Skip to content

Use emplace_back to reduce the number of copies and allocations #7

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wandernauta wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Use emplace_back to reduce the number of copies and allocations #7

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 3 additions & 4 deletions jsonhelper.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,10 @@ using namespace std;
nlohmann::json packResultsJson(const vector<unordered_map<string, MiniSQLite::outvar_t>>& result, bool fillnull)
{
nlohmann::json arr = nlohmann::json::array();

for(const auto& row : result) {
nlohmann::json j;
for(auto& col : row) {
nlohmann::json &j = arr.emplace_back();
for(const auto& col : row) {
std::visit([&j, &col, &fillnull](auto&& arg) {
using T = std::decay_t<decltype(arg)>;
if constexpr (std::is_same_v<T, nullptr_t>) {
Expand All @@ -23,7 +23,6 @@ nlohmann::json packResultsJson(const vector<unordered_map<string, MiniSQLite::ou
}
}, col.second);
}
arr += j;
}
return arr;
}
Expand Down
11 changes: 4 additions & 7 deletions sqlwriter.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -148,14 +148,14 @@ void MiniSQLite::execPrep(const std::string& table, std::vector<std::unordered_m
rows->clear();

DeadlineCatcher dc(d_sqlite, msec); // noop if msec = 0

std::unordered_map<string, outvar_t> row;

for(;;) {
rc = sqlite3_step(d_stmts[table]);
if(rc == SQLITE_DONE)
break;
else if(rows && rc == SQLITE_ROW) {
row.clear();
std::unordered_map<string, outvar_t>& row = rows->emplace_back();

for(int n = 0 ; n < sqlite3_column_count(d_stmts[table]);++n) {
int type = sqlite3_column_type(d_stmts[table], n);

Expand Down Expand Up @@ -184,9 +184,7 @@ void MiniSQLite::execPrep(const std::string& table, std::vector<std::unordered_m
else if(type == SQLITE_NULL) {
row[sqlite3_column_name(d_stmts[table], n)]= nullptr;
}

}
rows->push_back(row);
}
else {
sqlite3_reset(d_stmts[table]);
Expand Down Expand Up @@ -365,7 +363,7 @@ std::vector<std::unordered_map<std::string, std::string>> SQLiteWriter::query(co
auto res = queryGen(q, values);
std::vector<std::unordered_map<std::string, std::string>> ret;
for(const auto& rowin : res) {
std::unordered_map<std::string, std::string> rowout;
std::unordered_map<std::string, std::string>& rowout = ret.emplace_back();
for(const auto& f : rowin) {
string str;
std::visit([&str](auto&& arg) {
Expand All @@ -380,7 +378,6 @@ std::vector<std::unordered_map<std::string, std::string>> SQLiteWriter::query(co
}, f.second);
rowout[f.first] = str;
}
ret.push_back(rowout);
}
return ret;
}
Expand Down