/usr/lib/python2.7/dist-packages/psycopg2/pool.py is in python-psycopg2 2.7.4-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 | """Connection pooling for psycopg2
This module implements thread-safe (and not) connection pools.
"""
# psycopg/pool.py - pooling code for psycopg
#
# Copyright (C) 2003-2010 Federico Di Gregorio <fog@debian.org>
#
# psycopg2 is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# In addition, as a special exception, the copyright holders give
# permission to link this program with the OpenSSL library (or with
# modified versions of OpenSSL that use the same license as OpenSSL),
# and distribute linked combinations including the two.
#
# You must obey the GNU Lesser General Public License in all respects for
# all of the code used other than OpenSSL.
#
# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
# License for more details.
import psycopg2
from psycopg2 import extensions as _ext
class PoolError(psycopg2.Error):
pass
class AbstractConnectionPool(object):
"""Generic key-based pooling code."""
def __init__(self, minconn, maxconn, *args, **kwargs):
"""Initialize the connection pool.
New 'minconn' connections are created immediately calling 'connfunc'
with given parameters. The connection pool will support a maximum of
about 'maxconn' connections.
"""
self.minconn = int(minconn)
self.maxconn = int(maxconn)
self.closed = False
self._args = args
self._kwargs = kwargs
self._pool = []
self._used = {}
self._rused = {} # id(conn) -> key map
self._keys = 0
for i in range(self.minconn):
self._connect()
def _connect(self, key=None):
"""Create a new connection and assign it to 'key' if not None."""
conn = psycopg2.connect(*self._args, **self._kwargs)
if key is not None:
self._used[key] = conn
self._rused[id(conn)] = key
else:
self._pool.append(conn)
return conn
def _getkey(self):
"""Return a new unique key."""
self._keys += 1
return self._keys
def _getconn(self, key=None):
"""Get a free connection and assign it to 'key' if not None."""
if self.closed:
raise PoolError("connection pool is closed")
if key is None:
key = self._getkey()
if key in self._used:
return self._used[key]
if self._pool:
self._used[key] = conn = self._pool.pop()
self._rused[id(conn)] = key
return conn
else:
if len(self._used) == self.maxconn:
raise PoolError("connection pool exhausted")
return self._connect(key)
def _putconn(self, conn, key=None, close=False):
"""Put away a connection."""
if self.closed:
raise PoolError("connection pool is closed")
if key is None:
key = self._rused.get(id(conn))
if not key:
raise PoolError("trying to put unkeyed connection")
if len(self._pool) < self.minconn and not close:
# Return the connection into a consistent state before putting
# it back into the pool
if not conn.closed:
status = conn.get_transaction_status()
if status == _ext.TRANSACTION_STATUS_UNKNOWN:
# server connection lost
conn.close()
elif status != _ext.TRANSACTION_STATUS_IDLE:
# connection in error or in transaction
conn.rollback()
self._pool.append(conn)
else:
# regular idle connection
self._pool.append(conn)
# If the connection is closed, we just discard it.
else:
conn.close()
# here we check for the presence of key because it can happen that a
# thread tries to put back a connection after a call to close
if not self.closed or key in self._used:
del self._used[key]
del self._rused[id(conn)]
def _closeall(self):
"""Close all connections.
Note that this can lead to some code fail badly when trying to use
an already closed connection. If you call .closeall() make sure
your code can deal with it.
"""
if self.closed:
raise PoolError("connection pool is closed")
for conn in self._pool + list(self._used.values()):
try:
conn.close()
except:
pass
self.closed = True
class SimpleConnectionPool(AbstractConnectionPool):
"""A connection pool that can't be shared across different threads."""
getconn = AbstractConnectionPool._getconn
putconn = AbstractConnectionPool._putconn
closeall = AbstractConnectionPool._closeall
class ThreadedConnectionPool(AbstractConnectionPool):
"""A connection pool that works with the threading module."""
def __init__(self, minconn, maxconn, *args, **kwargs):
"""Initialize the threading lock."""
import threading
AbstractConnectionPool.__init__(
self, minconn, maxconn, *args, **kwargs)
self._lock = threading.Lock()
def getconn(self, key=None):
"""Get a free connection and assign it to 'key' if not None."""
self._lock.acquire()
try:
return self._getconn(key)
finally:
self._lock.release()
def putconn(self, conn=None, key=None, close=False):
"""Put away an unused connection."""
self._lock.acquire()
try:
self._putconn(conn, key, close)
finally:
self._lock.release()
def closeall(self):
"""Close all connections (even the one currently in use.)"""
self._lock.acquire()
try:
self._closeall()
finally:
self._lock.release()
class PersistentConnectionPool(AbstractConnectionPool):
"""A pool that assigns persistent connections to different threads.
Note that this connection pool generates by itself the required keys
using the current thread id. This means that until a thread puts away
a connection it will always get the same connection object by successive
`!getconn()` calls. This also means that a thread can't use more than one
single connection from the pool.
"""
def __init__(self, minconn, maxconn, *args, **kwargs):
"""Initialize the threading lock."""
import warnings
warnings.warn("deprecated: use ZPsycopgDA.pool implementation",
DeprecationWarning)
import threading
AbstractConnectionPool.__init__(
self, minconn, maxconn, *args, **kwargs)
self._lock = threading.Lock()
# we we'll need the thread module, to determine thread ids, so we
# import it here and copy it in an instance variable
import thread as _thread # work around for 2to3 bug - see ticket #348
self.__thread = _thread
def getconn(self):
"""Generate thread id and return a connection."""
key = self.__thread.get_ident()
self._lock.acquire()
try:
return self._getconn(key)
finally:
self._lock.release()
def putconn(self, conn=None, close=False):
"""Put away an unused connection."""
key = self.__thread.get_ident()
self._lock.acquire()
try:
if not conn:
conn = self._used[key]
self._putconn(conn, key, close)
finally:
self._lock.release()
def closeall(self):
"""Close all connections (even the one currently in use.)"""
self._lock.acquire()
try:
self._closeall()
finally:
self._lock.release()
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