fix : Synchronize read and writes to avoid race condition reading tra…

…nspiled files from disk cache

First add a maker file to check if the previous write was fully completed. Then again in writefile section change the write mode to wx which uses exclusive lock and if two writes happen same time and we get EEXist error then ignore that
FIX for #30577

packages/playwright/src/transform/compilationCache.ts

@@ -126,23 +126,35 @@ export function getFromCompilationCache(filename: string, hash: string, moduleUr
   const codePath = cachePath + '.js';
   const sourceMapPath = cachePath + '.map';
   const dataPath = cachePath + '.data';
-  try {
-    const cachedCode = fs.readFileSync(codePath, 'utf8');
-    const serializedCache = _innerAddToCompilationCacheAndSerialize(filename, { codePath, sourceMapPath, dataPath, moduleUrl });
-    return { cachedCode, serializedCache };
-  } catch {
+  const markerFile = codePath + '-marker';
+  if (fs.existsSync(markerFile)) {
+    try {
+      const cachedCode = fs.readFileSync(codePath, 'utf8');
+      const serializedCache = _innerAddToCompilationCacheAndSerialize(filename, { codePath, sourceMapPath, dataPath, moduleUrl });
+      return { cachedCode, serializedCache };
+    } catch {
+    }
   }
 
   return {
     addToCache: (code: string, map: any | undefined | null, data: Map<string, any>) => {
       if (isWorkerProcess())
         return {};
-      fs.mkdirSync(path.dirname(cachePath), { recursive: true });
-      if (map)
-        fs.writeFileSync(sourceMapPath, JSON.stringify(map), 'utf8');
-      if (data.size)
-        fs.writeFileSync(dataPath, JSON.stringify(Object.fromEntries(data.entries()), undefined, 2), 'utf8');
-      fs.writeFileSync(codePath, code, 'utf8');
+      try {
+        fs.mkdirSync(path.dirname(cachePath), { recursive: true });
+        if (map)
+          fs.writeFileSync(sourceMapPath, JSON.stringify(map), { encoding: 'utf8', flag: 'wx' });
+        if (data.size)
+          fs.writeFileSync(dataPath, JSON.stringify(Object.fromEntries(data.entries()), undefined, 2), { encoding: 'utf8', flag: 'wx' });
+        fs.writeFileSync(codePath, code, 'utf8');
+        fs.closeSync(fs.openSync(markerFile, 'wx'));
+      }
+      catch (error) {
+        if (error.code === 'EEXIST') {
+        } else {
+            throw error;
+        }
+      }
       const serializedCache = _innerAddToCompilationCacheAndSerialize(filename, { codePath, sourceMapPath, dataPath, moduleUrl });
       return { serializedCache };
     }