Transactional memory

关于 Transactional memory的理论知识，参见工程parallel-computing的Concurrent-computing\Concurrency-control\Transactional-memory章节。

cppreference Transactional memory

Transactional memory is a concurrency synchronization mechanism that combines groups of statements in transactions, that are

• atomic (either all statements occur, or nothing occurs)
• isolated (statements in a transaction may not observe half-written writes made by another transaction, even if they execute in parallel)

Synchronized blocks

synchronized compound-statement

#include <iostream>
#include <vector>
#include <thread>
int f()
{
    static int i = 0;
    synchronized { // begin synchronized block
        std::cout << i << " -> ";
        ++i;       // each call to f() obtains a unique value of i
        std::cout << i << '\n';
        return i; // end synchronized block
    }
}
int main()
{
    std::vector<std::thread> v(10);
    for(auto& t: v)
        t = std::thread([]{ for(int n = 0; n < 10; ++n) f(); });
    for(auto& t: v)
        t.join();
}

NOTE: 非常类似于Java的语法。

gcc.gnu Transactional Memory in GCC