What is Atomics?
- Atomics are used with SharedArrayBuffer(generic fixed-length binary data buffer) objects.
- Atomics are not constructors like other global objects.
- Atomics cannot be used with a new operator or can be invoked as a function.
Multiple threads can read and write the same data in memory when there shared memory is. To ensure that predicted values are written and read accurately, another operation cannot start until and unless the current one finishes. Atomic operations also cannot be interrupted.
- Among the Atomic Operations, there is an inbuilt operation Atomics.exchange() that is used to exchange and store a new value at a specific position in an array.
- No other write operation can happen between the read of the old value and write of the new value.
Difference between Atomics.compareExchange and Atomics.exchange
Both the operations return the older value which was present at the specified position.
Atomics.exchange(typedArray, index, value)
- typedarray: It is the shared integer typed array you want to modify.
- index:It is the position in the typedArray from where you want to exchange a value.
- value:It is the number to exchange.
Atomics.exchange() returns the old value at the given position (typedArray[index]).
Examples of the above function are provided below.
Input : arr = 9; Atomics.exchange(uint8, 0, 2); Output : 2
Input : arr = 3; Atomics.exchange(uint8, 0, 1); Output : 1
Codes for the above function are provided below.
- If the typedArray is not one of the allowed integer types then the Atomics.exchange( ) operation throws a TypeError.
- If the typedArray is not a shared typed array then the Atomics.exchange( ) operation throws a TypeError.
- If the index used as an argument to the Atomics.exchange( ) operation is out of the bound in the typedArray then the Atomics.exchange( ) operation throws a RangeError.