package client import ( "errors" "net" "reflect" "sync" "go.arsenm.dev/lrpc/codec" "go.arsenm.dev/lrpc/internal/reflectutil" "go.arsenm.dev/lrpc/internal/types" "github.com/gofrs/uuid" ) // <= go1.17 compatibility type any = interface{} // Client error values var ( ErrReturnNotChannel = errors.New("function call returns channel but return value is not a channel type") ErrReturnNotPointer = errors.New("function call returns value but return value is not a pointer") ErrMismatchedType = errors.New("type of channel does not match type returned by server") ) // Client is an lrpc client type Client struct { conn net.Conn codec codec.Codec chMtx sync.Mutex chs map[string]chan *types.Response } // New creates and returns a new client func New(conn net.Conn, cf codec.CodecFunc) *Client { out := &Client{ conn: conn, codec: cf(conn), chs: map[string]chan *types.Response{}, } go out.handleConn() return out } // Call calls a method on the server func (c *Client) Call(rcvr, method string, arg interface{}, ret interface{}) error { // Create new v4 UUOD id, err := uuid.NewV4() if err != nil { return err } idStr := id.String() // Create new channel using the generated ID c.chMtx.Lock() c.chs[idStr] = make(chan *types.Response, 1) c.chMtx.Unlock() // Encode request using codec err = c.codec.Encode(types.Request{ ID: idStr, Receiver: rcvr, Method: method, Arg: arg, }) if err != nil { return err } // Get response from channel resp := <-c.chs[idStr] // Close and delete channel c.chMtx.Lock() close(c.chs[idStr]) delete(c.chs, idStr) c.chMtx.Unlock() // If response is an error, return error if resp.IsError { return errors.New(resp.Error) } // If there is no return value, stop now if resp.Return == nil { return nil } // Get reflect value of return value retVal := reflect.ValueOf(ret) // If response is a channel if resp.IsChannel { // If return value is not a channel, return error if retVal.Kind() != reflect.Chan { return ErrReturnNotChannel } // Get channel ID returned in response chID := resp.Return.(string) // Create new channel using channel ID c.chMtx.Lock() c.chs[chID] = make(chan *types.Response, 5) c.chMtx.Unlock() go func() { // Get type of channel elements chElemType := retVal.Type().Elem() // For every value received from channel for val := range c.chs[chID] { if val.ChannelDone { // Close and delete channel c.chMtx.Lock() close(c.chs[chID]) delete(c.chs, chID) c.chMtx.Unlock() // Close return channel retVal.Close() break } // Get reflect value from channel response rVal := reflect.ValueOf(val.Return) // If return value is not the same as the channel if rVal.Type() != chElemType { // Attempt to convert value, skip if impossible newVal, err := reflectutil.Convert(rVal, chElemType) if err != nil { continue } rVal = newVal } // Send value to channel retVal.Send(rVal) } }() go func() { for { val, ok := retVal.Recv() if !ok && val.IsValid() { break } } c.Call("lrpc", "ChannelDone", id, nil) // Close and delete channel c.chMtx.Lock() close(c.chs[chID]) delete(c.chs, chID) c.chMtx.Unlock() }() } else { // IF return value is not a pointer, return error if retVal.Kind() != reflect.Ptr { return ErrReturnNotPointer } // Get return type retType := retVal.Type().Elem() // Get refkect value from response rVal := reflect.ValueOf(resp.Return) // If types do not match if rVal.Type() != retType { // Attempt to convert types, return error if not possible newVal, err := reflectutil.Convert(rVal, retType) if err != nil { return err } rVal = newVal } // Set return value to received value retVal.Elem().Set(rVal) } return nil } func (c *Client) handleConn() { for { resp := &types.Response{} // Attempt to decode response using codec err := c.codec.Decode(resp) if err != nil { continue } // Get channel from map, skip if it doesn't exist ch, ok := c.chs[resp.ID] if !ok { continue } // Send response to channel ch <- resp } } // Close closes the client func (c *Client) Close() error { return c.conn.Close() }