1 # Copyright (c) 2010 Google Inc. All rights reserved.

     2 #

     3 # Redistribution and use in source and binary forms, with or without

     4 # modification, are permitted provided that the following conditions are

     5 # met:

     6 # 

     7 #     * Redistributions of source code must retain the above copyright

     8 # notice, this list of conditions and the following disclaimer.

     9 #     * Redistributions in binary form must reproduce the above

    10 # copyright notice, this list of conditions and the following disclaimer

    11 # in the documentation and/or other materials provided with the

    12 # distribution.

    13 #     * Neither the name of Google Inc. nor the names of its

    14 # contributors may be used to endorse or promote products derived from

    15 # this software without specific prior written permission.

    16 # 

    17 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

    18 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

    19 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

    20 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

    21 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

    22 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

    23 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

    24 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

    25 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

    26 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

    27 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    28 

    29 

    30 class PersistentPatchCollectionDelegate:

    31     def collection_name(self):

    32         raise NotImplementedError, "subclasses must implement"

    33 

    34     def fetch_potential_patch_ids(self):

    35         raise NotImplementedError, "subclasses must implement"

    36 

    37     def status_server(self):

    38         raise NotImplementedError, "subclasses must implement"

    39 

    40     def is_terminal_status(self, status):

    41         raise NotImplementedError, "subclasses must implement"

    42 

    43 

    44 class PersistentPatchCollection:

    45     def __init__(self, delegate):

    46         self._delegate = delegate

    47         self._name = self._delegate.collection_name()

    48         self._status = self._delegate.status_server()

    49         self._status_cache = {}

    50 

    51     def _cached_status(self, patch_id):

    52         cached = self._status_cache.get(patch_id)

    53         if cached:

    54             return cached

    55         status = self._status.patch_status(self._name, patch_id)

    56         if status and self._delegate.is_terminal_status(status):

    57             self._status_cache[patch_id] = status

    58         return status

    59 

    60     def _is_active_patch_id(self, patch_id):

    61         """Active patches are patches waiting to be processed from this collection."""

    62         status = self._cached_status(patch_id)

    63         return not status or not self._delegate.is_terminal_status(status)

    64 

    65     def _fetch_active_patch_ids(self):

    66         patch_ids = self._delegate.fetch_potential_patch_ids()

    67         return filter(lambda patch_id: self._is_active_patch_id(patch_id), patch_ids)

    68 

    69     def next(self):

    70         # Note: We only fetch all the ids so we can post them back to the server.

    71         # This will go away once we have a feeder queue and all other queues are

    72         # just pulling their next work item from the server.

    73         patch_ids = self._fetch_active_patch_ids()

    74         # FIXME: We're assuming self._name is a valid queue-name.

    75         self._status.update_work_items(self._name, patch_ids)

    76         if not patch_ids:

    77             return None

    78         return patch_ids[0]