#include <MAtomic.h>
List of all members.
Detailed Description
Methods for atomic operations.
The MAtomic class implements several cross-platform atomic operations which are useful when writing a multithreaded application. Atomic operations are those that appear to happen as a single operation when viewed from other threads.
As a usage example, during reference counting in an SMP environment, it is important to ensure that decrementing and testing the counter against zero happens atomically. If coded this way:
if (--counter == 0) {}
then another thread could modify the value of counter between the decrement and the if test. The above code would therefore get the wrong value. This class provides a routine to perform the decrement and return the previous value atomically, so the above snippet could be written as:
if (MAtomic::preDecrement(&counter) == 0) {}
|
Static Public Member Functions |
static int | preIncrement (volatile int *variable) |
static int | postIncrement (volatile int *variable) |
static int | increment (volatile int *variable, int incrementValue) |
static int | preDecrement (volatile int *variable) |
static int | postDecrement (volatile int *variable) |
static int | decrement (volatile int *variable, int decrementValue) |
static int | set (volatile int *variable, int newValue) |
static int | compareAndSwap (volatile int *variable, int compareValue, int swapValue) |
Member Function Documentation
static int MAtomic::preIncrement |
( |
volatile int * |
variable |
) |
[inline, static] |
Increment variable, return value after increment
- Parameters:
-
[in] | variable | Value to be modified |
- Returns:
- . Variable value after incrementing
static int MAtomic::postIncrement |
( |
volatile int * |
variable |
) |
[inline, static] |
Increment variable, return value before increment
- Parameters:
-
[in] | variable | Value to be modified |
- Returns:
- . Variable value before incrementing
static int MAtomic::increment |
( |
volatile int * |
variable, |
|
|
int |
incrementValue | |
|
) |
| | [inline, static] |
Increment variable by incrementValue, return value before increment.
- Parameters:
-
[in] | variable | Value to be modified |
[in] | incrementValue | Value by which to increment variable |
- Returns:
- . Variable value before incrementing
static int MAtomic::preDecrement |
( |
volatile int * |
variable |
) |
[inline, static] |
Decrement variable, return value after increment
- Parameters:
-
[in] | variable | Value to be modified |
- Returns:
- . Variable value after decrementing
static int MAtomic::postDecrement |
( |
volatile int * |
variable |
) |
[inline, static] |
Decrement variable, return value before decrement
- Parameters:
-
[in] | variable | Value to be modified |
- Returns:
- . Variable value before decrementing
static int MAtomic::decrement |
( |
volatile int * |
variable, |
|
|
int |
decrementValue | |
|
) |
| | [inline, static] |
Decrement variable by decrementValue, return value before decrement.
- Parameters:
-
[in] | variable | Value to be modified |
[in] | decrementValue | Value by which to decrement variable |
- Returns:
- . Variable value before decrementing
static int MAtomic::set |
( |
volatile int * |
variable, |
|
|
int |
newValue | |
|
) |
| | [inline, static] |
Set variable to newValue, return value of variable before set.
- Parameters:
-
[in] | variable | Value to be modified |
[in] | newValue | Value to which to set variable |
- Returns:
- . Variable value before set
static int MAtomic::compareAndSwap |
( |
volatile int * |
variable, |
|
|
int |
compareValue, |
|
|
int |
swapValue | |
|
) |
| | [inline, static] |
Compare variable with compareValue and if the values are equal, sets *variable equal to swapValue. The result of the comparison is returned, true if the compare was sucessful, false otherwise.
- Parameters:
-
[in] | variable | First value to be compared |
[in] | compareValue | Second value to be compared |
- Returns:
- . True if variable equals compareValue, otherwise false