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aiopg.py
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aiopg.py
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import getpass
import json
import logging
import typing
import uuid
import aiopg
from aiopg.sa.engine import APGCompiler_psycopg2
from sqlalchemy.dialects.postgresql.psycopg2 import PGDialect_psycopg2
from sqlalchemy.engine.interfaces import Dialect, ExecutionContext
from sqlalchemy.engine.result import ResultMetaData
try:
from sqlalchemy.engine.result import Row
except ImportError: # pragma: no cover
from sqlalchemy.engine.result import RowProxy as Row
from sqlalchemy.sql import ClauseElement
from sqlalchemy.sql.ddl import DDLElement
from databases.core import DatabaseURL
from databases.interfaces import ConnectionBackend, DatabaseBackend, TransactionBackend
logger = logging.getLogger("databases")
class AiopgBackend(DatabaseBackend):
def __init__(
self, database_url: typing.Union[DatabaseURL, str], **options: typing.Any
) -> None:
self._database_url = DatabaseURL(database_url)
self._options = options
self._dialect = self._get_dialect()
self._pool = None
def _get_dialect(self) -> Dialect:
dialect = PGDialect_psycopg2(
json_serializer=json.dumps, json_deserializer=lambda x: x
)
dialect.statement_compiler = APGCompiler_psycopg2
dialect.implicit_returning = True
dialect.supports_native_enum = True
dialect.supports_smallserial = True # 9.2+
dialect._backslash_escapes = False
dialect.supports_sane_multi_rowcount = True # psycopg 2.0.9+
dialect._has_native_hstore = True
dialect.supports_native_decimal = True
return dialect
def _get_connection_kwargs(self) -> dict:
url_options = self._database_url.options
kwargs = {}
min_size = url_options.get("min_size")
max_size = url_options.get("max_size")
ssl = url_options.get("ssl")
if min_size is not None:
kwargs["minsize"] = int(min_size)
if max_size is not None:
kwargs["maxsize"] = int(max_size)
if ssl is not None:
kwargs["ssl"] = {"true": True, "false": False}[ssl.lower()]
for key, value in self._options.items():
# Coerce 'min_size' and 'max_size' for consistency.
if key == "min_size":
key = "minsize"
elif key == "max_size":
key = "maxsize"
kwargs[key] = value
return kwargs
async def connect(self) -> None:
assert self._pool is None, "DatabaseBackend is already running"
kwargs = self._get_connection_kwargs()
self._pool = await aiopg.create_pool(
host=self._database_url.hostname,
port=self._database_url.port,
user=self._database_url.username or getpass.getuser(),
password=self._database_url.password,
database=self._database_url.database,
**kwargs,
)
async def disconnect(self) -> None:
assert self._pool is not None, "DatabaseBackend is not running"
self._pool.close()
await self._pool.wait_closed()
self._pool = None
def connection(self) -> "AiopgConnection":
return AiopgConnection(self, self._dialect)
class CompilationContext:
def __init__(self, context: ExecutionContext):
self.context = context
class AiopgConnection(ConnectionBackend):
def __init__(self, database: AiopgBackend, dialect: Dialect):
self._database = database
self._dialect = dialect
self._connection = None # type: typing.Optional[aiopg.Connection]
async def acquire(self) -> None:
assert self._connection is None, "Connection is already acquired"
assert self._database._pool is not None, "DatabaseBackend is not running"
self._connection = await self._database._pool.acquire()
async def release(self) -> None:
assert self._connection is not None, "Connection is not acquired"
assert self._database._pool is not None, "DatabaseBackend is not running"
await self._database._pool.release(self._connection)
self._connection = None
async def fetch_all(self, query: ClauseElement) -> typing.List[typing.Mapping]:
assert self._connection is not None, "Connection is not acquired"
query, args, context = self._compile(query)
cursor = await self._connection.cursor()
try:
await cursor.execute(query, args)
rows = await cursor.fetchall()
metadata = ResultMetaData(context, cursor.description)
return [
Row(metadata, row, metadata._processors, metadata._keymap)
for row in rows
]
finally:
cursor.close()
async def fetch_one(self, query: ClauseElement) -> typing.Optional[typing.Mapping]:
assert self._connection is not None, "Connection is not acquired"
query, args, context = self._compile(query)
cursor = await self._connection.cursor()
try:
await cursor.execute(query, args)
row = await cursor.fetchone()
if row is None:
return None
metadata = ResultMetaData(context, cursor.description)
return Row(metadata, row, metadata._processors, metadata._keymap)
finally:
cursor.close()
async def execute(self, query: ClauseElement) -> typing.Any:
assert self._connection is not None, "Connection is not acquired"
query, args, context = self._compile(query)
cursor = await self._connection.cursor()
try:
await cursor.execute(query, args)
return cursor.lastrowid
finally:
cursor.close()
async def execute_many(self, queries: typing.List[ClauseElement]) -> None:
assert self._connection is not None, "Connection is not acquired"
cursor = await self._connection.cursor()
try:
for single_query in queries:
single_query, args, context = self._compile(single_query)
await cursor.execute(single_query, args)
finally:
cursor.close()
async def iterate(
self, query: ClauseElement
) -> typing.AsyncGenerator[typing.Any, None]:
assert self._connection is not None, "Connection is not acquired"
query, args, context = self._compile(query)
cursor = await self._connection.cursor()
try:
await cursor.execute(query, args)
metadata = ResultMetaData(context, cursor.description)
async for row in cursor:
yield Row(metadata, row, metadata._processors, metadata._keymap)
finally:
cursor.close()
def transaction(self) -> TransactionBackend:
return AiopgTransaction(self)
def _compile(
self, query: ClauseElement
) -> typing.Tuple[str, dict, CompilationContext]:
compiled = query.compile(dialect=self._dialect)
execution_context = self._dialect.execution_ctx_cls()
execution_context.dialect = self._dialect
if not isinstance(query, DDLElement):
args = compiled.construct_params()
for key, val in args.items():
if key in compiled._bind_processors:
args[key] = compiled._bind_processors[key](val)
execution_context.result_column_struct = (
compiled._result_columns,
compiled._ordered_columns,
compiled._textual_ordered_columns,
)
else:
args = {}
logger.debug("Query: %s\nArgs: %s", compiled.string, args)
return compiled.string, args, CompilationContext(execution_context)
@property
def raw_connection(self) -> aiopg.connection.Connection:
assert self._connection is not None, "Connection is not acquired"
return self._connection
class AiopgTransaction(TransactionBackend):
def __init__(self, connection: AiopgConnection):
self._connection = connection
self._is_root = False
self._savepoint_name = ""
async def start(
self, is_root: bool, extra_options: typing.Dict[typing.Any, typing.Any]
) -> None:
assert self._connection._connection is not None, "Connection is not acquired"
self._is_root = is_root
cursor = await self._connection._connection.cursor()
if self._is_root:
await cursor.execute("BEGIN")
else:
id = str(uuid.uuid4()).replace("-", "_")
self._savepoint_name = f"STARLETTE_SAVEPOINT_{id}"
try:
await cursor.execute(f"SAVEPOINT {self._savepoint_name}")
finally:
cursor.close()
async def commit(self) -> None:
assert self._connection._connection is not None, "Connection is not acquired"
cursor = await self._connection._connection.cursor()
if self._is_root:
await cursor.execute("COMMIT")
else:
try:
await cursor.execute(f"RELEASE SAVEPOINT {self._savepoint_name}")
finally:
cursor.close()
async def rollback(self) -> None:
assert self._connection._connection is not None, "Connection is not acquired"
cursor = await self._connection._connection.cursor()
if self._is_root:
await cursor.execute("ROLLBACK")
else:
try:
await cursor.execute(f"ROLLBACK TO SAVEPOINT {self._savepoint_name}")
finally:
cursor.close()