NekoCWD/libcamera
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libcamera: signal: Support cross-thread signals

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Allow signals to cross thread boundaries by posting them to the
recipient through messages instead of calling the slot directly when the
recipient lives in a different thread.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
This commit is contained in:
Laurent Pinchart 2019-07-10 14:47:30 +03:00
parent 01b930964a
commit cc3ae13d9e
5 changed files with 136 additions and 8 deletions
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67
include/libcamera/signal.h
View file

@ -8,6 +8,8 @@
#define __LIBCAMERA_SIGNAL_H__
#include <list>
#include <tuple>
#include <type_traits>
#include <vector>
#include <libcamera/object.h>
@ -27,6 +29,9 @@ public:
void *obj() { return obj_; }
bool isObject() const { return isObject_; }
void activatePack(void *pack);
virtual void invokePack(void *pack) = 0;
protected:
void *obj_;
bool isObject_;
@ -35,24 +40,70 @@ protected:
template<typename... Args>
class SlotArgs : public SlotBase
{
private:
#ifndef __DOXYGEN__
/*
* This is a cheap partial implementation of std::integer_sequence<>
* from C++14.
*/
template<int...>
struct sequence {
};
template<int N, int... S>
struct generator : generator<N-1, N-1, S...> {
};
template<int... S>
struct generator<0, S...> {
typedef sequence<S...> type;
};
#endif
using PackType = std::tuple<typename std::remove_reference<Args>::type...>;
template<int... S>
void invokePack(void *pack, sequence<S...>)
{
PackType *args = static_cast<PackType *>(pack);
invoke(std::get<S>(*args)...);
delete args;
}
public:
SlotArgs(void *obj, bool isObject)
: SlotBase(obj, isObject) {}
virtual void invoke(Args... args) = 0;
void invokePack(void *pack) override
{
invokePack(pack, typename generator<sizeof...(Args)>::type());
}
protected:
friend class Signal<Args...>;
virtual void activate(Args... args) = 0;
virtual void invoke(Args... args) = 0;
};
template<typename T, typename... Args>
class SlotMember : public SlotArgs<Args...>
{
public:
using PackType = std::tuple<typename std::remove_reference<Args>::type...>;
SlotMember(T *obj, bool isObject, void (T::*func)(Args...))
: SlotArgs<Args...>(obj, isObject), func_(func) {}
void invoke(Args... args) { (static_cast<T *>(this->obj_)->*func_)(args...); }
void activate(Args... args)
{
if (this->isObject_)
SlotBase::activatePack(new PackType{ args... });
else
(static_cast<T *>(this->obj_)->*func_)(args...);
}
void invoke(Args... args)
{
(static_cast<T *>(this->obj_)->*func_)(args...);
}
private:
friend class Signal<Args...>;
@ -66,7 +117,8 @@ public:
SlotStatic(void (*func)(Args...))
: SlotArgs<Args...>(nullptr, false), func_(func) {}
void invoke(Args... args) { (*func_)(args...); }
void activate(Args... args) { (*func_)(args...); }
void invoke(Args... args) {}
private:
friend class Signal<Args...>;
@ -186,9 +238,8 @@ public:
* disconnect operation, invalidating the iterator.
*/
std::vector<SlotBase *> slots{ slots_.begin(), slots_.end() };
for (SlotBase *slot : slots) {
static_cast<SlotArgs<Args...> *>(slot)->invoke(args...);
}
for (SlotBase *slot : slots)
static_cast<SlotArgs<Args...> *>(slot)->activate(args...);
}
};