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Merged
maureeungaro merged 1 commit into from
Jun 13, 2026
Merged

JSON streamer: emit valid, correctly-nested event objects #148

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36 changes: 25 additions & 11 deletions gemc/gstreamer/factories/JSON/event/event.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ bool GstreamerJsonFactory::startEventImpl(const std::shared_ptr<GEventDataCollec
current_event_has_header = false;
current_event_has_any_detector = false;
current_event_has_generated = false;
current_event_digitized_entries.clear();

// Cache the event number early so it is available to the root event object.
event_number = event_data->getHeader()->getG4LocalEvn();
Expand All @@ -47,24 +48,37 @@ bool GstreamerJsonFactory::endEventImpl(const std::shared_ptr<GEventDataCollecti
return false;
}

// If the caller skipped the header step, emit a minimal fallback so the JSON remains valid.
// If the caller skipped the header step, emit a minimal fallback and close the header
// object (startEventImpl opened it; publishEventHeaderImpl normally writes its fields
// and closes it).
if (!current_event_has_header) {
current_event << "\"timestamp\": \"\", \"thread_id\": -1";
current_event << "\"timestamp\": \"\", \"thread_id\": -1}";
}

// Detector publishers leave the "detectors" object open so digitized data
// can be appended after true-information banks without rewriting strings.
if (current_event_has_any_detector) {
current_event << "}";
// Ensure a "detectors" object exists so the schema stays predictable and any buffered
// digitized data has a place to live, even when no true-information banks were published.
bool detectors_has_content = current_event_has_any_detector;
if (!current_event_has_any_detector) {
current_event << ", \"detectors\": {";
current_event_has_any_detector = true;
}
current_event << "}";

// Keep the event schema predictable even when no detector banks were published.
if (!current_event_has_any_detector) {
current_event << ", \"detectors\": {}";
// Emit all buffered digitized detector arrays as a single, well-formed
// "digitized_by_detector" object nested inside "detectors".
if (!current_event_digitized_entries.empty()) {
if (detectors_has_content) { current_event << ", "; }
current_event << "\"digitized_by_detector\": {";
bool first = true;
for (const auto& entry : current_event_digitized_entries) {
if (!first) { current_event << ", "; }
first = false;
current_event << entry;
}
current_event << "}";
}

current_event << "}";
current_event << "}"; // close "detectors"
current_event << "}"; // close the event object

writeTopLevelEntry(current_event.str());

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1 change: 1 addition & 0 deletions gemc/gstreamer/factories/JSON/event/eventHeader.cc
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Expand Up @@ -26,6 +26,7 @@ bool GstreamerJsonFactory::publishEventHeaderImpl(const std::unique_ptr<GEventHe
current_event << "\"timestamp\": \"" << jsonEscape(timestamp) << "\""
<< ", \"thread_id\": " << thread_id
<< ", \"g4local_event\": " << gevent_header->getG4LocalEvn();
current_event << "}"; // close the "header" object opened in startEventImpl

current_event_has_header = true;
return true;
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62 changes: 18 additions & 44 deletions gemc/gstreamer/factories/JSON/event/publishDigitized.cc
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Expand Up @@ -17,80 +17,54 @@ bool GstreamerJsonFactory::publishEventDigitizedDataImpl(const std::string&
return false;
}

// The current design appends digitized content into a reserved object nested under
// "detectors". This avoids rewriting previously emitted detector JSON.
// Build this detector's digitized array into a standalone entry and buffer it.
// endEventImpl emits all buffered entries together as the "digitized_by_detector"
// object, which keeps the JSON valid regardless of how true-info and digitized
// publish calls interleave across detectors.
if (digitizedData.empty()) return true;

static const char* marker = "\"digitized_by_detector\": {";
const std::string assembled = current_event.str();

const bool has_digitized_container = (assembled.find(marker) != std::string::npos);

if (!has_digitized_container) {
// Ensure the event already has a detectors object before reserving a nested map
// for digitized collections keyed by detector name.
if (!current_event_has_any_detector) {
current_event << ", \"detectors\": {";
current_event_has_any_detector = true;
}
else {
current_event << ", ";
}

current_event << "\"digitized_by_detector\": {";
}

// If the reserved object already contains one detector entry, append a comma
// before adding the next one.
const std::string updated = current_event.str();
if (!updated.empty()) {
char last = updated.back();
if (last != '{') current_event << ", ";
}

current_event << "\"" << jsonEscape(detectorName) << "\": [";
std::ostringstream entry;
entry << "\"" << jsonEscape(detectorName) << "\": [";

bool wrote_first_hit = false;
for (const auto* hit : digitizedData) {
if (!hit) continue;

if (wrote_first_hit) current_event << ", ";
if (wrote_first_hit) entry << ", ";
wrote_first_hit = true;

current_event << "{";
entry << "{";

auto addr = getIdentityString(hit->getIdentity());

current_event << "\"address\": \"" << jsonEscape(addr) << "\"";
entry << "\"address\": \"" << jsonEscape(addr) << "\"";

current_event << ", \"vars\": {";
entry << ", \"vars\": {";

bool wrote_first_var = false;

// Integer observables:
// the argument 0 means "do not include SRO variables".
for (const auto& [name, value] : hit->getIntObservablesMap(0)) {
if (wrote_first_var) current_event << ", ";
if (wrote_first_var) entry << ", ";
wrote_first_var = true;
current_event << "\"" << jsonEscape(name) << "\": " << value;
entry << "\"" << jsonEscape(name) << "\": " << value;
}

// Floating-point observables.
for (const auto& [name, value] : hit->getDblObservablesMap(0)) {
if (wrote_first_var) current_event << ", ";
if (wrote_first_var) entry << ", ";
wrote_first_var = true;
current_event << "\"" << jsonEscape(name) << "\": " << value;
entry << "\"" << jsonEscape(name) << "\": " << value;
}

current_event << "}";
current_event << "}";
entry << "}";
entry << "}";
}

current_event << "]";
entry << "]";

// Close the temporary digitized_by_detector object immediately so the enclosing
// event remains structurally valid after this call.
current_event << "}";
current_event_digitized_entries.push_back(entry.str());

return true;
}
5 changes: 5 additions & 0 deletions gemc/gstreamer/factories/JSON/gstreamerJSONFactory.h
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Expand Up @@ -185,6 +185,11 @@ class GstreamerJsonFactory : public GStreamer {
/// \brief Tracks whether the current event already contains generated-particle banks.
bool current_event_has_generated = false;

/// \brief Buffered digitized detector arrays for the current event. endEventImpl emits
/// them together as the "digitized_by_detector" object, which keeps the JSON valid
/// regardless of how true-info and digitized publish calls interleave across detectors.
std::vector<std::string> current_event_digitized_entries;

/// \brief Tracks whether the plugin is currently assembling a frame object.
bool is_building_frame = false;

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