Synnefo

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from synnefo.lib.pool 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,

                 queue_module=None, queue_hosts=None,

                 queue_exchange=None,

                 free_versioning=True):

        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.queue_module = queue_module

        self.queue_hosts = queue_hosts

        self.queue_exchange = queue_exchange

        self.free_versioning = free_versioning

    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,

                                  queue_module=self.queue_module,

                                  queue_hosts=self.queue_hosts,

                                  queue_exchange=self.queue_exchange,

                                  free_versioning=self.free_versioning)

        backend._real_close = backend.close

        backend.close = instancemethod(_pooled_backend_close, backend,

                                       type(backend))

        backend._pool = self

        backend._use_count = USAGE_LIMIT

        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()

            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()

        if backend.messages:

            backend.messages = []

        return False

def _pooled_backend_close(backend):

    backend._pool.pool_put(backend)