completed code for cas functionality

assignment1/server.go

@@ -30,8 +30,9 @@ const (
 	//	DELETED = "DELETED"
 
 	//errors
-	ERR_CMD_ERR = "ERR_CMD_ERR"
+	ERR_CMD_ERR   = "ERR_CMD_ERR"
 	ERR_NOT_FOUND = "ERR_NOT_FOUND"
+	ERR_VERSION   = "ERR_VERSION"
 
 	//logging
 	LOG = true
@@ -229,7 +230,7 @@ func parseInput(conn net.Conn, msg string, table *KeyValueStore) {
 			buffer.WriteString(" ")
 			buffer.WriteString(strconv.FormatUint(data.version, 10))
 			buffer.WriteString(" ")
-			buffer.WriteString(strconv.FormatUint(data.expTime - uint64(time.Now().Unix()), 10))
+			buffer.WriteString(strconv.FormatUint(data.expTime-uint64(time.Now().Unix()), 10))
 			buffer.WriteString(" ")
 			buffer.WriteString(strconv.FormatUint(data.numBytes, 10))
 			write(conn, buffer.String())
@@ -242,7 +243,35 @@ func parseInput(conn net.Conn, msg string, table *KeyValueStore) {
 			write(conn, buffer.String())
 		}
 
-	//case CAS: performCas(tokens[1:len(tokens)])
+	case CAS:
+		if isValid(CAS, tokens, conn) != 0 {
+			return
+		}
+		if ver, ok, r := performCas(conn, tokens[1:len(tokens)], table); r {
+			if r {
+				switch ok {
+				case 0:
+					buffer.Reset()
+					buffer.WriteString(OK)
+					buffer.WriteString(" ")
+					buffer.WriteString(strconv.FormatUint(ver, 10))
+					logger.Println(buffer.String())
+					write(conn, buffer.String())
+				case 1:
+					buffer.Reset()
+					buffer.WriteString(ERR_CMD_ERR)
+					write(conn, buffer.String())
+				case 2:
+					buffer.Reset()
+					buffer.WriteString(ERR_VERSION)
+					write(conn, buffer.String())
+				case 3:
+					buffer.Reset()
+					buffer.WriteString(ERR_NOT_FOUND)
+					write(conn, buffer.String())
+				}
+			}
+		}
 	//case DELETE: performDelete(tokens[1:len(tokens)])
 	default:
 		logger.Println("Command not found")
@@ -265,7 +294,7 @@ func performSet(conn net.Conn, tokens []string, table *KeyValueStore) (uint64, b
 	v, ok := read(conn, n+2)
 	if !ok {
 		//error here
-		return 0, false, false
+		return 0, false, r
 	}
 
 	table.Lock()
@@ -282,7 +311,7 @@ func performSet(conn net.Conn, tokens []string, table *KeyValueStore) (uint64, b
 	val.numBytes = n
 	val.version = ver
 	if e == 0 {
-	val.expTime = e
+		val.expTime = e
 	} else {
 		val.expTime = e + uint64(time.Now().Unix())
 	}
@@ -296,12 +325,12 @@ func performSet(conn net.Conn, tokens []string, table *KeyValueStore) (uint64, b
 
 func performGet(conn net.Conn, tokens []string, table *KeyValueStore) (*Data, bool) {
 	k := tokens[0]
-	defer table.RUnlock()
+	table.RUnlock()
 	table.RLock()
 	//critical section begin
 	if v, ok := table.dictionary[k]; ok {
 		if v.expTime != 0 && v.expTime < uint64(time.Now().Unix()) {
-
+			table.RUnlock()
 			return nil, false
 		}
 		data := new(Data)
@@ -327,12 +356,52 @@ func performGetm(conn net.Conn, tokens []string, table *KeyValueStore) (*Data, b
 		data.expTime = v.expTime
 		data.numBytes = v.numBytes
 		data.value = v.value[:]
+
 		return data, true
 	} else {
 		return nil, false
 	}
 }
 
+func performCas(conn net.Conn, tokens []string, table *KeyValueStore) (uint64, int, bool) {
+	k := tokens[0]
+	e, _ := strconv.ParseUint(tokens[1], 10, 64)
+	ve, _ := strconv.ParseUint(tokens[2], 10, 64)
+	n, _ := strconv.ParseUint(tokens[3], 10, 64)
+	r := true 
+
+	logger.Println(k, e, ve, n, r)
+	if len(tokens) == 5 && tokens[4] == NOREPLY {
+		r = false
+	}
+
+	//read value
+	v, ok := read(conn, n+2)
+	if !ok {
+		//error here
+		return 0, 1, r //malformed
+	}
+
+	defer table.Unlock()
+	table.Lock()
+	if val, ok := table.dictionary[k]; ok {
+		if val.version == ve {
+			if e == 0 {
+				val.expTime = e
+			} else {
+				val.expTime = e + uint64(time.Now().Unix())
+			}
+			val.numBytes = n
+			ver++
+			val.version = ver
+			val.value = v
+			return val.version, 0, r //key found and changed
+		}
+		return 0, 2, r //version mismatch
+	}
+	return 0, 3, r //key not found
+}
+
 func debug(table *KeyValueStore) {
 	logger.Println("----start debug----")
 	for key, val := range (*table).dictionary {