f: make parallel requests

_webi/lint-builds.js

@@ -5,6 +5,7 @@ let Fs = require('node:fs/promises');
 let Path = require('node:path');
 
 let BuildsCacher = require('./builds-cacher.js');
+let Parallel = require('./parallel.js');
 
 var INSTALLERS_DIR = Path.join(__dirname, '..');
 var CACHE_DIR = Path.join(__dirname, '../_cache');
@@ -110,15 +111,17 @@ async function main() {
   // return triples;
   // // process.exit(1)
 
-  let triples = [];
   let rows = [];
+  let triples = [];
   let valids = Object.keys(dirs.valid);
   console.info(`Fetching builds for`);
-  for (let name of valids) {
+  let limit = 25;
+  //let limit = 1;
+  await Parallel.run(limit, valids, async function (name, i) {
     if (name === 'webi') {
       // TODO fix the webi faux package
       // (not sure why I even created it)
-      continue;
+      return;
     }
 
     console.info(`    ${name}`);
@@ -152,9 +155,9 @@ async function main() {
       }
 
       triples.push(triplet);
-      rows.push(`${triplet}\t${name}\t${build.version}`);
+      rows.push(`${triplet}\t${pkg.name}\t${build.version}`);
     }
-  }
+  });
   let tsv = rows.join('\n');
   console.info('');
   console.info('#rows', rows.length);

_webi/parallel.js

@@ -0,0 +1,44 @@
+'use strict';
+
+var Parallel = module.exports;
+Parallel.run = async function (limit, arr, fn) {
+  let index = 0;
+  let actives = [];
+  let results = [];
+  limit = Math.min(limit, arr.length);
+
+  function launch() {
+    let _index = index;
+    let p = fn(arr[_index], _index, arr);
+
+    // some tasks may be synchronous
+    // so we must push before removing
+    actives.push(p);
+
+    p.then(function _resolve(result) {
+      let i = actives.indexOf(p);
+      actives.splice(i, 1);
+      results[_index] = result;
+    });
+
+    index += 1;
+  }
+
+  // start tasks in parallel, up to limit
+  for (; actives.length < limit; ) {
+    launch();
+  }
+
+  // keep the task queue full
+  for (; index < arr.length; ) {
+    // wait for one task to complete
+    await Promise.race(actives);
+    // add one task again
+    launch();
+  }
+
+  // wait for all remaining tasks
+  await Promise.all(actives);
+
+  return results;
+};