs[i].Active = false
+				c.reduceWg.Done()
+			}
+		}
+	} else {
+		return errors.New("argument .TaskType not valid for this procedure")
+	}
+	return nil
+}
 
-//
 // start a thread that listens for RPCs from worker.go
-//
 func (c *Coordinator) server() {
 	rpc.Register(c)
 	rpc.HandleHTTP()
@@ -41,30 +194,105 @@ func (c *Coordinator) server() {
 	go http.Serve(l, nil)
 }
 
-//
+// check scheduled tasks; if their age > JOB_TIMEOUT_S
+// reset the job status, making it available for scheduling
+func (c *Coordinator) CheckTaskValidity() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	for i, mj := range c.MapJobs {
+		timeNow := time.Now()
+		duration := timeNow.Sub(mj.LastPing)
+		if DEBUG {
+			fmt.Printf("[Worker Status] id: %s | time: %s | active: %t | status: %t\n", mj.WorkerId, duration.String(), mj.Active, mj.Status)
+		}
+		if mj.Active && !mj.Status {
+			if duration >= JOB_TIMEOUT_S {
+				// unset worker id and set the status
+				if DEBUG {
+					fmt.Printf("[Terminating Worker] %s", mj.WorkerId)
+				}
+				c.MapJobs[i].WorkerId = ""
+				c.MapJobs[i].Active = false
+				c.MapJobs[i].Status = false
+			}
+		}
+	}
+	for i, rj := range c.ReduceJobs {
+		timeNow := time.Now()
+		if rj.Active && !rj.Status {
+			duration := timeNow.Sub(rj.LastPing)
+			if duration >= JOB_TIMEOUT_S {
+				if DEBUG {
+					fmt.Printf("[Terminating Worker] %s", rj.WorkerId)
+				}
+				c.ReduceJobs[i].WorkerId = ""
+				c.ReduceJobs[i].Active = false
+				c.ReduceJobs[i].Status = false
+			}
+		}
+	}
+}
+
 // main/mrcoordinator.go calls Done() periodically to find out
 // if the entire job has finished.
-//
 func (c *Coordinator) Done() bool {
 	ret := false
-
+	go c.CheckTaskValidity()
-	// Your code here.
+	// Check any non-completed jobs
-
+	for _, mj := range c.MapJobs {
-
+		if !mj.Status {
+			return ret
+		}
+	}
+	for _, mj := range c.ReduceJobs {
+		if !mj.Status {
+			return ret
+		}
+	}
+	// all mj completed
+	ret = true
 	return ret
 }
 
-//
 // create a Coordinator.
 // main/mrcoordinator.go calls this function.
 // nReduce is the number of reduce tasks to use.
-//
 func MakeCoordinator(files []string, nReduce int) *Coordinator {
 	c := Coordinator{}
 
-	// Your code here.
+	c.NReduce = nReduce
 
+	for i := range files {
+		mj := Job{}
+		mj.Filenames = []string{files[i]}
+		mj.Status = false
+		mj.Active = false
+		c.mapWg.Add(1)
+		c.MapJobs = append(c.MapJobs, mj)
+	}
+
+	for j := 0; j < nReduce; j++ {
+		reduceJob := Job{}
+		reduceJob.Active = false
+		reduceJob.Filenames = []string{}
+		reduceJob.Status = false
+		c.reduceWg.Add(1)
+		c.ReduceJobs = append(c.ReduceJobs, reduceJob)
+	}
 
 	c.server()
 	return &c
 }
+
+func genWorkerId() (string, error) {
+	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	result := make([]byte, 8)
+	for i := range result {
+		index, err := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
+		if err != nil {
+			return "", fmt.Errorf("error generating random number: %v", err)
+		}
+		result[i] = charset[index.Int64()]
+	}
+	return string(result), nil
+}

src/mr/rpc.go

@@ -6,25 +6,32 @@ package mr
 // remember to capitalize all names.
 //
 
-import "os"
+import (
-import "strconv"
+	"os"
+	"strconv"
+)
 
 //
 // example to show how to declare the arguments
 // and reply for an RPC.
 //
 
-type ExampleArgs struct {
+type RpcArgument struct {
-	X int
+	WorkerId          string
+	Method            string
+	TaskType          string
+	IntermediateFiles []string
 }
 
-type ExampleReply struct {
+type RpcReply struct {
-	Y int
+	WorkerId  string
+	TaskType  string
+	Filenames []string
+	NReduce   int
 }
 
 // Add your RPC definitions here.
 
-
 // Cook up a unique-ish UNIX-domain socket name
 // in /var/tmp, for the coordinator.
 // Can't use the current directory since

src/mr/worker.go

@@ -1,77 +1,245 @@
 package mr
 
-import "fmt"
+import (
-import "log"
+	"bytes"
-import "net/rpc"
+	"encoding/json"
-import "hash/fnv"
+	"fmt"
+	"hash/fnv"
+	"io"
+	"log"
+	"net/rpc"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+)
 
-
-//
 // Map functions return a slice of KeyValue.
-//
 type KeyValue struct {
 	Key   string
 	Value string
 }
 
-//
+// Sorting
+// for sorting by key.
+type ByKey []KeyValue
+
+// for sorting by key.
+func (a ByKey) Len() int           { return len(a) }
+func (a ByKey) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a ByKey) Less(i, j int) bool { return a[i].Key < a[j].Key }
+
 // use ihash(key) % NReduce to choose the reduce
 // task number for each KeyValue emitted by Map.
-//
 func ihash(key string) int {
 	h := fnv.New32a()
 	h.Write([]byte(key))
 	return int(h.Sum32() & 0x7fffffff)
 }
 
-
-//
 // main/mrworker.go calls this function.
-//
 func Worker(mapf func(string, string) []KeyValue,
 	reducef func(string, []string) string) {
-
 	// Your worker implementation here.
+	var workerId, taskType string
+	var inFilenames []string
+	var nReduce int
 
-	// uncomment to send the Example RPC to the coordinator.
+	taskType = "init"
-	// CallExample()
+	for taskType != "done" {
+		//for taskType != "done" && taskType != "init" && taskType != "map" && taskType != "reduce" {
+		//workerId, taskType, inFilenames, nReduce = RequestTask()
+		//}
+		for {
+			workerId, taskType, inFilenames, nReduce = RequestTask()
+
+			// Check if taskType is valid
+			if taskType == "done" || taskType == "init" || taskType == "map" || taskType == "reduce" {
+				break // Exit the loop if taskType is valid
+			}
+			time.Sleep(1 * time.Second)
+			//fmt.Println("Invalid taskType, retrying...")
+		}
+
+		if taskType == "done" {
+			return
+		}
+		if taskType == "map" {
+			ifn := inFilenames[0]
+			file, err := os.Open(ifn)
+			if err != nil {
+				log.Fatalf("cannot open %v", ifn)
+			}
+			content, err := io.ReadAll(file)
+			if err != nil {
+				log.Fatalf("cannot read %v", ifn)
+			}
+			file.Close()
+			kva := mapf(ifn, string(content))
+			//hash the map job id
+			mapTaskIdx := ihash(ifn)
+
+			IntermediaryFileMaps := make(map[int][]KeyValue)
+
+			for i := 0; i < nReduce; i++ {
+				IntermediaryFileMaps[i] = []KeyValue{}
+			}
+
+			for i := range kva {
+				//log.Printf("%s: %s", kva[i].Key, kva[i].Value)
+				idx := ihash(kva[i].Key) % nReduce
+				IntermediaryFileMaps[idx] = append(IntermediaryFileMaps[idx], kva[i])
+			}
+
+			intermediateFiles := []string{}
+			for idx := range IntermediaryFileMaps {
+				outFile := fmt.Sprintf("mr-%d-%d", mapTaskIdx, idx)
+				intermediateFiles = append(intermediateFiles, outFile)
+				jsonData, err := json.Marshal(IntermediaryFileMaps[idx])
+				if err != nil {
+					log.Fatal("failed to marshal json")
+				}
+				if err = WriteTempAtomic(outFile, jsonData); err != nil {
+					log.Fatalf("failed to write KV map to file")
+				}
+			}
+			SetTaskDone(workerId, "map", intermediateFiles)
+
+		} else if taskType == "reduce" {
+			var intermediate []KeyValue
+
+			for _, f := range inFilenames {
+				// Open the file
+				file, err := os.Open(f)
+				if err != nil {
+					log.Fatalf("Failed to open file: %v", err)
+				}
+				defer file.Close()
+
+				// Read the file contents
+				data, err := io.ReadAll(file)
+				if err != nil {
+					log.Fatalf("Failed to read file: %v", err)
+				}
+
+				// Parse the JSON data
+				var intermidateShard []KeyValue
+				if err := json.Unmarshal(data, &intermidateShard); err != nil {
+					log.Fatalf("Failed to parse JSON: %v", err)
+				}
+				intermediate = append(intermediate, intermidateShard...)
+			}
+
+			sort.Sort(ByKey(intermediate))
+
+			// Prepare output file
+			reduceJobNum := strings.Split(inFilenames[0], "-")[2]
+			oFilename := fmt.Sprintf("mr-out-%s", reduceJobNum)
+
+			var buffer bytes.Buffer
+			i := 0
+			for i < len(intermediate) {
+				j := i + 1
+				for j < len(intermediate) && intermediate[j].Key == intermediate[i].Key {
+					j++
+				}
+				values := []string{}
+				for k := i; k < j; k++ {
+					values = append(values, intermediate[k].Value)
+				}
+				output := reducef(intermediate[i].Key, values)
+
+				// this is the correct format for each line of Reduce output.
+				fmt.Fprintf(&buffer, "%v %v\n", intermediate[i].Key, output)
+				//fmt.Println(buffer.String())
+				i = j
+			}
+			if err := WriteTempAtomic(oFilename, buffer.Bytes()); err != nil {
+				log.Fatalf("failed to write KV map to file: %w", err)
+			}
+			SetTaskDone(workerId, "reduce", []string{})
+		}
+	}
 
 }
 
-//
+func WriteTempAtomic(fn string, data []byte) error {
-// example function to show how to make an RPC call to the coordinator.
+	// Create a temporary file in the target directory
-//
+	currentDir, err := os.Getwd()
-// the RPC argument and reply types are defined in rpc.go.
+	tempFile, err := os.CreateTemp(currentDir, fn)
-//
+	if err != nil {
-func CallExample() {
+		return fmt.Errorf("failed to create temp file: %w", err)
+	}
+	tempPath := tempFile.Name()
 
-	// declare an argument structure.
+	if _, err := tempFile.Write(data); err != nil {
-	args := ExampleArgs{}
+		tempFile.Close()
+		os.Remove(tempPath)
+		return fmt.Errorf("failed to write to temp file: %w", err)
+	}
 
-	// fill in the argument(s).
+	// Ensure the file is fully written to disk
-	args.X = 99
+	if err := tempFile.Sync(); err != nil {
+		tempFile.Close()
+		os.Remove(tempPath)
+		return fmt.Errorf("failed to sync temp file: %w", err)
+	}
 
-	// declare a reply structure.
+	if err := tempFile.Close(); err != nil {
-	reply := ExampleReply{}
+		os.Remove(tempPath)
+		return fmt.Errorf("failed to close temp file: %w", err)
+	}
 
-	// send the RPC request, wait for the reply.
+	// Compute the target file path
-	// the "Coordinator.Example" tells the
+	targetPath := filepath.Join(currentDir, fn)
-	// receiving server that we'd like to call
+
-	// the Example() method of struct Coordinator.
+	// Atomically replace the target file with the temporary file
-	ok := call("Coordinator.Example", &args, &reply)
+	if err := os.Rename(tempPath, targetPath); err != nil {
+		os.Remove(tempPath)
+		return fmt.Errorf("failed to rename temp file to target: %w", err)
+	}
+	return nil
+}
+
+// RPC call to set the task status to done
+func SetTaskDone(workerId string, taskType string, intermediateFiles []string) {
+	args := RpcArgument{}
+	args.WorkerId = workerId
+	args.Method = "set_task_done"
+	args.TaskType = taskType
+	args.IntermediateFiles = intermediateFiles
+	reply := RpcReply{}
+	ok := call("Coordinator.SetTaskDone", &args, &reply)
+	if !ok {
+		fmt.Printf("call failed!\n")
+	}
+	/*
 		if ok {
-		// reply.Y should be 100.
+			fmt.Printf("ok\n")
-		fmt.Printf("reply.Y %v\n", reply.Y)
 		} else {
 			fmt.Printf("call failed!\n")
 		}
+	*/
+}
+
+// RPC call to request task from coordinator
+func RequestTask() (string, string, []string, int) {
+	// declare an arg and reply
+	args := RpcArgument{}
+	args.Method = "request_task"
+	reply := RpcReply{}
+
+	ok := call("Coordinator.GetTasks", &args, &reply)
+	if !ok {
+		fmt.Printf("call failed!\n")
+	}
+	return reply.WorkerId, reply.TaskType, reply.Filenames, reply.NReduce
 }
 
-//
 // send an RPC request to the coordinator, wait for the response.
 // usually returns true.
 // returns false if something goes wrong.
-//
 func call(rpcname string, args interface{}, reply interface{}) bool {
 	// c, err := rpc.DialHTTP("tcp", "127.0.0.1"+":1234")
 	sockname := coordinatorSock()