CxxUtils::detail::IsUpdater Concept Reference

Concept check for Updater class used by concurrent classes. More...

#include <IsUpdater.h>

Concept definition

template<template< class > class UPDATER>
concept CxxUtils::detail::IsUpdater =  requires(UPDATER<int> x,
                             const typename UPDATER<int>::Context_t& ctx)
{
  typename UPDATER<int>::Context_t;
  { x.get() } -> std::same_as<const int&>;
  { x.update (std::make_unique<int>(0), ctx) };
  { x.quiescent (ctx) };
  { x.defaultContext() } -> std::convertible_to<typename UPDATER<int>::Context_t>;
}

Detailed Description

Concept check for Updater class used by concurrent classes.

In order to implement updating concurrently with reading, we need to defer deletion of objects until no thread can be referencing them any more. The policy for this for the internal implementation objects is set by the template UPDATER<T>. An object of this type owns an object of type T. It should provide a typedef Context_t, giving a type for an event context, identifying which thread/slot is currently executing. It should implement these operations:

• const T& get() const Return the current object.
• void update (std::unique_ptr<T> p, const Context_t& ctx); Atomically update the current object to be p. Deletion of the previous version should be deferred until no thread can be referencing it.
• void quiescent (const Context_t& ctx); Declare that the thread described by ctx is no longer accessing the object.
• static const Context_t& defaultContext(); Return a context object for the currently-executing thread.

For an example, see AthenaKernel/RCUUpdater.h.

Definition at line 51 of file IsUpdater.h.