SHD-WebsiteFingerprintingLab/part2/worker.js

const N= 393216;  // Number of cache lines 24MB/64B
// Number of sweep counts
// TODO (Exercise 2-1): Choose an appropriate value!
let P = 10;

// Number of elements in your trace
let K = 5 * 1000 / P; 

// Array of length K with your trace's values
let T;

// Value of performance.now() when you started recording your trace
let start;

function record() {
  
  // Create empty array for saving trace values
  T = new Array(K);

  // Fill array with -1 so we can be sure memory is allocated
  T.fill(-1, 0, T.length);
  const LINE_SIZE = 8; // 64/sizeof(double) Note that js treats all numbers as double
  const M = new Array(N * LINE_SIZE).fill(-1);
  // Save start timestamp
  start = performance.now();
  for (let i = 0; i < K; i++) {
    let count=0;
    while (performance.now() - start < P*(i+1)) {
      // sweep the cache
      for (let j = 0; j < N; j++) {
        let val = M[j * LINE_SIZE];
      }
      count++;
    }
    T[i]=count;
  }

  // TODO (Exercise 2-1): Record data for 5 seconds and save values to T.

  // Once done recording, send result to main thread
  postMessage(JSON.stringify(T));
  console.log(T);
}

// DO NOT MODIFY BELOW THIS LINE -- PROVIDED BY COURSE STAFF
self.onmessage = (e) => {
  if (e.data.type === "start") {
    setTimeout(record, 0);
  }
};