pyformance 0.3.4
Performance metrics, based on Coda Hale's Yammer metrics
License: Apache 2.0

# PyFormance

    pip install pyformance

A Python port of the core portion of a [Java Metrics library by Coda Hale](http://metrics.dropwizard.io/), with inspiration by [YUNOMI - Y U NO MEASURE IT?](https://github.com/richzeng/yunomi)

PyFormance is a toolset for performance measurement and statistics, with a signaling mechanism that allows to issue events in cases of unexpected behavior

## Core Features

### Gauge
A gauge metric is an instantaneous reading of a particular value.

### Counter
Simple interface to increment and decrement a value. For example, this can be used to measure the total number of jobs sent to the queue, as well as the pending (not yet complete) number of jobs in the queue. Simply increment the counter when an operation starts and decrement it when it completes.

### Meter
Measures the rate of events over time. Useful to track how often a certain portion of your application gets requests so you can set resources accordingly. Tracks the mean rate (the overall rate since the meter was reset) and the rate statistically significant regarding only events that have happened in the last 1, 5, and 15 minutes (Exponentally weighted moving average).

### Histogram
Measures the statistical distribution of values in a data stream. Keeps track of minimum, maximum, mean, standard deviatoin, etc. It also measures median, 75th, 90th, 95th, 98th, 99th, and 99.9th percentiles. An example use case would be for looking at the number of daily logins for 99 percent of your days, ignoring outliers.

### Timer
A useful combination of the Meter and the Histogram letting you measure the rate that a portion of code is called and a distribution of the duration of an operation. You can see, for example, how often your code hits the database and how long those operations tend to take.

### Regex Grouping
Useful when working with APIs. A RegexRegistry allows to group API calls and measure from a single location instead of having to define different timers in different places.

    >>> from pyformance.registry import RegexRegistry
    >>> reg = RegexRegistry(pattern='^/api/(?P<model>)/\d+/(?P<verb>)?$')
    >>> def rest_api_request(path):
    ...     with reg.timer(path).time():
    ...         # do stuff
    >>> print reg.dump_metrics()

## Reporters
### Hosted Graphite Reporter
A simple call which will periodically push out your metrics to [Hosted Graphite](https://www.hostedgraphite.com/) 
using the HTTP Interface. 

    registry = MetricsRegistry()	
    #Push metrics contained in registry to hosted graphite every 10s for the account specified by Key
	reporter = HostedGraphiteReporter(registry, 10, "XXXXXXXX-XXX-XXXXX-XXXX-XXXXXXXXXX")
    # Some time later we increment metrics
    histogram = registry.histogram("test.histogram")
    histogram.add(0)
	histogram.add(10)
	histogram.add(25)

### Carbon Reporter
A simple call which will periodically push out your metrics to graphite using the Carbon TCP Interface (line protocol).

    registry = MetricsRegistry()	
    #Push metrics contained in registry to graphite every 10s
    reporter = CarbonReporter(registry, reporting_interval=10, prefix="my-host", server="graphite-host", port=2003)
    reporter.start()
    
    # Some time later we increment metrics
    histogram = registry.histogram("test.histogram")
    histogram.add(0)
	histogram.add(10)
	histogram.add(25)
	
### OpenTSDB Reporter
Declare a reporter to push your metrics to the OpenTSDB API

    registry = MetricsRegistry()	
    reporter = OpenTSDBReporter(registry=registry,
                                reporting_interval=10,
                                prefix="my-host",
                                url="http://opentsdb.com/api/put",
                                application_name="appname",
                                write_key="writekey")
    reporter.start()


## Examples
### Decorators
The simplest and easiest way to use the PyFormance library.
##### Counter
You can use the 'count_calls' decorator to count the number of times a function is called.

    >>> from pyformance import counter, count_calls
    >>> @count_calls
    ... def test():
    ...     pass
    ... 
    >>> for i in range(10):
    ...     test()
    ... 
    >>> print counter("test_calls").get_count()
    10

##### Timer
You can use the 'time_calls' decorator to time the execution of a function and get distributtion data from it.

    >>> import time
    >>> from pyformance import timer, time_calls
    >>> @time_calls
    ... def test():
    ...     time.sleep(0.1)
    ... 
    >>> for i in range(10):
    ...     test()
    ... 
    >>> print timer("test_calls").get_mean()
    0.100820207596

### With statement
You can also use a timer using the with statement
##### Timer

    >>> import time
    >>> from pyformance import timer
    >>> with timer("test").time():
    ...    time.sleep(0.1)
    >>> print timer("test").get_mean()
    0.10114598274230957
    

## Development

The unit tests are run with [Tox](https://tox.readthedocs.org/en/latest/).

    pip install tox
    tox