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src,tools: speed up startup by 2.5%
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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>
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@bnoordhuis @MylesBorins
bnoordhuis authored and MylesBorins committed Jan 23, 2017
1 parent ba6a1b6 commit 95ae885
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Showing 2 changed files with 62 additions and 151 deletions.
49 changes: 31 additions & 18 deletions src/node_javascript.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,33 +6,46 @@

namespace node {

using v8::HandleScope;
using v8::Local;
using v8::NewStringType;
using v8::Object;
using v8::String;

// id##_data is defined in node_natives.h.
#define V(id) \
static struct : public String::ExternalOneByteStringResource { \
const char* data() const override { \
return reinterpret_cast<const char*>(id##_data); \
} \
size_t length() const override { return sizeof(id##_data); } \
void Dispose() override { /* Default calls `delete this`. */ } \
} id##_external_data;
NODE_NATIVES_MAP(V)
#undef V

Local<String> MainSource(Environment* env) {
return String::NewFromUtf8(
env->isolate(),
reinterpret_cast<const char*>(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();
}

void DefineJavaScript(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<const char*>(native.source),
NewStringType::kNormal, native.source_len).ToLocalChecked();
target->Set(name, source);
}
}
auto context = env->context();
#define V(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
164 changes: 31 additions & 133 deletions tools/js2c.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,8 +37,11 @@
import string


def ToCArray(filename, lines):
return ','.join(str(ord(c)) for c in lines)
def ToCString(contents):
step = 20
slices = (contents[i:i+step] for i in xrange(0, len(contents), step))
slices = map(lambda s: ','.join(str(ord(c)) for c in s), slices)
return ',\n'.join(slices)


def ReadFile(filename):
Expand All @@ -61,21 +64,6 @@ def ReadLines(filename):
return result


def LoadConfigFrom(name):
import ConfigParser
config = ConfigParser.ConfigParser()
config.read(name)
return config


def ParseValue(string):
string = string.strip()
if string.startswith('[') and string.endswith(']'):
return string.lstrip('[').rstrip(']').split()
else:
return string


def ExpandConstants(lines, constants):
for key, value in constants.items():
lines = lines.replace(key, str(value))
Expand Down Expand Up @@ -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);
"""

def JS2C(source, target):
ids = []
delay_ids = []
modules = []
# Locate the macros file name.
consts = {}
macros = {}
macro_lines = []
Expand All @@ -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 = []

for s in modules:
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.
Expand All @@ -258,89 +226,19 @@ def JS2C(source, target):
if '.' in id:
id = id.split('.', 1)[0]

if delay: id = id[:-6]
if delay:
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) in delay_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) in 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
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()

if len(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()

def main():
natives = sys.argv[1]
source_files = sys.argv[2:]
Expand Down

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