Synnefo

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from objpool import ObjectPool

from new import instancemethod

from select import select

from traceback import print_exc

from pithos.backends import connect_backend

USAGE_LIMIT = 500

class PithosBackendPool(ObjectPool):

    def __init__(self, size=None, db_module=None, db_connection=None,

                 block_module=None, block_path=None, block_umask=None,

                 block_size=None, hash_algorithm=None,

                 queue_module=None, queue_hosts=None,

                 queue_exchange=None, free_versioning=True,

                 astakos_url=None, service_token=None,

                 astakosclient_poolsize=None,

                 block_params=None,

                 public_url_security=None,

                 public_url_alphabet=None,

                 account_quota_policy=None,

                 container_quota_policy=None,

                 container_versioning_policy=None

        ):

        super(PithosBackendPool, self).__init__(size=size)

        self.db_module = db_module

        self.db_connection = db_connection

        self.block_module = block_module

        self.block_path = block_path

        self.block_umask = block_umask

        self.block_size = block_size

        self.hash_algorithm = hash_algorithm

        self.queue_module = queue_module

        self.block_params = block_params

        self.queue_hosts = queue_hosts

        self.queue_exchange = queue_exchange

        self.astakos_url = astakos_url

        self.service_token = service_token

        self.astakosclient_poolsize = astakosclient_poolsize

        self.free_versioning = free_versioning

        self.public_url_security = public_url_security

        self.public_url_alphabet = public_url_alphabet

        self.account_quota_policy = account_quota_policy

        self.container_quota_policy = container_quota_policy

        self.container_versioning_policy = container_versioning_policy

    def _pool_create(self):

        backend = connect_backend(

                db_module=self.db_module,

                db_connection=self.db_connection,

                block_module=self.block_module,

                block_path=self.block_path,

                block_umask=self.block_umask,

                block_size = self.block_size,

                hash_algorithm = self.hash_algorithm,

                queue_module=self.queue_module,

                block_params=self.block_params,

                queue_hosts=self.queue_hosts,

                queue_exchange=self.queue_exchange,

                astakos_url=self.astakos_url,

                service_token=self.service_token,

                astakosclient_poolsize=self.astakosclient_poolsize,

                free_versioning=self.free_versioning,

                public_url_security=self.public_url_security,

                public_url_alphabet=self.public_url_alphabet,

                account_quota_policy=self.account_quota_policy,

                container_quota_policy=self.container_quota_policy,

                container_versioning_policy=self.container_versioning_policy)

        backend._real_close = backend.close

        backend.close = instancemethod(_pooled_backend_close, backend,

                                       type(backend))

        backend._pool = self

        backend._use_count = USAGE_LIMIT

        backend.messages = []

        return backend

    def _pool_verify(self, backend):

        wrapper = backend.wrapper

        conn = wrapper.conn

        if conn.closed:

            return False

        if conn.in_transaction():

            conn.close()

            return False

        try:

            fd = conn.connection.connection.fileno()

        except AttributeError:

            # probably sqlite, assume success

            pass

        else:

            try:

                r, w, x = select([fd], (), (), 0)

                if r:

                    conn.close()

                    return False

            except:

                print_exc()

                return False

        return True

    def _pool_cleanup(self, backend):

        c = backend._use_count - 1

        if c < 0:

            backend._real_close()

            return True

        backend._use_count = c

        wrapper = backend.wrapper

        if wrapper.trans is not None:

            conn = wrapper.conn

            if conn.closed:

                wrapper.trans = None

            else:

                wrapper.rollback()

        backend.messages = []

        return False

def _pooled_backend_close(backend):

    backend._pool.pool_put(backend)