feat: Parallel Jetifier, scale up to cpu count (#24)

* feat: parallel files jetifying
* fix: typo
* removed unnecessary console.logs

index.js

@@ -1,21 +1,19 @@
-const { readFileSync, writeFileSync } = require('fs');
-const { loadCSV, readDir } = require('./src/utils');
+const { fork } = require('child_process');
+const { join } = require('path');
+const { getClassesMapping, readDir, chunk } = require('./src/utils');
+
+const cpus = require('os').cpus().length;
 
 const arg = process.argv.slice(2)[0];
 const mode = arg && ((arg === 'reverse') || (arg === '-r')) ? 'reverse' : 'forward';
-
 const SEARCH_DIR = 'node_modules';
 
-const csv = loadCSV();
+const classesMapping = getClassesMapping();
 const files = readDir(SEARCH_DIR);
 
-for (const file of files) {
-  let data = readFileSync(file, { encoding: 'utf8' });
-  for (const c in csv) {
-    if (data.includes(mode === 'forward' ? c : csv[c])) {
-      console.log(`${mode}-jetifying: ${file}`);
-      data = mode === 'forward' ? data.replace(new RegExp(c, 'g'), csv[c]) : data.replace(new RegExp(csv[c], 'g'), c);
-      writeFileSync(file, data, { encoding: 'utf8' });
-    }
-  }
-}
+console.log(`Jetifier found ${files.length} file(s) to ${mode}-jetify. Using ${cpus} workers...`);
+
+for (const filesChunk of chunk(files, cpus)) {
+  const worker = fork(join(__dirname, 'src', 'worker.js'));
+  worker.send({ filesChunk, classesMapping, mode });
+}

src/utils.js

@@ -1,6 +1,15 @@
 const { readFileSync, readdirSync, statSync } = require('fs');
 const { join } = require('path');
 
+const chunk = (array, chunkSize) => {
+  const size = Math.ceil(array.length / chunkSize);
+  const result = [];
+  while (array.length) {
+    result.push(array.splice(0, size));
+  }
+  return result;
+};
+
 const readDir = (dir, filesList = []) => {
   const files = readdirSync(dir);
   for (let file of files) {
@@ -16,29 +25,38 @@ const readDir = (dir, filesList = []) => {
   return filesList;
 };
 
-const loadCSV = () => {
-  const csvFilePath = join(__dirname, 'androidx-class-mapping.csv');
+const loadCSVFile = () => {
+  const csvFilePath = join(__dirname, '..', 'mapping', 'androidx-class-mapping.csv');
   const lines = readFileSync(csvFilePath, { encoding: 'utf8' }).split(/\r?\n/);
-
+
+  // Remove redundant "Support Library class,Android X class" from array
+  lines.shift();
+
   // last element will always be an empty line so removing it from the array
-  if(lines[lines.length - 1] === "") {
-    lines.pop(); 
+  if (lines[lines.length - 1] === "") {
+    lines.pop();
   }
-
-  const result = {};
-  for (let line of lines) {
+
+  return lines;
+};
+
+const getClassesMapping = () => {
+  const csv = loadCSVFile();
+  const result = [];
+  for (let line of csv) {
     const oldValue = line.split(',')[0];
     const newValue = line.split(',')[1];
-    result[oldValue] = newValue;
+    result.push([oldValue, newValue]);
   }
 
   // renderscript must be added to the canonical androidx-class-mapping.csv - it is not upstream
-  result['android.support.v8.renderscript'] = 'android.renderscript';
+  result.push(['android.support.v8.renderscript', 'android.renderscript']);
 
   return result;
-}
+};
 
 module.exports = {
-  loadCSV,
-  readDir
-}
+  getClassesMapping,
+  readDir,
+  chunk
+};

src/worker.js

@@ -0,0 +1,18 @@
+const { readFileSync, writeFileSync } = require('fs');
+
+process.on('message', ({ filesChunk, classesMapping, mode }) => {
+
+  for (const file of filesChunk) {
+    let data = readFileSync(file, { encoding: 'utf8' });
+    for (const [oldClass, newClass] of classesMapping) {
+      if (data.includes(mode === 'forward' ? oldClass : newClass)) {
+        data = mode === 'forward' ?
+          data.replace(new RegExp(oldClass, 'g'), newClass) :
+          data.replace(new RegExp(newClass, 'g'), oldClass);
+        writeFileSync(file, data, { encoding: 'utf8' });
+      }
+    }
+  }
+
+  process.exit(0);
+});