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pool.py
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pool.py
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import asyncio
import collections
import sys
import warnings
from psycopg2.extensions import TRANSACTION_STATUS_IDLE
from .connection import connect, TIMEOUT
from .log import logger
from .utils import (PY_35, _PoolContextManager, _PoolConnectionContextManager,
_PoolCursorContextManager, _PoolAcquireContextManager,
ensure_future, create_future)
PY_341 = sys.version_info >= (3, 4, 1)
def create_pool(dsn=None, *, minsize=1, maxsize=10,
loop=None, timeout=TIMEOUT, pool_recycle=-1,
enable_json=True, enable_hstore=True, enable_uuid=True,
echo=False, on_connect=None,
**kwargs):
coro = _create_pool(dsn=dsn, minsize=minsize, maxsize=maxsize, loop=loop,
timeout=timeout, pool_recycle=pool_recycle,
enable_json=enable_json, enable_hstore=enable_hstore,
enable_uuid=enable_uuid, echo=echo,
on_connect=on_connect, **kwargs)
return _PoolContextManager(coro)
@asyncio.coroutine
def _create_pool(dsn=None, *, minsize=1, maxsize=10,
loop=None, timeout=TIMEOUT, pool_recycle=-1,
enable_json=True, enable_hstore=True, enable_uuid=True,
echo=False, on_connect=None,
**kwargs):
if loop is None:
loop = asyncio.get_event_loop()
pool = Pool(dsn, minsize, maxsize, loop, timeout,
enable_json=enable_json, enable_hstore=enable_hstore,
enable_uuid=enable_uuid, echo=echo, on_connect=on_connect,
pool_recycle=pool_recycle, **kwargs)
if minsize > 0:
with (yield from pool._cond):
yield from pool._fill_free_pool(False)
return pool
class Pool(asyncio.AbstractServer):
"""Connection pool"""
def __init__(self, dsn, minsize, maxsize, loop, timeout, *,
enable_json, enable_hstore, enable_uuid, echo,
on_connect, pool_recycle, **kwargs):
if minsize < 0:
raise ValueError("minsize should be zero or greater")
if maxsize < minsize and maxsize != 0:
raise ValueError("maxsize should be not less than minsize")
self._dsn = dsn
self._minsize = minsize
self._loop = loop
self._timeout = timeout
self._recycle = pool_recycle
self._enable_json = enable_json
self._enable_hstore = enable_hstore
self._enable_uuid = enable_uuid
self._echo = echo
self._on_connect = on_connect
self._conn_kwargs = kwargs
self._acquiring = 0
self._free = collections.deque(maxlen=maxsize or None)
self._cond = asyncio.Condition(loop=loop)
self._used = set()
self._terminated = set()
self._closing = False
self._closed = False
@property
def echo(self):
return self._echo
@property
def minsize(self):
return self._minsize
@property
def maxsize(self):
return self._free.maxlen
@property
def size(self):
return self.freesize + len(self._used) + self._acquiring
@property
def freesize(self):
return len(self._free)
@property
def timeout(self):
return self._timeout
@asyncio.coroutine
def clear(self):
"""Close all free connections in pool."""
with (yield from self._cond):
while self._free:
conn = self._free.popleft()
yield from conn.close()
self._cond.notify()
@property
def closed(self):
return self._closed
def close(self):
"""Close pool.
Mark all pool connections to be closed on getting back to pool.
Closed pool doesn't allow to acquire new connections.
"""
if self._closed:
return
self._closing = True
def terminate(self):
"""Terminate pool.
Close pool with instantly closing all acquired connections also.
"""
self.close()
for conn in list(self._used):
conn.close()
self._terminated.add(conn)
self._used.clear()
@asyncio.coroutine
def wait_closed(self):
"""Wait for closing all pool's connections."""
if self._closed:
return
if not self._closing:
raise RuntimeError(".wait_closed() should be called "
"after .close()")
while self._free:
conn = self._free.popleft()
conn.close()
with (yield from self._cond):
while self.size > self.freesize:
yield from self._cond.wait()
self._closed = True
def acquire(self):
"""Acquire free connection from the pool."""
coro = self._acquire()
return _PoolAcquireContextManager(coro, self)
@asyncio.coroutine
def _acquire(self):
if self._closing:
raise RuntimeError("Cannot acquire connection after closing pool")
with (yield from self._cond):
while True:
yield from self._fill_free_pool(True)
if self._free:
conn = self._free.popleft()
assert not conn.closed, conn
assert conn not in self._used, (conn, self._used)
self._used.add(conn)
if self._on_connect is not None:
yield from self._on_connect(conn)
return conn
else:
yield from self._cond.wait()
@asyncio.coroutine
def _fill_free_pool(self, override_min):
# iterate over free connections and remove timeouted ones
n, free = 0, len(self._free)
while n < free:
conn = self._free[-1]
if conn.closed:
self._free.pop()
elif self._recycle > -1 \
and self._loop.time() - conn.last_usage > self._recycle:
conn.close()
self._free.pop()
else:
self._free.rotate()
n += 1
while self.size < self.minsize:
self._acquiring += 1
try:
conn = yield from connect(
self._dsn, loop=self._loop, timeout=self._timeout,
enable_json=self._enable_json,
enable_hstore=self._enable_hstore,
enable_uuid=self._enable_uuid,
echo=self._echo,
**self._conn_kwargs)
# raise exception if pool is closing
self._free.append(conn)
self._cond.notify()
finally:
self._acquiring -= 1
if self._free:
return
if override_min and self.size < self.maxsize:
self._acquiring += 1
try:
conn = yield from connect(
self._dsn, loop=self._loop, timeout=self._timeout,
enable_json=self._enable_json,
enable_hstore=self._enable_hstore,
enable_uuid=self._enable_uuid,
echo=self._echo,
**self._conn_kwargs)
# raise exception if pool is closing
self._free.append(conn)
self._cond.notify()
finally:
self._acquiring -= 1
@asyncio.coroutine
def _wakeup(self):
with (yield from self._cond):
self._cond.notify()
def release(self, conn):
"""Release free connection back to the connection pool.
"""
fut = create_future(self._loop)
fut.set_result(None)
if conn in self._terminated:
assert conn.closed, conn
self._terminated.remove(conn)
return fut
assert conn in self._used, (conn, self._used)
self._used.remove(conn)
if not conn.closed:
tran_status = conn._conn.get_transaction_status()
if tran_status != TRANSACTION_STATUS_IDLE:
logger.warning(
"Invalid transaction status on released connection: %d",
tran_status)
conn.close()
return fut
if self._closing:
conn.close()
else:
self._free.append(conn)
fut = ensure_future(self._wakeup(), loop=self._loop)
return fut
@asyncio.coroutine
def cursor(self, name=None, cursor_factory=None,
scrollable=None, withhold=False, *, timeout=None):
"""XXX"""
conn = yield from self.acquire()
cur = yield from conn.cursor(name=name, cursor_factory=cursor_factory,
scrollable=scrollable, withhold=withhold,
timeout=timeout)
return _PoolCursorContextManager(self, conn, cur)
def __enter__(self):
raise RuntimeError(
'"yield from" should be used as context manager expression')
def __exit__(self, *args):
# This must exist because __enter__ exists, even though that
# always raises; that's how the with-statement works.
pass # pragma: nocover
def __iter__(self):
# This is not a coroutine. It is meant to enable the idiom:
#
# with (yield from pool) as conn:
# <block>
#
# as an alternative to:
#
# conn = yield from pool.acquire()
# try:
# <block>
# finally:
# conn.release()
conn = yield from self.acquire()
return _PoolConnectionContextManager(self, conn)
if PY_35: # pragma: no branch
@asyncio.coroutine
def __aenter__(self):
return self
@asyncio.coroutine
def __aexit__(self, exc_type, exc_val, exc_tb):
self.close()
yield from self.wait_closed()
if PY_341: # pragma: no branch
def __del__(self):
try:
self._free
except AttributeError:
return # frame has been cleared, __dict__ is empty
if self._free:
left = 0
while self._free:
conn = self._free.popleft()
conn.close()
left += 1
warnings.warn(
"Unclosed {} connections in {!r}".format(left, self),
ResourceWarning)