merge files from the blockchain infra repo (#59)

code/protocol_demos/long-polling/index.js

@@ -0,0 +1,36 @@
+const app = require("express")();
+const jobs = {}
+
+app.post("/submit", (req, res) =>  {
+    const jobId = `job:${Date.now()}`
+    jobs[jobId] = 0;
+    updateJob(jobId,0); 
+    res.end("\n\n" + jobId + "\n\n");
+})
+
+app.get("/checkstatus", async (req, res) => {
+    console.log(jobs[req.query.jobId])
+    //long polling, don't respond until done
+    while(await checkJobComplete(req.query.jobId) == false);
+    res.end("\n\nJobStatus: Complete " + jobs[req.query.jobId] + "%\n\n")
+
+} )
+
+app.listen(8080, () => console.log("listening on 8080"));
+
+async function checkJobComplete(jobId) {
+    return new Promise( (resolve, reject) => {
+        if (jobs[jobId] < 100)
+            this.setTimeout(()=> resolve(false),  1000);
+        else
+            resolve(true);
+    })
+   
+}
+
+function updateJob(jobId, prg) {
+    jobs[jobId] = prg;
+    console.log(`updated ${jobId} to ${prg}`)
+    if (prg == 100) return;
+    this.setTimeout(()=> updateJob(jobId, prg + 10), 10000)
+}