| 🛟 Updated. 28d5985 k33g 17h ago | 1 | package jsonrpc |
| 2 | |
| 3 | import ( |
| 4 | "bufio" |
| 5 | "context" |
| 6 | "encoding/json" |
| 7 | "errors" |
| 8 | "fmt" |
| 9 | "io" |
| 10 | "sync" |
| 11 | ) |
| 12 | |
| 13 | // Conn is a JSON-RPC 2.0 connection over a framed stream. |
| 14 | // |
| 15 | // It is safe for concurrent use: several goroutines may call and notify at |
| 16 | // once, and replies are matched back to their callers by request id. |
| 17 | type Conn struct { |
| 18 | stream io.ReadWriteCloser |
| 19 | reader *bufio.Reader |
| 20 | framer Framer |
| 21 | |
| 22 | onNotify NotificationFunc |
| 23 | onRequest RequestFunc |
| 24 | |
| 25 | writeMu sync.Mutex |
| 26 | |
| 27 | mu sync.Mutex |
| 28 | nextID int64 |
| 29 | pending map[int64]chan *message |
| 30 | closed bool |
| 31 | } |
| 32 | |
| 33 | // NewConn returns a connection over stream, using framer to mark one message |
| 34 | // off from the next. Call Run in a goroutine of its own to start reading. |
| 35 | // |
| 36 | // onNotify and onRequest may both be nil, in which case notifications are |
| 37 | // dropped and the peer's requests are answered with "method not found". |
| 38 | // |
| 39 | // conn := jsonrpc.NewConn(stream, lsp.Framing{}, client.onNotify, client.onRequest) |
| 40 | // go conn.Run() |
| 41 | func NewConn(stream io.ReadWriteCloser, framer Framer, onNotify NotificationFunc, onRequest RequestFunc) *Conn { |
| 42 | return &Conn{ |
| 43 | stream: stream, |
| 44 | reader: bufio.NewReader(stream), |
| 45 | framer: framer, |
| 46 | onNotify: onNotify, |
| 47 | onRequest: onRequest, |
| 48 | pending: map[int64]chan *message{}, |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | // Run reads messages until the stream ends or the connection is closed, then |
| 53 | // fails every call still waiting for an answer. |
| 54 | // |
| 55 | // It returns nil for a clean end of stream and the read error otherwise. |
| 56 | func (c *Conn) Run() error { |
| 57 | err := c.readLoop() |
| 58 | c.failPending() |
| 59 | return err |
| 60 | } |
| 61 | |
| 62 | // readLoop dispatches every message that arrives. |
| 63 | func (c *Conn) readLoop() error { |
| 64 | for { |
| 65 | body, err := c.framer.ReadMessage(c.reader) |
| 66 | if err != nil { |
| 67 | if errors.Is(err, io.EOF) || c.isClosed() { |
| 68 | return nil |
| 69 | } |
| 70 | return err |
| 71 | } |
| 72 | |
| 73 | var msg message |
| 74 | if err := json.Unmarshal(body, &msg); err != nil { |
| 75 | return fmt.Errorf("jsonrpc: unreadable message: %w", err) |
| 76 | } |
| 77 | c.dispatch(&msg) |
| 78 | } |
| 79 | } |
| 80 | |
| 81 | // dispatch sends a message where it belongs: to the call that is waiting for |
| 82 | // it, to the notification handler, or to the request handler. |
| 83 | // |
| 84 | // A notification and a request differ only by the id: the peer expects an |
| 85 | // answer to exactly the messages that carry one. |
| 86 | func (c *Conn) dispatch(msg *message) { |
| 87 | switch { |
| 88 | case msg.Method != "" && len(msg.ID) == 0: |
| 89 | if c.onNotify != nil { |
| 90 | c.onNotify(msg.Method, msg.Params) |
| 91 | } |
| 92 | case msg.Method != "": |
| 93 | c.answer(msg) |
| 94 | default: |
| 95 | c.deliver(msg) |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | // deliver hands a response to the call that is waiting for it. |
| 100 | // |
| 101 | // The id is looked up among the ids *this* connection sent. A peer numbering |
| 102 | // its own requests from zero — which the Agent Client Protocol's agents do — |
| 103 | // therefore cannot collide with a call in flight here. |
| 104 | func (c *Conn) deliver(msg *message) { |
| 105 | var id int64 |
| 106 | if err := json.Unmarshal(msg.ID, &id); err != nil { |
| 107 | return // a response to an id we never sent; nothing to do with it |
| 108 | } |
| 109 | |
| 110 | c.mu.Lock() |
| 111 | waiting, ok := c.pending[id] |
| 112 | delete(c.pending, id) |
| 113 | c.mu.Unlock() |
| 114 | |
| 115 | if ok { |
| 116 | waiting <- msg |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | // answer hands a request the peer made to the handler, which replies now or |
| 121 | // later. |
| 122 | func (c *Conn) answer(msg *message) { |
| 123 | request := &Request{Method: msg.Method, Params: msg.Params, conn: c, id: msg.ID} |
| 124 | |
| 125 | if c.onRequest == nil { |
| 126 | request.Reply(nil, &ResponseError{Code: CodeMethodNotFound, Message: msg.Method}) |
| 127 | return |
| 128 | } |
| 129 | c.onRequest(request) |
| 130 | } |
| 131 | |
| 132 | // Call sends a request and waits for its answer, decoding it into result. |
| 133 | // |
| 134 | // Passing a nil result discards the answer. The call ends early if ctx does, |
| 135 | // which is what stops a slow request from freezing the caller. |
| 136 | // |
| 137 | // var items CompletionList |
| 138 | // err := conn.Call(ctx, "textDocument/completion", params, &items) |
| 139 | func (c *Conn) Call(ctx context.Context, method string, params, result any) error { |
| 140 | id, waiting, err := c.register() |
| 141 | if err != nil { |
| 142 | return err |
| 143 | } |
| 144 | defer c.forget(id) |
| 145 | |
| 146 | if err := c.sendRequest(id, method, params); err != nil { |
| 147 | return err |
| 148 | } |
| 149 | |
| 150 | select { |
| 151 | case <-ctx.Done(): |
| 152 | return ctx.Err() |
| 153 | case reply := <-waiting: |
| 154 | return decodeReply(reply, result) |
| 155 | } |
| 156 | } |
| 157 | |
| 158 | // Notify sends a notification, which expects no answer. |
| 159 | // |
| 160 | // err := conn.Notify("session/cancel", map[string]string{"sessionId": id}) |
| 161 | func (c *Conn) Notify(method string, params any) error { |
| 162 | encodedParams, err := encodeParams(params) |
| 163 | if err != nil { |
| 164 | return err |
| 165 | } |
| 166 | return c.write(&message{JSONRPC: Version, Method: method, Params: encodedParams}) |
| 167 | } |
| 168 | |
| 169 | // sendRequest encodes and writes one request. |
| 170 | func (c *Conn) sendRequest(id int64, method string, params any) error { |
| 171 | encodedID, err := json.Marshal(id) |
| 172 | if err != nil { |
| 173 | return fmt.Errorf("jsonrpc: encoding the request id: %w", err) |
| 174 | } |
| 175 | encodedParams, err := encodeParams(params) |
| 176 | if err != nil { |
| 177 | return err |
| 178 | } |
| 179 | return c.write(&message{JSONRPC: Version, ID: encodedID, Method: method, Params: encodedParams}) |
| 180 | } |
| 181 | |
| 182 | // register allocates a request id and the channel its answer will arrive on. |
| 183 | func (c *Conn) register() (int64, chan *message, error) { |
| 184 | c.mu.Lock() |
| 185 | defer c.mu.Unlock() |
| 186 | |
| 187 | if c.closed { |
| 188 | return 0, nil, ErrClosed |
| 189 | } |
| 190 | c.nextID++ |
| 191 | // The channel is buffered so that the read loop never blocks handing over |
| 192 | // an answer whose caller has already given up. |
| 193 | waiting := make(chan *message, 1) |
| 194 | c.pending[c.nextID] = waiting |
| 195 | return c.nextID, waiting, nil |
| 196 | } |
| 197 | |
| 198 | // forget drops a pending request, whether it was answered or abandoned. |
| 199 | func (c *Conn) forget(id int64) { |
| 200 | c.mu.Lock() |
| 201 | delete(c.pending, id) |
| 202 | c.mu.Unlock() |
| 203 | } |
| 204 | |
| 205 | // write frames and sends one message. |
| 206 | func (c *Conn) write(msg *message) error { |
| 207 | body, err := json.Marshal(msg) |
| 208 | if err != nil { |
| 209 | return fmt.Errorf("jsonrpc: encoding a message: %w", err) |
| 210 | } |
| 211 | |
| 212 | c.writeMu.Lock() |
| 213 | defer c.writeMu.Unlock() |
| 214 | if c.isClosed() { |
| 215 | return ErrClosed |
| 216 | } |
| 217 | return c.framer.WriteMessage(c.stream, body) |
| 218 | } |
| 219 | |
| 220 | // failPending wakes every waiting call once the connection has ended. |
| 221 | // |
| 222 | // Requests the *peer* sent are not answered here. There is no answer to give, |
| 223 | // and the peer whose connection has just ended is not waiting for one. |
| 224 | func (c *Conn) failPending() { |
| 225 | c.mu.Lock() |
| 226 | defer c.mu.Unlock() |
| 227 | |
| 228 | c.closed = true |
| 229 | for id, waiting := range c.pending { |
| 230 | close(waiting) |
| 231 | delete(c.pending, id) |
| 232 | } |
| 233 | } |
| 234 | |
| 235 | // isClosed reports whether the connection has been closed. |
| 236 | func (c *Conn) isClosed() bool { |
| 237 | c.mu.Lock() |
| 238 | defer c.mu.Unlock() |
| 239 | return c.closed |
| 240 | } |
| 241 | |
| 242 | // Close shuts the connection down. Calls still waiting fail with ErrClosed. |
| 243 | func (c *Conn) Close() error { |
| 244 | c.mu.Lock() |
| 245 | if c.closed { |
| 246 | c.mu.Unlock() |
| 247 | return nil |
| 248 | } |
| 249 | c.closed = true |
| 250 | c.mu.Unlock() |
| 251 | |
| 252 | return c.stream.Close() |
| 253 | } |