feat: consolidate select write

.gitignore

@@ -2,3 +2,4 @@ node_modules
 .nyc_output
 coverage
 docs
+package-lock.json

package.json

@@ -44,10 +44,11 @@
     "buffer": "^5.2.1",
     "debug": "^4.1.1",
     "err-code": "^2.0.0",
-    "it-length-prefixed": "jacobheun/pull-length-prefixed#v2.0.0-rc.0",
+    "it-handshake": "^1.0.0",
+    "it-length-prefixed": "^2.0.0",
     "it-pipe": "^1.0.1",
     "it-pushable": "^1.3.1",
-    "it-reader": "jacobheun/it-reader#v2.0.0-rc.0",
+    "it-reader": "^2.0.0",
     "p-defer": "^3.0.0"
   },
   "devDependencies": {

src/constants.js

@@ -0,0 +1,3 @@
+'use strict'
+
+exports.PROTOCOL_ID = '/multistream/1.0.0'

src/handle.js

@@ -3,33 +3,40 @@
 const log = require('debug')('mss:handle')
 const BufferList = require('bl/BufferList')
 const multistream = require('./multistream')
-const toReaderWriter = require('./to-reader-writer')
+const handshake = require('it-handshake')
+const { PROTOCOL_ID } = require('./constants')
 
 module.exports = async (stream, protocols) => {
   protocols = Array.isArray(protocols) ? protocols : [protocols]
-  const { reader, writer, rest } = toReaderWriter(stream)
+  const { writer, reader, rest, stream: shakeStream } = handshake(stream)
 
   while (true) {
     const protocol = (await multistream.read(reader)).toString()
     log('read "%s"', protocol)
 
+    if (protocol === PROTOCOL_ID) {
+      log('respond with "%s" for "%s"', PROTOCOL_ID, protocol)
+      multistream.write(writer, PROTOCOL_ID)
+      continue
+    }
+
     if (protocols.includes(protocol)) {
       multistream.write(writer, protocol)
-      log('write "%s" "%s"', protocol, protocol)
-      writer.end()
-      return { stream: rest, protocol }
+      log('respond with "%s" for "%s"', protocol, protocol)
+      rest()
+      return { stream: shakeStream, protocol }
     }
 
     if (protocol === 'ls') {
       // <varint-msg-len><varint-proto-name-len><proto-name>\n<varint-proto-name-len><proto-name>\n\n
       multistream.write(writer, new BufferList(
         protocols.map(p => multistream.encode(p))
       ))
-      log('write "%s" %s', protocol, protocols)
+      log('respond with "%s" for %s', protocols, protocol)
       continue
     }
 
     multistream.write(writer, 'na')
-    log('write "%s" "na"', protocol)
+    log('respond with "na" for "%s"', protocol)
   }
 }

src/index.js

@@ -3,8 +3,7 @@
 const select = require('./select')
 const handle = require('./handle')
 const ls = require('./ls')
-
-const PROTOCOL_ID = '/multistream/1.0.0'
+const { PROTOCOL_ID } = require('./constants')
 
 exports.PROTOCOL_ID = PROTOCOL_ID
 
@@ -24,9 +23,8 @@ class MultistreamSelect {
 }
 
 class Dialer extends MultistreamSelect {
-  async select (protocols) {
-    await this._handshake()
-    return select(this._stream, protocols)
+  select (protocols) {
+    return select(this._stream, protocols, this._shaken ? null : PROTOCOL_ID)
   }
 
   async ls () {
@@ -40,8 +38,7 @@ class Dialer extends MultistreamSelect {
 exports.Dialer = Dialer
 
 class Listener extends MultistreamSelect {
-  async handle (protocols) {
-    await this._handshake()
+  handle (protocols) {
     return handle(this._stream, protocols)
   }
 }

src/ls.js

@@ -3,16 +3,16 @@
 const Reader = require('it-reader')
 const log = require('debug')('it-multistream-select:ls')
 const multistream = require('./multistream')
-const toReaderWriter = require('./to-reader-writer')
+const handshake = require('it-handshake')
 const lp = require('it-length-prefixed')
 const pipe = require('it-pipe')
 
 module.exports = async stream => {
-  const { reader, writer, rest } = toReaderWriter(stream)
+  const { reader, writer, rest, stream: shakeStream } = handshake(stream)
 
   log('write "ls"')
   multistream.write(writer, 'ls')
-  writer.end()
+  rest()
 
   // Next message from remote will be (e.g. for 2 protocols):
   // <varint-msg-len><varint-proto-name-len><proto-name>\n<varint-proto-name-len><proto-name>\n
@@ -35,5 +35,5 @@ module.exports = async stream => {
     }
   )
 
-  return { stream: rest, protocols }
+  return { stream: shakeStream, protocols }
 }

src/multistream.js

@@ -14,8 +14,14 @@ async function oneChunk (source) {
 
 exports.encode = buffer => lp.encode.single(new BufferList([buffer, NewLine]))
 
+// `write` encodes and writes a single buffer
 exports.write = (writer, buffer) => writer.push(exports.encode(buffer))
 
+// `writeAll` behaves like `write`, except it encodes an array of items as a single write
+exports.writeAll = (writer, buffers) => {
+  writer.push(buffers.reduce((bl, buffer) => bl.append(exports.encode(buffer)), new BufferList()))
+}
+
 exports.read = async reader => {
   let byteLength = 1 // Read single byte chunks until the length is known
   const varByteSource = { // No return impl - we want the reader to remain readable

src/select.js

@@ -3,24 +3,49 @@
 const log = require('debug')('mss:select')
 const errCode = require('err-code')
 const multistream = require('./multistream')
-const toReaderWriter = require('./to-reader-writer')
+const handshake = require('it-handshake')
 
-module.exports = async (stream, protocols) => {
+module.exports = async (stream, protocols, protocolId) => {
   protocols = Array.isArray(protocols) ? protocols : [protocols]
-  const { reader, writer, rest } = toReaderWriter(stream)
+  const { reader, writer, rest, stream: shakeStream } = handshake(stream)
 
+  const protocol = protocols.shift()
+  if (protocolId) {
+    log('select: write ["%s", "%s"]', protocolId, protocol)
+    multistream.writeAll(writer, [protocolId, protocol])
+  } else {
+    log('select: write "%s"', protocol)
+    multistream.write(writer, protocol)
+  }
+
+  let response = (await multistream.read(reader)).toString()
+  log('select: read "%s"', response)
+
+  // Read the protocol response if we got the protocolId in return
+  if (response === protocolId) {
+    response = (await multistream.read(reader)).toString()
+    log('select: read "%s"', response)
+  }
+
+  // We're done
+  if (response === protocol) {
+    rest()
+    return { stream: shakeStream, protocol }
+  }
+
+  // We haven't gotten a valid ack, try the other protocols
   for (const protocol of protocols) {
-    log('write "%s"', protocol)
+    log('select: write "%s"', protocol)
     multistream.write(writer, protocol)
     const response = (await multistream.read(reader)).toString()
-    log('read "%s" "%s"', protocol, response)
+    log('select: read "%s" for "%s"', response, protocol)
 
     if (response === protocol) {
-      writer.end() // End our writer so others can start writing to stream
-      return { stream: rest, protocol }
+      rest() // End our writer so others can start writing to stream
+      return { stream: shakeStream, protocol }
     }
   }
 
-  writer.end()
+  rest()
   throw errCode(new Error('protocol selection failed'), 'ERR_UNSUPPORTED_PROTOCOL')
 }