Smooth download speed and time remaining

web/static/js/speed.js

@@ -0,0 +1,39 @@
+const windowMs = 30000;
+const minimumSpanMs = 4000;
+const samplesByJob = new Map();
+
+export function updateSpeeds(jobs) {
+  const now = performance.now();
+  const seenIds = new Set();
+
+  for (const job of jobs) {
+    seenIds.add(job.id);
+    let samples = samplesByJob.get(job.id) || [];
+    const last = samples[samples.length - 1];
+    const progressWentBack = last && job.bytesDone < last.bytes;
+    const notTransferring = job.status !== "downloading" && job.status !== "extracting" && job.status !== "moving";
+    if (progressWentBack || notTransferring || (last && last.status !== job.status)) {
+      samples = [];
+    }
+
+    samples.push({ bytes: job.bytesDone, time: now, status: job.status });
+    while (samples.length > 2 && now - samples[1].time >= windowMs) {
+      samples.shift();
+    }
+    samplesByJob.set(job.id, samples);
+  }
+
+  for (const id of samplesByJob.keys()) {
+    if (!seenIds.has(id)) samplesByJob.delete(id);
+  }
+}
+
+export function speedOf(jobId) {
+  const samples = samplesByJob.get(jobId);
+  if (!samples || samples.length < 2) return 0;
+  const first = samples[0];
+  const last = samples[samples.length - 1];
+  const spanMs = last.time - first.time;
+  if (spanMs < minimumSpanMs) return 0;
+  return ((last.bytes - first.bytes) * 1000) / spanMs;
+}