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Before developing a module, one should have a bare idea of what the QualityControl is and how it is designed. The following sections explore these aspects.
The main data flow is represented in blue. Data samples are selected by the Data Sampling (not represented) and sent to the QC tasks, either on the same machines or on other machines. The tasks produce TObjects, usually histograms, that are merged (if needed) and then checked. The checkers output the received TObject along with a quality flag. The TObject can be modified by the Checker. Finally the TObject and its quality are stored in the repository.
Data Processing Layer is a software framework developed as a part of O2 project. It structurizes the computing into units called Data Processors - processes that communicate with each other via messages. DPL takes care of generating and running the processing topology out of user declaration code, serializing and deserializing messages, providing the data processors with all the anticipated messages for a given timestamp and much more. Each piece of data is characterized by its DataHeader, which consists (among others) of dataOrigin, dataDescription and SubSpecification - for example {"MFT", "TRACKS", 0}.
An example of a workflow definition which describes the processing steps (Data Processors), their inputs and their outputs can be seen in runBasic.cxx. In the QC we define the workflows in files whose names are prefixed with run.
The Data Sampling provides the possibility to sample data in DPL workflows, based on certain conditions ( 5% randomly, when payload is greater than 4234 bytes, etc.). The job of passing the right data is done by a data processor called Dispatcher. A desired data stream is specified in the form of Data Sampling Policies, defined in the QC JSON configuration file. Please refer to the main Data Sampling readme for more details.
Data Sampling is used by Quality Control to feed the tasks with data. Below we present an example of a configuration file. It instructs Data Sampling to provide a QC task with 10% randomly selected data that has the header {"ITS", "RAWDATA", 0}. The data will be accessible inside the QC task by the binding "raw".
{
"qc": {
...
"tasks": {
"QcTask": {
...
"dataSource": {
"type": "dataSamplingPolicy",
"name": "its-raw"
},
...
}
}
},
"dataSamplingPolicies": [
{
"id": "its-raw",
"active": "true",
"machines": [],
"dataHeaders": [
{
"binding": "raw",
"dataOrigin": "ITS",
"dataDescription": "RAWDATA"
}
],
"subSpec": "0",
"samplingConditions": [
{
"condition": "random",
"fraction": "0.1",
"seed": "1234"
}
],
"blocking": "false"
}
]
}An example of using the data sampling in a DPL workflow is visible in runAdvanced.cxx.
In case one needs to sample at a very high rate, or even monitor 100% of the data, the Data Sampling can be omitted altogether. As a result the task is connected directly to the the Device producing the data to be monitored. To do so, change the dataSource's type in the config file from dataSamplingPolicy to direct. In addition, add the information about the type of data that is expected (dataOrigin, binding, etc...) and remove the dataSamplingPolicies :
{
"qc": {
...
"tasks": {
"QcTask": {
...
"dataSource": {
"type": "direct",
"binding": "its-rawdata",
"dataOrigin": "ITS",
"dataDescription": "RAWDATA",
"subSpec": "0"
},
...
}
}
},
"dataSamplingPolicies": [
]
}The file basic-no-sampling.json is provided as an example. To test it, you can run qcRunBasic with the option --no-data-sampling (it makes it use this config file instead of basic.json).
The repository QualityControl contains the Framework and the Modules in the respectively named directories.
The Data Sampling code is part of the AliceO2 repository.
The Quality Control uses plugins to load the actual code to be executed by the Tasks and the Checkers. A module, or plugin, can contain one or several Tasks and/or one or several Checks. They must subclass TaskInterface.h and CheckInterface.h respectively. We use the Template Method Design Pattern.
Before starting to develop the code, one should create a new module if it does not exist yet. Typically each detector team should prepare a module.
The script modulesHelper.sh, in the directory Modules, is able to prepare a new module or to add a new Task or a new Check to an existing module. It must be run from within QualityControl/Modules. See the help message below:
Usage: ./modulesHelper.sh -m MODULE_NAME [OPTION]
Generate template QC module and/or tasks, checks.
If a module with specified name already exists, new tasks and checks are inserted to the existing one.
Please follow UpperCamelCase convention for modules', tasks' and checks' names.
Example:
# create new module and some task
./modulesHelper.sh -m MyModule -t SuperTask
# add one task and two checks
./modulesHelper.sh -m MyModule -t EvenBetterTask -c HistoUniformityCheck -c MeanTest
Options:
-h print this message
-m MODULE_NAME create module named MODULE_NAME or add there some task/checker
-t TASK_NAME create task named TASK_NAME
-c CHECK_NAME create check named CHECK_NAME
For example, if your detector 3-letter code is ABC you might want to do
# we are in ~/alice
cd QualityControl/Modules
./modulesHelper.sh -m Abc # create the module
./modulesHelper.sh -t RawDataQcTask # add a task
Now that there is a module, we can build it and test it. First let's build it :
# We are in ~/alice
# Go to the build directory of QualityControl
cd sw/slc7_x86-64/BUILD/QualityControl-latest/QualityControl
make -j8 install # replace 8 by the number of cores on your machine
To test whether it works, we are going to run a basic DPL workflow defined in runBasic.cxx.
We need to modify slightly the config file to indicate our freshly created module and classes.
The config file is called basic.json and is located in $QUALITYCONTROL_ROOT/etc/ (after installation, if you want to modify the original one it is in the source directory Framework).
Change the lines as indicated below :
"QcTask": {
"className": "o2::quality_control_modules::abc::RawDataQcTask",
"moduleName": "QcAbc",
Now we can run it
qcRunBasic
You should see the QcTask at qcg-test.cern.ch with an object Example updating.
Fill in the methods in RawDataQcTask.cxx. For example, make it send a second histogram. Once done, recompile it (see section above) and run it. You should see the second object published in the qcg.
TODO give actual steps
You can rename the task by simply changing its name in the config file. Change the name from
QcTask to whatever you like and run it again (no need to recompile). You should see the new name
appear in the QCG.
TODO
To commit your new or modified code, please follow this procedure
- Fork the QualityControl repo using github webpage or github desktop app.
- Clone it :
git clone https://github.com/<yourIdentifier>/QualityControl.git - Before you start working on your code, create a branch in your fork :
git checkout -b feature-new-stuff - Push the branch :
git push --set-upstream origin feature-new-stuff - Add and commit your changes onto this branch :
git add Abc.cxx ; git commit Abc.cxx - Push your commits :
git push - Once you are satisfied with your changes, make a Pull Request (PR). Go to your branches on the github webpage, and click "New Pull Request". Explain what you did.
- One of the QC developers will check your code. It will also be automatically tested.
- Once approved the changes will be merged in the main repo. You can delete your branch.
For a new feature, just create a new branch for it and use the same procedure. Do not fork again. You can work on several features at the same time by having parallel branches.
General ALICE Git guidelines can be accessed here.
If you want to change the workflow, edit or copy runBasic.cxx or runReadout.cxx. For example...
TODO
TODO
One can tell the DPL driver to accept new arguments. This is done using the customize method at the top of your workflow definition (usually called "runXXX" in the QC).
For example, to add two parameters of different types do :
void customize(std::vector<ConfigParamSpec>& workflowOptions)
{
workflowOptions.push_back(
ConfigParamSpec{ "config-path", VariantType::String, "", { "Path to the config file. Overwrite the default paths. Do not use with no-data-sampling." } });
workflowOptions.push_back(
ConfigParamSpec{ "no-data-sampling", VariantType::Bool, false, { "Skips data sampling, connects directly the task to the producer." } });
}
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