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Improve JSON::stringify performance

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- Changed stringify to call static function _stringify directly, instead of creating JSON object
- Changed colon and end_statement from String to const char * to avoid extra allocations in each _stringify call
- Pass result String reference to each _stringify call to append to instead of allocating new String in each call

These changes make JSON::stringify around 2-3x faster in most cases
This commit is contained in:
aaronp64
2024-06-29 22:53:25 -04:00
parent 6a6a1168a5
commit f13b4b760a
3 changed files with 151 additions and 43 deletions
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105
core/io/json.cpp
View File

@@ -47,42 +47,47 @@ const char *JSON::tk_name[TK_MAX] = {
"EOF",
};
String JSON::_make_indent(const String &p_indent, int p_size) {
return p_indent.repeat(p_size);
void JSON::_add_indent(String &r_result, const String &p_indent, int p_size) {
for (int i = 0; i < p_size; i++) {
r_result += p_indent;
}
}
String JSON::_stringify(const Variant &p_var, const String &p_indent, int p_cur_indent, bool p_sort_keys, HashSet<const void *> &p_markers, bool p_full_precision) {
ERR_FAIL_COND_V_MSG(p_cur_indent > Variant::MAX_RECURSION_DEPTH, "...", "JSON structure is too deep. Bailing.");
String colon = ":";
String end_statement = "";
if (!p_indent.is_empty()) {
colon += " ";
end_statement += "\n";
void JSON::_stringify(String &r_result, const Variant &p_var, const String &p_indent, int p_cur_indent, bool p_sort_keys, HashSet<const void *> &p_markers, bool p_full_precision) {
if (p_cur_indent > Variant::MAX_RECURSION_DEPTH) {
r_result += "...";
ERR_FAIL_MSG("JSON structure is too deep. Bailing.");
}
const char *colon = p_indent.is_empty() ? ":" : ": ";
const char *end_statement = p_indent.is_empty() ? "" : "\n";
switch (p_var.get_type()) {
case Variant::NIL:
return "null";
r_result += "null";
return;
case Variant::BOOL:
return p_var.operator bool() ? "true" : "false";
r_result += p_var.operator bool() ? "true" : "false";
return;
case Variant::INT:
return itos(p_var);
r_result += itos(p_var);
return;
case Variant::FLOAT: {
double num = p_var;
// Only for exactly 0. If we have approximately 0 let the user decide how much
// precision they want.
if (num == double(0)) {
return String("0.0");
r_result += "0.0";
return;
}
double magnitude = std::log10(Math::abs(num));
int total_digits = p_full_precision ? 17 : 14;
int precision = MAX(1, total_digits - (int)Math::floor(magnitude));
return String::num(num, precision);
r_result += String::num(num, precision);
return;
}
case Variant::PACKED_INT32_ARRAY:
case Variant::PACKED_INT64_ARRAY:
@@ -91,13 +96,19 @@ String JSON::_stringify(const Variant &p_var, const String &p_indent, int p_cur_
case Variant::PACKED_STRING_ARRAY:
case Variant::ARRAY: {
Array a = p_var;
if (a.is_empty()) {
return "[]";
if (p_markers.has(a.id())) {
r_result += "\"[...]\"";
ERR_FAIL_MSG("Converting circular structure to JSON.");
}
String s = "[";
s += end_statement;
ERR_FAIL_COND_V_MSG(p_markers.has(a.id()), "\"[...]\"", "Converting circular structure to JSON.");
if (a.is_empty()) {
r_result += "[]";
return;
}
r_result += '[';
r_result += end_statement;
p_markers.insert(a.id());
bool first = true;
@@ -105,21 +116,27 @@ String JSON::_stringify(const Variant &p_var, const String &p_indent, int p_cur_
if (first) {
first = false;
} else {
s += ",";
s += end_statement;
r_result += ',';
r_result += end_statement;
}
s += _make_indent(p_indent, p_cur_indent + 1) + _stringify(var, p_indent, p_cur_indent + 1, p_sort_keys, p_markers);
_add_indent(r_result, p_indent, p_cur_indent + 1);
_stringify(r_result, var, p_indent, p_cur_indent + 1, p_sort_keys, p_markers);
}
s += end_statement + _make_indent(p_indent, p_cur_indent) + "]";
r_result += end_statement;
_add_indent(r_result, p_indent, p_cur_indent);
r_result += ']';
p_markers.erase(a.id());
return s;
return;
}
case Variant::DICTIONARY: {
String s = "{";
s += end_statement;
Dictionary d = p_var;
if (p_markers.has(d.id())) {
r_result += "\"{...}\"";
ERR_FAIL_MSG("Converting circular structure to JSON.");
}
ERR_FAIL_COND_V_MSG(p_markers.has(d.id()), "\"{...}\"", "Converting circular structure to JSON.");
r_result += '{';
r_result += end_statement;
p_markers.insert(d.id());
LocalVector<Variant> keys = d.get_key_list();
@@ -129,24 +146,30 @@ String JSON::_stringify(const Variant &p_var, const String &p_indent, int p_cur_
}
bool first_key = true;
for (const Variant &E : keys) {
for (const Variant &key : keys) {
if (first_key) {
first_key = false;
} else {
s += ",";
s += end_statement;
r_result += ',';
r_result += end_statement;
}
s += _make_indent(p_indent, p_cur_indent + 1) + _stringify(String(E), p_indent, p_cur_indent + 1, p_sort_keys, p_markers);
s += colon;
s += _stringify(d[E], p_indent, p_cur_indent + 1, p_sort_keys, p_markers);
_add_indent(r_result, p_indent, p_cur_indent + 1);
_stringify(r_result, String(key), p_indent, p_cur_indent + 1, p_sort_keys, p_markers);
r_result += colon;
_stringify(r_result, d[key], p_indent, p_cur_indent + 1, p_sort_keys, p_markers);
}
s += end_statement + _make_indent(p_indent, p_cur_indent) + "}";
r_result += end_statement;
_add_indent(r_result, p_indent, p_cur_indent);
r_result += '}';
p_markers.erase(d.id());
return s;
return;
}
default:
return "\"" + String(p_var).json_escape() + "\"";
r_result += '"';
r_result += String(p_var).json_escape();
r_result += '"';
return;
}
}
@@ -568,10 +591,10 @@ String JSON::get_parsed_text() const {
}
String JSON::stringify(const Variant &p_var, const String &p_indent, bool p_sort_keys, bool p_full_precision) {
Ref<JSON> json;
json.instantiate();
String result;
HashSet<const void *> markers;
return json->_stringify(p_var, p_indent, 0, p_sort_keys, markers, p_full_precision);
_stringify(result, p_var, p_indent, 0, p_sort_keys, markers, p_full_precision);
return result;
}
Variant JSON::parse_string(const String &p_json_string) {

4
core/io/json.h
View File

@@ -71,8 +71,8 @@ class JSON : public Resource {
static const char *tk_name[];
static String _make_indent(const String &p_indent, int p_size);
static String _stringify(const Variant &p_var, const String &p_indent, int p_cur_indent, bool p_sort_keys, HashSet<const void *> &p_markers, bool p_full_precision = false);
static void _add_indent(String &r_result, const String &p_indent, int p_size);
static void _stringify(String &r_result, const Variant &p_var, const String &p_indent, int p_cur_indent, bool p_sort_keys, HashSet<const void *> &p_markers, bool p_full_precision = false);
static Error _get_token(const char32_t *p_str, int &index, int p_len, Token &r_token, int &line, String &r_err_str);
static Error _parse_value(Variant &value, Token &token, const char32_t *p_str, int &index, int p_len, int &line, int p_depth, String &r_err_str);
static Error _parse_array(Array &array, const char32_t *p_str, int &index, int p_len, int &line, int p_depth, String &r_err_str);

85
tests/core/io/test_json.h
View File

@@ -36,6 +36,91 @@
namespace TestJSON {
TEST_CASE("[JSON] Stringify single data types") {
CHECK(JSON::stringify(Variant()) == "null");
CHECK(JSON::stringify(false) == "false");
CHECK(JSON::stringify(true) == "true");
CHECK(JSON::stringify(0) == "0");
CHECK(JSON::stringify(12345) == "12345");
CHECK(JSON::stringify(0.75) == "0.75");
CHECK(JSON::stringify("test") == "\"test\"");
CHECK(JSON::stringify("\\\b\f\n\r\t\v\"") == "\"\\\\\\b\\f\\n\\r\\t\\v\\\"\"");
}
TEST_CASE("[JSON] Stringify arrays") {
CHECK(JSON::stringify(Array()) == "[]");
Array int_array;
for (int i = 0; i < 10; i++) {
int_array.push_back(i);
}
CHECK(JSON::stringify(int_array) == "[0,1,2,3,4,5,6,7,8,9]");
Array str_array;
str_array.push_back("Hello");
str_array.push_back("World");
str_array.push_back("!");
CHECK(JSON::stringify(str_array) == "[\"Hello\",\"World\",\"!\"]");
Array indented_array;
Array nested_array;
for (int i = 0; i < 5; i++) {
indented_array.push_back(i);
nested_array.push_back(i);
}
indented_array.push_back(nested_array);
CHECK(JSON::stringify(indented_array, "\t") == "[\n\t0,\n\t1,\n\t2,\n\t3,\n\t4,\n\t[\n\t\t0,\n\t\t1,\n\t\t2,\n\t\t3,\n\t\t4\n\t]\n]");
ERR_PRINT_OFF
Array self_array;
self_array.push_back(self_array);
CHECK(JSON::stringify(self_array) == "[\"[...]\"]");
self_array.clear();
Array max_recursion_array;
for (int i = 0; i < Variant::MAX_RECURSION_DEPTH + 1; i++) {
Array next;
next.push_back(max_recursion_array);
max_recursion_array = next;
}
CHECK(JSON::stringify(max_recursion_array).contains("[...]"));
ERR_PRINT_ON
}
TEST_CASE("[JSON] Stringify dictionaries") {
CHECK(JSON::stringify(Dictionary()) == "{}");
Dictionary single_entry;
single_entry["key"] = "value";
CHECK(JSON::stringify(single_entry) == "{\"key\":\"value\"}");
Dictionary indented;
indented["key1"] = "value1";
indented["key2"] = 2;
CHECK(JSON::stringify(indented, "\t") == "{\n\t\"key1\": \"value1\",\n\t\"key2\": 2\n}");
Dictionary outer;
Dictionary inner;
inner["key"] = "value";
outer["inner"] = inner;
CHECK(JSON::stringify(outer) == "{\"inner\":{\"key\":\"value\"}}");
ERR_PRINT_OFF
Dictionary self_dictionary;
self_dictionary["key"] = self_dictionary;
CHECK(JSON::stringify(self_dictionary) == "{\"key\":\"{...}\"}");
self_dictionary.clear();
Dictionary max_recursion_dictionary;
for (int i = 0; i < Variant::MAX_RECURSION_DEPTH + 1; i++) {
Dictionary next;
next["key"] = max_recursion_dictionary;
max_recursion_dictionary = next;
}
CHECK(JSON::stringify(max_recursion_dictionary).contains("{...:...}"));
ERR_PRINT_ON
}
// NOTE: The current JSON parser accepts many non-conformant strings such as
// single-quoted strings, duplicate commas and trailing commas.
// This is intentionally not tested as users shouldn't rely on this behavior.