/*
* Read command/input from connection.
* @param b *bufioReadWriter - reader
* @return cmd string - read input
* @return err error - error state
*/
func readCmd(b *bufio.ReadWriter) (cmd string, err error) {
line, err := b.ReadBytes('\n')
if err != nil {
return "", err
}
// get rid of enclosing white spaces
return strings.Trim(string(line), " \t\n\v\r"), nil
}
func (s *Server) handleSingle(rw *bufio.ReadWriter) error {
line, err := rw.ReadBytes('\n')
if err != nil {
return err
}
args := bytes.Fields(line)
if len(args) == 0 {
return nil
}
switch {
case bytes.Equal(args[0], []byte("READ")):
// READ topic offset limit\n
if len(args) != 4 {
fmt.Fprintf(rw, "ERR READ requires 3 arg, got %d\n", len(args)-1)
return nil
}
s.mu.Lock()
defer s.mu.Unlock()
stack, ok := s.stacks[string(args[1])]
if !ok {
fmt.Fprintf(rw, "ERR stack %s does not exist\n", args[1])
return nil
}
offset, err := strconv.ParseInt(string(args[2]), 10, 64)
if err != nil || offset < 0 {
fmt.Fprint(rw, "ERR invalid offset\n")
return nil
}
limit, err := strconv.ParseInt(string(args[3]), 10, 64)
if err != nil || limit <= 0 {
fmt.Fprint(rw, "ERR invalid limit\n")
return nil
}
if offset > int64(len(stack)) {
return nil
}
if offset+limit > int64(len(stack)) {
limit = int64(len(stack)) - offset
}
for i, msg := range stack[offset : offset+limit] {
fmt.Fprintf(rw, "MSG %d %d\n", offset+int64(i), len(msg))
rw.Write(msg)
rw.WriteByte('\n')
}
rw.WriteString("END\n")
case bytes.Equal(args[0], []byte("PUSH")):
// PUSH topic msg-size\n
// msg\n
if len(args) != 3 {
fmt.Fprintf(rw, "ERR PUSH requires 2 args, got %d\n", len(args)-1)
return nil
}
msgsize, err := strconv.ParseInt(string(args[2]), 10, 64)
if err != nil || msgsize <= 0 {
fmt.Fprint(rw, "ERR invalid message size\n")
return nil
}
b := make([]byte, msgsize+1)
if n, err := rw.Read(b); err != nil {
fmt.Fprintf(rw, "ERR cannot read: %s\n", err)
return nil
} else if n != len(b) {
fmt.Fprint(rw, "ERR incompete message\n")
return nil
}
if b[msgsize] != '\n' {
fmt.Fprint(rw, "ERR invalid message termination\n")
return nil
}
s.mu.Lock()
defer s.mu.Unlock()
s.stacks[string(args[1])] = append(s.stacks[string(args[1])], b[:msgsize])
fmt.Fprint(rw, "OK\n")
case bytes.Equal(args[0], []byte("LEN")):
// LEN topic \n
if len(args) != 2 {
fmt.Fprintf(rw, "ERR LEN requires 1 arg, got %d\n", len(args)-1)
return nil
}
s.mu.Lock()
fmt.Fprintf(rw, "%d\n", len(s.stacks[string(args[1])]))
defer s.mu.Unlock()
case bytes.Equal(args[0], []byte("DUMP")):
s.mu.Lock()
for name, stack := range s.stacks {
fmt.Fprintf(rw, "%s %s\n", name, stack)
}
rw.WriteString("END\n")
defer s.mu.Unlock()
default:
fmt.Fprintf(rw, "ERR unknown command: %q\n", args)
}
return nil
}