An example of custom sampling condition (#211)

Framework/example-default.json

@@ -73,7 +73,14 @@
         }
       ],
       "subSpec": "0",
-      "samplingConditions": []
+      "samplingConditions": [
+        {
+          "condition": "custom",
+          "moduleName": "QcExample",
+          "className": "o2::quality_control_modules::example::ExampleCondition",
+          "threshold": "120"
+        }
+      ]
     },
     {
       "id": "mftclusters",

Modules/Example/CMakeLists.txt

@@ -1,7 +1,7 @@
 # ---- Library ----
 
 add_library(QcExample src/BenchmarkTask.cxx src/ExampleTask.cxx
-                      src/FakeCheck.cxx)
+                      src/FakeCheck.cxx src/ExampleCondition.cxx)
 
 target_include_directories(
   QcExample
@@ -15,6 +15,7 @@ add_root_dictionary(QcExample
                     HEADERS include/Example/BenchmarkTask.h
                             include/Example/ExampleTask.h
                             include/Example/FakeCheck.h
+                            include/Example/ExampleCondition.h
                     LINKDEF include/Example/LinkDef.h
                     BASENAME QcExample)
 

Modules/Example/include/Example/ExampleCondition.h

@@ -0,0 +1,50 @@
+// Copyright CERN and copyright holders of ALICE O2. This software is
+// distributed under the terms of the GNU General Public License v3 (GPL
+// Version 3), copied verbatim in the file "COPYING".
+//
+// See http://alice-o2.web.cern.ch/license for full licensing information.
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+///
+/// \file   ExampleCondition.h
+/// \author Piotr Konopka
+///
+
+#ifndef QC_MODULE_EXAMPLE_EXAMPLECONDITION_H
+#define QC_MODULE_EXAMPLE_EXAMPLECONDITION_H
+
+#include "QualityControl/TaskInterface.h"
+#include <Framework/DataSamplingCondition.h>
+#include <TROOT.h>
+
+namespace o2::quality_control_modules::example
+{
+
+/// \brief Example of custom Data Sampling Condition
+/// \author Piotr Konopka
+
+/// \brief A DataSamplingCondition which approves messages which have their first byte in the payload higher than
+/// specified value.
+class ExampleCondition : public o2::framework::DataSamplingCondition
+{
+ public:
+  /// \brief Constructor.
+  ExampleCondition() : DataSamplingCondition(){};
+  /// \brief Default destructor
+  ~ExampleCondition() override = default;
+
+  /// \brief Reads 'threshold'
+  void configure(const boost::property_tree::ptree& config) override;
+  /// \brief Makes a positive decision if first byte is higher than 'threshold'
+  bool decide(const o2::framework::DataRef& dataRef) override;
+
+ private:
+  uint8_t mThreshold;
+};
+
+} // namespace o2::quality_control_modules::example
+
+#endif //QC_MODULE_EXAMPLE_EXAMPLECONDITION_H

Modules/Example/include/Example/LinkDef.h

@@ -6,4 +6,6 @@
 #pragma link C++ class o2::quality_control_modules::example::ExampleTask + ;
 #pragma link C++ class o2::quality_control_modules::example::FakeCheck + ;
 #pragma link C++ class o2::quality_control_modules::example::BenchmarkTask + ;
+#pragma link C++ class o2::quality_control_modules::example::ExampleCondition + ;
+
 #endif

Modules/Example/src/ExampleCondition.cxx

@@ -0,0 +1,31 @@
+// Copyright CERN and copyright holders of ALICE O2. This software is
+// distributed under the terms of the GNU General Public License v3 (GPL
+// Version 3), copied verbatim in the file "COPYING".
+//
+// See http://alice-o2.web.cern.ch/license for full licensing information.
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+///
+/// \file   ExampleCondition.cxx
+/// \author Piotr Konopka
+///
+
+#include "Example/ExampleCondition.h"
+
+namespace o2::quality_control_modules::example
+{
+
+void ExampleCondition::configure(const boost::property_tree::ptree& config)
+{
+  mThreshold = config.get<uint8_t>("threshold");
+}
+
+bool ExampleCondition::decide(const o2::framework::DataRef& dataRef)
+{
+  return dataRef.payload != nullptr ? dataRef.payload[0] > mThreshold : false;
+}
+
+} // namespace o2::quality_control_modules::example

doc/ModulesDevelopment.md

@@ -44,7 +44,7 @@ An example of a workflow definition which describes the processing steps (_Data
 
 ### Data Sampling
 
-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](https://github.com/AliceO2Group/AliceO2/blob/dev/Framework/Core/README.md#data-sampling) for more details.
+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 or others, including custom conditions). 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](https://github.com/AliceO2Group/AliceO2/blob/dev/Framework/Core/README.md#data-sampling) 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"`.
 ```json
@@ -90,6 +90,12 @@ Data Sampling is used by Quality Control to feed the tasks with data. Below we p
 
 An example of using the data sampling in a DPL workflow is visible in [runAdvanced.cxx](https://github.com/AliceO2Group/QualityControl/blob/master/Framework/runAdvanced.cxx).
 
+#### Custom Data Sampling Condition
+
+If needed, a custom data selection can be performed by inheriting the `DataSamplingCondition` class and implementing the `configure` and `decide` methods. Then, to use it, one needs to specify the library and class names in the config file.
+
+The class [ExampleCondition](https://github.com/AliceO2Group/QualityControl/blob/master/Modules/Example/include/Example/ExampleCondition.h) presents the how to write one's own condition, while in [example-default.json](https://github.com/AliceO2Group/QualityControl/blob/master/Framework/example-default.json) the policy `ex1` shows how it should be configured.
+
 #### Bypassing the Data Sampling
 
 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 :