Reentrancy and Thread-Safety

Throughout the Qt documentation, the terms reentrant and thread-safe are used to specify how a function can be used in multithreaded applications:

• A reentrant function can be called simultaneously by multiple threads provided that each invocation of the function references unique data.
• A thread-safe function can be called simultaneously by multiple threads when each invocation references shared data. All access to the shared data is serialized.

By extension, a class is said to be reentrant if each and every one of its functions can be called simultaneously by multiple threads on different instances of the class. Similarly, the class is said to be thread-safe if the functions can be called by different threads on the same instance.

Classes in the documentation will be documented as thread-safe only if they are intended to be used by multiple threads.