/**
 * \page thread-safety Reentrancy and Thread-Safety
 *
 * Through the documentation, several terms are used to define how classes and
 * their member functions can be used from multiple threads.
 *
 * - A **reentrant** function may be called simultaneously from multiple
 *   threads if and only if each invocation uses a different instance of the
 *   class. This is the default for all member functions not explictly marked
 *   otherwise.
 *
 * - \anchor thread-safe A **thread-safe** function may be called
 *   simultaneously from multiple threads on the same instance of a class. A
 *   thread-safe function is thus reentrant. Thread-safe functions may also be
 *   called simultaneously with any other reentrant function of the same class
 *   on the same instance.
 *
 * \internal
 * - \anchor thread-bound A **thread-bound** function may be called only from
 *   the thread that the class instances lives in (see section \ref
 *   thread-objects). For instances of classes that do not derive from the
 *   Object class, this is the thread in which the instance was created. A
 *   thread-bound function is not thread-safe, and may or may not be reentrant.
 * \endinternal
 *
 * Neither reentrancy nor thread-safety, in this context, mean that a function
 * may be called simultaneously from the same thread, for instance from a
 * callback invoked by the function. This may deadlock and isn't allowed unless
 * separately documented.
 *
 * \if internal
 * A class is defined as reentrant, thread-safe or thread-bound if all its
 * member functions are reentrant, thread-safe or thread-bound respectively.
 * \else
 * A class is defined as reentrant or thread-safe if all its member functions
 * are reentrant or thread-safe respectively.
 * \endif
 * Some member functions may additionally be documented as having additional
 * thread-related attributes.
 *
 * Most classes are reentrant but not thread-safe, as making them fully
 * thread-safe would incur locking costs considered prohibitive for the
 * expected use cases.
 */