src: lazily load internalBinding('uv') and build the errmap lazily

This removes the `internalBinding('uv')` call from the normal
bootstrap for now, and avoids building `errmap` by default which
expands to a lot of calls into V8.

PR-URL: #25143
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/internal/errors.js

@@ -15,11 +15,6 @@ const kInfo = Symbol('info');
 const messages = new Map();
 const codes = {};
 
-const {
- errmap,
- UV_EAI_NODATA,
- UV_EAI_NONAME
-} = internalBinding('uv');
 const { kMaxLength } = internalBinding('buffer');
 const { defineProperty } = Object;
 
@@ -237,6 +232,24 @@ function getMessage(key, args) {
  return util.format.apply(null, args);
 }
 
+let uvBinding;
+
+function lazyUv() {
+ if (!uvBinding) {
+ uvBinding = internalBinding('uv');
+ }
+ return uvBinding;
+}
+
+function lazyErrmapGet(name) {
+ uvBinding = lazyUv();
+ if (!uvBinding.errmap) {
+ uvBinding.errmap = uvBinding.getErrorMap();
+ }
+ return uvBinding.errmap.get(name);
+}
+
+
 /**
  * This creates an error compatible with errors produced in the C++
  * function UVException using a context object with data assembled in C++.
@@ -247,7 +260,7 @@ function getMessage(key, args) {
  * @returns {Error}
  */
 function uvException(ctx) {
- const [ code, uvmsg ] = errmap.get(ctx.errno);
+ const [ code, uvmsg ] = lazyErrmapGet(ctx.errno);
  let message = `${code}: ${ctx.message || uvmsg}, ${ctx.syscall}`;
 
  let path;
@@ -303,7 +316,7 @@ function uvException(ctx) {
  * @returns {Error}
  */
 function uvExceptionWithHostPort(err, syscall, address, port) {
- const [ code, uvmsg ] = errmap.get(err);
+ const [ code, uvmsg ] = lazyErrmapGet(err);
  const message = `${syscall} ${code}: ${uvmsg}`;
  let details = '';
 
@@ -421,7 +434,7 @@ function dnsException(code, syscall, hostname) {
  if (typeof code === 'number') {
  // FIXME(bnoordhuis) Remove this backwards compatibility nonsense and pass
  // the true error to the user. ENOTFOUND is not even a proper POSIX error!
- if (code === UV_EAI_NODATA || code === UV_EAI_NONAME) {
+ if (code === lazyUv().UV_EAI_NODATA || code === lazyUv().UV_EAI_NONAME) {
  code = 'ENOTFOUND'; // Fabricated error name.
  } else {
  code = lazyInternalUtil().getSystemErrorName(code);

lib/internal/util.js

@@ -16,8 +16,6 @@ const {
  isNativeError
 } = internalBinding('types');
 
-const { errmap } = internalBinding('uv');
-
 const noCrypto = !process.versions.openssl;
 
 const experimentalWarnings = new Set();
@@ -250,8 +248,19 @@ function getConstructorOf(obj) {
  return null;
 }
 
+let uvBinding;
+function lazyErrmapGet(name) {
+ if (!uvBinding) {
+ uvBinding = internalBinding('uv');
+ }
+ if (!uvBinding.errmap) {
+ uvBinding.errmap = uvBinding.getErrorMap();
+ }
+ return uvBinding.errmap.get(name);
+}
+
 function getSystemErrorName(err) {
- const entry = errmap.get(err);
+ const entry = lazyErrmapGet(err);
  return entry ? entry[0] : `Unknown system error ${err}`;
 }
 

src/uv.cc

@@ -25,20 +25,39 @@
 #include "env-inl.h"
 
 namespace node {
+
+namespace per_process {
+struct UVError {
+ int value;
+ const char* name;
+ const char* message;
+};
+
+// We only expand the macro once here to reduce the amount of code
+// generated.
+static const struct UVError uv_errors_map[] = {
+#define V(name, message) {UV_##name, #name, message},
+ UV_ERRNO_MAP(V)
+#undef V
+};
+} // namespace per_process
+
 namespace {
 
 using v8::Array;
 using v8::Context;
+using v8::DontDelete;
 using v8::FunctionCallbackInfo;
 using v8::Integer;
 using v8::Isolate;
 using v8::Local;
 using v8::Map;
 using v8::Object;
+using v8::PropertyAttribute;
+using v8::ReadOnly;
 using v8::String;
 using v8::Value;
 
-
 void ErrName(const FunctionCallbackInfo<Value>& args) {
  Environment* env = Environment::GetCurrent(args);
  if (env->options()->pending_deprecation && env->EmitErrNameWarning()) {
@@ -57,6 +76,29 @@ void ErrName(const FunctionCallbackInfo<Value>& args) {
  args.GetReturnValue().Set(OneByteString(env->isolate(), name));
 }
 
+void GetErrMap(const FunctionCallbackInfo<Value>& args) {
+ Environment* env = Environment::GetCurrent(args);
+ Isolate* isolate = env->isolate();
+ Local<Context> context = env->context();
+
+ Local<Map> err_map = Map::New(isolate);
+
+ size_t errors_len = arraysize(per_process::uv_errors_map);
+ for (size_t i = 0; i < errors_len; ++i) {
+ const auto& error = per_process::uv_errors_map[i];
+ Local<Value> arr[] = {OneByteString(isolate, error.name),
+ OneByteString(isolate, error.message)};
+ if (err_map
+ ->Set(context,
+ Integer::New(isolate, error.value),
+ Array::New(isolate, arr, arraysize(arr)))
+ .IsEmpty()) {
+ return;
+ }
+ }
+
+ args.GetReturnValue().Set(err_map);
+}
 
 void Initialize(Local<Object> target,
  Local<Value> unused,
@@ -70,28 +112,21 @@ void Initialize(Local<Object> target,
  ->GetFunction(env->context())
  .ToLocalChecked()).FromJust();
 
-#define V(name, _) NODE_DEFINE_CONSTANT(target, UV_##name);
- UV_ERRNO_MAP(V)
-#undef V
-
- Local<Map> err_map = Map::New(isolate);
-
-#define V(name, msg) do { \
- Local<Value> arr[] = { \
- OneByteString(isolate, #name), \
- OneByteString(isolate, msg) \
- }; \
- if (err_map->Set(context, \
- Integer::New(isolate, UV_##name), \
- Array::New(isolate, arr, arraysize(arr))).IsEmpty()) { \
- return; \
- } \
-} while (0);
- UV_ERRNO_MAP(V)
-#undef V
+ // TODO(joyeecheung): This should be deprecated in user land in favor of
+ // `util.getSystemErrorName(err)`.
+ PropertyAttribute attributes =
+ static_cast<PropertyAttribute>(ReadOnly | DontDelete);
+ size_t errors_len = arraysize(per_process::uv_errors_map);
+ const std::string prefix = "UV_";
+ for (size_t i = 0; i < errors_len; ++i) {
+ const auto& error = per_process::uv_errors_map[i];
+ const std::string prefixed_name = prefix + error.name;
+ Local<String> name = OneByteString(isolate, prefixed_name.c_str());
+ Local<Integer> value = Integer::New(isolate, error.value);
+ target->DefineOwnProperty(context, name, value, attributes).FromJust();
+ }
 
- target->Set(context, FIXED_ONE_BYTE_STRING(isolate, "errmap"),
- err_map).FromJust();
+ env->SetMethod(target, "getErrorMap", GetErrMap);
 }
 
 } // anonymous namespace