SEMS-on-device-server/scanner.js

import * as fs from "node:fs"
import * as path from "node:path"
import { Buffer } from 'node:buffer';
import { unpack, pack } from 'msgpackr';
import * as pako from 'pako';


function get_latest_file_path(raw_spectral_data_dir){
    
    let files=fs.readdirSync(raw_spectral_data_dir)
    files=files.sort()
    let latest_name=files.pop()
    // console.log(latest_name,files.length)
    return path.resolve(raw_spectral_data_dir,latest_name)

}


async function main(){
    try {
        // process.send("child process started");
    const raw_spectral_data_dir="/data"

    let last_data_file=null
    let latest_data_file=null
    let fd_csv=null
    let fd_bin=null
    while(true){
     latest_data_file=get_latest_file_path(raw_spectral_data_dir)

     if (latest_data_file!=last_data_file){

         fd_csv=fs.openSync(latest_data_file)

         fd_bin=fs.openSync(path.format({
            dir: path.dirname(latest_data_file),
            name: path.basename(latest_data_file,".csv"),
            ext: 'bin',
        }))
        last_data_file=latest_data_file
     }
    
    let last_pointer=fs.statSync(latest_data_file).size

    while(true){
        const stat=fs.statSync(latest_data_file)
        if(stat.size>last_pointer){
            let buffer=Buffer.alloc(stat.size-last_pointer)
            fs.readSync(fd_csv,buffer,0,stat.size-last_pointer,last_pointer)
            let info=buffer.toString().split(",")
            let timeStamp=Number(info[0])
            let start_pointer=Number(info[1])
            let length=Number(info[2])
            let spectral_buffer=Buffer.alloc(length)
            const spectral_data=fs.readSync(fd_bin,spectral_buffer,0,length,start_pointer)


            let upload_data={"spectral_data_bin":spectral_buffer }
            let upload_data_compressed = pako.gzip(pack(upload_data))

            let response=await fetch("http://inference_server:8000/post", {
                            method: "post",
                            body: upload_data_compressed
                        })
            let response_data_compressed= await response.arrayBuffer()
            let response_data=unpack(pako.ungzip(response_data_compressed)) 
            // console.log(response_data)

            process.send(response_data);
            
            break
        }
    }

}
    }catch (err) {
        console.error(err.message);
      }
    


}

main().then(()=>{
    // process.send("child process end");
})