Reduce number of heap allocations for string array

mattyclarkson · mattyclarkson · commit 3d4cecfb2df0 · 2015-03-03T15:07:53.000Z
diff --git a/generate/templates/manual/src/str_array_converter.cc b/generate/templates/manual/src/str_array_converter.cc
@@ -24,10 +24,17 @@ git_strarray *StrArrayConverter::Convert(Handle<v8::Value> val) {
   }
 }
 
+static git_strarray * AllocGitStrArray(const size_t count) {
+  const size_t size = sizeof(git_strarray) + (sizeof(char*) * count);
+  uint8_t* memory = reinterpret_cast<uint8_t*>(malloc(size));
+  git_strarray *result = reinterpret_cast<git_strarray *>(memory);
+  result->count = count;
+  result->strings = reinterpret_cast<char**>(memory + sizeof(git_strarray));
+  return result;
+}
+
 git_strarray *StrArrayConverter::ConvertArray(Array *val) {
-  git_strarray *result = (git_strarray *)malloc(sizeof(git_strarray));
-  result->count = val->Length();
-  result->strings = (char **)malloc(sizeof(char*) * result->count);
+  git_strarray *result = AllocGitStrArray(val->Length());
 
   for(size_t i = 0; i < result->count; i++) {
     NanUtf8String entry(val->Get(i));
@@ -47,9 +54,7 @@ git_strarray* StrArrayConverter::ConvertString(Handle<String> val) {
 }
 
 git_strarray *StrArrayConverter::ConstructStrArray(int argc, char** argv) {
-  git_strarray *result = (git_strarray *)malloc(sizeof(git_strarray));
-  result->count = argc;
-  result->strings = (char **)malloc(sizeof(char*) * result->count);
+  git_strarray *result = AllocGitStrArray(argc);
 
   for(size_t i = 0; i < result->count; i++) {
     result->strings[i] = strdup(argv[i]);
