streamdrill core with the exponential decay trend and some helper functions to store and load the data
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README.md

streamdrill-core library

Version 1.0 (initial public release)

This is the core streamdrill functionality. It contains the exponential decay trend and some helper functions to store and load the data.

Further information on streamdrill can be found on https://streamdrill.com/

BUILDING

This is a standard maven project, so type mvn package to create the jar file.

In order to use the library in your project, add the following dependencies to your pom.xml and install it into your local repository (mvn install):

<dependency>
    <groupId>streamdrill</groupId>
    <artifactId>streamdrill-core</artifactId>
    <version>1.0</version>
</dependency>

streamdrill is written in Scala and currently uses version 2.11.2.

OVERVIEW

The main class in the package is ExpDecayTrend in streamdrill.core. It allows you to accumulate counts over a given half time for millions of objects in parallel. At construction, you specify the maximum number of objects you want to track at in the trend. If there occur more elements, the least active ones are replaced in the trend to make place for the new elements.

In addition, you can defined secondary indices, which allow you to drill down on the trends to look for subtrends in your data.

Here is simple example which creates a trend, pushes some data into it and then queries the trend:

  val t = new ExpDecayTrend[Long](1000, 1000L)
  ...
  t.update(number, timestamp)
  ...
  val result = t.query(numberOfElements)
  ...
  val count = t.score(number)

For defining a secondary index, you have to define an IndexMap which maps an entry to the value you want to index on.

See the "examples" directory for Scala scripts.

LICENSE

Copyright (c) 2015, streamdrill UG (haftungsbeschränkt) All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.