75 lines
2.7 KiB
Python
75 lines
2.7 KiB
Python
# Copyright (c) 2023-present Plane Software, Inc. and contributors
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# SPDX-License-Identifier: AGPL-3.0-only
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# See the LICENSE file for details.
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"""
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Database router for read replica selection.
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This router determines which database to use for read/write operations
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based on the request context set by the ReadReplicaRoutingMiddleware.
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"""
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import logging
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from typing import Type
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from django.db import models
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from .request_scope import should_use_read_replica
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logger = logging.getLogger("plane.db")
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class ReadReplicaRouter:
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"""
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Database router that directs read operations to replica when appropriate.
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This router works in conjunction with ReadReplicaRoutingMiddleware to:
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- Route read operations to replica database when request context allows
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- Always route write operations to primary database
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- Ensure migrations only run on primary database
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"""
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def db_for_read(self, model: Type[models.Model], **hints) -> str:
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"""
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Determine which database to use for read operations.
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Args:
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model: The Django model class being queried
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**hints: Additional routing hints
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Returns:
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str: Database alias ('replica' or 'default')
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"""
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if should_use_read_replica():
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logger.debug(f"Routing read for {model._meta.label} to replica database")
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return "replica"
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else:
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logger.debug(f"Routing read for {model._meta.label} to primary database")
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return "default"
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def db_for_write(self, model: Type[models.Model], **hints) -> str:
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"""
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Determine which database to use for write operations.
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All write operations always go to the primary database to ensure
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data consistency and avoid replication lag issues.
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Args:
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model: The Django model class being written to
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**hints: Additional routing hints
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Returns:
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str: Always returns 'default' (primary database)
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"""
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logger.debug(f"Routing write for {model._meta.label} to primary database")
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return "default"
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def allow_migrate(self, db: str, app_label: str, model_name: str = None, **hints) -> bool:
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"""
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Ensure migrations only run on the primary database.
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Args:
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db: Database alias
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app_label: Application label
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model_name: Model name (optional)
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**hints: Additional routing hints
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Returns:
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bool: True if migration is allowed on this database
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"""
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# Only allow migrations on the primary database
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allowed = db == "default"
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if not allowed:
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logger.debug(f"Blocking migration for {app_label} on {db} database")
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return allowed
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