fix(realtime): simplify serializer by removing unnecessary types of messages (#1871)

Author: edgurgel

packages/core/realtime-js/src/lib/serializer.ts

@@ -1,7 +1,5 @@
 // This file draws heavily from https://github.com/phoenixframework/phoenix/commit/cf098e9cf7a44ee6479d31d911a97d3c7430c6fe
 // License: https://github.com/phoenixframework/phoenix/blob/master/LICENSE.md
-import { CHANNEL_EVENTS } from '../lib/constants'
-
 export type Msg<T> = {
   join_ref?: string | null
   ref?: string | null
@@ -14,21 +12,14 @@ export default class Serializer {
   HEADER_LENGTH = 1
   META_LENGTH = 4
   USER_BROADCAST_PUSH_META_LENGTH = 5
-  KINDS = { push: 0, reply: 1, broadcast: 2, userBroadcastPush: 3, userBroadcast: 4 }
+  KINDS = { userBroadcastPush: 3, userBroadcast: 4 }
   BINARY_ENCODING = 0
   JSON_ENCODING = 1
-  BROADCAST = 'broadcast'
-
-  encode(
-    msg: Msg<{ [key: string]: any } | ArrayBuffer>,
-    callback: (result: ArrayBuffer | string) => any
-  ) {
-    if (this._isArrayBuffer(msg.payload)) {
-      return callback(this._binaryEncodePush(msg as Msg<ArrayBuffer>))
-    }
+  BROADCAST_EVENT = 'broadcast'
 
+  encode(msg: Msg<{ [key: string]: any }>, callback: (result: ArrayBuffer | string) => any) {
     if (
-      msg.event === this.BROADCAST &&
+      msg.event === this.BROADCAST_EVENT &&
       !(msg.payload instanceof ArrayBuffer) &&
       typeof msg.payload.event === 'string'
     ) {
@@ -41,34 +32,6 @@ export default class Serializer {
     return callback(JSON.stringify(payload))
   }
 
-  private _binaryEncodePush(message: Msg<ArrayBuffer>) {
-    const { event, topic, payload } = message
-    const ref = message.ref ?? ''
-    const joinRef = message.join_ref ?? ''
-
-    const metaLength = this.META_LENGTH + joinRef.length + ref.length + topic.length + event.length
-
-    const header = new ArrayBuffer(this.HEADER_LENGTH + metaLength)
-    let view = new DataView(header)
-    let offset = 0
-
-    view.setUint8(offset++, this.KINDS.push) // kind
-    view.setUint8(offset++, joinRef.length)
-    view.setUint8(offset++, ref.length)
-    view.setUint8(offset++, topic.length)
-    view.setUint8(offset++, event.length)
-    Array.from(joinRef, (char) => view.setUint8(offset++, char.charCodeAt(0)))
-    Array.from(ref, (char) => view.setUint8(offset++, char.charCodeAt(0)))
-    Array.from(topic, (char) => view.setUint8(offset++, char.charCodeAt(0)))
-    Array.from(event, (char) => view.setUint8(offset++, char.charCodeAt(0)))
-
-    var combined = new Uint8Array(header.byteLength + payload.byteLength)
-    combined.set(new Uint8Array(header), 0)
-    combined.set(new Uint8Array(payload), header.byteLength)
-
-    return combined.buffer
-  }
-
   private _binaryEncodeUserBroadcastPush(message: Msg<{ event: string } & { [key: string]: any }>) {
     if (this._isArrayBuffer(message.payload?.payload)) {
       return this._encodeBinaryUserBroadcastPush(message)
@@ -172,106 +135,11 @@ export default class Serializer {
     const kind = view.getUint8(0)
     const decoder = new TextDecoder()
     switch (kind) {
-      case this.KINDS.push:
-        return this._decodePush(buffer, view, decoder)
-      case this.KINDS.reply:
-        return this._decodeReply(buffer, view, decoder)
-      case this.KINDS.broadcast:
-        return this._decodeBroadcast(buffer, view, decoder)
       case this.KINDS.userBroadcast:
         return this._decodeUserBroadcast(buffer, view, decoder)
     }
   }
 
-  private _decodePush(
-    buffer: ArrayBuffer,
-    view: DataView,
-    decoder: TextDecoder
-  ): {
-    join_ref: string
-    ref: null
-    topic: string
-    event: string
-    payload: { [key: string]: any }
-  } {
-    const joinRefSize = view.getUint8(1)
-    const topicSize = view.getUint8(2)
-    const eventSize = view.getUint8(3)
-    let offset = this.HEADER_LENGTH + this.META_LENGTH - 1 // pushes have no ref
-    const joinRef = decoder.decode(buffer.slice(offset, offset + joinRefSize))
-    offset = offset + joinRefSize
-    const topic = decoder.decode(buffer.slice(offset, offset + topicSize))
-    offset = offset + topicSize
-    const event = decoder.decode(buffer.slice(offset, offset + eventSize))
-    offset = offset + eventSize
-    const data = JSON.parse(decoder.decode(buffer.slice(offset, buffer.byteLength)))
-    return {
-      join_ref: joinRef,
-      ref: null,
-      topic: topic,
-      event: event,
-      payload: data,
-    }
-  }
-
-  private _decodeReply(
-    buffer: ArrayBuffer,
-    view: DataView,
-    decoder: TextDecoder
-  ): {
-    join_ref: string
-    ref: string
-    topic: string
-    event: CHANNEL_EVENTS.reply
-    payload: { status: string; response: { [key: string]: any } }
-  } {
-    const joinRefSize = view.getUint8(1)
-    const refSize = view.getUint8(2)
-    const topicSize = view.getUint8(3)
-    const eventSize = view.getUint8(4)
-    let offset = this.HEADER_LENGTH + this.META_LENGTH
-    const joinRef = decoder.decode(buffer.slice(offset, offset + joinRefSize))
-    offset = offset + joinRefSize
-    const ref = decoder.decode(buffer.slice(offset, offset + refSize))
-    offset = offset + refSize
-    const topic = decoder.decode(buffer.slice(offset, offset + topicSize))
-    offset = offset + topicSize
-    const event = decoder.decode(buffer.slice(offset, offset + eventSize))
-    offset = offset + eventSize
-    const data = JSON.parse(decoder.decode(buffer.slice(offset, buffer.byteLength)))
-    const payload = { status: event, response: data }
-    return {
-      join_ref: joinRef,
-      ref: ref,
-      topic: topic,
-      event: CHANNEL_EVENTS.reply,
-      payload: payload,
-    }
-  }
-
-  private _decodeBroadcast(
-    buffer: ArrayBuffer,
-    view: DataView,
-    decoder: TextDecoder
-  ): {
-    join_ref: null
-    ref: null
-    topic: string
-    event: string
-    payload: { [key: string]: any }
-  } {
-    const topicSize = view.getUint8(1)
-    const eventSize = view.getUint8(2)
-    let offset = this.HEADER_LENGTH + 2
-    const topic = decoder.decode(buffer.slice(offset, offset + topicSize))
-    offset = offset + topicSize
-    const event = decoder.decode(buffer.slice(offset, offset + eventSize))
-    offset = offset + eventSize
-    const data = JSON.parse(decoder.decode(buffer.slice(offset, buffer.byteLength)))
-
-    return { join_ref: null, ref: null, topic: topic, event: event, payload: data }
-  }
-
   private _decodeUserBroadcast(
     buffer: ArrayBuffer,
     view: DataView,
@@ -301,7 +169,7 @@ export default class Serializer {
       payloadEncoding === this.JSON_ENCODING ? JSON.parse(decoder.decode(payload)) : payload
 
     const data: { [key: string]: any } = {
-      type: this.BROADCAST,
+      type: this.BROADCAST_EVENT,
       event: userEvent,
       payload: parsedPayload,
     }
@@ -311,7 +179,7 @@ export default class Serializer {
       data['meta'] = JSON.parse(metadata)
     }
 
-    return { join_ref: null, ref: null, topic: topic, event: this.BROADCAST, payload: data }
+    return { join_ref: null, ref: null, topic: topic, event: this.BROADCAST_EVENT, payload: data }
   }
 
   private _isArrayBuffer(buffer: any): boolean {

packages/core/realtime-js/test/serializer.test.ts

@@ -67,57 +67,6 @@ describe('JSON', () => {
 })
 
 describe('binary', () => {
-  it('encodes push', async () => {
-    let buffer = binPayload()
-    let bin = '\0\x01\x01\x01\x0101te\x01\x04'
-    const result = await encodeAsync(serializer, {
-      join_ref: '0',
-      ref: '1',
-      topic: 't',
-      event: 'e',
-      payload: buffer,
-    })
-    expect(decoder.decode(result as ArrayBuffer)).toBe(bin)
-  })
-
-  it('encodes push with undefined join_ref and ref', async () => {
-    let buffer = binPayload()
-    let bin = '\0\x00\x00\x01\x01te\x01\x04'
-    const result = await encodeAsync(serializer, {
-      join_ref: undefined,
-      ref: undefined,
-      topic: 't',
-      event: 'e',
-      payload: buffer,
-    })
-    expect(decoder.decode(result as ArrayBuffer)).toBe(bin)
-  })
-
-  it('encodes push with no join_ref no ref', async () => {
-    let buffer = binPayload()
-    let bin = '\0\x00\x00\x01\x01te\x01\x04'
-    const result = await encodeAsync(serializer, {
-      topic: 't',
-      event: 'e',
-      payload: buffer,
-    })
-    expect(decoder.decode(result as ArrayBuffer)).toBe(bin)
-  })
-
-  it('encodes variable length segments', async () => {
-    let buffer = binPayload()
-    let bin = '\0\x02\x01\x03\x02101topev\x01\x04'
-
-    const result = await encodeAsync(serializer, {
-      join_ref: '10',
-      ref: '1',
-      topic: 'top',
-      event: 'ev',
-      payload: buffer,
-    })
-    expect(decoder.decode(result as ArrayBuffer)).toBe(bin)
-  })
-
   it('encodes user broadcast push with JSON payload', async () => {
     // 3 -> user_broadcast_push
     // 2 join_ref length
@@ -226,49 +175,6 @@ describe('binary', () => {
     expect(decoder.decode(result as ArrayBuffer)).toBe(bin)
   })
 
-  it('decodes push payload as JSON', async () => {
-    let bin = '\0\x03\x03\n123topsome-event{"a":"b"}'
-    let buffer = new TextEncoder().encode(bin).buffer
-
-    const result = await decodeAsync(serializer, buffer)
-
-    expect(result.join_ref).toBe('123')
-    expect(result.ref).toBeNull()
-    expect(result.topic).toBe('top')
-    expect(result.event).toBe('some-event')
-    expect(result.payload.constructor).toBe(Object)
-    expect(result.payload).toStrictEqual({ a: 'b' })
-  })
-
-  it('decodes reply payload as JSON', async () => {
-    let bin = '\x01\x03\x02\x03\x0210012topok{"a":"b"}'
-    let buffer = new TextEncoder().encode(bin).buffer
-
-    const result = await decodeAsync(serializer, buffer)
-
-    expect(result.join_ref).toBe('100')
-    expect(result.ref).toBe('12')
-    expect(result.topic).toBe('top')
-    expect(result.event).toBe('phx_reply')
-    expect(result.payload.status).toBe('ok')
-    expect(result.payload.response.constructor).toBe(Object)
-    expect(result.payload.response).toStrictEqual({ a: 'b' })
-  })
-
-  it('decodes broadcast payload as JSON', async () => {
-    let bin = '\x02\x03\ntopsome-event{"a":"b"}'
-    let buffer = new TextEncoder().encode(bin).buffer
-
-    const result = await decodeAsync(serializer, buffer)
-
-    expect(result.join_ref).toBeNull()
-    expect(result.ref).toBeNull()
-    expect(result.topic).toBe('top')
-    expect(result.event).toBe('some-event')
-    expect(result.payload.constructor).toBe(Object)
-    expect(result.payload).toStrictEqual({ a: 'b' })
-  })
-
   it('decodes user broadcast with JSON payload and no metadata', async () => {
     // 4 -> user_broadcast
     // 3 for topic length