Thread-safe, high performance, PostgreSQL connection pooling library for C++ (17+)
Tip
Please read this document before using the library. I know, you don't have time but reading this document will save you time. I mean just this file, it's not long at all. Trial and error will cost you more time.
- How to add it to my project
- How to use? (Simple Connection)
- How to use? (Shared Connection)
- Semantic Versioning
- Full function list
- License
- Contact
This is a header only library. So actually, all you need is to add the libcpp-pg-pool.hpp file in src folder to your project and start using it with #include.
But this library is uses libpqxx under the hood. So, you also need to add libpqxx to your project before to use it.
You can find usage examples in the examples folder, also find a sample CMakeLists.txt file content below.
cmake_minimum_required(VERSION 3.14)
project(myProject)
find_package(libpqxx CONFIG REQUIRED)
add_executable(myProject main.cpp libcpp-pg-pool.hpp)
target_link_libraries(myProject PRIVATE libpqxx::pqxx)
You can use the "acquire" method to obtain a new connection. The value returned from the acquire method is a shared pointer and the connection is automatically returned to the pool as soon as it goes out of scope. Therefore, you do not need to close the connection manually.
Important
Connection Pool should be created only once in the application It may take up to 1 second to be ready depending on the pool size
#include "libcpp-pg-pool.hpp"
using namespace lklibs;
int main() {
const auto connectionString = "dbname=my_db user=my_user password=my_password host=localhost port=5432";
// You can optionally specify the connection pool size, but if you don't, the default value will be 100
PgPool pool(connectionString, 10);
{
// Acquire a connection from the pool
const auto dbConnection = pool.acquire();
pqxx::work txn(*dbConnection);
const auto result = txn.exec("SELECT * FROM my_table");
for (const auto& row : result)
{
std::cout << row[0].c_str() << std::endl;
}
}
// Connection is automatically returned to the pool when the dbConnection goes out of scope
// So, no need to manually close the connection
return 0;
}Important
The connection pool size should not exceed PostgreSQL's max_connections limit, otherwise you will get an error like "too many clients"
The return value from the acquire method is a shared pointer and counts shared references. When you open a connection and share it with another class, even if the acquired connection object goes out of scope, it keeps the connection open until the last shared class object is destroyed.
#include "libcpp-pg-pool.hpp"
using namespace lklibs;
class SampleConsumer
{
public:
void setDbConnection(std::shared_ptr<pqxx::connection> dbConnection)
{
this->dbConnection = std::move(dbConnection);
}
void queryData() const
{
pqxx::work txn(*dbConnection);
const auto result = txn.exec("SELECT * FROM my_table");
for (const auto& row : result)
{
std::cout << row[0].c_str() << std::endl;
}
}
[[nodiscard]] bool isConnectionOpen() const
{
return dbConnection->is_open();
}
private:
std::shared_ptr<pqxx::connection> dbConnection;
};
int main() {
const auto connectionString = "dbname=my_db user=my_user password=my_password host=localhost port=5432";
PgPool pool(connectionString);
{
SampleConsumer myConsumer{};
{
// Acquire a connection from the pool
const auto dbConnection = pool.acquire();
// Connection is shared with SampleConsumer
myConsumer.setDbConnection(dbConnection);
myConsumer.queryData();
}
// Connection is still alive even after the dbConnection goes out of scope because SampleConsumer is still holding the shared_ptr
std::cout << "Connection status:" << myConsumer.isConnectionOpen() << std::endl;
}
// Connection is automatically returned to the pool when all shared_ptr holding the connection go out of scope
return 0;Versioning of the library is done using conventional semantic versioning. Accordingly, in the versioning made as MAJOR.MINOR.PATCH;
PATCH: Includes possible Bug&Fixes and improvements. You definitely want to get this.
MINOR: Additional functionality added via backwards compatibility. You probably want to get this, it doesn't hurt.
MAJOR: Additional functionality that breaks backwards compatibility. You'll need to know what's changed before you get it, and you'll probably have to make changes to your own code. If I publish something like this, I will definitely add the changes required for migration section to the documentation.
You can find the complete list of functions in the library below.
Tip
All functions and parameters descriptions are also available within the code as comment for IDEs.
std::shared_ptr<pqxx::connection> acquire();MIT License
Copyright (c) 2024 Levent KARAGÖL
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
If you have problems regarding the library, please open an issue on GitHub. Please describe your request, issue, or question in as much detail as possible and also include the version of your compiler and operating system, as well as the version of the library you are using. Before opening a new issue, please confirm that the topic is not already exists in closed issues.