Compression: Sending compressed messages

client/src/app/core/core-services/websocket.service.ts

@@ -5,7 +5,7 @@ import { Router } from '@angular/router';
 import { TranslateService } from '@ngx-translate/core';
 import { Observable, Subject } from 'rxjs';
 import { take } from 'rxjs/operators';
-import { decompress } from 'lz4js';
+import { compress, decompress } from 'lz4js';
 
 import { formatQueryParams, QueryParams } from '../query-params';
 import { OpenSlidesStatusService } from './openslides-status.service';
@@ -282,12 +282,10 @@ export class WebsocketService {
             );
             const textDecoder = new TextDecoder();
             data = textDecoder.decode(decompressedBuffer);
-        } else {
-            const recvSize = new TextEncoder().encode(data).byteLength;
-            console.log(`Received ${recvSize} KB uncompressed`);
         }
 
         const message: IncommingWebsocketMessage = JSON.parse(data);
+        console.log('Received', message);
         const type = message.type;
         const inResponse = message.in_response;
         const callbacks = this.responseCallbacks[inResponse];
@@ -464,10 +462,17 @@ export class WebsocketService {
         // Either send directly or add to queue, if not connected.
         const jsonMessage = JSON.stringify(message);
 
+        const textEncoder = new TextEncoder();
+        const bytesMessage = textEncoder.encode(jsonMessage);
+        const compressedMessage: ArrayBuffer = compress(bytesMessage);
+        const ratio = bytesMessage.byteLength / compressedMessage.byteLength;
+
+        const toSend = ratio > 1 ? compressedMessage : jsonMessage;
+
         if (this.isConnected) {
-            this.websocket.send(jsonMessage);
+            this.websocket.send(toSend);
         } else {
-            this.sendQueueWhileNotConnected.push(jsonMessage);
+            this.sendQueueWhileNotConnected.push(toSend);
         }
 
         return message.id;

openslides/utils/websocket.py

@@ -52,12 +52,23 @@ class AsyncCompressedJsonWebsocketConsumer(AsyncWebsocketConsumer):
 
     async def send_json(self, content: Any, close: bool = False) -> None:
         text_data = json.dumps(content)
+        bytes_data = None  # type: ignore
 
         b_text_data = text_data.encode("utf-8")
         uncompressed_len = len(b_text_data)
-        await WebsocketThroughputLogger.send(uncompressed_len)
 
-        await self.send(text_data=text_data, close=close)
+        if getattr(settings, "COMPRESSION", True):
+            compressed_data = lz4.frame.compress(b_text_data)
+            ratio = len(b_text_data) / len(compressed_data)
+            if ratio > 1:
+                bytes_data = compressed_data
+                text_data = None  # type: ignore
+                await WebsocketThroughputLogger.send(uncompressed_len, len(bytes_data))
+
+        if not bytes_data:
+            await WebsocketThroughputLogger.send(uncompressed_len)
+
+        await self.send(text_data=text_data, bytes_data=bytes_data, close=close)
 
     async def receive_json(self, content: str, **kwargs: Dict[str, Any]) -> None:
         pass

tests/integration/utils/test_consumers.py

@@ -1,10 +1,10 @@
 import asyncio
 from importlib import import_module
+from typing import Optional
 from unittest.mock import patch
 
 import pytest
 from asgiref.sync import sync_to_async
-from channels.testing import WebsocketCommunicator
 from django.conf import settings
 from django.contrib.auth import BACKEND_SESSION_KEY, HASH_SESSION_KEY, SESSION_KEY
 
@@ -20,6 +20,7 @@ from openslides.utils.websocket import WEBSOCKET_CHANGE_ID_TOO_HIGH
 
 from ...unit.utils.cache_provider import Collection1, Collection2, get_cachable_provider
 from ..helpers import TConfig, TProjector, TUser
+from ..websocket import WebsocketCommunicator
 
 
 @pytest.fixture(autouse=True)
@@ -45,7 +46,7 @@ async def prepare_element_cache(settings):
 
 @pytest.fixture
 async def get_communicator():
-    communicator: WebsocketCommunicator = None
+    communicator: Optional[WebsocketCommunicator] = None
 
     def get_communicator(query_string=""):
         nonlocal communicator  # use the outer communicator variable

tests/integration/websocket.py

@@ -0,0 +1,25 @@
+import json
+
+import lz4.frame
+from channels.testing import WebsocketCommunicator as ChannelsWebsocketCommunicator
+
+
+class WebsocketCommunicator(ChannelsWebsocketCommunicator):
+    """
+    Implements decompression when receiving JSON data.
+    """
+
+    async def receive_json_from(self, timeout=1):
+        """
+        Receives a JSON text frame or a compressed JSON bytes object, decompresses and decodes it
+        """
+        payload = await self.receive_from(timeout)
+        if isinstance(payload, bytes):
+            # try to decompress the message
+            uncompressed_data = lz4.frame.decompress(payload)
+            text_data = uncompressed_data.decode("utf-8")
+        else:
+            text_data = payload
+
+        assert isinstance(text_data, str), "JSON data is not a text frame"
+        return json.loads(text_data)