src,tools: speed up startup by 2.5%

Use zero-copy external string resources for storing the built-in JS
source code. Saves a few hundred kilobyte of memory and consistently
speeds up `benchmark/misc/startup.js` by 2.5%.
Everything old is new again! Commit 74954ce ("Add string class that
uses ExternalAsciiStringResource.") from 2011 did the same thing but
I removed that in 2013 in commit 34b0a36 ("src: don't use NewExternal()
with unaligned strings") because of a limitation in the V8 API.
V8 no longer requires that strings are aligned if they are one-byte
strings so it should be safe to re-enable external strings again.
PR-URL: #5458
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Robert Jefe Lindstaedt <robert.lindstaedt@gmail.com>

Author: bnoordhuis

src/node_javascript.cc

@@ -6,33 +6,46 @@
 
 namespacenode {
 
-using v8::HandleScope;
 using v8::Local;
 using v8::NewStringType;
 using v8::Object;
 using v8::String;
 
+// id##_data is defined in node_natives.h.
+#defineV(id) \
+staticstruct : publicString::ExternalOneByteStringResource { \
+constchar* data() constoverride { \
+returnreinterpret_cast<constchar*>(id##_data); \
+ } \
+size_tlength() constoverride { returnsizeof(id##_data); } \
+voidDispose() override { /* Default calls `delete this`. */ } \
+ } id##_external_data;
+NODE_NATIVES_MAP(V)
+#undef V
+
 Local<String> MainSource(Environment* env) {
-returnString::NewFromUtf8(
-env->isolate(),
-reinterpret_cast<constchar*>(internal_bootstrap_node_native),
-NewStringType::kNormal,
-sizeof(internal_bootstrap_node_native)).ToLocalChecked();
+auto maybe_string =
+String::NewExternalOneByte(
+ env->isolate(),
+ &internal_bootstrap_node_external_data);
+return maybe_string.ToLocalChecked();
 }
 
 voidDefineJavaScript(Environment* env, Local<Object> target) {
- HandleScope scope(env->isolate());
-
-for (auto native : natives) {
-if (native.source != internal_bootstrap_node_native) {
- Local<String> name = String::NewFromUtf8(env->isolate(), native.name);
- Local<String> source =
-String::NewFromUtf8(
- env->isolate(), reinterpret_cast<constchar*>(native.source),
- NewStringType::kNormal, native.source_len).ToLocalChecked();
- target->Set(name, source);
- }
- }
+auto context = env->context();
+#defineV(id) \
+do { \
+auto key = \
+String::NewFromOneByte( \
+ env->isolate(), id##_name, NewStringType::kNormal, \
+sizeof(id##_name)).ToLocalChecked(); \
+auto value = \
+String::NewExternalOneByte( \
+ env->isolate(), &id##_external_data).ToLocalChecked(); \
+CHECK(target->Set(context, key, value).FromJust()); \
+ } while (0);
+NODE_NATIVES_MAP(V)
+#undef V
 }
 
 } // namespace node

tools/js2c.py

@@ -37,8 +37,11 @@
 importstring
 
 
-defToCArray(filename, lines):
-return','.join(str(ord(c)) forcinlines)
+defToCString(contents):
+step=20
+slices= (contents[i:i+step] foriinxrange(0, len(contents), step))
+slices=map(lambdas: ','.join(str(ord(c)) forcins), slices)
+return',\n'.join(slices)
 
 
 defReadFile(filename):
@@ -61,21 +64,6 @@ def ReadLines(filename):
 returnresult
 
 
-defLoadConfigFrom(name):
-importConfigParser
-config=ConfigParser.ConfigParser()
-config.read(name)
-returnconfig
-
-
-defParseValue(string):
-string=string.strip()
-ifstring.startswith('[') andstring.endswith(']'):
-returnstring.lstrip('[').rstrip(']').split()
-else:
-returnstring
-
-
 defExpandConstants(lines, constants):
 forkey, valueinconstants.items():
 lines=lines.replace(key, str(value))
@@ -174,53 +162,37 @@ def ReadMacros(lines):
 
 
 HEADER_TEMPLATE="""\
-#ifndef node_natives_h
-#define node_natives_h
-namespace node {
-
-%(source_lines)s\
+#ifndef NODE_NATIVES_H_
+#define NODE_NATIVES_H_
 
-struct _native {
- const char* name;
- const unsigned char* source;
- size_t source_len;
-};
+#include <stdint.h>
 
-static const struct _native natives[] = { %(native_lines)s };
+#define NODE_NATIVES_MAP(V) \\
+{node_natives_map}
 
-}
-#endif
-"""
-
-
-NATIVE_DECLARATION="""\
- { "%(id)s", %(escaped_id)s_native, sizeof(%(escaped_id)s_native) },
-"""
+namespace node {{
+{sources}
+}} // namespace node
 
-SOURCE_DECLARATION="""\
- const unsigned char %(escaped_id)s_native[] = { %(data)s };
+#endif // NODE_NATIVES_H_
 """
 
 
-GET_DELAY_INDEX_CASE="""\
- if (strcmp(name, "%(id)s") == 0) return %(i)i;
+NODE_NATIVES_MAP="""\
+V({escaped_id}) \\
 """
 
 
-GET_DELAY_SCRIPT_SOURCE_CASE="""\
- if (index == %(i)i) return Vector<const char>(%(id)s, %(length)i);
+SOURCES="""\
+static const uint8_t {escaped_id}_name[] = {{
+{name}}};
+static const uint8_t {escaped_id}_data[] = {{
+{data}}};
 """
 
 
-GET_DELAY_SCRIPT_NAME_CASE="""\
- if (index == %(i)i) return Vector<const char>("%(name)s", %(length)i);
-"""
-
 defJS2C(source, target):
-ids= []
-delay_ids= []
 modules= []
-# Locate the macros file name.
 consts= {}
 macros= {}
 macro_lines= []
@@ -235,18 +207,14 @@ def JS2C(source, target):
  (consts, macros) =ReadMacros(macro_lines)
 
 # Build source code lines
-source_lines= [ ]
-source_lines_empty= []
-
-native_lines= []
+node_natives_map= []
+sources= []
 
 forsinmodules:
-delay=str(s).endswith('-delay.js')
 lines=ReadFile(str(s))
-
 lines=ExpandConstants(lines, consts)
 lines=ExpandMacros(lines, macros)
-data=ToCArray(s, lines)
+data=ToCString(lines)
 
 # On Windows, "./foo.bar" in the .gyp file is passed as "foo.bar"
 # so don't assume there is always a slash in the file path.
@@ -258,89 +226,19 @@ def JS2C(source, target):
 if'.'inid:
 id=id.split('.', 1)[0]
 
-ifdelay: id=id[:-6]
-ifdelay:
-delay_ids.append((id, len(lines)))
-else:
-ids.append((id, len(lines)))
-
+name=ToCString(id)
 escaped_id=id.replace('-', '_').replace('/', '_')
-source_lines.append(SOURCE_DECLARATION% {
-'id': id,
-'escaped_id': escaped_id,
-'data': data
- })
-source_lines_empty.append(SOURCE_DECLARATION% {
-'id': id,
-'escaped_id': escaped_id,
-'data': 0
- })
-native_lines.append(NATIVE_DECLARATION% {
-'id': id,
-'escaped_id': escaped_id
- })
-
-# Build delay support functions
-get_index_cases= [ ]
-get_script_source_cases= [ ]
-get_script_name_cases= [ ]
-
-i=0
-for (id, length) indelay_ids:
-native_name="native %s.js"%id
-get_index_cases.append(GET_DELAY_INDEX_CASE% { 'id': id, 'i': i })
-get_script_source_cases.append(GET_DELAY_SCRIPT_SOURCE_CASE% {
-'id': id,
-'length': length,
-'i': i
- })
-get_script_name_cases.append(GET_DELAY_SCRIPT_NAME_CASE% {
-'name': native_name,
-'length': len(native_name),
-'i': i
- });
-i=i+1
-
-for (id, length) inids:
-native_name="native %s.js"%id
-get_index_cases.append(GET_DELAY_INDEX_CASE% { 'id': id, 'i': i })
-get_script_source_cases.append(GET_DELAY_SCRIPT_SOURCE_CASE% {
-'id': id,
-'length': length,
-'i': i
- })
-get_script_name_cases.append(GET_DELAY_SCRIPT_NAME_CASE% {
-'name': native_name,
-'length': len(native_name),
-'i': i
- });
-i=i+1
+node_natives_map.append(NODE_NATIVES_MAP.format(**locals()))
+sources.append(SOURCES.format(**locals()))
+
+node_natives_map=''.join(node_natives_map)
+sources=''.join(sources)
 
 # Emit result
 output=open(str(target[0]), "w")
-output.write(HEADER_TEMPLATE% {
-'builtin_count': len(ids) +len(delay_ids),
-'delay_count': len(delay_ids),
-'source_lines': "\n".join(source_lines),
-'native_lines': "\n".join(native_lines),
-'get_index_cases': "".join(get_index_cases),
-'get_script_source_cases': "".join(get_script_source_cases),
-'get_script_name_cases': "".join(get_script_name_cases)
- })
+output.write(HEADER_TEMPLATE.format(**locals()))
 output.close()
 
-iflen(target) >1:
-output=open(str(target[1]), "w")
-output.write(HEADER_TEMPLATE% {
-'builtin_count': len(ids) +len(delay_ids),
-'delay_count': len(delay_ids),
-'source_lines': "\n".join(source_lines_empty),
-'get_index_cases': "".join(get_index_cases),
-'get_script_source_cases': "".join(get_script_source_cases),
-'get_script_name_cases': "".join(get_script_name_cases)
- })
-output.close()
-
 defmain():
 natives=sys.argv[1]
 source_files=sys.argv[2:]