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# -*- coding: utf-8 -*- |
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""" |
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The Render class is used to "render" metrics into a specific format. |
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It is an abstract base class and must be sub-classed for each desired |
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metrics format. |
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eg. the graphite plaintext format is supported by GraphiteRenderPlain |
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which sub-classes Render and defines the process() and flush() methods. |
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.. moduleauthor:: Kenny Freeman <[email protected]> |
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""" |
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import collections |
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from plumd import Int, Float, String, Boolean, Render, Meta |
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from Queue import Queue |
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from abc import ABCMeta, abstractmethod |
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__author__ = 'Kenny Freeman' |
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__email__ = '[email protected]' |
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__version__ = '0.7' |
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__license__ = "ISCL" |
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__docformat__ = 'reStructuredText' |
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class BasicRender(Render): |
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"""A plugin that renders metrics and is also iterable. |
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:param rconfig: config.Conf object passed from a writer plugin instance |
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:type rconfig: :class:`config.Conf` |
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""" |
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__metaclass__ = ABCMeta |
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defaults = { |
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'meta': {} |
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} |
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def __init__(self, log, config): |
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"""Create a Render instance. |
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todo: fix me / complete this |
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:param log: A logger |
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:type log: logging.RootLogger |
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:param config: a plumd.config.Conf configuration helper instance. |
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:type config: plumd.config.Conf |
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""" |
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super(BasicRender, self).__init__(log, config) |
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# ensure default configuration is set |
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config.defaults(BasicRender.defaults) |
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# Use a double ended queue with a maximum size |
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self.metrics = collections.deque() |
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# define a metadata object and copy in any configured host metadata |
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self.meta = Meta() |
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clookup = { |
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int: Int, |
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float: Float, |
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str: String, |
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bool: Boolean |
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} |
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for entry in config.get('meta'): |
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for key, val in entry.items(): |
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if val.__class__ not in clookup: |
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args = (key, val.__class__.__name__) |
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err = "host metadata: unsupported type: {0}={1}".format(*args) |
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raise ValueError(err) |
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self.meta.add(clookup[val.__class__](key, val)) |
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self.buff = "" |
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def __str__(self): |
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"""Return our current metrics buffer.""" |
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return self.buff |
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def __repr__(self): |
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"""Return our current metrics buffer.""" |
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return self.buff |
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def get_metrics(self): |
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"""Return our deque of metrics. |
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:rtype: collections.deque |
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""" |
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raise NotImplementedError("process must be defined by a subclass") |
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def reset(self): |
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"""Clear our metrics buffer and deque.""" |
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self.metrics.clear() |
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self.buff = str() |
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@abstractmethod |
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def process(self, rset): |
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"""Render a result set into our supported format and enqueue it. |
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Subclasses for specific backends must define this method. |
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:param rset: A :class:`ResultSet` object |
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:type rset: :class:`ResultSet` |
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""" |
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raise NotImplementedError("process must be defined by a subclass") |
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@abstractmethod |
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def process_many(self, rsets): |
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"""Render result sets into our supported format and enqueue. |
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Subclasses for specific backends must define this method. |
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:param rsets: An iterable of :class:`ResultSet` objects |
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:type rsets: iterable(:class:`ResultSet`) |
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""" |
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raise NotImplementedError("process must be defined by a subclass") |
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class ChunkedRender(Render): |
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"""A plugin that renders metrics and is also iterable. |
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:param rconfig: config.Conf object passed from a writer plugin instance |
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:type rconfig: :class:`config.Conf` |
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""" |
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__metaclass__ = ABCMeta |
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defaults = { |
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# todo: move max items, bytes out of here into graphite render |
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'max_queue': 2048, # maxlen of deque used for metrics |
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'max_items': 64, # maximum number of items to send at once |
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'max_bytes': 1400, # maximum number of bytes to send at once |
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'meta': {} # metadata to add to each metric |
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} |
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def __init__(self, log, config): |
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"""Create a Render instance. |
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:param log: A logger |
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:type log: logging.RootLogger |
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:param config: a plumd.config.Conf configuration helper instance. |
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:type config: plumd.config.Conf |
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""" |
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super(ChunkedRender, self).__init__(log, config) |
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# ensure default configuration is set |
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config.defaults(ChunkedRender.defaults) |
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self.max_bytes = config.get('max_bytes') |
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self.max_items = config.get('max_items') |
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# Use a double ended queue with a maximum size |
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self.metrics = collections.deque(maxlen=config.get('max_queue')) |
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# define a metadata object and copy in any configured host metadata |
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self.meta = Meta() |
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clookup = { |
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int: Int, |
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float: Float, |
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str: String, |
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bool: Boolean |
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} |
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for entry in config.get('meta'): |
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for key, val in entry.items(): |
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if val.__class__ not in clookup: |
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args = (key, val.__class__.__name__) |
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err = "host metadata: unsupported type: {0}={1}".format(*args) |
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raise ValueError(err) |
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self.meta.add(clookup[val.__class__](key, val)) |
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self.queues = dict() |
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def register(self, writer): |
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"""Register the writer plugin name to read from this renderer. |
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This creates a queue internally for the writer and returns it. |
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Writers read from this queue and it is used exclusively for a given |
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writer. |
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:param writer: The name of a writer plugin to register. |
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:type writer: str |
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:rtype: threading.Queue |
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""" |
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if writer in self.queues: |
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err = "duplicate writer registered: {0}" |
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raise ValueError(err.format(writer)) |
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qobj = Queue(maxsize=self.max_queue) |
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self.queues[writer] = qobj |
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return qobj |
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def deregister(self, writer): |
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"""De-Register the writer plugin. |
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This removes the writers queue. |
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:param writer: The name of a writer plugin to register. |
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:type writer: str |
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:rtype: threading.Queue |
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""" |
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if writer not in self.queues: |
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return |
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del(self.queues[writer]) |
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@abstractmethod |
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def flush(self): |
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"""Return any partially rendered metrics. |
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This is useful for eg. during shutdown when there may be |
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partially rendered chunks of metrics to send. |
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Subclasses for specific backends can define this method when |
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appropriate. |
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""" |
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raise NotImplementedError("process must be defined by a subclass") |
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@abstractmethod |
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def process(self, rset): |
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"""Render a result set into our supported format and enqueue it. |
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Subclasses for specific backends must define this method. |
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:param rset: A :class:`ResultSet` object |
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:type rset: :class:`ResultSet` |
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""" |
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raise NotImplementedError("process must be defined by a subclass") |
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@abstractmethod |
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def process_many(self, rsets): |
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"""Render result sets into our supported format and enqueue. |
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Subclasses for specific backends must define this method. |
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:param rsets: An iterable of :class:`ResultSet` objects |
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:type rsets: iterable(:class:`ResultSet`) |
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""" |
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raise NotImplementedError("process must be defined by a subclass") |