Rework query handling

[frensing]

Rework of the query handling

Each Worker gets their own QueryHandler.

The updated config will have for example the following structure:

...
workers:
  - className: "WorkerName"
    queries:
      location: "path/to/file"
      format: "one-per-line"
      caching: true
      order: linear
      pattern:
        endpoint: "http://localhost:3030/sparql"
        outputFolder: "queryCache"
        limit: 10
      lang: "lang.SPARQL"
...

QueryHandler

Each QueryHandler has:

• location of the query file or folder containing the query files
• QuerySet, containing all the queries from the file (or folder)
• QuerySelector, which generates the index of the next query
• langProcessor to generate TripleStats
• pattern to generate queries from pattern queries

QuerySet

The QuerySet is either in-memory or file-based.

• InMemoryQuerySet loads all the queries into Strings in memory when initializing.
• FileBasedQuerySet retrieves a query directly from the file when its requested.

The config option caching can be set to true for in-memory or false for file-based.

Each QuerySet has a QuerySource from which the queries are read.

QuerySource

A QuerySource is the wrapper for the handling of the query files.
3 different QuerySources are implemented:

• FileLineQuerySource expects a query file with one query per line
• FileSeparatorQuerySource expects a file with (multi-line) queries separated by a separator line. Default separator line is "###"
• FolderQuerySource expects a directory with query files that each contain one (multi-line) query

QuerySelector

A QuerySelector is basically a number generator giving the next index of a query to load.
2 QuerySelectors are implemented:

• LinearQuerySelector which gives each index in ascending order, restarting at 0 when reaching the last one.
• RandomQuerySelector uses java.util.Random to generate the next index. The seed is either provided in the config or the workerID is used

TODO

• update documentation
• update javadoc
• update IGUANA schema

[frensing]

All prior functionality is now in the new QueryHandler.
All prior test cases have been updated where it made sense and run successfully.

Next step is to update the documentations

[bigerl]

Thank you for the PR. Looks very good. I've pointed out only some minor things and added some questions here and there.

As you wrote, todos left are:

• JavaDoc
• update the Documentation

[nck-mlcnv]

Things left to do:

• update development section of documentation
• update the README.md file

[bigerl]

Documentation looks very good and the code around query handling, also. In general, there still seems to be a long way to go.

-[ ] Besides the comments please review if we really need interfaces+abstract classes for various abstractions. It seems to me that there is no real value in the interface and that the interface could be merged into the abstract class.

[bigerl]

@nck-mlcnv

• Was SPARQLWorker removed from the Documentation?
• Please double check that the removed abstractions are not referenced in the documentation.
• update documentation to reflect renaming QueryList and getQuery

Please check the boxes here when done.