init

backend/core/db.py

@@ -0,0 +1,73 @@
+"""
+Shared SQLAlchemy engine / session + schema bootstrap
+"""
+from __future__ import annotations
+import importlib, datetime
+import os
+
+from sqlalchemy import (
+    create_engine, event, Table, Column, Text, DateTime, Index, make_url
+)
+from sqlalchemy.engine import url
+from sqlalchemy.orm import sessionmaker, registry
+from backend.core.settings import (
+    SQLALCHEMY_DATABASE_URI, DB_POOL_SIZE, DB_ECHO, SKIP_SCHEMA_BOOTSTRAP
+)
+
+IS_PG = SQLALCHEMY_DATABASE_URI.startswith("postgresql")
+
+parsed_url   = make_url(SQLALCHEMY_DATABASE_URI)          # string into URL object
+
+# engine & session
+connect_args = {"sslmode": "require"} if parsed_url.drivername.startswith("postgresql") else {}
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URI,
+    pool_size     = DB_POOL_SIZE,
+    max_overflow  = 20,
+    pool_timeout  = 30,
+    echo          = DB_ECHO,
+    future        = True,
+    pool_pre_ping = True,
+    pool_recycle=3600,
+    connect_args  = connect_args
+)
+
+# SQLite -> WAL for concurrency
+if SQLALCHEMY_DATABASE_URI.startswith("sqlite:///"):
+
+    @event.listens_for(engine, "connect")
+    def _set_wal(dbapi_conn, _):
+        dbapi_conn.execute("PRAGMA journal_mode=WAL;")
+
+SessionLocal = sessionmaker(bind=engine, autoflush=False,
+                             expire_on_commit=False, future=True)
+
+# metadata (tables from every module)
+mapper_registry = registry()
+metadata = mapper_registry.metadata
+
+# download-cache table
+download_cache = Table(
+    "download_cache", metadata,
+    Column("key",  Text, primary_key=True),
+    Column("path", Text, nullable=False),
+    Column("ext",  Text, nullable=False),
+    Column("created_at", DateTime, default=datetime.datetime.utcnow,
+           nullable=False, index=True),
+)
+Index("ix_download_cache_created", download_cache.c.created_at)
+
+# auto-bootstrap all
+def _bootstrap_schema() -> None:
+    """Import modules then create."""
+    table_modules = (
+        "backend.core.db_xp",
+        "backend.web.db_extra",
+        "backend.core.formats",
+    )
+    for mod in table_modules:
+        importlib.import_module(mod)
+
+    metadata.create_all(engine)
+if SKIP_SCHEMA_BOOTSTRAP != "1":
+    _bootstrap_schema()