| 1 |  |  | # -*- coding: utf-8 -*- | 
            
                                                                                                            
                            
            
                                    
            
            
                | 2 |  |  | """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 3 |  |  | The Render class is used to "render" metrics into a specific format. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 4 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 5 |  |  | It is an abstract base class and must be sub-classed for each desired | 
            
                                                                                                            
                            
            
                                    
            
            
                | 6 |  |  | metrics format. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 7 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 8 |  |  | eg. the graphite plaintext format is supported by GraphiteRenderPlain | 
            
                                                                                                            
                            
            
                                    
            
            
                | 9 |  |  | which sub-classes Render and defines the process() and flush() methods. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 10 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 11 |  |  | .. moduleauthor:: Kenny Freeman <[email protected]> | 
            
                                                                                                            
                            
            
                                    
            
            
                | 12 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 13 |  |  | """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 14 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 15 |  |  | import collections | 
            
                                                                                                            
                            
            
                                    
            
            
                | 16 |  |  | from plumd import Int, Float, String, Boolean, Render, Meta | 
            
                                                                                                            
                            
            
                                    
            
            
                | 17 |  |  | from Queue import Queue | 
            
                                                                                                            
                            
            
                                    
            
            
                | 18 |  |  | from abc import ABCMeta, abstractmethod | 
            
                                                                                                            
                            
            
                                    
            
            
                | 19 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 20 |  |  | __author__ = 'Kenny Freeman' | 
            
                                                                                                            
                            
            
                                    
            
            
                | 21 |  |  | __email__ = '[email protected]' | 
            
                                                                                                            
                            
            
                                    
            
            
                | 22 |  |  | __version__ = '0.7' | 
            
                                                                                                            
                            
            
                                    
            
            
                | 23 |  |  | __license__ = "ISCL" | 
            
                                                                                                            
                            
            
                                    
            
            
                | 24 |  |  | __docformat__ = 'reStructuredText' | 
            
                                                                                                            
                            
            
                                    
            
            
                | 25 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 26 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 27 |  |  | class BasicRender(Render): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 28 |  |  |     """A plugin that renders metrics and is also iterable. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 29 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 30 |  |  |     :param rconfig: config.Conf object passed from a writer plugin instance | 
            
                                                                                                            
                            
            
                                    
            
            
                | 31 |  |  |     :type rconfig: :class:`config.Conf` | 
            
                                                                                                            
                            
            
                                    
            
            
                | 32 |  |  |     """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 33 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 34 |  |  |     __metaclass__ = ABCMeta | 
            
                                                                                                            
                            
            
                                    
            
            
                | 35 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 36 |  |  |     defaults = { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 37 |  |  |         'meta': {} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 38 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 39 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 40 |  |  |     def __init__(self, log, config): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 41 |  |  |         """Create a Render instance. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 42 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 43 |  |  |         todo: fix me / complete this | 
            
                                                                                                            
                            
            
                                    
            
            
                | 44 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 45 |  |  |         :param log: A logger | 
            
                                                                                                            
                            
            
                                    
            
            
                | 46 |  |  |         :type log: logging.RootLogger | 
            
                                                                                                            
                            
            
                                    
            
            
                | 47 |  |  |         :param config: a plumd.config.Conf configuration helper instance. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 48 |  |  |         :type config: plumd.config.Conf | 
            
                                                                                                            
                            
            
                                    
            
            
                | 49 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 50 |  |  |         super(BasicRender, self).__init__(log, config) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 51 |  |  |         # ensure default configuration is set | 
            
                                                                                                            
                            
            
                                    
            
            
                | 52 |  |  |         config.defaults(BasicRender.defaults) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 53 |  |  |         # Use a double ended queue with a maximum size | 
            
                                                                                                            
                            
            
                                    
            
            
                | 54 |  |  |         self.metrics = collections.deque() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 55 |  |  |         # define a metadata object and copy in any configured host metadata | 
            
                                                                                                            
                            
            
                                    
            
            
                | 56 |  |  |         self.meta = Meta() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 57 |  |  |         clookup = { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 58 |  |  |             int: Int, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 59 |  |  |             float: Float, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 60 |  |  |             str: String, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 61 |  |  |             bool: Boolean | 
            
                                                                                                            
                            
            
                                    
            
            
                | 62 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 63 |  |  |         for entry in config.get('meta'): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 64 |  |  |             for key, val in entry.items(): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 65 |  |  |                 if val.__class__ not in clookup: | 
            
                                                                                                            
                            
            
                                    
            
            
                | 66 |  |  |                     args = (key, val.__class__.__name__) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 67 |  |  |                     err = "host metadata: unsupported type: {0}={1}".format(*args) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 68 |  |  |                     raise ValueError(err) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 69 |  |  |                 self.meta.add(clookup[val.__class__](key, val)) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 70 |  |  |         self.buff = "" | 
            
                                                                                                            
                            
            
                                    
            
            
                | 71 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 72 |  |  |     def __str__(self): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 73 |  |  |         """Return our current metrics buffer.""" | 
            
                                                                                                            
                            
            
                                    
            
            
                | 74 |  |  |         return self.buff | 
            
                                                                                                            
                            
            
                                    
            
            
                | 75 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 76 |  |  |     def __repr__(self): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 77 |  |  |         """Return our current metrics buffer.""" | 
            
                                                                                                            
                            
            
                                    
            
            
                | 78 |  |  |         return self.buff | 
            
                                                                                                            
                            
            
                                    
            
            
                | 79 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 80 |  |  |     def get_metrics(self): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 81 |  |  |         """Return our deque of metrics. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 82 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 83 |  |  |         :rtype: collections.deque | 
            
                                                                                                            
                            
            
                                    
            
            
                | 84 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 85 |  |  |         raise NotImplementedError("process must be defined by a subclass") | 
            
                                                                                                            
                            
            
                                    
            
            
                | 86 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 87 |  |  |     def reset(self): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 88 |  |  |         """Clear our metrics buffer and deque.""" | 
            
                                                                                                            
                            
            
                                    
            
            
                | 89 |  |  |         self.metrics.clear() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 90 |  |  |         self.buff = str() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 91 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 92 |  |  |     @abstractmethod | 
            
                                                                                                            
                            
            
                                    
            
            
                | 93 |  |  |     def process(self, rset): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 94 |  |  |         """Render a result set into our supported format and enqueue it. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 95 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 96 |  |  |         Subclasses for specific backends must define this method. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 97 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 98 |  |  |         :param rset: A :class:`ResultSet` object | 
            
                                                                                                            
                            
            
                                    
            
            
                | 99 |  |  |         :type rset: :class:`ResultSet` | 
            
                                                                                                            
                            
            
                                    
            
            
                | 100 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 101 |  |  |         raise NotImplementedError("process must be defined by a subclass") | 
            
                                                                                                            
                            
            
                                    
            
            
                | 102 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 103 |  |  |     @abstractmethod | 
            
                                                                                                            
                            
            
                                    
            
            
                | 104 |  |  |     def process_many(self, rsets): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 105 |  |  |         """Render result sets into our supported format and enqueue. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 106 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 107 |  |  |         Subclasses for specific backends must define this method. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 108 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 109 |  |  |         :param rsets: An iterable of :class:`ResultSet` objects | 
            
                                                                                                            
                            
            
                                    
            
            
                | 110 |  |  |         :type rsets: iterable(:class:`ResultSet`) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 111 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 112 |  |  |         raise NotImplementedError("process must be defined by a subclass") | 
            
                                                                                                            
                            
            
                                    
            
            
                | 113 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 114 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 115 |  |  | class ChunkedRender(Render): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 116 |  |  |     """A plugin that renders metrics and is also iterable. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 117 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 118 |  |  |     :param rconfig: config.Conf object passed from a writer plugin instance | 
            
                                                                                                            
                            
            
                                    
            
            
                | 119 |  |  |     :type rconfig: :class:`config.Conf` | 
            
                                                                                                            
                            
            
                                    
            
            
                | 120 |  |  |     """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 121 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 122 |  |  |     __metaclass__ = ABCMeta | 
            
                                                                                                            
                            
            
                                    
            
            
                | 123 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 124 |  |  |     defaults = { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 125 |  |  |         # todo: move max items, bytes out of here into graphite render | 
            
                                                                                                            
                            
            
                                    
            
            
                | 126 |  |  |         'max_queue': 2048,      # maxlen of deque used for metrics | 
            
                                                                                                            
                            
            
                                    
            
            
                | 127 |  |  |         'max_items': 64,        # maximum number of items to send at once | 
            
                                                                                                            
                            
            
                                    
            
            
                | 128 |  |  |         'max_bytes': 1400,      # maximum number of bytes to send at once | 
            
                                                                                                            
                            
            
                                    
            
            
                | 129 |  |  |         'meta': {}              # metadata to add to each metric | 
            
                                                                                                            
                            
            
                                    
            
            
                | 130 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 131 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 132 |  |  |     def __init__(self, log, config): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 133 |  |  |         """Create a Render instance. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 134 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 135 |  |  |         :param log: A logger | 
            
                                                                                                            
                            
            
                                    
            
            
                | 136 |  |  |         :type log: logging.RootLogger | 
            
                                                                                                            
                            
            
                                    
            
            
                | 137 |  |  |         :param config: a plumd.config.Conf configuration helper instance. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 138 |  |  |         :type config: plumd.config.Conf | 
            
                                                                                                            
                            
            
                                    
            
            
                | 139 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 140 |  |  |         super(ChunkedRender, self).__init__(log, config) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 141 |  |  |         # ensure default configuration is set | 
            
                                                                                                            
                            
            
                                    
            
            
                | 142 |  |  |         config.defaults(ChunkedRender.defaults) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 143 |  |  |         self.max_bytes = config.get('max_bytes') | 
            
                                                                                                            
                            
            
                                    
            
            
                | 144 |  |  |         self.max_items = config.get('max_items') | 
            
                                                                                                            
                            
            
                                    
            
            
                | 145 |  |  |         # Use a double ended queue with a maximum size | 
            
                                                                                                            
                            
            
                                    
            
            
                | 146 |  |  |         self.metrics = collections.deque(maxlen=config.get('max_queue')) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 147 |  |  |         # define a metadata object and copy in any configured host metadata | 
            
                                                                                                            
                            
            
                                    
            
            
                | 148 |  |  |         self.meta = Meta() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 149 |  |  |         clookup = { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 150 |  |  |             int: Int, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 151 |  |  |             float: Float, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 152 |  |  |             str: String, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 153 |  |  |             bool: Boolean | 
            
                                                                                                            
                            
            
                                    
            
            
                | 154 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 155 |  |  |         for entry in config.get('meta'): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 156 |  |  |             for key, val in entry.items(): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 157 |  |  |                 if val.__class__ not in clookup: | 
            
                                                                                                            
                            
            
                                    
            
            
                | 158 |  |  |                     args = (key, val.__class__.__name__) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 159 |  |  |                     err = "host metadata: unsupported type: {0}={1}".format(*args) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 160 |  |  |                     raise ValueError(err) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 161 |  |  |                 self.meta.add(clookup[val.__class__](key, val)) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 162 |  |  |         self.queues = dict() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 163 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 164 |  |  |     def register(self, writer): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 165 |  |  |         """Register the writer plugin name to read from this renderer. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 166 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 167 |  |  |         This creates a queue internally for the writer and returns it. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 168 |  |  |         Writers read from this queue and it is used exclusively for a given | 
            
                                                                                                            
                            
            
                                    
            
            
                | 169 |  |  |         writer. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 170 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 171 |  |  |         :param writer: The name of a writer plugin to register. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 172 |  |  |         :type writer: str | 
            
                                                                                                            
                            
            
                                    
            
            
                | 173 |  |  |         :rtype: threading.Queue | 
            
                                                                                                            
                            
            
                                    
            
            
                | 174 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 175 |  |  |         if writer in self.queues: | 
            
                                                                                                            
                            
            
                                    
            
            
                | 176 |  |  |             err = "duplicate writer registered: {0}" | 
            
                                                                                                            
                            
            
                                    
            
            
                | 177 |  |  |             raise ValueError(err.format(writer)) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 178 |  |  |         qobj = Queue(maxsize=self.max_queue) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 179 |  |  |         self.queues[writer] = qobj | 
            
                                                                                                            
                            
            
                                    
            
            
                | 180 |  |  |         return qobj | 
            
                                                                                                            
                            
            
                                    
            
            
                | 181 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 182 |  |  |     def deregister(self, writer): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 183 |  |  |         """De-Register the writer plugin. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 184 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 185 |  |  |         This removes the writers queue. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 186 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 187 |  |  |         :param writer: The name of a writer plugin to register. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 188 |  |  |         :type writer: str | 
            
                                                                                                            
                            
            
                                    
            
            
                | 189 |  |  |         :rtype: threading.Queue | 
            
                                                                                                            
                            
            
                                    
            
            
                | 190 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 191 |  |  |         if writer not in self.queues: | 
            
                                                                                                            
                            
            
                                    
            
            
                | 192 |  |  |             return | 
            
                                                                                                            
                            
            
                                    
            
            
                | 193 |  |  |         del(self.queues[writer]) | 
                            
                    |  |  |  | 
                                                                                        
                                                                                     | 
            
                                                                                                            
                            
            
                                    
            
            
                | 194 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 195 |  |  |     @abstractmethod | 
            
                                                                                                            
                            
            
                                    
            
            
                | 196 |  |  |     def flush(self): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 197 |  |  |         """Return any partially rendered metrics. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 198 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 199 |  |  |         This is useful for eg. during shutdown when there may be | 
            
                                                                                                            
                            
            
                                    
            
            
                | 200 |  |  |         partially rendered chunks of metrics to send. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 201 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 202 |  |  |         Subclasses for specific backends can define this method when | 
            
                                                                                                            
                            
            
                                    
            
            
                | 203 |  |  |         appropriate. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 204 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 205 |  |  |         raise NotImplementedError("process must be defined by a subclass") | 
            
                                                                                                            
                            
            
                                    
            
            
                | 206 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 207 |  |  |     @abstractmethod | 
            
                                                                                                            
                            
            
                                    
            
            
                | 208 |  |  |     def process(self, rset): | 
            
                                                                                                            
                            
            
                                    
            
            
                | 209 |  |  |         """Render a result set into our supported format and enqueue it. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 210 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 211 |  |  |         Subclasses for specific backends must define this method. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 212 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 213 |  |  |         :param rset: A :class:`ResultSet` object | 
            
                                                                                                            
                            
            
                                    
            
            
                | 214 |  |  |         :type rset: :class:`ResultSet` | 
            
                                                                                                            
                            
            
                                    
            
            
                | 215 |  |  |         """ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 216 |  |  |         raise NotImplementedError("process must be defined by a subclass") | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 217 |  |  |  | 
            
                                                        
            
                                    
            
            
                | 218 |  |  |     @abstractmethod | 
            
                                                        
            
                                    
            
            
                | 219 |  |  |     def process_many(self, rsets): | 
            
                                                        
            
                                    
            
            
                | 220 |  |  |         """Render result sets into our supported format and enqueue. | 
            
                                                        
            
                                    
            
            
                | 221 |  |  |  | 
            
                                                        
            
                                    
            
            
                | 222 |  |  |         Subclasses for specific backends must define this method. | 
            
                                                        
            
                                    
            
            
                | 223 |  |  |  | 
            
                                                        
            
                                    
            
            
                | 224 |  |  |         :param rsets: An iterable of :class:`ResultSet` objects | 
            
                                                        
            
                                    
            
            
                | 225 |  |  |         :type rsets: iterable(:class:`ResultSet`) | 
            
                                                        
            
                                    
            
            
                | 226 |  |  |         """ | 
            
                                                        
            
                                    
            
            
                | 227 |  |  |         raise NotImplementedError("process must be defined by a subclass") |