Input port mutability

When an input port is configured as mutating, the operator logic intends to modify the tuples that arrive on that port.

The Teracloud® Streams instance ensures that tuples delivered to this input port can be safely mutated.

When an input port is defined as mutating, the operator code receives a non-constant reference to a tuple. The tuples for that input port are processed by the function with signature void process(Tuple & tuple,uint32_t port), which means that the operator code can modify the content of the incoming tuple.

When an input port is configured as non-mutating, the operator code receives a constant reference to a tuple. The tuples for the input port are processed by the function with signature void process(const Tuple & tuple,uint32_t port). Any attempt to modify a constant reference is forbidden by the C++ compiler.

The following figure provides a general guideline for setting input port mutability.