gstreamerJSONConnection.cc

Go to the documentation of this file.

// gstreamer
#include "gstreamerJSONFactory.h"
#include "gstreamerConventions.h"
 
// c++
#include <iomanip>
 
bool GstreamerJsonFactory::openConnection() {
    if (ofile.is_open()) {
        // Already open for this thread; nothing to do.
        return true;
    }
 
    ofile.clear();
    ofile.open(filename(), std::ios::out | std::ios::trunc);
 
    if (!ofile.is_open() || !ofile) {
        log->error(ERR_CANTOPENOUTPUT, SFUNCTION_NAME, " could not open file ", filename());
        return false;
    }
 
    log->info(0, "GstreamerJsonFactory: opened file " + filename());
 
    // Defer writing the top-level JSON object until we know whether this is an event or stream writer.
    is_file_initialized         = false;
    wrote_first_top_level_entry = false;
    top_level_type.clear();
 
    return true;
}
 
bool GstreamerJsonFactory::closeConnectionImpl() {
    // Ensure buffered events are written before closing the JSON structure.
    flushEventBuffer();
 
    // Close the JSON document if we ever started it.
    closeTopLevelObjectIfNeeded();
 
    if (ofile.is_open()) ofile.close();
    if (ofile.is_open()) {
        log->error(ERR_CANTCLOSEOUTPUT, SFUNCTION_NAME, " could not close file ", filename());
        return false;
    }
 
    return true;
}
 
void GstreamerJsonFactory::ensureFileInitializedForType(const std::string& type) {
    if (is_file_initialized) return;
 
    top_level_type = type;
 
    // Single top-level object with a single array.
    // { "type":"event", "events":[ ... ] }
    ofile << "{\n";
    ofile << "  \"type\": \"" << jsonEscape(type) << "\",\n";
 
    if (type == "event") {
        ofile << "  \"events\": [\n";
    }
    else {
        ofile << "  \"frames\": [\n";
    }
 
    is_file_initialized         = true;
    wrote_first_top_level_entry = false;
}
 
void GstreamerJsonFactory::writeTopLevelEntry(const std::string& entry_json) {
    // The caller must have initialized the file for the correct type.
    if (!is_file_initialized) {
        log->error(ERR_PUBLISH_ERROR, "JSON file is not initialized in GstreamerJsonFactory::writeTopLevelEntry");
        return;
    }
 
    // Comma-separate entries inside the array.
    if (wrote_first_top_level_entry) {
        ofile << ",\n";
    }
    wrote_first_top_level_entry = true;
 
    // Indent entries consistently.
    ofile << "    " << entry_json;
}
 
void GstreamerJsonFactory::closeTopLevelObjectIfNeeded() {
    if (!is_file_initialized) return;
 
    // Close array and object.
    ofile << "\n  ]\n";
    ofile << "}\n";
    is_file_initialized = false;
}