Trigger Primitive Communication Interface for testing at protoDUNE Brett Viren with input from Phil, Kurt, Josh Physics Department DAQ DS – 15 Feb 2019
What we have now (from Kurt) Brett Viren (BNL) TP IPC API 15 Feb 2019 2 / 9
What we want (from Kurt, IPC version) Brett Viren (BNL) TP IPC API 15 Feb 2019 3 / 9
API: Transport Pipeline • TP finder code uses a TPSink , new BR uses a TPSource . • These classes hide IPC details from the apps. • Middleware replaceable w/out app code changes o Test different communication patterns, insert functionality o Shown here, use PUB/SUB pattern for network traffic. // TP finder TPSink s(cfg); // new TP BR TPSource s(cfg); TPSet tps; while (true) { TPSet tps; make_tps(tps); auto rc = s(tps); while (0 == s(tps)) { // serve TPs to EB if (rc) { cerr << "Oops!\n" } } } Brett Viren (BNL) TP IPC API 15 Feb 2019 4 / 9
API: Data TPSet with metadata about its TrigPrim ’s detid APA face number or smaller address count sequence each set datatime absolute time measured by det. elec. timespan of all TPs in the set chanspan dittor for channels TrigPrim values self-explanatory Data rate here is not an issue, room to add more. Brett Viren (BNL) TP IPC API 15 Feb 2019 5 / 9
Why the explicit TPSet ? Why not just pass individual TrigPrim messages? • 39 Ar will produce 50-150 kHz TP per APA face. • This is only a few MB/s but is an uncomfortably high network packet rate if each TP is sent as one message. • Thus, must do some bundling . o ZeroMQ can auto-bundle messages up to 8kB. o API can do the bundling but it must do so “dumbly” (treat data as opaque), else transport becomes application. o The sending app can do smarter bundling and provide TPSet metadata. • Why make the app do it? o Receiving app can use metadata to assist in marshalling w/out having to read TP data. o Gets us one step closer to MLT functionality. Brett Viren (BNL) TP IPC API 15 Feb 2019 6 / 9
Packaging Will provide a “ PTMP ” software package: • “Prototype Trigger Message Passing” • C++ source in stand-alone repository. • Portable build system producing shared lib + headers. • Reference applications sending dummy TPs. • External dependencies: o libzmq o libczmq o protoc (build time) Brett Viren (BNL) TP IPC API 15 Feb 2019 7 / 9
FIN Brett Viren (BNL) TP IPC API 15 Feb 2019 8 / 9
API: Alternative Patterns Use PUSH/PULL instead of PUB/SUB Make direct sink/source connect, eg between two threads in same app. Can replace or even remove intervening actors: • Investigate different socket patterns and their performance. • Insert additional processing steps: o filters, refiners, loggers, monitors • App can also be implemented inside an actor function. These added value/features are for free. Brett Viren (BNL) TP IPC API 15 Feb 2019 9 / 9
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