v8cache experimental flag

vercel · Dec 6, 2018 · fd312d2 · fd312d2
1 parent 8032a35
commit fd312d2
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Showing 2 changed files with 26 additions and 4 deletions.
diff --git a/src/cli.js b/src/cli.js
@@ -16,6 +16,7 @@ Options:
   -S, --no-source-map   Skip source map output
   -e, --external [mod]  Skip bundling 'mod'. Can be used many times
   -q, --quiet           Disable build summaries / non-error outputs
+  --v8-cache            Emit a build using the v8 compile cache
 `;
 
 let args;
@@ -30,7 +31,8 @@ try {
     "--no-source-map": Boolean,
     "-S": "--no-source-map",
     "--quiet": Boolean,
-    "-q": "--quiet"
+    "-q": "--quiet",
+    "--v8-cache": Boolean
   });
 } catch (e) {
   if (e.message.indexOf("Unknown or unexpected option") === -1) throw e;
@@ -123,7 +125,8 @@ switch (args._[0]) {
       {
         minify: !args["--no-minify"] && !run,
         externals: args["--external"],
-        sourceMap: !args["--no-source-map"]
+        sourceMap: !args["--no-source-map"],
+        v8cache: args["--v8-cache"]
       }
     );
     ncc.then(

diff --git a/src/index.js b/src/index.js
@@ -51,12 +51,18 @@ module.exports = async (
     externals = [],
     minify = false,
     sourceMap = false,
-    filename = "index.js"
+    filename = "index.js",
+    v8cache = false
   } = {}
 ) => {
   const shebangMatch = fs.readFileSync(resolve.sync(entry)).toString().match(shebangRegEx);
   const mfs = new MemoryFS();
   const assetNames = Object.create(null);
+  assetNames[filename] = true;
+  if (sourceMap)
+    assetNames[filename + '.map'] = true;
+  if (v8cache)
+    assetNames[filename + '.cache'] = assetNames[filename + '.cache.js'] = true;
   const assets = Object.create(null);
   const compiler = webpack({
     entry,
@@ -212,12 +218,25 @@ module.exports = async (
       return { code, map, assets };
     return { code: result.code, map: result.map, assets };
   })
+  .then(({ code, map, assets }) => {
+    if (!v8cache)
+      return { code, map, assets };
+    const { Script } = require('vm');
+    assets[filename + '.cache'] = new Script(code).createCachedData();
+    assets[filename + '.cache.js'] = code;
+    assets[filename + '.map'] = map;
+    code = `const { readFileSync } = require('fs'), { Script } = require('vm');\n` +
+        `const source = readFileSync(__dirname + '/${filename}.cache.js').toString(), cachedData = readFileSync(__dirname + '/${filename}.cache');\n` +
+        `new Script(source, { cachedData }).runInNewContext(Object.assign({}, global, { module, exports, require, __filename, __dirname }));\n`;
+    if (map) map = {};
+    return { code, map, assets };
+  })
   .then(({ code, map, assets}) => {
     if (!shebangMatch)
       return { code, map, assets };
     code = shebangMatch[0] + code;
     // add a line offset to the sourcemap
-    if (map)
+    if (map && map.mappings)
       map.mappings = ";" + map.mappings;
     return { code, map, assets };
   })