86 lines
2.9 KiB
Python
86 lines
2.9 KiB
Python
from typing import Optional
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from django.db.models import Max
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from mypy_extensions import TypedDict
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from . import logging
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logger = logging.getLogger(__name__)
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SchemaVersion = TypedDict("SchemaVersion", {"migration": int, "config": int, "db": str})
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class SchemaVersionHandler:
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"""
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Handler for the schema version of this running OpenSlides instance.
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What is a schema version? This is an indictor of the current schema of the data
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in the database, config variables, and the database itself. E.b. with a migration,
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new/changed config variables or with a database change, the schema of the data changes.
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To detect this is needed to reset the cache, so it does not hold any old data. This
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affects the server cache, but also the client uses this technique to flush the cache.
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Get the current schema with `get`. The schema version is built just once. After a change
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in the schema, all workers needs a restart!
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"""
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def __init__(self) -> None:
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self._schema_version: Optional[SchemaVersion] = None
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def get(self) -> SchemaVersion:
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if self._schema_version is not None:
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return self._schema_version
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from django.db.migrations.recorder import MigrationRecorder
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migration = MigrationRecorder.Migration.objects.aggregate(Max("id"))["id__max"]
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from openslides.core.config import ConfigStore
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try:
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config = ConfigStore.objects.get(key="config_version").value
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except ConfigStore.DoesNotExist:
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config = 0
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try:
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db = ConfigStore.objects.get(key="db_id").value
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except ConfigStore.DoesNotExist:
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db = ""
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self._schema_version = {"migration": migration, "config": config, "db": db}
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return self._schema_version
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def compare(self, other: Optional[SchemaVersion]) -> bool:
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current = self.get()
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if not other:
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logger.info("No old schema version")
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return False
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equal = True
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if current["db"] != other["db"]:
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other_db = other["db"] or "<empty>"
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logger.info(f"DB changed from {other_db} to {current['db']}")
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equal = False
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if current["config"] != other["config"]:
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other_config = other["config"] or "<empty>"
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logger.info(f"Config changed from {other_config} to {current['config']}")
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equal = False
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if current["migration"] != other["migration"]:
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logger.info(
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f"Migration changed from {other['migration']} to {current['migration']}"
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)
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equal = False
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return equal
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def log_current(self) -> None:
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current = self.get()
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logger.info(
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f"""Schema version:
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DB: {current["db"]}
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migration: {current["migration"]}
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config: {current["config"]}"""
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)
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schema_version_handler = SchemaVersionHandler()
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