RAII and Exception Safety

Snippet

RAII and Exception Safety

Resource Acquisition Is Initialization (RAII) is a core C++ idiom. Resources are tied to object lifetime; they are acquired in the constructor and released in the destructor, ensuring they are never leaked, even during exceptions.

snippet.cpp
cpp
#include <mutex>
 
std::mutex mtx;
 
void shared_resource_access() {
    // Mutex is locked in constructor
    std::lock_guard<std::mutex> lock(mtx);
    
    // Critical section: performing work
    if (/* something fails */ false) {
        throw std::runtime_error("Error");
    }
    
} // Mutex is released in destructor, even if exception occurs

Breakdown

std::lock_guard<std::mutex> lock(mtx);

Locks the mutex immediately. The 'lock' object manages the mutex state until it goes out of scope.

throw std::runtime_error

If an exception is thrown, stack unwinding ensures that the lock_guard destructor is still called.

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