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# Copyright 2011-2012 GRNET S.A. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or
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# without modification, are permitted provided that the following
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# conditions are met:
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#
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#   1. Redistributions of source code must retain the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer.
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#
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#   2. Redistributions in binary form must reproduce the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer in the documentation and/or other materials
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#      provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
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# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and
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# documentation are those of the authors and should not be
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# interpreted as representing official policies, either expressed
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# or implied, of GRNET S.A.
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from synnefo.lib.pool import ObjectPool
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from new import instancemethod
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from select import select
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from traceback import print_exc
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from pithos.backends import connect_backend
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USAGE_LIMIT = 500
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class PithosBackendPool(ObjectPool):
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    def __init__(self, size=None, db_module=None, db_connection=None,
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                 block_module=None, block_path=None, block_umask=None,
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                 queue_module=None, queue_hosts=None,
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                 queue_exchange=None, free_versioning=True,
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                 quotaholder_url=None, quotaholder_token=None,
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                 block_params=None):
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        super(PithosBackendPool, self).__init__(size=size)
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        self.db_module = db_module
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        self.db_connection = db_connection
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        self.block_module = block_module
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        self.block_path = block_path
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        self.block_umask = block_umask
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        self.queue_module = queue_module
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        self.block_params = block_params
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        self.queue_hosts = queue_hosts
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        self.queue_exchange = queue_exchange
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        self.quotaholder_url = quotaholder_url
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        self.quotaholder_token = quotaholder_token
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        self.free_versioning = free_versioning
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    def _pool_create(self):
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        backend = connect_backend(db_module=self.db_module,
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                                  db_connection=self.db_connection,
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                                  block_module=self.block_module,
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                                  block_path=self.block_path,
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                                  block_umask=self.block_umask,
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                                  queue_module=self.queue_module,
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                                  block_params=self.block_params,
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                                  queue_hosts=self.queue_hosts,
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                                  queue_exchange=self.queue_exchange,
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                                  quotaholder_url=self.quotaholder_url,
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                                  quotaholder_token=self.quotaholder_token,
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                                  free_versioning=self.free_versioning)
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        backend._real_close = backend.close
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        backend.close = instancemethod(_pooled_backend_close, backend,
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                                       type(backend))
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        backend._pool = self
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        backend._use_count = USAGE_LIMIT
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        backend.messages = []
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        return backend
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    def _pool_verify(self, backend):
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        wrapper = backend.wrapper
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        conn = wrapper.conn
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        if conn.closed:
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            return False
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        if conn.in_transaction():
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            conn.close()
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            return False
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        try:
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            fd = conn.connection.connection.fileno()
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            r, w, x = select([fd], (), (), 0)
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            if r:
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                conn.close()
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                return False
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        except:
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            print_exc()
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            return False
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        return True
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    def _pool_cleanup(self, backend):
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        c = backend._use_count - 1
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        if c < 0:
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            backend._real_close()
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            return True
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        backend._use_count = c
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        wrapper = backend.wrapper
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        if wrapper.trans is not None:
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            conn = wrapper.conn
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            if conn.closed:
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                wrapper.trans = None
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            else:
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                wrapper.rollback()
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        backend.messages = []
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        return False
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def _pooled_backend_close(backend):
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    backend._pool.pool_put(backend)