Function modify
Summary
#include <lib/inc/drogon/Session.h>
(1) template <typename T, typename Callable>
void modify(const std::string &key, Callable &&handler)
(2) template <typename Callable>
void modify(Callable &&handler)
Function overload
Synopsis
#include <lib/inc/drogon/Session.h>
template <typename T, typename Callable>
void modify(const std::string &key, Callable &&handler)
Description
Modify or visit the data identified by the key parameter.
- Template Parameters
T- the type of the data.- Parameters
key-handler- A callable that can modify or visit the data. The signature of the handler should be equivalent to 'void(T&)' or 'void(const T&)'- Note
- This function is multiple-thread safe. if the data identified by the key doesn't exist, a new one is created and passed to the handler. The changing of the data is protected by the mutex of the session.
Source
Lines 105-127 in lib/inc/drogon/Session.h.
template <typename T, typename Callable>
void modify(const std::string &key, Callable &&handler)
{
std::lock_guard<std::mutex> lck(mutex_);
auto it = sessionMap_.find(key);
if (it != sessionMap_.end())
{
if (typeid(T) == it->second.type())
{
handler(*(any_cast<T>(&(it->second))));
}
else
{
LOG_ERROR << "Bad type";
}
}
else
{
auto item = T();
handler(item);
sessionMap_.insert(std::make_pair(key, any(std::move(item))));
}
}
Synopsis
#include <lib/inc/drogon/Session.h>
template <typename Callable>
void modify(Callable &&handler)
Description
Modify or visit the session data.
- Template Parameters
Callable- The signature of the callable should be equivalent tovoid (Session::SessionMap &)orvoid (const Session::SessionMap &)- Parameters
handler- A callable that can modify the sessionMap_ inside the session.- Note
- This function is multiple-thread safe.
Source
Lines 137-142 in lib/inc/drogon/Session.h.
template <typename Callable>
void modify(Callable &&handler)
{
std::lock_guard<std::mutex> lck(mutex_);
handler(sessionMap_);
}