/usr/lib/python2.7/dist-packages/eventlet/db_pool.py is in python-eventlet 0.13.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 | from collections import deque
import sys
import time
from eventlet.pools import Pool
from eventlet import timeout
from eventlet import hubs
from eventlet.hubs.timer import Timer
from eventlet.greenthread import GreenThread
class ConnectTimeout(Exception):
pass
class BaseConnectionPool(Pool):
def __init__(self, db_module,
min_size = 0, max_size = 4,
max_idle = 10, max_age = 30,
connect_timeout = 5,
*args, **kwargs):
"""
Constructs a pool with at least *min_size* connections and at most
*max_size* connections. Uses *db_module* to construct new connections.
The *max_idle* parameter determines how long pooled connections can
remain idle, in seconds. After *max_idle* seconds have elapsed
without the connection being used, the pool closes the connection.
*max_age* is how long any particular connection is allowed to live.
Connections that have been open for longer than *max_age* seconds are
closed, regardless of idle time. If *max_age* is 0, all connections are
closed on return to the pool, reducing it to a concurrency limiter.
*connect_timeout* is the duration in seconds that the pool will wait
before timing out on connect() to the database. If triggered, the
timeout will raise a ConnectTimeout from get().
The remainder of the arguments are used as parameters to the
*db_module*'s connection constructor.
"""
assert(db_module)
self._db_module = db_module
self._args = args
self._kwargs = kwargs
self.max_idle = max_idle
self.max_age = max_age
self.connect_timeout = connect_timeout
self._expiration_timer = None
super(BaseConnectionPool, self).__init__(min_size=min_size,
max_size=max_size,
order_as_stack=True)
def _schedule_expiration(self):
""" Sets up a timer that will call _expire_old_connections when the
oldest connection currently in the free pool is ready to expire. This
is the earliest possible time that a connection could expire, thus, the
timer will be running as infrequently as possible without missing a
possible expiration.
If this function is called when a timer is already scheduled, it does
nothing.
If max_age or max_idle is 0, _schedule_expiration likewise does nothing.
"""
if self.max_age is 0 or self.max_idle is 0:
# expiration is unnecessary because all connections will be expired
# on put
return
if ( self._expiration_timer is not None
and not getattr(self._expiration_timer, 'called', False)):
# the next timer is already scheduled
return
try:
now = time.time()
self._expire_old_connections(now)
# the last item in the list, because of the stack ordering,
# is going to be the most-idle
idle_delay = (self.free_items[-1][0] - now) + self.max_idle
oldest = min([t[1] for t in self.free_items])
age_delay = (oldest - now) + self.max_age
next_delay = min(idle_delay, age_delay)
except (IndexError, ValueError):
# no free items, unschedule ourselves
self._expiration_timer = None
return
if next_delay > 0:
# set up a continuous self-calling loop
self._expiration_timer = Timer(next_delay, GreenThread(hubs.get_hub().greenlet).switch,
self._schedule_expiration, [], {})
self._expiration_timer.schedule()
def _expire_old_connections(self, now):
""" Iterates through the open connections contained in the pool, closing
ones that have remained idle for longer than max_idle seconds, or have
been in existence for longer than max_age seconds.
*now* is the current time, as returned by time.time().
"""
original_count = len(self.free_items)
expired = [
conn
for last_used, created_at, conn in self.free_items
if self._is_expired(now, last_used, created_at)]
new_free = [
(last_used, created_at, conn)
for last_used, created_at, conn in self.free_items
if not self._is_expired(now, last_used, created_at)]
self.free_items.clear()
self.free_items.extend(new_free)
# adjust the current size counter to account for expired
# connections
self.current_size -= original_count - len(self.free_items)
for conn in expired:
self._safe_close(conn, quiet=True)
def _is_expired(self, now, last_used, created_at):
""" Returns true and closes the connection if it's expired."""
if ( self.max_idle <= 0
or self.max_age <= 0
or now - last_used > self.max_idle
or now - created_at > self.max_age ):
return True
return False
def _unwrap_connection(self, conn):
""" If the connection was wrapped by a subclass of
BaseConnectionWrapper and is still functional (as determined
by the __nonzero__ method), returns the unwrapped connection.
If anything goes wrong with this process, returns None.
"""
base = None
try:
if conn:
base = conn._base
conn._destroy()
else:
base = None
except AttributeError:
pass
return base
def _safe_close(self, conn, quiet = False):
""" Closes the (already unwrapped) connection, squelching any
exceptions."""
try:
conn.close()
except (KeyboardInterrupt, SystemExit):
raise
except AttributeError:
pass # conn is None, or junk
except:
if not quiet:
print "Connection.close raised: %s" % (sys.exc_info()[1])
def get(self):
conn = super(BaseConnectionPool, self).get()
# None is a flag value that means that put got called with
# something it couldn't use
if conn is None:
try:
conn = self.create()
except Exception:
# unconditionally increase the free pool because
# even if there are waiters, doing a full put
# would incur a greenlib switch and thus lose the
# exception stack
self.current_size -= 1
raise
# if the call to get() draws from the free pool, it will come
# back as a tuple
if isinstance(conn, tuple):
_last_used, created_at, conn = conn
else:
created_at = time.time()
# wrap the connection so the consumer can call close() safely
wrapped = PooledConnectionWrapper(conn, self)
# annotating the wrapper so that when it gets put in the pool
# again, we'll know how old it is
wrapped._db_pool_created_at = created_at
return wrapped
def put(self, conn):
created_at = getattr(conn, '_db_pool_created_at', 0)
now = time.time()
conn = self._unwrap_connection(conn)
if self._is_expired(now, now, created_at):
self._safe_close(conn, quiet=False)
conn = None
else:
# rollback any uncommitted changes, so that the next client
# has a clean slate. This also pokes the connection to see if
# it's dead or None
try:
if conn:
conn.rollback()
except KeyboardInterrupt:
raise
except:
# we don't care what the exception was, we just know the
# connection is dead
print "WARNING: connection.rollback raised: %s" % (sys.exc_info()[1])
conn = None
if conn is not None:
super(BaseConnectionPool, self).put( (now, created_at, conn) )
else:
# wake up any waiters with a flag value that indicates
# they need to manufacture a connection
if self.waiting() > 0:
super(BaseConnectionPool, self).put(None)
else:
# no waiters -- just change the size
self.current_size -= 1
self._schedule_expiration()
def clear(self):
""" Close all connections that this pool still holds a reference to,
and removes all references to them.
"""
if self._expiration_timer:
self._expiration_timer.cancel()
free_items, self.free_items = self.free_items, deque()
for item in free_items:
# Free items created using min_size>0 are not tuples.
conn = item[2] if isinstance(item, tuple) else item
self._safe_close(conn, quiet=True)
def __del__(self):
self.clear()
class TpooledConnectionPool(BaseConnectionPool):
"""A pool which gives out :class:`~eventlet.tpool.Proxy`-based database
connections.
"""
def create(self):
now = time.time()
return now, now, self.connect(self._db_module,
self.connect_timeout, *self._args, **self._kwargs)
@classmethod
def connect(cls, db_module, connect_timeout, *args, **kw):
t = timeout.Timeout(connect_timeout, ConnectTimeout())
try:
from eventlet import tpool
conn = tpool.execute(db_module.connect, *args, **kw)
return tpool.Proxy(conn, autowrap_names=('cursor',))
finally:
t.cancel()
class RawConnectionPool(BaseConnectionPool):
"""A pool which gives out plain database connections.
"""
def create(self):
now = time.time()
return now, now, self.connect(self._db_module,
self.connect_timeout, *self._args, **self._kwargs)
@classmethod
def connect(cls, db_module, connect_timeout, *args, **kw):
t = timeout.Timeout(connect_timeout, ConnectTimeout())
try:
return db_module.connect(*args, **kw)
finally:
t.cancel()
# default connection pool is the tpool one
ConnectionPool = TpooledConnectionPool
class GenericConnectionWrapper(object):
def __init__(self, baseconn):
self._base = baseconn
def __enter__(self): return self._base.__enter__()
def __exit__(self, exc, value, tb): return self._base.__exit__(exc, value, tb)
def __repr__(self): return self._base.__repr__()
def affected_rows(self): return self._base.affected_rows()
def autocommit(self,*args, **kwargs): return self._base.autocommit(*args, **kwargs)
def begin(self): return self._base.begin()
def change_user(self,*args, **kwargs): return self._base.change_user(*args, **kwargs)
def character_set_name(self,*args, **kwargs): return self._base.character_set_name(*args, **kwargs)
def close(self,*args, **kwargs): return self._base.close(*args, **kwargs)
def commit(self,*args, **kwargs): return self._base.commit(*args, **kwargs)
def cursor(self, *args, **kwargs): return self._base.cursor(*args, **kwargs)
def dump_debug_info(self,*args, **kwargs): return self._base.dump_debug_info(*args, **kwargs)
def errno(self,*args, **kwargs): return self._base.errno(*args, **kwargs)
def error(self,*args, **kwargs): return self._base.error(*args, **kwargs)
def errorhandler(self, *args, **kwargs): return self._base.errorhandler(*args, **kwargs)
def insert_id(self, *args, **kwargs): return self._base.insert_id(*args, **kwargs)
def literal(self, *args, **kwargs): return self._base.literal(*args, **kwargs)
def set_character_set(self, *args, **kwargs): return self._base.set_character_set(*args, **kwargs)
def set_sql_mode(self, *args, **kwargs): return self._base.set_sql_mode(*args, **kwargs)
def show_warnings(self): return self._base.show_warnings()
def warning_count(self): return self._base.warning_count()
def ping(self,*args, **kwargs): return self._base.ping(*args, **kwargs)
def query(self,*args, **kwargs): return self._base.query(*args, **kwargs)
def rollback(self,*args, **kwargs): return self._base.rollback(*args, **kwargs)
def select_db(self,*args, **kwargs): return self._base.select_db(*args, **kwargs)
def set_server_option(self,*args, **kwargs): return self._base.set_server_option(*args, **kwargs)
def server_capabilities(self,*args, **kwargs): return self._base.server_capabilities(*args, **kwargs)
def shutdown(self,*args, **kwargs): return self._base.shutdown(*args, **kwargs)
def sqlstate(self,*args, **kwargs): return self._base.sqlstate(*args, **kwargs)
def stat(self, *args, **kwargs): return self._base.stat(*args, **kwargs)
def store_result(self,*args, **kwargs): return self._base.store_result(*args, **kwargs)
def string_literal(self,*args, **kwargs): return self._base.string_literal(*args, **kwargs)
def thread_id(self,*args, **kwargs): return self._base.thread_id(*args, **kwargs)
def use_result(self,*args, **kwargs): return self._base.use_result(*args, **kwargs)
class PooledConnectionWrapper(GenericConnectionWrapper):
""" A connection wrapper where:
- the close method returns the connection to the pool instead of closing it directly
- ``bool(conn)`` returns a reasonable value
- returns itself to the pool if it gets garbage collected
"""
def __init__(self, baseconn, pool):
super(PooledConnectionWrapper, self).__init__(baseconn)
self._pool = pool
def __nonzero__(self):
return (hasattr(self, '_base') and bool(self._base))
def _destroy(self):
self._pool = None
try:
del self._base
except AttributeError:
pass
def close(self):
""" Return the connection to the pool, and remove the
reference to it so that you can't use it again through this
wrapper object.
"""
if self and self._pool:
self._pool.put(self)
self._destroy()
def __del__(self):
return # this causes some issues if __del__ is called in the
# main coroutine, so for now this is disabled
#self.close()
class DatabaseConnector(object):
"""\
This is an object which will maintain a collection of database
connection pools on a per-host basis."""
def __init__(self, module, credentials,
conn_pool=None, *args, **kwargs):
"""\
constructor
*module*
Database module to use.
*credentials*
Mapping of hostname to connect arguments (e.g. username and password)"""
assert(module)
self._conn_pool_class = conn_pool
if self._conn_pool_class is None:
self._conn_pool_class = ConnectionPool
self._module = module
self._args = args
self._kwargs = kwargs
self._credentials = credentials # this is a map of hostname to username/password
self._databases = {}
def credentials_for(self, host):
if host in self._credentials:
return self._credentials[host]
else:
return self._credentials.get('default', None)
def get(self, host, dbname):
""" Returns a ConnectionPool to the target host and schema. """
key = (host, dbname)
if key not in self._databases:
new_kwargs = self._kwargs.copy()
new_kwargs['db'] = dbname
new_kwargs['host'] = host
new_kwargs.update(self.credentials_for(host))
dbpool = self._conn_pool_class(self._module,
*self._args, **new_kwargs)
self._databases[key] = dbpool
return self._databases[key]
|