os: improve networkInterfaces() performance

benchmark/os/networkInterfaces.js

@@ -0,0 +1,15 @@
+'use strict';
+
+const common = require('../common.js');
+const networkInterfaces = require('os').networkInterfaces;
+
+const bench = common.createBenchmark(main, {
+  n: [1e4]
+});
+
+function main({ n }) {
+  bench.start();
+  for (var i = 0; i < n; ++i)
+    networkInterfaces();
+  bench.end(n);
+}

lib/os.js

@@ -143,18 +143,13 @@ endianness[Symbol.toPrimitive] = () => kEndianness;
 // Returns the number of ones in the binary representation of the decimal
 // number.
 function countBinaryOnes(n) {
-  let count = 0;
-  // Remove one "1" bit from n until n is the power of 2. This iterates k times
-  // while k is the number of "1" in the binary representation.
-  // For more check https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators
-  while (n !== 0) {
-    n = n & (n - 1);
-    count++;
-  }
-  return count;
+  // Count the number of bits set in parallel, which is faster than looping
+  n = n - ((n >>> 1) & 0x55555555);
+  n = (n & 0x33333333) + ((n >>> 2) & 0x33333333);
+  return ((n + (n >>> 4) & 0xF0F0F0F) * 0x1010101) >>> 24;
 }
 
-function getCIDR({ address, netmask, family }) {
+function getCIDR(address, netmask, family) {
   let ones = 0;
   let split = '.';
   let range = 10;
@@ -190,17 +185,33 @@ function getCIDR({ address, netmask, family }) {
 }
 
 function networkInterfaces() {
-  const interfaceAddresses = getInterfaceAddresses();
+  const data = getInterfaceAddresses();
+  const result = {};
 
-  const keys = Object.keys(interfaceAddresses);
-  for (var i = 0; i < keys.length; i++) {
-    const arr = interfaceAddresses[keys[i]];
-    for (var j = 0; j < arr.length; j++) {
-      arr[j].cidr = getCIDR(arr[j]);
-    }
+  if (data === undefined)
+    return result;
+  for (var i = 0; i < data.length; i += 7) {
+    const name = data[i];
+    const entry = {
+      address: data[i + 1],
+      netmask: data[i + 2],
+      family: data[i + 3],
+      mac: data[i + 4],
+      internal: data[i + 5],
+      cidr: getCIDR(data[i + 1], data[i + 2], data[i + 3])
+    };
+    const scopeid = data[i + 6];
+    if (scopeid !== -1)
+      entry.scopeid = scopeid;
+
+    const existing = result[name];
+    if (existing !== undefined)
+      existing.push(entry);
+    else
+      result[name] = [entry];
   }
 
-  return interfaceAddresses;
+  return result;
 }
 
 function setPriority(pid, priority) {

src/node_os.cc

@@ -213,28 +213,28 @@ static void GetLoadAvg(const FunctionCallbackInfo<Value>& args) {
 
 static void GetInterfaceAddresses(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
+  Isolate* isolate = env->isolate();
   uv_interface_address_t* interfaces;
   int count, i;
   char ip[INET6_ADDRSTRLEN];
   char netmask[INET6_ADDRSTRLEN];
   std::array<char, 18> mac;
-  Local<Object> ret, o;
   Local<String> name, family;
-  Local<Array> ifarr;
 
   int err = uv_interface_addresses(&interfaces, &count);
 
-  ret = Object::New(env->isolate());
+  if (err == UV_ENOSYS)
+    return args.GetReturnValue().SetUndefined();
 
-  if (err == UV_ENOSYS) {
-    return args.GetReturnValue().Set(ret);
-  } else if (err) {
+  if (err) {
     CHECK_GE(args.Length(), 1);
     env->CollectUVExceptionInfo(args[args.Length() - 1], errno,
                                 "uv_interface_addresses");
     return args.GetReturnValue().SetUndefined();
   }
 
+  Local<Value> no_scope_id = Integer::New(isolate, -1);
+  std::vector<Local<Value>> result(count * 7);
   for (i = 0; i < count; i++) {
     const char* const raw_name = interfaces[i].name;
 
@@ -243,17 +243,9 @@ static void GetInterfaceAddresses(const FunctionCallbackInfo<Value>& args) {
     // to assume UTF8 as the default as well. It’s what people will expect if
     // they name the interface from any input that uses UTF-8, which should be
     // the most frequent case by far these days.)
-    name = String::NewFromUtf8(env->isolate(), raw_name,
+    name = String::NewFromUtf8(isolate, raw_name,
         v8::NewStringType::kNormal).ToLocalChecked();
 
-    if (ret->Has(env->context(), name).FromJust()) {
-      ifarr = Local<Array>::Cast(ret->Get(env->context(),
-                                          name).ToLocalChecked());
-    } else {
-      ifarr = Array::New(env->isolate());
-      ret->Set(env->context(), name, ifarr).FromJust();
-    }
-
     snprintf(mac.data(),
              mac.size(),
              "%02x:%02x:%02x:%02x:%02x:%02x",
@@ -277,34 +269,23 @@ static void GetInterfaceAddresses(const FunctionCallbackInfo<Value>& args) {
       family = env->unknown_string();
     }
 
-    o = Object::New(env->isolate());
-    o->Set(env->context(),
-           env->address_string(),
-           OneByteString(env->isolate(), ip)).FromJust();
-    o->Set(env->context(),
-           env->netmask_string(),
-           OneByteString(env->isolate(), netmask)).FromJust();
-    o->Set(env->context(),
-           env->family_string(), family).FromJust();
-    o->Set(env->context(),
-           env->mac_string(),
-           FIXED_ONE_BYTE_STRING(env->isolate(), mac)).FromJust();
-
+    result[i * 7] = name;
+    result[i * 7 + 1] = OneByteString(isolate, ip);
+    result[i * 7 + 2] = OneByteString(isolate, netmask);
+    result[i * 7 + 3] = family;
+    result[i * 7 + 4] = FIXED_ONE_BYTE_STRING(isolate, mac);
+    result[i * 7 + 5] =
+      interfaces[i].is_internal ? True(isolate) : False(isolate);
     if (interfaces[i].address.address4.sin_family == AF_INET6) {
       uint32_t scopeid = interfaces[i].address.address6.sin6_scope_id;
-      o->Set(env->context(), env->scopeid_string(),
-             Integer::NewFromUnsigned(env->isolate(), scopeid)).FromJust();
+      result[i * 7 + 6] = Integer::NewFromUnsigned(isolate, scopeid);
+    } else {
+      result[i * 7 + 6] = no_scope_id;
     }
-
-    const bool internal = interfaces[i].is_internal;
-    o->Set(env->context(), env->internal_string(),
-           internal ? True(env->isolate()) : False(env->isolate())).FromJust();
-
-    ifarr->Set(env->context(), ifarr->Length(), o).FromJust();
   }
 
   uv_free_interface_addresses(interfaces, count);
-  args.GetReturnValue().Set(ret);
+  args.GetReturnValue().Set(Array::New(isolate, result.data(), result.size()));
 }