Atomic access
Interlocked series functions are a set of atomic operation functions provided by the Windows API to safely operate shared variables in a multi-threaded environment. When we execute these Interlocked series functions, the function will send a hardware signal to the bus, which can prevent the CPU from accessing the same memory address at the same time, thereby greatly experiencing the purpose of atomic access. Here are some commonly used Interlocked series functions:
1. InterlockedIncrement: Increment the specified variable.
2. InterlockedDecrement: Decrement the specified variable.
3. InterlockedExchange: Set the specified variable to the specified value and return the original value of the variable.
4. InterlockedExchangeAdd: Add the specified value to the specified variable and return the original value of the variable.
5. InterlockedCompareExchange: If the current value of the specified variable is equal to the specified comparison value, set the variable to the specified value.
6. InterlockedAnd: Perform bitwise and operations on the specified variable.
7. InterlockedOr: Perform bitwise or operation on the specified variable.
8. InterlockedXor: Perform a bitwise XOR operation on the specified variable.
LONG InterlockedIncrement(
_Inout_ LONG volatile *Addend
);
LONG InterlockedDecrement(
_Inout_ LONG volatile *Addend
);
LONG InterlockedExchange(
_Inout_ LONG volatile *Target,
_In_ LONG Value
);
LONG InterlockedExchangeAdd(
_Inout_ LONG volatile *Addend,
_In_ LONG Value
);
LONG InterlockedCompareExchange(
_Inout_ LONG volatile *Destination,
_In_ LONG Exchange,
_In_ LONG Comperand
);
LONG InterlockedAnd(
_Inout_ LONG volatile *Destination,
_In_ LONG Value
);
LONG InterlockedOr(
_Inout_ LONG volatile *Destination,
_In_ LONG Value
);
LONG InterlockedXor(
_Inout_ LONG volatile *Destination,
_In_ LONG Value
);Here is a simple example code:
#include <iostream>
#include <>
#include <>
int main()
{
long value = 0;
InterlockedIncrement(&value);//Add 1 in the variable value
std::cout << "Value: " << value << std::endl;//Output 1
InterlockedDecrement(&value);//The variable value is reduced by 1
std::cout << "Value: " << value << std::endl;//Output 0
InterlockedExchange(&value, 10);//Set the variable value to 10
std::cout << "Value: " << value << std::endl;//Output 10
InterlockedExchangeAdd(&value, 5);//Add the variable value by 5
std::cout << "Value: " << value << std::endl;//Output 15
InterlockedCompareExchange(&value, 20, 15);// If the variable value is equal to 15, set the variable value to 20
std::cout << "Value: " << value << std::endl;//Output 20
return 0;
}