0.7.0 Jul 29, 2016: SerDe API changes; Added MemoryMappedFile

Quantiles and FrequentItems Sketches:

• API changes to ArrayOfDoublesSerDe, ArrayOfItemsSerDe, ArrayOfLongsSerDe, ArrayOfStringsSerDe, ArrayOfUtf16StringsSerDe
  • Changed the SerDe TYPE, which was a static final constant, quite fragile from a maintenance point-of-view, and had to be assigned by the class developer.
  • TYPE has been changed to a more robust TypeID, which is automatically assigned using hashCode() based on the to a SerDe class and can be overridden by the SerDe class developer.
    This is used to detect incorrect SerDe instances. Refer to the Javadocs and code documentation of ArrayOfItemsSerDe.
• Corrected problem of downsampling with quantiles/Union: If you set k to a lower value, it was ignored with the first sketch update with a larger k.

All Sketches:

Changed the leaf-node classes to final. These classes are not designed to be extended.

Static analyzers

• Ran FindBugs, which found a few minor coding issues, which have been corrected.
• Running PMD and Checkstyle found a lot of "style" issues. All of the style issues that I agree with have been corrected.
• The /tools directory has a FindBugsExcludeFilter.xml and a SketchesCheckstyle.xml that you can use to run these static checkers yourself.
• They are not yet integrated into the maven pom.xml.

Memory Package

• Added MemoryMappedFile to the Memory package.
• This capability allows mapping a file, which can be larger than 2GB, into native memory and the ability to write any changes back to that file.
• It is similar to, but much simpler than Java's FileChannel.map() function that returns a MappedByteBuffer, which is restricted to files less than 2GB.
• This capability should be considered experimental and is not thread safe.