Supported MySQL Changes Listening

app/operations.py

@@ -1,4 +1,5 @@
-from fastapi import WebSocket
+import asyncio, time, decimal, datetime
+from fastapi import WebSocket, WebSocketDisconnect, WebSocketException
 from fastapi.routing import APIRouter
 from fastapi.responses import StreamingResponse
 from typing_extensions import Annotated
@@ -17,9 +18,12 @@ from core.exceptions import (
     CursorNotFound,
 )
 from dbs import mysql
+from utils.binlog import changes_queue, queue
 
 router = APIRouter()
 
+database_changes_active_websocket: WebSocket | None = None
+
 
 @router.post("/execute", dependencies=[Depends(get_current_user)])
 async def execute_select(
@@ -97,7 +101,7 @@ async def server_side_events_stream_cursor(
             result = await fetch_cursor(cursor_id=cursor_id, page_size=page_size)
 
             serialized_result = result.model_dump_json()
-            yield f"data: {serialized_result}\n\n"  # Format as Server-Sent Event (SSE)
+            yield f"data: {serialized_result}\n\n"
             if result.cursor.is_closed:
                 break
 
@@ -119,7 +123,7 @@ async def websocket_stream_cursor(
     if user is None:
         await websocket.close(reason="Invalid credentials", code=1008)
         return
-    
+
     cached_cursor = mysql.cached_cursors.get(cursor_id, None)
     if cached_cursor is None:
         e = CursorNotFound()
@@ -136,3 +140,69 @@ async def websocket_stream_cursor(
         if result.cursor.is_closed:
             break
     await websocket.close(reason="Done")
+
+
+@router.websocket("/databases_changes")
+async def websocket_endpoint(
+    websocket: WebSocket,
+    db=Depends(get_db),
+):
+    global database_changes_active_websocket
+
+    await websocket.accept()
+
+    api_key = websocket.headers.get("Authorization")
+    user = await get_user_from_api_key(db=db, api_key=api_key)
+    if user is None:
+        await websocket.close(reason="Invalid credentials", code=1008)
+        return
+
+    if database_changes_active_websocket:
+        try:
+            await database_changes_active_websocket.close(
+                code=1001, reason="New connection established"
+            )
+        except Exception as e:
+            print(e)
+
+    database_changes_active_websocket = websocket
+    await websocket.send_json({"message":"status", "status":"Accepted."})
+
+    try:
+        await feed_databases_changes_ws(websocket=websocket)
+    except WebSocketDisconnect:
+        print('Closed websocket.')
+
+def serialize_list(l:list):
+    serialized = []
+    for value in l:
+        if isinstance(value, str | int | None | float):
+            serialized.append(str(value))
+        elif isinstance(value, decimal.Decimal):
+            serialized.append(float(value))
+        elif isinstance(value, datetime.date):
+            serialized.append(value.strftime("%Y-%m-%d"))
+        else:
+            serialized.append(str(value))
+    return serialized
+
+
+
+async def feed_databases_changes_ws(websocket:WebSocket):
+
+    last_update = 0
+    while True:
+        try:
+            change = changes_queue.get_nowait()
+            if change.action == 'UPDATE':
+                change.after_values = serialize_list(change.after_values)
+                change.before_values = serialize_list(change.before_values)
+            else:
+                change.values = serialize_list(change.values)
+            await websocket.send_json({"message": "change", 'change': change.model_dump()})
+        except queue.Empty:
+            if last_update + 10 < time.time():
+                await websocket.send_json({"message":"status", "status":"Alive."})
+                last_update = time.time()
+            await asyncio.sleep(1)
+            continue