Event Building Algorithm in a Distributed Stream Processing Data Acquisition Platform: D-Matrix

Event building is an important task for data acquisition (DAQ) systems in high-energy physics experiments. D-Matrix is designed as a generic distributed stream processing DAQ platform, containing hardware description language (HDL)-based modules and software modules. In the D-Matrix system, the data transfer is abstracted into the form of a stream, and the event building is implemented through a cascade of various reusable stream processing modules. These stream processing modules will determine their work modes automatically based on a set of attributes, which describe the abstracted data stream characteristics, such as spatiotemporal organization and granularity. This article introduces the event building architecture, the physics data structure abstraction, and the algorithmic implementation of specific event building modules in the D-Matrix system. An application of the D-Matrix event building architecture in the CSR external-target experiment is presented in the end.