plumd.Result.record_metrics() - Code Metrics - Inspection of "removed elastic writer (may re-add in future), mis..." - s4z/plumd - Measure and Improve Code Quality continuously with Scrutinizer

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by Kenny

created 2016-02-20 16:27 UTC

plumd.Result.record_metrics() A

↳ Parent: plumd.ResultSet

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loc	14
rs	9.4285

# -*- coding: utf-8 -*-
"""There are many differences in the various time series databases. Plumd is
designed to support multiple backends using the classes defined here to
represent metrics in a uniform way:

    ResultSet - a collection of one or more Results from a call to poll()
    Result - a measurement of a single thing eg. disk free=0.0,used=100.0
    Meta - metadata associated with a Result eg. dev=sda1
    Int/Float/String/Boolean/Gauge/Rate/Counter/Timer - primitives for above

The ResultSet class is used to encapsulate all of the measurements taken
during a plugins poll() call and uses a single timestamp for that poll.

The Result class is used to encapsulate a single measurement - for example
measuring cpu utilization may result in idle, user, system etc values. These
would be recorded in a single Result object. In addition the Result class
allows for arbitrary metadata to be associated with a Result - eg. when
recording disk space there may be used, free, total however also metadata such
as dev=sda1 to associate the measurements with a specific block device.

The Meta class is used to encapsulate arbitrary metadata. The Result class
uses it to associate metadata with a measurement however it can also be used
for example to describe host level metadata (eg. hostname=<hostname>). The
Meta class allows writer plugins such as graphite to render the metadata as
part of the metric path (eg. servers.host.<hostname>.disk.used.dev.<device>) -
if there was no distiction between metadata key=value and metric key=value this
would not be possible. Also, the Meta class ensures that metadata keys are
unique.

The _Metrics classes are used to allow plumd to render metrics in a specific
format. For example influxdb wants integer values to end with an i when sending
via their line protocol. The various _Metric classes force the plugin to
explicitly say what each metric is (eg. Int, Float, String, Boolean, Counter,
Gauge, Timer, etc). Metrics are defined as namedtuples for reduced memory
utilization.

The Render class is an abstract base class that writer plugins can subclass. The
render() function needs to be defined so that it returns a formatted metric. A
writer plugin would then instantiate the subclassed Render and use it to record
formatted metrics an each push() call. It can then step through the passed
metrics in chunks and send them to its backend. Having the metric types defined
explicitly allows the writers renderer to format metrics for arbitrary backends.


.. moduleauthor:: Kenny Freeman <[email protected]>

"""

__author__ = 'Kenny Freeman'
__email__ = '[email protected]'
__version__ = '0.3.3'
__license__     = "ISCL"
__docformat__   = 'reStructuredText'

import abc
import logging
import inspect
import collections

import arrow # pip install arrow


DEFAULT_CONFIG = {
    'log.level':        "warn",               # crit, error, warn, info, debug
    'config.file':      "/etc/plumd.yaml",    # path to main configuration file
    'config.plugins':   "/etc/plumd.conf.d/", # path to the plugin confs
    'delay.startup':    1,                    # random delay for plugin start
    'delay.poll':       1,                    # random delay for first poll()
    'poll.interval':    15,                   # interval of reader poll() calls
    'max.queue':        512,                  # maximum size of internal queues
    'meta':             {},                   # key=value's for all metrics
    'auto.hostname':    True                  # set and use hostname in meta
}


LOG_LEVELS = {
    'crit':  logging.CRITICAL,
    'error': logging.ERROR,
    'warn':  logging.WARN,
    'info':  logging.INFO,
    'debug': logging.DEBUG
}


class DuplicatePlugin(Exception):
    """Two or more plugins with the same id were defined."""
    pass


class PluginNotFoundError(Exception):
    """Configured plugin file, module or class not found during load."""
    pass


class PluginLoadError(Exception):
    """Exception(s) were raised during plugin loading."""
    pass


class ConfigError(Exception):
    """Invalid configuration."""
    pass


#_Metric : the base class of all metric primitives is a named tuple.
_Metric = collections.namedtuple('metric', ['name', 'value'])


class Int(_Metric):
    """An integer metric - ensures the value passed is an int.

    raises:
        ValueError if the passed value doesn't cast properly to int

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: int
    :raises: ValueError
    """

    def __new__(self, name, value):
        value = int(value)
        self = super(Int, self).__new__(self, name, value)
        return self


class Float(_Metric):
    """A float metric.

    raises:
        ValueError if the passed value doesn't cast properly to float

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: float
    :raises: ValueError
    """

    def __new__(self, name, value):
        value = float(value)
        self = super(Float, self).__new__(self, name, value)
        return self


class String(_Metric):
    """A string metric.

    raises:
        ValueError if the passed value doesn't cast properly to str

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: str
    :raises: ValueError
    """

    def __new__(self, name, value):
        value = str(value)
        self = super(String, self).__new__(self, name, value)
        return self


class Boolean(_Metric):
    """A boolean metric.

    raises:
        ValueError if the passed value doesn't cast properly to bool

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: bool
    :raises: ValueError
    """

    def __new__(self, name, value):
        value = bool(value)
        self = super(Boolean, self).__new__(self, name, value)
        return self


class Gauge(Float):
    """A gauge value - this is always a Float value.


    raises:
        ValueError if the passed value doesn't cast properly to int

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: float
    :raises: ValueError
    """
    pass


class Counter(Int):
    """A metric that counts things - this is always an Integer value.


    raises:
        ValueError if the passed value doesn't cast properly to int

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: int
    :raises: ValueError
    """
    pass


class Rate(Float):
    """A metric that describes a rate - this is always a Float.

    raises:
        ValueError if the passed value doesn't cast properly to float

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: float
    :raises: ValueError
    """
    pass


class Timer(Float):
    """A metric that describes a timer value - this is always a Float.

    raises:
        ValueError if the passed value doesn't cast properly to float

    :param name: The name of the metric
    :type name: str
    :param value: The recorded value of the metric
    :type value: float
    :raises: ValueError
    """
    pass


class Meta(object):
    """Encapsulates generic key=value metadata however ensures that the
    values recorded are one of the four supported base types of Int, Float,
    String and Boolean. Also ensures keys are unique.

    :param metas: Variable list of values.
    :type metas: Int or Float or String or Boolean
    :raises: ValueError if metas is not one of the expected types or if any of
        the keys already exist.
    """
    __slots__ = [ '_meta', 'types' ]
    types = [Int, Float, String, Boolean]

    def __init__(self):
        self._meta = {}


    def __str__(self):
        """Return a human readable str.
        :rtype: str"""
        s = "Meta(items={0})"
        return s.format(sorted(self._meta.keys()))


    def __repr__(self):
        """Return a human readable str.
        :rtype: str"""
        s = "Meta(items={0})"
        return s.format(sorted(self._meta.keys()))


    @property
    def nkeys(self):
        """Return the number of key=value pairs."""
        return len(self._meta.keys())


    @property
    def keys(self):
        """Return a (by default) sorted list of metadata keys.

        :rtype: :class:`list`"""
        return sorted(self._meta.keys())

    @property
    def items(self):
        """Return a (by default) sorted list of (key, value) tuples.

        :rtype: :class:`list`"""
        mlist = [(k, self._meta[k]) for k in sorted(self._meta.keys())]
        return mlist


    def add(self, val):
        """Record a value to our metadata.

        :param val: The value to add.
        :type val: Int or Float or String or Boolean
        :raises: ValueError if val is an unexpected type or the
            keys already exist.
        """
        if val.__class__ not in self.types:
            cname = val.__class__.__name__
            err = "Class not supported: class: {0} : value: {1}"
            raise ValueError(err.format(cname, val))
        # using indexes: 0 => name, 1 => value
        if val[0] not in self._meta:
            self._meta[val[0]] = val
            return
        raise ValueError("key exists: {0}".format(val[0]))


    def add_list(self, vals):
        """Record value(s) to our metadata.

        :param vals: The value(s) to add - variable list of values.
        :type vals: Int or Float or String or Boolean
        :raises: ValueError if any values are unexpected types or any of the
            keys already exist.
        """
        for val in vals:
            if val.__class__ not in self.types:
                cname = val.__class__.__name__
                err = "Class not supported: class: {0} : value: {1}"
                raise ValueError(err.format(cname, val))
            # using indexes: 0 => name, 1 => value
            if val[0] not in self._meta:
                self._meta[val[0]] = val
                continue
            raise ValueError("key exists: {0}".format(val[0]))


class Result(object):
    """Encapsulates a set of metrics and an optional Meta metadata object. Does
    not check for duplicate metrics in the same Result.

    :param name: The name of the result eg. cpu
    :type name: str
    :param metrics: Variable list of optional metrics
    :type metrics: Int or Float or String or Boolean or Gauge or Counter
        or Rate or Timer
    """
    __slots__ = [ '_name', '_metrics', '_meta', 'types' ]
    types = [Int, Float, String, Boolean, Gauge, Counter, Rate, Timer]

    def __init__(self, name, metrics):
        """Create a new Result."""
        self._name = name
        for metric in metrics:
            mclass = metric.__class__
            if mclass not in self.types:
                err = "Class not supported: class: {0} : metric: {1}"
                raise ValueError(err.format(mclass.__name__, metric))
        self._metrics = list(metrics)
        self._meta = Meta()


    def __str__(self):
        """Return a human readable str.
        :rtype: str"""
        s = "Result(name={0}, metrics={1})"
        return s.format(len(self._name), self._metrics)


    def __repr__(self):
        """Return a human readable str.
        :rtype: str"""
        s = "Result(name={0}, metrics={1})"
        return s.format(len(self._name), self._metrics)


    @property
    def name(self):
        """Return the Result name."""
        return self._name


    @property
    def metrics(self):
        """Return the Results list of metrics."""
        return self._metrics


    @property
    def meta(self):
        """Return the results metadata object."""
        return self._meta


class ResultSet(object):
    """A class to encapsulate a series of measurement Results during a plugins
    poll() call. Each poll() must return a ResultSet object.

    The class has a list of Result objects and a timestamp. The timestamp
    is set to the current UTC time when the object is created. This is done
    since each poll() call should normally complete within ms or us and the
    target audience for the recorded metrics are eg. grafana graphs and
    system alerts with resolutions down to 1 second typically. The difference
    in time between the first recorded metric and last is generally going to
    be much less than 1 second.

    :Example:

    >>>import plumd
    >>>metrics = [ plumd.Float("idle", 0.0), plumd.Float("user", 100.0) ]
    >>>res = Result("cpu", metrics)
    >>>rset = ResultSet(res)

    >>>metrics = [ plumd.Float("free", 0.0), plumd.Float("used", 100.0) ]
    >>>res = Result("disk", metrics)
    >>>res.meta.add(plumd.String("dev", "sda1"))
    >>>rset = ResultSet(res)
    """
    __slots__ = [ '_results', '_time' ] # do this to save memory

    def __init__(self, *results):
        """Class to encapsulate a collection of metrics eg. from poll()."""
        self._results = list(results)
        self._time = arrow.utcnow()


    @property
    def time(self):
        """Return our timestamp.
        :rtype: float
        """
        return self._time


    @property
    def nresults(self):
        """Return the number of results recorded so far.
        :rtype: int
        """
        return len(self._results)


    @property
    def results(self):
        """Yields a tuple for each Result recorded in the format:

        ( time, result_name, result_meta, [metric, metric, metric] )

        :rtype: generator
        """
        for robj in self._results:
            yield (self._time, robj.name, robj.meta, robj.metrics)


    def __str__(self):
        """Return a human readable str.
        :rtype: str"""
        s = "ResultSet(results={0}, time={1})"
        return s.format(len(self._results), self._time.timestamp)


    def __repr__(self):
        """Return a human readable str.
        :rtype: str"""
        s = "ResultSet(results={0}, time={1})"
        return s.format(len(self._results), self._time.timestamp)


    def record(self, *results):
        """Record a variable list of results in this ResultSet. This design is
        based around the Influxdb concept of measurements and fields and
        diffrentiates between a metric key=value and a metadata key=value.

        Each result has a list of metric (key=value)s and a list of metadata
        (key=value)s. The ResultSet has a list of Results and an Arrow
        time object.

        :param results: variable list of Result objects
        :type results: Result
        """
        for robj in results:
            self._results.append(robj)


class Render(object):
    """A helper class to render metrics, buffer them and return chunks of
    metrics. Used as a superclass for the various metric writers (eg.
    influxdb, graphite, etc).

    The idea is to feed this object a ResultSet on each call to a writer
    plugins push() and then consume chunks of metrics from it until a full
    chunk cannot be returned.

    To use this, a writer plugin subclasses Render and defines the process
    method.The plugins implementation of process() should format the metrics it
    gets passed in a format suitable for sending to its backend and store them
    in the metrics dequeue.

    The plugin can then create an instance of it's render object and in push()
    simply call instance.process(results) and instance.get_chunk() to get the
    next chunk of metrics.

    On shutdown it can also call instance.get_chunk(partial=True) to get the
    remaining metrics. Normally it would want to fetch full batches of metrics.

    :param rconfig: config.Conf object passed from a writer plugin instance
    :type rconfig: :class:`config.Conf`
    """
    __metaclass__ = abc.ABCMeta

    def __init__(self, rconfig):
        # Use a double ended queue with a maximum size
        maxlen = rconfig.get('maxqueue', default=8192)
        self.metrics = collections.deque(maxlen=maxlen)
        # define a metadata object and copy in any configured host metadata
        self.meta = Meta()
        clookup = {
            int: Int,
            float: Float,
            str: String,
            bool: Boolean
        }
        for key, val in rconfig.get('meta', default={}).items():
            if val.__class__ not in clookup:
                args = ( key, val.__class__.__name__ )
                err = "host metadata: unsupported type: {0}={1}".format(*args)
                raise ValueError(err)
            self.meta.add(clookup[val.__class__](key, val))


    @abc.abstractmethod
    def process(self, rset):
        """Record a result set in our backends format. Subclasses for specific
        backends must define this method.

        :param rset: A :class:`ResultSet` object
        :type rset: :class:`ResultSet`
        """
        raise NotImplementedError("process must be defined by a subclass")


    def next_batch(self, bsize, partial=None):
        """Return the next full batch of metrics - if partial is True and
        self.metrics contains less than nmetrics metrics then return
        the remaining metrics.

        Returns a tuple of (queue size, the number of metrics returned,
        list of metrics).

        :param bsize: the batch size of metrics to return
        :type bsize: int
        :param partial: return less than chunk_size metrics if not enough
        :type partial: bool
        :rtype: tuple(int, int, list)
        """
        qlen = len(self.metrics)
        mlist = []
        if qlen >= bsize:
            mlist = [ self.metrics.popleft() for i in range(0, bsize) ]
            qlen = len(self.metrics)
        elif partial:
            mlist = [ self.metrics.popleft() for i in range(0, qlen) ]
            qlen = len(self.metrics)
        return ( qlen, len(mlist), mlist )


1			# -- coding: utf-8 --
2			"""There are many differences in the various time series databases. Plumd is
3			designed to support multiple backends using the classes defined here to
4			represent metrics in a uniform way:
5
6			ResultSet - a collection of one or more Results from a call to poll()
7			Result - a measurement of a single thing eg. disk free=0.0,used=100.0
8			Meta - metadata associated with a Result eg. dev=sda1
9			Int/Float/String/Boolean/Gauge/Rate/Counter/Timer - primitives for above
10
11			The ResultSet class is used to encapsulate all of the measurements taken
12			during a plugins poll() call and uses a single timestamp for that poll.
13
14			The Result class is used to encapsulate a single measurement - for example
15			measuring cpu utilization may result in idle, user, system etc values. These
16			would be recorded in a single Result object. In addition the Result class
17			allows for arbitrary metadata to be associated with a Result - eg. when
18			recording disk space there may be used, free, total however also metadata such
19			as dev=sda1 to associate the measurements with a specific block device.
20
21			The Meta class is used to encapsulate arbitrary metadata. The Result class
22			uses it to associate metadata with a measurement however it can also be used
23			for example to describe host level metadata (eg. hostname=<hostname>). The
24			Meta class allows writer plugins such as graphite to render the metadata as
25			part of the metric path (eg. servers.host.<hostname>.disk.used.dev.<device>) -
26			if there was no distiction between metadata key=value and metric key=value this
27			would not be possible. Also, the Meta class ensures that metadata keys are
28			unique.
29
30			The _Metrics classes are used to allow plumd to render metrics in a specific
31			format. For example influxdb wants integer values to end with an i when sending
32			via their line protocol. The various _Metric classes force the plugin to
33			explicitly say what each metric is (eg. Int, Float, String, Boolean, Counter,
34			Gauge, Timer, etc). Metrics are defined as namedtuples for reduced memory
35			utilization.
36
37			The Render class is an abstract base class that writer plugins can subclass. The
38			render() function needs to be defined so that it returns a formatted metric. A
39			writer plugin would then instantiate the subclassed Render and use it to record
40			formatted metrics an each push() call. It can then step through the passed
41			metrics in chunks and send them to its backend. Having the metric types defined
42			explicitly allows the writers renderer to format metrics for arbitrary backends.
43
44
45			.. moduleauthor:: Kenny Freeman <[email protected]>
46
47			"""
48
49			__author__ = 'Kenny Freeman'
50			__email__ = '[email protected]'
51			__version__ = '0.3.3'
52			__license__ = "ISCL"
53			__docformat__ = 'reStructuredText'
54
55			import abc
56			import logging
57			import inspect
58			import collections
59
60			import arrow # pip install arrow
61
62
63			DEFAULT_CONFIG = {
64			'log.level': "warn", # crit, error, warn, info, debug
65			'config.file': "/etc/plumd.yaml", # path to main configuration file
66			'config.plugins': "/etc/plumd.conf.d/", # path to the plugin confs
67			'delay.startup': 1, # random delay for plugin start
68			'delay.poll': 1, # random delay for first poll()
69			'poll.interval': 15, # interval of reader poll() calls
70			'max.queue': 512, # maximum size of internal queues
71			'meta': {}, # key=value's for all metrics
72			'auto.hostname': True # set and use hostname in meta
73			}
74
75
76			LOG_LEVELS = {
77			'crit': logging.CRITICAL,
78			'error': logging.ERROR,
79			'warn': logging.WARN,
80			'info': logging.INFO,
81			'debug': logging.DEBUG
82			}
83
84
85			class DuplicatePlugin(Exception):
86			"""Two or more plugins with the same id were defined."""
87			pass
88
89
90			class PluginNotFoundError(Exception):
91			"""Configured plugin file, module or class not found during load."""
92			pass
93
94
95			class PluginLoadError(Exception):
96			"""Exception(s) were raised during plugin loading."""
97			pass
98
99
100			class ConfigError(Exception):
101			"""Invalid configuration."""
102			pass
103
104
105			#_Metric : the base class of all metric primitives is a named tuple.
106			_Metric = collections.namedtuple('metric', ['name', 'value'])
107
108
109			class Int(_Metric):
110			"""An integer metric - ensures the value passed is an int.
111
112			raises:
113			ValueError if the passed value doesn't cast properly to int
114
115			:param name: The name of the metric
116			:type name: str
117			:param value: The recorded value of the metric
118			:type value: int
119			:raises: ValueError
120			"""
121
122			def __new__(self, name, value):
123			value = int(value)
124			self = super(Int, self).__new__(self, name, value)
125			return self
126
127
128			class Float(_Metric):
129			"""A float metric.
130
131			raises:
132			ValueError if the passed value doesn't cast properly to float
133
134			:param name: The name of the metric
135			:type name: str
136			:param value: The recorded value of the metric
137			:type value: float
138			:raises: ValueError
139			"""
140
141			def __new__(self, name, value):
142			value = float(value)
143			self = super(Float, self).__new__(self, name, value)
144			return self
145
146
147			class String(_Metric):
148			"""A string metric.
149
150			raises:
151			ValueError if the passed value doesn't cast properly to str
152
153			:param name: The name of the metric
154			:type name: str
155			:param value: The recorded value of the metric
156			:type value: str
157			:raises: ValueError
158			"""
159
160			def __new__(self, name, value):
161			value = str(value)
162			self = super(String, self).__new__(self, name, value)
163			return self
164
165
166			class Boolean(_Metric):
167			"""A boolean metric.
168
169			raises:
170			ValueError if the passed value doesn't cast properly to bool
171
172			:param name: The name of the metric
173			:type name: str
174			:param value: The recorded value of the metric
175			:type value: bool
176			:raises: ValueError
177			"""
178
179			def __new__(self, name, value):
180			value = bool(value)
181			self = super(Boolean, self).__new__(self, name, value)
182			return self
183
184
185			class Gauge(Float):
186			"""A gauge value - this is always a Float value.
187
188
189			raises:
190			ValueError if the passed value doesn't cast properly to int
191
192			:param name: The name of the metric
193			:type name: str
194			:param value: The recorded value of the metric
195			:type value: float
196			:raises: ValueError
197			"""
198			pass
199
200
201			class Counter(Int):
202			"""A metric that counts things - this is always an Integer value.
203
204
205			raises:
206			ValueError if the passed value doesn't cast properly to int
207
208			:param name: The name of the metric
209			:type name: str
210			:param value: The recorded value of the metric
211			:type value: int
212			:raises: ValueError
213			"""
214			pass
215
216
217			class Rate(Float):
218			"""A metric that describes a rate - this is always a Float.
219
220			raises:
221			ValueError if the passed value doesn't cast properly to float
222
223			:param name: The name of the metric
224			:type name: str
225			:param value: The recorded value of the metric
226			:type value: float
227			:raises: ValueError
228			"""
229			pass
230
231
232			class Timer(Float):
233			"""A metric that describes a timer value - this is always a Float.
234
235			raises:
236			ValueError if the passed value doesn't cast properly to float
237
238			:param name: The name of the metric
239			:type name: str
240			:param value: The recorded value of the metric
241			:type value: float
242			:raises: ValueError
243			"""
244			pass
245
246
247			class Meta(object):
248			"""Encapsulates generic key=value metadata however ensures that the
249			values recorded are one of the four supported base types of Int, Float,
250			String and Boolean. Also ensures keys are unique.
251
252			:param metas: Variable list of values.
253			:type metas: Int or Float or String or Boolean
254			:raises: ValueError if metas is not one of the expected types or if any of
255			the keys already exist.
256			"""
257			__slots__ = [ '_meta', 'types' ]
258			types = [Int, Float, String, Boolean]
259
260			def __init__(self):
261			self._meta = {}
262
263
264			def __str__(self):
265			"""Return a human readable str.
266			:rtype: str"""
267			s = "Meta(items={0})"
268			return s.format(sorted(self._meta.keys()))
269
270
271			def __repr__(self):
272			"""Return a human readable str.
273			:rtype: str"""
274			s = "Meta(items={0})"
275			return s.format(sorted(self._meta.keys()))
276
277
278			@property
279			def nkeys(self):
280			"""Return the number of key=value pairs."""
281			return len(self._meta.keys())
282
283
284			@property
285			def keys(self):
286			"""Return a (by default) sorted list of metadata keys.
287
288			:rtype: :class:`list`"""
289			return sorted(self._meta.keys())
290
291			@property
292			def items(self):
293			"""Return a (by default) sorted list of (key, value) tuples.
294
295			:rtype: :class:`list`"""
296			mlist = [(k, self._meta[k]) for k in sorted(self._meta.keys())]
297			return mlist
298
299
300			def add(self, val):
301			"""Record a value to our metadata.
302
303			:param val: The value to add.
304			:type val: Int or Float or String or Boolean
305			:raises: ValueError if val is an unexpected type or the
306			keys already exist.
307			"""
308			if val.__class__ not in self.types:
309			cname = val.__class__.__name__
310			err = "Class not supported: class: {0} : value: {1}"
311			raise ValueError(err.format(cname, val))
312			# using indexes: 0 => name, 1 => value
313			if val[0] not in self._meta:
314			self._meta[val[0]] = val
315			return
316			raise ValueError("key exists: {0}".format(val[0]))
317
318
319			def add_list(self, vals):
320			"""Record value(s) to our metadata.
321
322			:param vals: The value(s) to add - variable list of values.
323			:type vals: Int or Float or String or Boolean
324			:raises: ValueError if any values are unexpected types or any of the
325			keys already exist.
326			"""
327			for val in vals:
328			if val.__class__ not in self.types:
329			cname = val.__class__.__name__
330			err = "Class not supported: class: {0} : value: {1}"
331			raise ValueError(err.format(cname, val))
332			# using indexes: 0 => name, 1 => value
333			if val[0] not in self._meta:
334			self._meta[val[0]] = val
335			continue
336			raise ValueError("key exists: {0}".format(val[0]))
337
338
339			class Result(object):
340			"""Encapsulates a set of metrics and an optional Meta metadata object. Does
341			not check for duplicate metrics in the same Result.
342
343			:param name: The name of the result eg. cpu
344			:type name: str
345			:param metrics: Variable list of optional metrics
346			:type metrics: Int or Float or String or Boolean or Gauge or Counter
347			or Rate or Timer
348			"""
349			__slots__ = [ '_name', '_metrics', '_meta', 'types' ]
350			types = [Int, Float, String, Boolean, Gauge, Counter, Rate, Timer]
351
352			def __init__(self, name, metrics):
353			"""Create a new Result."""
354			self._name = name
355			for metric in metrics:
356			mclass = metric.__class__
357			if mclass not in self.types:
358			err = "Class not supported: class: {0} : metric: {1}"
359			raise ValueError(err.format(mclass.__name__, metric))
360			self._metrics = list(metrics)
361			self._meta = Meta()
362
363
364			def __str__(self):
365			"""Return a human readable str.
366			:rtype: str"""
367			s = "Result(name={0}, metrics={1})"
368			return s.format(len(self._name), self._metrics)
369
370
371			def __repr__(self):
372			"""Return a human readable str.
373			:rtype: str"""
374			s = "Result(name={0}, metrics={1})"
375			return s.format(len(self._name), self._metrics)
376
377
378			@property
379			def name(self):
380			"""Return the Result name."""
381			return self._name
382
383
384			@property
385			def metrics(self):
386			"""Return the Results list of metrics."""
387			return self._metrics
388
389
390			@property
391			def meta(self):
392			"""Return the results metadata object."""
393			return self._meta
394
395
396			class ResultSet(object):
397			"""A class to encapsulate a series of measurement Results during a plugins
398			poll() call. Each poll() must return a ResultSet object.
399
400			The class has a list of Result objects and a timestamp. The timestamp
401			is set to the current UTC time when the object is created. This is done
402			since each poll() call should normally complete within ms or us and the
403			target audience for the recorded metrics are eg. grafana graphs and
404			system alerts with resolutions down to 1 second typically. The difference
405			in time between the first recorded metric and last is generally going to
406			be much less than 1 second.
407
408			:Example:
409
410			>>>import plumd
411			>>>metrics = [ plumd.Float("idle", 0.0), plumd.Float("user", 100.0) ]
412			>>>res = Result("cpu", metrics)
413			>>>rset = ResultSet(res)
414
415			>>>metrics = [ plumd.Float("free", 0.0), plumd.Float("used", 100.0) ]
416			>>>res = Result("disk", metrics)
417			>>>res.meta.add(plumd.String("dev", "sda1"))
418			>>>rset = ResultSet(res)
419			"""
420			__slots__ = [ '_results', '_time' ] # do this to save memory
421
422			def __init__(self, *results):
423			"""Class to encapsulate a collection of metrics eg. from poll()."""
424			self._results = list(results)
425			self._time = arrow.utcnow()
426
427
428			@property
429			def time(self):
430			"""Return our timestamp.
431			:rtype: float
432			"""
433			return self._time
434
435
436			@property
437			def nresults(self):
438			"""Return the number of results recorded so far.
439			:rtype: int
440			"""
441			return len(self._results)
442
443
444			@property
445			def results(self):
446			"""Yields a tuple for each Result recorded in the format:
447
448			( time, result_name, result_meta, [metric, metric, metric] )
449
450			:rtype: generator
451			"""
452			for robj in self._results:
453			yield (self._time, robj.name, robj.meta, robj.metrics)
454
455
456			def __str__(self):
457			"""Return a human readable str.
458			:rtype: str"""
459			s = "ResultSet(results={0}, time={1})"
460			return s.format(len(self._results), self._time.timestamp)
461
462
463			def __repr__(self):
464			"""Return a human readable str.
465			:rtype: str"""
466			s = "ResultSet(results={0}, time={1})"
467			return s.format(len(self._results), self._time.timestamp)
468
469
470			def record(self, *results):
471			"""Record a variable list of results in this ResultSet. This design is
472			based around the Influxdb concept of measurements and fields and
473			diffrentiates between a metric key=value and a metadata key=value.
474
475			Each result has a list of metric (key=value)s and a list of metadata
476			(key=value)s. The ResultSet has a list of Results and an Arrow
477			time object.
478
479			:param results: variable list of Result objects
480			:type results: Result
481			"""
482			for robj in results:
483			self._results.append(robj)
484
485
486			class Render(object):
487			"""A helper class to render metrics, buffer them and return chunks of
488			metrics. Used as a superclass for the various metric writers (eg.
489			influxdb, graphite, etc).
490
491			The idea is to feed this object a ResultSet on each call to a writer
492			plugins push() and then consume chunks of metrics from it until a full
493			chunk cannot be returned.
494
495			To use this, a writer plugin subclasses Render and defines the process
496			method.The plugins implementation of process() should format the metrics it
497			gets passed in a format suitable for sending to its backend and store them
498			in the metrics dequeue.
499
500			The plugin can then create an instance of it's render object and in push()
501			simply call instance.process(results) and instance.get_chunk() to get the
502			next chunk of metrics.
503
504			On shutdown it can also call instance.get_chunk(partial=True) to get the
505			remaining metrics. Normally it would want to fetch full batches of metrics.
506
507			:param rconfig: config.Conf object passed from a writer plugin instance
508			:type rconfig: :class:`config.Conf`
509			"""
510			__metaclass__ = abc.ABCMeta
511
512			def __init__(self, rconfig):
513			# Use a double ended queue with a maximum size
514			maxlen = rconfig.get('maxqueue', default=8192)
515			self.metrics = collections.deque(maxlen=maxlen)
516			# define a metadata object and copy in any configured host metadata
517			self.meta = Meta()
518			clookup = {
519			int: Int,
520			float: Float,
521			str: String,
522			bool: Boolean
523			}
524			for key, val in rconfig.get('meta', default={}).items():
525			if val.__class__ not in clookup:
526			args = ( key, val.__class__.__name__ )
527			err = "host metadata: unsupported type: {0}={1}".format(*args)
528			raise ValueError(err)
529			self.meta.add(clookup[val.__class__](key, val))
530
531
532			@abc.abstractmethod
533			def process(self, rset):
534			"""Record a result set in our backends format. Subclasses for specific
535			backends must define this method.
536
537			:param rset: A :class:`ResultSet` object
538			:type rset: :class:`ResultSet`
539			"""
540			raise NotImplementedError("process must be defined by a subclass")
541
542
543			def next_batch(self, bsize, partial=None):
544			"""Return the next full batch of metrics - if partial is True and
545			self.metrics contains less than nmetrics metrics then return
546			the remaining metrics.
547
548			Returns a tuple of (queue size, the number of metrics returned,
549			list of metrics).
550
551			:param bsize: the batch size of metrics to return
552			:type bsize: int
553			:param partial: return less than chunk_size metrics if not enough
554			:type partial: bool
555			:rtype: tuple(int, int, list)
556			"""
557			qlen = len(self.metrics)
558			mlist = []
559			if qlen >= bsize:
560			mlist = [ self.metrics.popleft() for i in range(0, bsize) ]
561			qlen = len(self.metrics)
562			elif partial:
563			mlist = [ self.metrics.popleft() for i in range(0, qlen) ]
564			qlen = len(self.metrics)
565			return ( qlen, len(mlist), mlist )
566

s4z / plumd

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