module: integrate TypeScript into compile cache

This integrates TypeScript into the compile cache by caching
the transpilation (either type-stripping or transforming) output
in addition to the V8 code cache that's generated from the
transpilation output.

Locally this speeds up loading with type stripping of
`benchmark/fixtures/strip-types-benchmark.ts` by ~65% and
loading with type transforms of
`fixtures/transform-types-benchmark.ts` by ~128%.

When comparing loading .ts and loading pre-transpiled .js on-disk
with the compile cache enabled, previously .ts loaded 46% slower
with type-stripping and 66% slower with transforms compared to
loading .js files directly.
After this patch, .ts loads 12% slower with type-stripping and
22% slower with transforms compared to .js.

(Note that the numbers are based on microbenchmark fixtures and
do not necessarily represent real-world workloads, though with
bigger real-world files, the speed up should be more significant).

PR-URL: #56629
Fixes: #54741
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: joyeecheung

lib/internal/modules/typescript.js

@@ -22,6 +22,11 @@ const {
 const { getOptionValue } = require('internal/options');
 const assert = require('internal/assert');
 const { Buffer } = require('buffer');
+const {
+  getCompileCacheEntry,
+  saveCompileCacheEntry,
+  cachedCodeTypes: { kStrippedTypeScript, kTransformedTypeScript, kTransformedTypeScriptWithSourceMaps },
+} = internalBinding('modules');
 
 /**
  * The TypeScript parsing mode, either 'strip-only' or 'transform'.
@@ -105,11 +110,19 @@ function stripTypeScriptTypes(code, options = kEmptyObject) {
   });
 }
 
+/**
+ * @typedef {'strip-only' | 'transform'} TypeScriptMode
+ * @typedef {object} TypeScriptOptions
+ * @property {TypeScriptMode} mode Mode.
+ * @property {boolean} sourceMap Whether to generate source maps.
+ * @property {string|undefined} filename Filename.
+ */
+
 /**
  * Processes TypeScript code by stripping types or transforming.
  * Handles source maps if needed.
  * @param {string} code TypeScript code to process.
- * @param {object} options The configuration object.
+ * @param {TypeScriptOptions} options The configuration object.
  * @returns {string} The processed code.
  */
 function processTypeScriptCode(code, options) {
@@ -126,6 +139,20 @@ function processTypeScriptCode(code, options) {
   return transformedCode;
 }
 
+/**
+ * Get the type enum used for compile cache.
+ * @param {TypeScriptMode} mode Mode of transpilation.
+ * @param {boolean} sourceMap Whether source maps are enabled.
+ * @returns {number}
+ */
+function getCachedCodeType(mode, sourceMap) {
+  if (mode === 'transform') {
+    if (sourceMap) { return kTransformedTypeScriptWithSourceMaps; }
+    return kTransformedTypeScript;
+  }
+  return kStrippedTypeScript;
+}
+
 /**
  * Performs type-stripping to TypeScript source code internally.
  * It is used by internal loaders.
@@ -142,12 +169,40 @@ function stripTypeScriptModuleTypes(source, filename, emitWarning = true) {
   if (isUnderNodeModules(filename)) {
     throw new ERR_UNSUPPORTED_NODE_MODULES_TYPE_STRIPPING(filename);
   }
+  const sourceMap = getOptionValue('--enable-source-maps');
+
+  const mode = getTypeScriptParsingMode();
+
+  // Instead of caching the compile cache status, just go into C++ to fetch it,
+  // as checking process.env equally involves calling into C++ anyway, and
+  // the compile cache can be enabled dynamically.
+  const type = getCachedCodeType(mode, sourceMap);
+  // Get a compile cache entry into the native compile cache store,
+  // keyed by the filename. If the cache can already be loaded on disk,
+  // cached.transpiled contains the cached string. Otherwise we should do
+  // the transpilation and save it in the native store later using
+  // saveCompileCacheEntry().
+  const cached = (filename ? getCompileCacheEntry(source, filename, type) : undefined);
+  if (cached?.transpiled) {  // TODO(joyeecheung): return Buffer here.
+    return cached.transpiled;
+  }
+
   const options = {
-    mode: getTypeScriptParsingMode(),
-    sourceMap: getOptionValue('--enable-source-maps'),
+    mode,
+    sourceMap,
     filename,
   };
-  return processTypeScriptCode(source, options);
+
+  const transpiled = processTypeScriptCode(source, options);
+  if (cached) {
+    // cached.external contains a pointer to the native cache entry.
+    // The cached object would be unreachable once it's out of scope,
+    // but the pointer inside cached.external would stay around for reuse until
+    // environment shutdown or when the cache is manually flushed
+    // to disk. Unwrap it in JS before passing into C++ since it's faster.
+    saveCompileCacheEntry(cached.external, transpiled);
+  }
+  return transpiled;
 }
 
 /**

src/compile_cache.cc

@@ -77,10 +77,27 @@ v8::ScriptCompiler::CachedData* CompileCacheEntry::CopyCache() const {
 // See comments in CompileCacheHandler::Persist().
 constexpr uint32_t kCacheMagicNumber = 0x8adfdbb2;
 
+const char* CompileCacheEntry::type_name() const {
+  switch (type) {
+    case CachedCodeType::kCommonJS:
+      return "CommonJS";
+    case CachedCodeType::kESM:
+      return "ESM";
+    case CachedCodeType::kStrippedTypeScript:
+      return "StrippedTypeScript";
+    case CachedCodeType::kTransformedTypeScript:
+      return "TransformedTypeScript";
+    case CachedCodeType::kTransformedTypeScriptWithSourceMaps:
+      return "TransformedTypeScriptWithSourceMaps";
+    default:
+      UNREACHABLE();
+  }
+}
+
 void CompileCacheHandler::ReadCacheFile(CompileCacheEntry* entry) {
   Debug("[compile cache] reading cache from %s for %s %s...",
         entry->cache_filename,
-        entry->type == CachedCodeType::kCommonJS ? "CommonJS" : "ESM",
+        entry->type_name(),
         entry->source_filename);
 
   uv_fs_t req;
@@ -256,7 +273,8 @@ void CompileCacheHandler::MaybeSaveImpl(CompileCacheEntry* entry,
                                         v8::Local<T> func_or_mod,
                                         bool rejected) {
   DCHECK_NOT_NULL(entry);
-  Debug("[compile cache] cache for %s was %s, ",
+  Debug("[compile cache] V8 code cache for %s %s was %s, ",
+        entry->type_name(),
         entry->source_filename,
         rejected                    ? "rejected"
         : (entry->cache == nullptr) ? "not initialized"
@@ -287,6 +305,25 @@ void CompileCacheHandler::MaybeSave(CompileCacheEntry* entry,
   MaybeSaveImpl(entry, func, rejected);
 }
 
+void CompileCacheHandler::MaybeSave(CompileCacheEntry* entry,
+                                    std::string_view transpiled) {
+  CHECK(entry->type == CachedCodeType::kStrippedTypeScript ||
+        entry->type == CachedCodeType::kTransformedTypeScript ||
+        entry->type == CachedCodeType::kTransformedTypeScriptWithSourceMaps);
+  Debug("[compile cache] saving transpilation cache for %s %s\n",
+        entry->type_name(),
+        entry->source_filename);
+
+  // TODO(joyeecheung): it's weird to copy it again here. Convert the v8::String
+  // directly into buffer held by v8::ScriptCompiler::CachedData here.
+  int cache_size = static_cast<int>(transpiled.size());
+  uint8_t* data = new uint8_t[cache_size];
+  memcpy(data, transpiled.data(), cache_size);
+  entry->cache.reset(new v8::ScriptCompiler::CachedData(
+      data, cache_size, v8::ScriptCompiler::CachedData::BufferOwned));
+  entry->refreshed = true;
+}
+
 /**
  * Persist the compile cache accumulated in memory to disk.
  *
@@ -316,18 +353,25 @@ void CompileCacheHandler::Persist() {
   // incur a negligible overhead from thread synchronization.
   for (auto& pair : compiler_cache_store_) {
     auto* entry = pair.second.get();
+    const char* type_name = entry->type_name();
     if (entry->cache == nullptr) {
-      Debug("[compile cache] skip %s because the cache was not initialized\n",
+      Debug("[compile cache] skip persisting %s %s because the cache was not "
+            "initialized\n",
+            type_name,
             entry->source_filename);
       continue;
     }
     if (entry->refreshed == false) {
-      Debug("[compile cache] skip %s because cache was the same\n",
-            entry->source_filename);
+      Debug(
+          "[compile cache] skip persisting %s %s because cache was the same\n",
+          type_name,
+          entry->source_filename);
       continue;
     }
     if (entry->persisted == true) {
-      Debug("[compile cache] skip %s because cache was already persisted\n",
+      Debug("[compile cache] skip persisting %s %s because cache was already "
+            "persisted\n",
+            type_name,
             entry->source_filename);
       continue;
     }
@@ -363,17 +407,20 @@ void CompileCacheHandler::Persist() {
     auto cleanup_mkstemp =
         OnScopeLeave([&mkstemp_req]() { uv_fs_req_cleanup(&mkstemp_req); });
     std::string cache_filename_tmp = entry->cache_filename + ".XXXXXX";
-    Debug("[compile cache] Creating temporary file for cache of %s...",
-          entry->source_filename);
+    Debug("[compile cache] Creating temporary file for cache of %s (%s)...",
+          entry->source_filename,
+          type_name);
     int err = uv_fs_mkstemp(
         nullptr, &mkstemp_req, cache_filename_tmp.c_str(), nullptr);
     if (err < 0) {
       Debug("failed. %s\n", uv_strerror(err));
       continue;
     }
     Debug(" -> %s\n", mkstemp_req.path);
-    Debug("[compile cache] writing cache for %s to temporary file %s [%d %d %d "
+    Debug("[compile cache] writing cache for %s %s to temporary file %s [%d "
+          "%d %d "
           "%d %d]...",
+          type_name,
           entry->source_filename,
           mkstemp_req.path,
           headers[kMagicNumberOffset],

src/compile_cache.h

@@ -13,10 +13,17 @@
 namespace node {
 class Environment;
 
-// TODO(joyeecheung): move it into a CacheHandler class.
+#define CACHED_CODE_TYPES(V)                                                   \
+  V(kCommonJS, 0)                                                              \
+  V(kESM, 1)                                                                   \
+  V(kStrippedTypeScript, 2)                                                    \
+  V(kTransformedTypeScript, 3)                                                 \
+  V(kTransformedTypeScriptWithSourceMaps, 4)
+
 enum class CachedCodeType : uint8_t {
-  kCommonJS = 0,
-  kESM,
+#define V(type, value) type = value,
+  CACHED_CODE_TYPES(V)
+#undef V
 };
 
 struct CompileCacheEntry {
@@ -34,6 +41,7 @@ struct CompileCacheEntry {
   // Copy the cache into a new store for V8 to consume. Caller takes
   // ownership.
   v8::ScriptCompiler::CachedData* CopyCache() const;
+  const char* type_name() const;
 };
 
 #define COMPILE_CACHE_STATUS(V)                                                \
@@ -70,6 +78,7 @@ class CompileCacheHandler {
   void MaybeSave(CompileCacheEntry* entry,
                  v8::Local<v8::Module> mod,
                  bool rejected);
+  void MaybeSave(CompileCacheEntry* entry, std::string_view transpiled);
   std::string_view cache_dir() { return compile_cache_dir_; }
 
  private: