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choc_ThreadSafeFunctor.h
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choc_ThreadSafeFunctor.h
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//
// ██████ ██ ██ ██████ ██████
// ██ ██ ██ ██ ██ ██ ** Classy Header-Only Classes **
// ██ ███████ ██ ██ ██
// ██ ██ ██ ██ ██ ██ https://github.com/Tracktion/choc
// ██████ ██ ██ ██████ ██████
//
// CHOC is (C)2022 Tracktion Corporation, and is offered under the terms of the ISC license:
//
// Permission to use, copy, modify, and/or distribute this software for any purpose with or
// without fee is hereby granted, provided that the above copyright notice and this permission
// notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
// WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
// CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
// WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#ifndef CHOC_THREADSAFEFUNCTOR_HEADER_INCLUDED
#define CHOC_THREADSAFEFUNCTOR_HEADER_INCLUDED
#include <mutex>
#include <memory>
namespace choc::threading
{
//==============================================================================
/**
This acts as a smart-pointer to a shared function, which can be invoked and
cleared in a thread-safe way. So all calls to invoke or to change the target
function are safely locked.
A good use-case for this is if you trigger an async callback using
something like `choc::messageloop::postMessage` but need the option to be
able to cancel the callback before it arrives.
*/
template <typename FunctionType>
struct ThreadSafeFunctor
{
ThreadSafeFunctor();
ThreadSafeFunctor (FunctionType&&);
ThreadSafeFunctor (const ThreadSafeFunctor&) = default;
ThreadSafeFunctor (ThreadSafeFunctor&&) = default;
ThreadSafeFunctor& operator= (const ThreadSafeFunctor&) = default;
ThreadSafeFunctor& operator= (ThreadSafeFunctor&&) = default;
~ThreadSafeFunctor() = default;
/// Changes the function that will be called - this is thread-safe
/// and will block until it's safe to change the function
ThreadSafeFunctor& operator= (FunctionType&& newFunctor);
/// Changes the function that will be called - this is thread-safe
/// and will block until it's safe to change the function
ThreadSafeFunctor& operator= (const FunctionType& newFunctor);
/// Tries to invoke the function if one has been set. Returns true if
/// the target function is valid and was invoked, or false if there was
/// no function to call.
template <typename... Args>
bool operator() (Args&&... args) const;
/// Returns true if the function isn't null (although it's still safe to
/// call this when it's null, and it will do nothing)
operator bool() const;
/// Clears the function - this is thread-safe, and will block until
/// the function can safely be changed
void reset();
private:
//==============================================================================
struct CallbackHolder : public std::enable_shared_from_this<CallbackHolder>
{
std::recursive_mutex lock;
FunctionType fn;
};
std::shared_ptr<CallbackHolder> callback;
};
//==============================================================================
// _ _ _ _
// __| | ___ | |_ __ _ (_)| | ___
// / _` | / _ \| __| / _` || || |/ __|
// | (_| || __/| |_ | (_| || || |\__ \ _ _ _
// \__,_| \___| \__| \__,_||_||_||___/(_)(_)(_)
//
// Code beyond this point is implementation detail...
//
//==============================================================================
template <typename FunctionType>
ThreadSafeFunctor<FunctionType>::ThreadSafeFunctor() : callback (std::make_shared<CallbackHolder>())
{
}
template <typename FunctionType>
ThreadSafeFunctor<FunctionType>::ThreadSafeFunctor (FunctionType&& f) : ThreadSafeFunctor()
{
callback->fn = std::move (f);
}
template <typename FunctionType>
template <typename... Args>
bool ThreadSafeFunctor<FunctionType>::operator() (Args&&... args) const
{
std::scoped_lock l (callback->lock);
if (callback->fn)
{
callback->fn (std::forward<Args> (args)...);
return true;
}
return false;
}
template <typename FunctionType>
ThreadSafeFunctor<FunctionType>& ThreadSafeFunctor<FunctionType>::operator= (FunctionType&& f)
{
std::scoped_lock l (callback->lock);
callback->fn = std::move (f);
return *this;
}
template <typename FunctionType>
ThreadSafeFunctor<FunctionType>& ThreadSafeFunctor<FunctionType>::operator= (const FunctionType& f)
{
std::scoped_lock l (callback->lock);
callback->fn = f;
return *this;
}
template <typename FunctionType>
ThreadSafeFunctor<FunctionType>::operator bool() const
{
std::scoped_lock l (callback->lock);
return callback->fn;
}
template <typename FunctionType>
void ThreadSafeFunctor<FunctionType>::reset()
{
std::scoped_lock l (callback->lock);
callback->fn = {};
}
} // namespace choc::threading
#endif // CHOC_THREADSAFEFUNCTOR_HEADER_INCLUDED