khenaidoo | ffe076b | 2019-01-15 16:08:08 -0500 | [diff] [blame^] | 1 | // Copyright (c) 2012-2018 Ugorji Nwoke. All rights reserved. |
| 2 | // Use of this source code is governed by a MIT license found in the LICENSE file. |
| 3 | |
| 4 | package codec |
| 5 | |
| 6 | import ( |
| 7 | "bufio" |
| 8 | "errors" |
| 9 | "io" |
| 10 | "net/rpc" |
| 11 | "sync" |
| 12 | ) |
| 13 | |
| 14 | // Rpc provides a rpc Server or Client Codec for rpc communication. |
| 15 | type Rpc interface { |
| 16 | ServerCodec(conn io.ReadWriteCloser, h Handle) rpc.ServerCodec |
| 17 | ClientCodec(conn io.ReadWriteCloser, h Handle) rpc.ClientCodec |
| 18 | } |
| 19 | |
| 20 | // RPCOptions holds options specific to rpc functionality |
| 21 | type RPCOptions struct { |
| 22 | // RPCNoBuffer configures whether we attempt to buffer reads and writes during RPC calls. |
| 23 | // |
| 24 | // Set RPCNoBuffer=true to turn buffering off. |
| 25 | // Buffering can still be done if buffered connections are passed in, or |
| 26 | // buffering is configured on the handle. |
| 27 | RPCNoBuffer bool |
| 28 | } |
| 29 | |
| 30 | // rpcCodec defines the struct members and common methods. |
| 31 | type rpcCodec struct { |
| 32 | c io.Closer |
| 33 | r io.Reader |
| 34 | w io.Writer |
| 35 | f ioFlusher |
| 36 | |
| 37 | dec *Decoder |
| 38 | enc *Encoder |
| 39 | // bw *bufio.Writer |
| 40 | // br *bufio.Reader |
| 41 | mu sync.Mutex |
| 42 | h Handle |
| 43 | |
| 44 | cls bool |
| 45 | clsmu sync.RWMutex |
| 46 | clsErr error |
| 47 | } |
| 48 | |
| 49 | func newRPCCodec(conn io.ReadWriteCloser, h Handle) rpcCodec { |
| 50 | // return newRPCCodec2(bufio.NewReader(conn), bufio.NewWriter(conn), conn, h) |
| 51 | return newRPCCodec2(conn, conn, conn, h) |
| 52 | } |
| 53 | |
| 54 | func newRPCCodec2(r io.Reader, w io.Writer, c io.Closer, h Handle) rpcCodec { |
| 55 | // defensive: ensure that jsonH has TermWhitespace turned on. |
| 56 | if jsonH, ok := h.(*JsonHandle); ok && !jsonH.TermWhitespace { |
| 57 | panic(errors.New("rpc requires a JsonHandle with TermWhitespace set to true")) |
| 58 | } |
| 59 | // always ensure that we use a flusher, and always flush what was written to the connection. |
| 60 | // we lose nothing by using a buffered writer internally. |
| 61 | f, ok := w.(ioFlusher) |
| 62 | bh := h.getBasicHandle() |
| 63 | if !bh.RPCNoBuffer { |
| 64 | if bh.WriterBufferSize <= 0 { |
| 65 | if !ok { |
| 66 | bw := bufio.NewWriter(w) |
| 67 | f, w = bw, bw |
| 68 | } |
| 69 | } |
| 70 | if bh.ReaderBufferSize <= 0 { |
| 71 | if _, ok = w.(ioPeeker); !ok { |
| 72 | if _, ok = w.(ioBuffered); !ok { |
| 73 | br := bufio.NewReader(r) |
| 74 | r = br |
| 75 | } |
| 76 | } |
| 77 | } |
| 78 | } |
| 79 | return rpcCodec{ |
| 80 | c: c, |
| 81 | w: w, |
| 82 | r: r, |
| 83 | f: f, |
| 84 | h: h, |
| 85 | enc: NewEncoder(w, h), |
| 86 | dec: NewDecoder(r, h), |
| 87 | } |
| 88 | } |
| 89 | |
| 90 | func (c *rpcCodec) write(obj1, obj2 interface{}, writeObj2 bool) (err error) { |
| 91 | if c.isClosed() { |
| 92 | return c.clsErr |
| 93 | } |
| 94 | err = c.enc.Encode(obj1) |
| 95 | if err == nil { |
| 96 | if writeObj2 { |
| 97 | err = c.enc.Encode(obj2) |
| 98 | } |
| 99 | // if err == nil && c.f != nil { |
| 100 | // err = c.f.Flush() |
| 101 | // } |
| 102 | } |
| 103 | if c.f != nil { |
| 104 | if err == nil { |
| 105 | err = c.f.Flush() |
| 106 | } else { |
| 107 | _ = c.f.Flush() // swallow flush error, so we maintain prior error on write |
| 108 | } |
| 109 | } |
| 110 | return |
| 111 | } |
| 112 | |
| 113 | func (c *rpcCodec) swallow(err *error) { |
| 114 | defer panicToErr(c.dec, err) |
| 115 | c.dec.swallow() |
| 116 | } |
| 117 | |
| 118 | func (c *rpcCodec) read(obj interface{}) (err error) { |
| 119 | if c.isClosed() { |
| 120 | return c.clsErr |
| 121 | } |
| 122 | //If nil is passed in, we should read and discard |
| 123 | if obj == nil { |
| 124 | // var obj2 interface{} |
| 125 | // return c.dec.Decode(&obj2) |
| 126 | c.swallow(&err) |
| 127 | return |
| 128 | } |
| 129 | return c.dec.Decode(obj) |
| 130 | } |
| 131 | |
| 132 | func (c *rpcCodec) isClosed() (b bool) { |
| 133 | if c.c != nil { |
| 134 | c.clsmu.RLock() |
| 135 | b = c.cls |
| 136 | c.clsmu.RUnlock() |
| 137 | } |
| 138 | return |
| 139 | } |
| 140 | |
| 141 | func (c *rpcCodec) Close() error { |
| 142 | if c.c == nil || c.isClosed() { |
| 143 | return c.clsErr |
| 144 | } |
| 145 | c.clsmu.Lock() |
| 146 | c.cls = true |
| 147 | c.clsErr = c.c.Close() |
| 148 | c.clsmu.Unlock() |
| 149 | return c.clsErr |
| 150 | } |
| 151 | |
| 152 | func (c *rpcCodec) ReadResponseBody(body interface{}) error { |
| 153 | return c.read(body) |
| 154 | } |
| 155 | |
| 156 | // ------------------------------------- |
| 157 | |
| 158 | type goRpcCodec struct { |
| 159 | rpcCodec |
| 160 | } |
| 161 | |
| 162 | func (c *goRpcCodec) WriteRequest(r *rpc.Request, body interface{}) error { |
| 163 | // Must protect for concurrent access as per API |
| 164 | c.mu.Lock() |
| 165 | defer c.mu.Unlock() |
| 166 | return c.write(r, body, true) |
| 167 | } |
| 168 | |
| 169 | func (c *goRpcCodec) WriteResponse(r *rpc.Response, body interface{}) error { |
| 170 | c.mu.Lock() |
| 171 | defer c.mu.Unlock() |
| 172 | return c.write(r, body, true) |
| 173 | } |
| 174 | |
| 175 | func (c *goRpcCodec) ReadResponseHeader(r *rpc.Response) error { |
| 176 | return c.read(r) |
| 177 | } |
| 178 | |
| 179 | func (c *goRpcCodec) ReadRequestHeader(r *rpc.Request) error { |
| 180 | return c.read(r) |
| 181 | } |
| 182 | |
| 183 | func (c *goRpcCodec) ReadRequestBody(body interface{}) error { |
| 184 | return c.read(body) |
| 185 | } |
| 186 | |
| 187 | // ------------------------------------- |
| 188 | |
| 189 | // goRpc is the implementation of Rpc that uses the communication protocol |
| 190 | // as defined in net/rpc package. |
| 191 | type goRpc struct{} |
| 192 | |
| 193 | // GoRpc implements Rpc using the communication protocol defined in net/rpc package. |
| 194 | // |
| 195 | // Note: network connection (from net.Dial, of type io.ReadWriteCloser) is not buffered. |
| 196 | // |
| 197 | // For performance, you should configure WriterBufferSize and ReaderBufferSize on the handle. |
| 198 | // This ensures we use an adequate buffer during reading and writing. |
| 199 | // If not configured, we will internally initialize and use a buffer during reads and writes. |
| 200 | // This can be turned off via the RPCNoBuffer option on the Handle. |
| 201 | // var handle codec.JsonHandle |
| 202 | // handle.RPCNoBuffer = true // turns off attempt by rpc module to initialize a buffer |
| 203 | // |
| 204 | // Example 1: one way of configuring buffering explicitly: |
| 205 | // var handle codec.JsonHandle // codec handle |
| 206 | // handle.ReaderBufferSize = 1024 |
| 207 | // handle.WriterBufferSize = 1024 |
| 208 | // var conn io.ReadWriteCloser // connection got from a socket |
| 209 | // var serverCodec = GoRpc.ServerCodec(conn, handle) |
| 210 | // var clientCodec = GoRpc.ClientCodec(conn, handle) |
| 211 | // |
| 212 | // Example 2: you can also explicitly create a buffered connection yourself, |
| 213 | // and not worry about configuring the buffer sizes in the Handle. |
| 214 | // var handle codec.Handle // codec handle |
| 215 | // var conn io.ReadWriteCloser // connection got from a socket |
| 216 | // var bufconn = struct { // bufconn here is a buffered io.ReadWriteCloser |
| 217 | // io.Closer |
| 218 | // *bufio.Reader |
| 219 | // *bufio.Writer |
| 220 | // }{conn, bufio.NewReader(conn), bufio.NewWriter(conn)} |
| 221 | // var serverCodec = GoRpc.ServerCodec(bufconn, handle) |
| 222 | // var clientCodec = GoRpc.ClientCodec(bufconn, handle) |
| 223 | // |
| 224 | var GoRpc goRpc |
| 225 | |
| 226 | func (x goRpc) ServerCodec(conn io.ReadWriteCloser, h Handle) rpc.ServerCodec { |
| 227 | return &goRpcCodec{newRPCCodec(conn, h)} |
| 228 | } |
| 229 | |
| 230 | func (x goRpc) ClientCodec(conn io.ReadWriteCloser, h Handle) rpc.ClientCodec { |
| 231 | return &goRpcCodec{newRPCCodec(conn, h)} |
| 232 | } |