feat: add a flask_context_manager. (#21061)

Signed-off-by: -LAN- <laipz8200@outlook.com>

.gitignore

 
 # Next.js build output
 .next/
+
+# AI Assistant
+.roo/

api/core/app/apps/advanced_chat/app_generator.py

 from collections.abc import Generator, Mapping
 from typing import Any, Literal, Optional, Union, overload
 
-from flask import Flask, copy_current_request_context, current_app, has_request_context
+from flask import Flask, current_app
 from pydantic import ValidationError
 from sqlalchemy.orm import sessionmaker
 
 from core.workflow.repositories.workflow_node_execution_repository import WorkflowNodeExecutionRepository
 from extensions.ext_database import db
 from factories import file_factory
+from libs.flask_utils import preserve_flask_contexts
 from models import Account, App, Conversation, EndUser, Message, Workflow, WorkflowNodeExecutionTriggeredFrom
 from models.enums import WorkflowRunTriggeredFrom
 from services.conversation_service import ConversationService
         # new thread with request context and contextvars
         context = contextvars.copy_context()
 
-        @copy_current_request_context
-        def worker_with_context():
-            # Run the worker within the copied context
-            return context.run(
-                self._generate_worker,
-                flask_app=current_app._get_current_object(),  # type: ignore
-                application_generate_entity=application_generate_entity,
-                queue_manager=queue_manager,
-                conversation_id=conversation.id,
-                message_id=message.id,
-                context=context,
-            )
-
-        worker_thread = threading.Thread(target=worker_with_context)
+        worker_thread = threading.Thread(
+            target=self._generate_worker,
+            kwargs={
+                "flask_app": current_app._get_current_object(),  # type: ignore
+                "application_generate_entity": application_generate_entity,
+                "queue_manager": queue_manager,
+                "conversation_id": conversation.id,
+                "message_id": message.id,
+                "context": context,
+            },
+        )
 
         worker_thread.start()
 
         :param message_id: message ID
         :return:
         """
-        for var, val in context.items():
-            var.set(val)
-
-        # FIXME(-LAN-): Save current user before entering new app context
-        from flask import g
 
-        saved_user = None
-        if has_request_context() and hasattr(g, "_login_user"):
-            saved_user = g._login_user
-
-        with flask_app.app_context():
+        with preserve_flask_contexts(flask_app, context_vars=context):
             try:
-                # Restore user in new app context
-                if saved_user is not None:
-                    from flask import g
-
-                    g._login_user = saved_user
-
                 # get conversation and message
                 conversation = self._get_conversation(conversation_id)
                 message = self._get_message(message_id)

api/core/app/apps/agent_chat/app_generator.py

 from collections.abc import Generator, Mapping
 from typing import Any, Literal, Union, overload
 
-from flask import Flask, copy_current_request_context, current_app, has_request_context
+from flask import Flask, current_app
 from pydantic import ValidationError
 
 from configs import dify_config
 from core.ops.ops_trace_manager import TraceQueueManager
 from extensions.ext_database import db
 from factories import file_factory
+from libs.flask_utils import preserve_flask_contexts
 from models import Account, App, EndUser
 from services.conversation_service import ConversationService
 from services.errors.message import MessageNotExistsError
         # new thread with request context and contextvars
         context = contextvars.copy_context()
 
-        @copy_current_request_context
-        def worker_with_context():
-            # Run the worker within the copied context
-            return context.run(
-                self._generate_worker,
-                flask_app=current_app._get_current_object(),  # type: ignore
-                context=context,
-                application_generate_entity=application_generate_entity,
-                queue_manager=queue_manager,
-                conversation_id=conversation.id,
-                message_id=message.id,
-            )
-
-        worker_thread = threading.Thread(target=worker_with_context)
+        worker_thread = threading.Thread(
+            target=self._generate_worker,
+            kwargs={
+                "flask_app": current_app._get_current_object(),  # type: ignore
+                "context": context,
+                "application_generate_entity": application_generate_entity,
+                "queue_manager": queue_manager,
+                "conversation_id": conversation.id,
+                "message_id": message.id,
+            },
+        )
 
         worker_thread.start()
 
         :param message_id: message ID
         :return:
         """
-        for var, val in context.items():
-            var.set(val)
-
-        # FIXME(-LAN-): Save current user before entering new app context
-        from flask import g
 
-        saved_user = None
-        if has_request_context() and hasattr(g, "_login_user"):
-            saved_user = g._login_user
-
-        with flask_app.app_context():
+        with preserve_flask_contexts(flask_app, context_vars=context):
             try:
-                # Restore user in new app context
-                if saved_user is not None:
-                    from flask import g
-
-                    g._login_user = saved_user
-
                 # get conversation and message
                 conversation = self._get_conversation(conversation_id)
                 message = self._get_message(message_id)

api/core/app/apps/workflow/app_generator.py

 from collections.abc import Generator, Mapping, Sequence
 from typing import Any, Literal, Optional, Union, overload
 
-from flask import Flask, copy_current_request_context, current_app, has_request_context
+from flask import Flask, current_app
 from pydantic import ValidationError
 from sqlalchemy.orm import sessionmaker
 
 from core.workflow.repositories.workflow_node_execution_repository import WorkflowNodeExecutionRepository
 from extensions.ext_database import db
 from factories import file_factory
+from libs.flask_utils import preserve_flask_contexts
 from models import Account, App, EndUser, Workflow, WorkflowNodeExecutionTriggeredFrom
 from models.enums import WorkflowRunTriggeredFrom
 
         # new thread with request context and contextvars
         context = contextvars.copy_context()
 
-        @copy_current_request_context
-        def worker_with_context():
-            # Run the worker within the copied context
-            return context.run(
-                self._generate_worker,
-                flask_app=current_app._get_current_object(),  # type: ignore
-                application_generate_entity=application_generate_entity,
-                queue_manager=queue_manager,
-                context=context,
-                workflow_thread_pool_id=workflow_thread_pool_id,
-            )
-
-        worker_thread = threading.Thread(target=worker_with_context)
+        worker_thread = threading.Thread(
+            target=self._generate_worker,
+            kwargs={
+                "flask_app": current_app._get_current_object(),  # type: ignore
+                "application_generate_entity": application_generate_entity,
+                "queue_manager": queue_manager,
+                "context": context,
+                "workflow_thread_pool_id": workflow_thread_pool_id,
+            },
+        )
 
         worker_thread.start()
 
         :param workflow_thread_pool_id: workflow thread pool id
         :return:
         """
-        for var, val in context.items():
-            var.set(val)
-
-        # FIXME(-LAN-): Save current user before entering new app context
-        from flask import g
 
-        saved_user = None
-        if has_request_context() and hasattr(g, "_login_user"):
-            saved_user = g._login_user
-
-        with flask_app.app_context():
+        with preserve_flask_contexts(flask_app, context_vars=context):
             try:
-                # Restore user in new app context
-                if saved_user is not None:
-                    from flask import g
-
-                    g._login_user = saved_user
-
                 # workflow app
                 runner = WorkflowAppRunner(
                     application_generate_entity=application_generate_entity,

api/core/workflow/graph_engine/graph_engine.py

 from datetime import UTC, datetime
 from typing import Any, Optional, cast
 
-from flask import Flask, current_app, has_request_context
+from flask import Flask, current_app
 
 from configs import dify_config
 from core.app.apps.base_app_queue_manager import GenerateTaskStoppedError
 from core.workflow.nodes.enums import ErrorStrategy, FailBranchSourceHandle
 from core.workflow.nodes.event import RunCompletedEvent, RunRetrieverResourceEvent, RunStreamChunkEvent
 from core.workflow.nodes.node_mapping import NODE_TYPE_CLASSES_MAPPING
+from libs.flask_utils import preserve_flask_contexts
 from models.enums import UserFrom
 from models.workflow import WorkflowType
 
         """
         Run parallel nodes
         """
-        for var, val in context.items():
-            var.set(val)
 
-        # FIXME(-LAN-): Save current user before entering new app context
-        from flask import g
-
-        saved_user = None
-        if has_request_context() and hasattr(g, "_login_user"):
-            saved_user = g._login_user
-
-        with flask_app.app_context():
+        with preserve_flask_contexts(flask_app, context_vars=context):
             try:
-                # Restore user in new app context
-                if saved_user is not None:
-                    from flask import g
-
-                    g._login_user = saved_user
-
                 q.put(
                     ParallelBranchRunStartedEvent(
                         parallel_id=parallel_id,

api/core/workflow/nodes/iteration/iteration_node.py

 from queue import Empty, Queue
 from typing import TYPE_CHECKING, Any, Optional, cast
 
-from flask import Flask, current_app, has_request_context
+from flask import Flask, current_app
 
 from configs import dify_config
 from core.variables import ArrayVariable, IntegerVariable, NoneVariable
 from core.workflow.nodes.enums import NodeType
 from core.workflow.nodes.event import NodeEvent, RunCompletedEvent
 from core.workflow.nodes.iteration.entities import ErrorHandleMode, IterationNodeData
+from libs.flask_utils import preserve_flask_contexts
 
 from .exc import (
     InvalidIteratorValueError,
         """
         run single iteration in parallel mode
         """
-        for var, val in context.items():
-            var.set(val)
-
-        # FIXME(-LAN-): Save current user before entering new app context
-        from flask import g
-
-        saved_user = None
-        if has_request_context() and hasattr(g, "_login_user"):
-            saved_user = g._login_user
-
-        with flask_app.app_context():
-            # Restore user in new app context
-            if saved_user is not None:
-                from flask import g
-
-                g._login_user = saved_user
 
+        with preserve_flask_contexts(flask_app, context_vars=context):
             parallel_mode_run_id = uuid.uuid4().hex
             graph_engine_copy = graph_engine.create_copy()
             variable_pool_copy = graph_engine_copy.graph_runtime_state.variable_pool

api/libs/flask_utils.py

+import contextvars
+from collections.abc import Iterator
+from contextlib import contextmanager
+from typing import TypeVar
+
+from flask import Flask, g, has_request_context
+
+T = TypeVar("T")
+
+
+@contextmanager
+def preserve_flask_contexts(
+    flask_app: Flask,
+    context_vars: contextvars.Context,
+) -> Iterator[None]:
+    """
+    A context manager that handles:
+    1. flask-login's UserProxy copy
+    2. ContextVars copy
+    3. flask_app.app_context()
+
+    This context manager ensures that the Flask application context is properly set up,
+    the current user is preserved across context boundaries, and any provided context variables
+    are set within the new context.
+
+    Note:
+        This manager aims to allow use current_user cross thread and app context,
+        but it's not the recommend use, it's better to pass user directly in parameters.
+
+    Args:
+        flask_app: The Flask application instance
+        context_vars: contextvars.Context object containing context variables to be set in the new context
+
+    Yields:
+        None
+
+    Example:
+        ```python
+        with preserve_flask_contexts(flask_app, context_vars=context_vars):
+            # Code that needs Flask app context and context variables
+            # Current user will be preserved if available
+        ```
+    """
+    # Set context variables if provided
+    if context_vars:
+        for var, val in context_vars.items():
+            var.set(val)
+
+    # Save current user before entering new app context
+    saved_user = None
+    if has_request_context() and hasattr(g, "_login_user"):
+        saved_user = g._login_user
+
+    # Enter Flask app context
+    with flask_app.app_context():
+        try:
+            # Restore user in new app context if it was saved
+            if saved_user is not None:
+                g._login_user = saved_user
+
+            # Yield control back to the caller
+            yield
+        finally:
+            # Any cleanup can be added here if needed
+            pass

api/tests/unit_tests/libs/test_flask_utils.py

+import contextvars
+import threading
+from typing import Optional
+
+import pytest
+from flask import Flask
+from flask_login import LoginManager, UserMixin, current_user, login_user
+
+from libs.flask_utils import preserve_flask_contexts
+
+
+class User(UserMixin):
+    """Simple User class for testing."""
+
+    def __init__(self, id: str):
+        self.id = id
+
+    def get_id(self) -> str:
+        return self.id
+
+
+@pytest.fixture
+def login_app(app: Flask) -> Flask:
+    """Set up a Flask app with flask-login."""
+    # Set a secret key for the app
+    app.config["SECRET_KEY"] = "test-secret-key"
+
+    login_manager = LoginManager()
+    login_manager.init_app(app)
+
+    @login_manager.user_loader
+    def load_user(user_id: str) -> Optional[User]:
+        if user_id == "test_user":
+            return User("test_user")
+        return None
+
+    return app
+
+
+@pytest.fixture
+def test_user() -> User:
+    """Create a test user."""
+    return User("test_user")
+
+
+def test_current_user_not_accessible_across_threads(login_app: Flask, test_user: User):
+    """
+    Test that current_user is not accessible in a different thread without preserve_flask_contexts.
+
+    This test demonstrates that without the preserve_flask_contexts, we cannot access
+    current_user in a different thread, even with app_context.
+    """
+    # Log in the user in the main thread
+    with login_app.test_request_context():
+        login_user(test_user)
+        assert current_user.is_authenticated
+        assert current_user.id == "test_user"
+
+        # Store the result of the thread execution
+        result = {"user_accessible": True, "error": None}
+
+        # Define a function to run in a separate thread
+        def check_user_in_thread():
+            try:
+                # Try to access current_user in a different thread with app_context
+                with login_app.app_context():
+                    # This should fail because current_user is not accessible across threads
+                    # without preserve_flask_contexts
+                    result["user_accessible"] = current_user.is_authenticated
+            except Exception as e:
+                result["error"] = str(e)  # type: ignore
+
+        # Run the function in a separate thread
+        thread = threading.Thread(target=check_user_in_thread)
+        thread.start()
+        thread.join()
+
+        # Verify that we got an error or current_user is not authenticated
+        assert result["error"] is not None or (result["user_accessible"] is not None and not result["user_accessible"])
+
+
+def test_current_user_accessible_with_preserve_flask_contexts(login_app: Flask, test_user: User):
+    """
+    Test that current_user is accessible in a different thread with preserve_flask_contexts.
+
+    This test demonstrates that with the preserve_flask_contexts, we can access
+    current_user in a different thread.
+    """
+    # Log in the user in the main thread
+    with login_app.test_request_context():
+        login_user(test_user)
+        assert current_user.is_authenticated
+        assert current_user.id == "test_user"
+
+        # Save the context variables
+        context_vars = contextvars.copy_context()
+
+        # Store the result of the thread execution
+        result = {"user_accessible": False, "user_id": None, "error": None}
+
+        # Define a function to run in a separate thread
+        def check_user_in_thread_with_manager():
+            try:
+                # Use preserve_flask_contexts to access current_user in a different thread
+                with preserve_flask_contexts(login_app, context_vars):
+                    from flask_login import current_user
+
+                    if current_user:
+                        result["user_accessible"] = True
+                        result["user_id"] = current_user.id
+                    else:
+                        result["user_accessible"] = False
+            except Exception as e:
+                result["error"] = str(e)  # type: ignore
+
+        # Run the function in a separate thread
+        thread = threading.Thread(target=check_user_in_thread_with_manager)
+        thread.start()
+        thread.join()
+
+        # Verify that current_user is accessible and has the correct ID
+        assert result["error"] is None
+        assert result["user_accessible"] is True
+        assert result["user_id"] == "test_user"