Concepts in LArSoft

The goal of this material to help LArSoft users understand the big picture of what is going on within LArSoft code. The aim is not to show specific code examples, but to lay the foundation for a conceptual understanding. The code base, moreover, has evolved, so some of the specific details noted in talks are no longer current. Follow the heading links for more information on each of the topics.

Basic steps in a simulation

The simulation is a chain or series of steps. Each step models a specific physical process. Based on Robert Hatcher’s Simulation Tools in Neutrino Experiments.

Geometry

Detector-specific information is contained within the Geometry so other software doesn’t have to explicitly depend on which detector is being considered. Based on Erica Snider’s Introduction to LArSoft – source materialDiego Garcia-Gamez’s slides and Wiki detailed page on Geometry.

Reconstruction steps

Reconstruction extracts physical information provided by the wire output signals. The space coordinates and energy deposited by the different particles are used to build a picture of the event. Based on Introduction to LArSoft – source material.

Designing software in LArSoft

Best practices for how to design software for LArSoft. Based on Erica Snider’s Introduction to LArSoft – source material.

Data Products

Data products are classes which can be saved into the art ROOT output file. They are the means by which a module can learn the result of other modules.

Algorithms

An algorithm is a class, with one or more instances managed by user code, that performs a task or part of it.  Based on Gianluca  Petrillo’s slides for algorithms and services from the LArSoft class and  LArSoft Wiki on Writing LArSoft Algorithms.

Services

A LArSoft service is a class, with a single instance managed by the framework, that performs an operation. A service is used by LArSoft algorithms and art modules. Based on Gianluca  Petrillo’s slides for algorithms and services from the LArSoft class and  LArSoft Wiki on Writing LArSoft Services.

LArSoft code organization

How to code for LArSoft. Based on Erica Snider’s Introduction to LArSoft – source material.

Multi-threading in LArSoft

To make code thread-safe, it is important to know what objects are shared and know when they are shared. The difficulty depends on the context. Based on: Making Code Thread-Safe by Kyle Knoepfel and Introduction to multi-threading and vectorization by Matti Kortelainen.

Code analysis process

How LArSoft is doing code analysis. Based on LArSoft Redmine wiki page on code analysis  and  Erica Snider’s  – LArSoft code analysis process presentation.

Configuration

LArSoft jobs obtain configuration information from the art event processing framework via user-written FHiCL configuration files. The configuration page contains information and links to recommendations on developing configurations and configuration-aware C++ code.

Testing in LArSoft

How to test LArsoft. Based on Erica Snider’s Introduction to LArSoft – source material and Erica Snider’s Introduction to LArSoft CI System.)

Continuous Integration (CI) in LArSoft

The set of tools, applications and machines that allows users to specify and automate the execution of tests of LArSoft software. This material is based on Erica Snider’s Introduction to LArSoft CI System and the redmine wiki page on CI.