improve rebuild performance in site builder

Author: leebyron

resources/Site.js

@@ -43,10 +43,13 @@ async function readSite(siteRoot) {
   return site;
 }
 
-function buildSite(buildRoot, site) {
-  return Promise.all(site.files.map(file =>
-    writer(buildRoot, file, site)
-  ));
+function buildSite(buildRoot, site, filter) {
+  return Promise.all(site.files
+    .filter(file =>
+      !filter ||
+      (filter.test ? filter.test(file.absPath) : filter === file.absPath))
+    .map(file => writer(buildRoot, file, site))
+  );
 }
 
 

resources/build.js

@@ -24,10 +24,10 @@ var buildDir = process.env.npm_package_site_build || './_build';
 var SITE_ROOT = path.resolve(pwd, sourceDir);
 var BUILD_ROOT = path.resolve(pwd, buildDir);
 
-async function build() {
+async function build(filter) {
   console.log('building...');
   var site = await Site.readSite(SITE_ROOT);
-  await Site.buildSite(BUILD_ROOT, site);
+  await Site.buildSite(BUILD_ROOT, site, filter);
   console.log('built');
 }
 

resources/watch.js

@@ -51,14 +51,48 @@ function startWatch() {
   console.log('watching...');
 }
 
+function changeFile(fileName) {
+  enqueue(fileName);
+}
+
 function deleteFile(fileName) {
-  clearCache(fileName);
-  build().catch(error => console.error(error.stack || error));
+  enqueue(fileName);
 }
 
-function changeFile(fileName) {
+const queue = [];
+
+function enqueue(fileName) {
+  queue.push(fileName);
+  if (queue.length === 1) {
+    rebuild();
+  } else {
+    console.log('queue', fileName);
+  }
+}
+
+function rebuild() {
+  const fileName = queue[0];
+  const filter =
+    /_core\//.test(fileName) ? /\.(js|md)$/ :
+    /\.less$/.test(fileName) ? /\.less$/ :
+    fileName ? SITE_ROOT + '/' + fileName :
+    null;
   clearCache(fileName);
-  build().catch(error => console.error(error.stack || error));
+  return build(filter).then(
+    () => {
+      queue.shift();
+      if (queue.length) {
+        return rebuild();
+      }
+    },
+    error => {
+      console.error(error.stack || error);
+      queue.shift();
+      if (queue.length) {
+        return rebuild();
+      }
+    }
+  );
 }
 
 function clearCache(causeFileName) {

resources/writer.js

@@ -22,6 +22,7 @@ module.exports = writer;
 
 async function writer(buildDir, file, site) {
   var writePath = getWritePath(buildDir, file);
+  console.log('  writing', file.relPath);
 
   // Render Less file
   if (endsWith(file.absPath, '.less')) {