Commit d3f7280
os: performance improvement in vector allocation
We were using the result vector with an object which is not a primitive
data type, and going with the constructor allocation pattern it creates
a size of that vector and also initializes the spaces with the data type
as well which is in our case is `Local<Value>`. It leads to waste of
some CPU cycles and instead we just wanted to have some reserved space
in our vector.
We can use `reserve` method on vector to reserve some space for the
vector but doesn't initialize the value since we are anyways doing it in
the following loop.
PR-URL: #36748
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: James M Snell <jasnell@gmail.com>1 parent 3d20415 commit d3f7280
1 file changed
Lines changed: 21 additions & 19 deletions
| Original file line number | Diff line number | Diff line change | |
|---|---|---|---|
@@ -112,16 +112,17 @@ static void GetCPUInfo(const FunctionCallbackInfo<Value>& args) { | |||
| 112 | 112 | // assemble them into objects in JS than to call Object::Set() repeatedly | |
| 113 | 113 | // The array is in the format | |
| 114 | 114 | // [model, speed, (5 entries of cpu_times), model2, speed2, ...] | |
| 115 | - std::vector<Local<Value>> result(count * 7); | ||
| 116 | - for (int i = 0, j = 0; i < count; i++) { | ||
| 115 | + std::vector<Local<Value>> result; | ||
| 116 | + result.reserve(count * 7); | ||
| 117 | + for (int i = 0; i < count; i++) { | ||
| 117 | 118 | uv_cpu_info_t* ci = cpu_infos + i; | |
| 118 | - result[j++] = OneByteString(isolate, ci->model); | ||
| 119 | - result[j++] = Number::New(isolate, ci->speed); | ||
| 120 | - result[j++] = Number::New(isolate, ci->cpu_times.user); | ||
| 121 | - result[j++] = Number::New(isolate, ci->cpu_times.nice); | ||
| 122 | - result[j++] = Number::New(isolate, ci->cpu_times.sys); | ||
| 123 | - result[j++] = Number::New(isolate, ci->cpu_times.idle); | ||
| 124 | - result[j++] = Number::New(isolate, ci->cpu_times.irq); | ||
| 119 | + result.emplace_back(OneByteString(isolate, ci->model)); | ||
| 120 | + result.emplace_back(Number::New(isolate, ci->speed)); | ||
| 121 | + result.emplace_back(Number::New(isolate, ci->cpu_times.user)); | ||
| 122 | + result.emplace_back(Number::New(isolate, ci->cpu_times.nice)); | ||
| 123 | + result.emplace_back(Number::New(isolate, ci->cpu_times.sys)); | ||
| 124 | + result.emplace_back(Number::New(isolate, ci->cpu_times.idle)); | ||
| 125 | + result.emplace_back(Number::New(isolate, ci->cpu_times.irq)); | ||
| 125 | 126 | } | |
| 126 | 127 | ||
| 127 | 128 | uv_free_cpu_info(cpu_infos, count); | |
@@ -182,7 +183,8 @@ static void GetInterfaceAddresses(const FunctionCallbackInfo<Value>& args) { | |||
| 182 | 183 | } | |
| 183 | 184 | ||
| 184 | 185 | Local<Value> no_scope_id = Integer::New(isolate, -1); | |
| 185 | - std::vector<Local<Value>> result(count * 7); | ||
| 186 | + std::vector<Local<Value>> result; | ||
| 187 | + result.reserve(count * 7); | ||
| 186 | 188 | for (i = 0; i < count; i++) { | |
| 187 | 189 | const char* const raw_name = interfaces[i].name; | |
| 188 | 190 | ||
@@ -216,18 +218,18 @@ static void GetInterfaceAddresses(const FunctionCallbackInfo<Value>& args) { | |||
| 216 | 218 | family = env->unknown_string(); | |
| 217 | 219 | } | |
| 218 | 220 | ||
| 219 | - result[i * 7] = name; | ||
| 220 | - result[i * 7 + 1] = OneByteString(isolate, ip); | ||
| 221 | - result[i * 7 + 2] = OneByteString(isolate, netmask); | ||
| 222 | - result[i * 7 + 3] = family; | ||
| 223 | - result[i * 7 + 4] = FIXED_ONE_BYTE_STRING(isolate, mac); | ||
| 224 | - result[i * 7 + 5] = | ||
| 225 | - interfaces[i].is_internal ? True(isolate) : False(isolate); | ||
| 221 | + result.emplace_back(name); | ||
| 222 | + result.emplace_back(OneByteString(isolate, ip)); | ||
| 223 | + result.emplace_back(OneByteString(isolate, netmask)); | ||
| 224 | + result.emplace_back(family); | ||
| 225 | + result.emplace_back(FIXED_ONE_BYTE_STRING(isolate, mac)); | ||
| 226 | + result.emplace_back( | ||
| 227 | + interfaces[i].is_internal ? True(isolate) : False(isolate)); | ||
| 226 | 228 | if (interfaces[i].address.address4.sin_family == AF_INET6) { | |
| 227 | 229 | uint32_t scopeid = interfaces[i].address.address6.sin6_scope_id; | |
| 228 | - result[i * 7 + 6] = Integer::NewFromUnsigned(isolate, scopeid); | ||
| 230 | + result.emplace_back(Integer::NewFromUnsigned(isolate, scopeid)); | ||
| 229 | 231 | } else { | |
| 230 | - result[i * 7 + 6] = no_scope_id; | ||
| 232 | + result.emplace_back(no_scope_id); | ||
| 231 | 233 | } | |
| 232 | 234 | } | |
| 233 | 235 | ||
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