fix: room concurrency (theoretically) (#511)

* fix: room concurrency (theoretically)

* cleanup

* cleanup

server/migrations/versions/b7df9609542c_add_unique_constraint_one_active_.py

@@ -0,0 +1,35 @@
+"""add_unique_constraint_one_active_meeting_per_room
+
+Revision ID: b7df9609542c
+Revises: d7fbb74b673b
+Create Date: 2025-07-25 16:27:06.959868
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'b7df9609542c'
+down_revision: Union[str, None] = 'd7fbb74b673b'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Create a partial unique index that ensures only one active meeting per room
+    # This works for both PostgreSQL and SQLite
+    op.create_index(
+        'idx_one_active_meeting_per_room',
+        'meeting',
+        ['room_id'],
+        unique=True,
+        postgresql_where=sa.text('is_active = true'),
+        sqlite_where=sa.text('is_active = 1')
+    )
+
+
+def downgrade() -> None:
+    op.drop_index('idx_one_active_meeting_per_room', table_name='meeting')

server/reflector/views/rooms.py

@@ -1,5 +1,6 @@
 from datetime import datetime, timedelta
 from typing import Annotated, Optional, Literal
+import logging
 
 import reflector.auth as auth
 from fastapi import APIRouter, Depends, HTTPException
@@ -7,10 +8,14 @@ from fastapi_pagination import Page
 from fastapi_pagination.ext.databases import paginate
 from pydantic import BaseModel
 from reflector.db import database
-from reflector.db.meetings import meetings_controller
+from reflector.db.meetings import Meeting, meetings_controller
 from reflector.db.rooms import rooms_controller
 from reflector.settings import settings
 from reflector.whereby import create_meeting, upload_logo
+import asyncpg.exceptions
+import sqlite3
+
+logger = logging.getLogger(__name__)
 
 router = APIRouter()
 
@@ -30,7 +35,7 @@ class Room(BaseModel):
     is_shared: bool
 
 
-class Meeting(BaseModel):
+class Meeting(BaseModel):  # noqa: F811  # Response model, different from db.meetings.Meeting
     id: str
     room_name: str
     room_url: str
@@ -149,19 +154,47 @@ async def rooms_create_meeting(
 
     if meeting is None:
         end_date = current_time + timedelta(hours=8)
-        meeting = await create_meeting("", end_date=end_date, room=room)
-        await upload_logo(meeting["roomName"], "./images/logo.png")
 
+        whereby_meeting = await create_meeting("", end_date=end_date, room=room)
+        await upload_logo(whereby_meeting["roomName"], "./images/logo.png")
+
+        # Now try to save to database
+        try:
             meeting = await meetings_controller.create(
-            id=meeting["meetingId"],
-            room_name=meeting["roomName"],
-            room_url=meeting["roomUrl"],
-            host_room_url=meeting["hostRoomUrl"],
-            start_date=datetime.fromisoformat(meeting["startDate"]),
-            end_date=datetime.fromisoformat(meeting["endDate"]),
+                id=whereby_meeting["meetingId"],
+                room_name=whereby_meeting["roomName"],
+                room_url=whereby_meeting["roomUrl"],
+                host_room_url=whereby_meeting["hostRoomUrl"],
+                start_date=datetime.fromisoformat(whereby_meeting["startDate"]),
+                end_date=datetime.fromisoformat(whereby_meeting["endDate"]),
                 user_id=user_id,
                 room=room,
             )
+        except (asyncpg.exceptions.UniqueViolationError, sqlite3.IntegrityError):
+            # Another request already created a meeting for this room
+            # Log this race condition occurrence
+            logger.info(
+                "Race condition detected for room %s - fetching existing meeting",
+                room.name,
+            )
+            logger.warning(
+                "Whereby meeting %s was created but not used (resource leak) for room %s",
+                whereby_meeting["meetingId"],
+                room.name,
+            )
+
+            # Fetch the meeting that was created by the other request
+            meeting = await meetings_controller.get_active(
+                room=room, current_time=current_time
+            )
+            if meeting is None:
+                # Edge case: meeting was created but expired/deleted between checks
+                logger.error(
+                    "Meeting disappeared after race condition for room %s", room.name
+                )
+                raise HTTPException(
+                    status_code=503, detail="Unable to join meeting - please try again"
+                )
 
     if user_id != room.user_id:
         meeting.host_room_url = ""