| Message ID | 20200120002437.6633-13-laurent.pinchart@ideasonboard.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series |
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| Related | show |
Hi Laurent, On Mon, Jan 20, 2020 at 02:24:30AM +0200, Laurent Pinchart wrote: > Make the signal connection and disconnection thread-safe, and document > them as such. This is required to make objects connectable from > different threads. > > The connect(), disconnect() and emit() methods are now all protected by > a global mutex, which may generate a high lock contention. This could be > improved with finer-grained locks or with a pool of mutexes. > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > src/libcamera/signal.cpp | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/src/libcamera/signal.cpp b/src/libcamera/signal.cpp > index 9bb7eca8ed6e..6eab1fa74d42 100644 > --- a/src/libcamera/signal.cpp > +++ b/src/libcamera/signal.cpp > @@ -7,6 +7,8 @@ > > #include <libcamera/signal.h> > > +#include "thread.h" > + Isn't it weird we need to include thread.h to access MutexLocker ? Anyway, Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Thanks j > /** > * \file signal.h > * \brief Signal & slot implementation > @@ -14,8 +16,21 @@ > > namespace libcamera { > > +namespace { > + > +/* > + * Mutex to protect the SignalBase::slots_ and Object::signals_ lists. If lock > + * contention needs to be decreased, this could be replaced with locks in > + * Object and SignalBase, or with a mutex pool. > + */ > +Mutex signalsLock; > + > +} /* namespace */ > + > void SignalBase::connect(BoundMethodBase *slot) > { > + MutexLocker locker(signalsLock); > + > Object *object = slot->object(); > if (object) > object->connect(this); > @@ -31,6 +46,8 @@ void SignalBase::disconnect(Object *object) > > void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) > { > + MutexLocker locker(signalsLock); > + > for (auto iter = slots_.begin(); iter != slots_.end(); ) { > if (match(iter)) { > Object *object = (*iter)->object(); > @@ -47,6 +64,7 @@ void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) > > SignalBase::SlotList SignalBase::slots() > { > + MutexLocker locker(signalsLock); > return slots_; > } > > @@ -99,23 +117,31 @@ SignalBase::SlotList SignalBase::slots() > * disconnected from the \a func slot of \a object when \a object is destroyed. > * Otherwise the caller shall disconnect signals manually before destroying \a > * object. > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::connect(R (*func)(Args...)) > * \brief Connect the signal to a static function slot > * \param[in] func The slot static function > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::disconnect() > * \brief Disconnect the signal from all slots > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::disconnect(T *object) > * \brief Disconnect the signal from all slots of the \a object > * \param[in] object The object pointer whose slots to disconnect > + * > + * \context This function is \threadsafe. > */ > > /** > @@ -123,12 +149,16 @@ SignalBase::SlotList SignalBase::slots() > * \brief Disconnect the signal from the \a object slot member function \a func > * \param[in] object The object pointer whose slots to disconnect > * \param[in] func The slot member function to disconnect > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::disconnect(R (*func)(Args...)) > * \brief Disconnect the signal from the slot static function \a func > * \param[in] func The slot static function to disconnect > + * > + * \context This function is \threadsafe. > */ > > /** > @@ -141,6 +171,9 @@ SignalBase::SlotList SignalBase::slots() > * function are passed to the slot functions unchanged. If a slot modifies one > * of the arguments (when passed by pointer or reference), the modification is > * thus visible to all subsequently called slots. > + * > + * This function is not \threadsafe, but thread-safety is guaranteed against > + * concurrent connect() and disconnect() calls. > */ > > } /* namespace libcamera */ > -- > Regards, > > Laurent Pinchart > > _______________________________________________ > libcamera-devel mailing list > libcamera-devel@lists.libcamera.org > https://lists.libcamera.org/listinfo/libcamera-devel
Hi Jacopo, On Mon, Jan 20, 2020 at 04:02:31PM +0100, Jacopo Mondi wrote: > On Mon, Jan 20, 2020 at 02:24:30AM +0200, Laurent Pinchart wrote: > > Make the signal connection and disconnection thread-safe, and document > > them as such. This is required to make objects connectable from > > different threads. > > > > The connect(), disconnect() and emit() methods are now all protected by > > a global mutex, which may generate a high lock contention. This could be > > improved with finer-grained locks or with a pool of mutexes. > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > > --- > > src/libcamera/signal.cpp | 33 +++++++++++++++++++++++++++++++++ > > 1 file changed, 33 insertions(+) > > > > diff --git a/src/libcamera/signal.cpp b/src/libcamera/signal.cpp > > index 9bb7eca8ed6e..6eab1fa74d42 100644 > > --- a/src/libcamera/signal.cpp > > +++ b/src/libcamera/signal.cpp > > @@ -7,6 +7,8 @@ > > > > #include <libcamera/signal.h> > > > > +#include "thread.h" > > + > > Isn't it weird we need to include thread.h to access MutexLocker ? We could move that to a separate file, but it's so small that I didn't think it was worth when I added it. Mutexes are useless without threads anyway. > Anyway, > Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> > > > /** > > * \file signal.h > > * \brief Signal & slot implementation > > @@ -14,8 +16,21 @@ > > > > namespace libcamera { > > > > +namespace { > > + > > +/* > > + * Mutex to protect the SignalBase::slots_ and Object::signals_ lists. If lock > > + * contention needs to be decreased, this could be replaced with locks in > > + * Object and SignalBase, or with a mutex pool. > > + */ > > +Mutex signalsLock; > > + > > +} /* namespace */ > > + > > void SignalBase::connect(BoundMethodBase *slot) > > { > > + MutexLocker locker(signalsLock); > > + > > Object *object = slot->object(); > > if (object) > > object->connect(this); > > @@ -31,6 +46,8 @@ void SignalBase::disconnect(Object *object) > > > > void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) > > { > > + MutexLocker locker(signalsLock); > > + > > for (auto iter = slots_.begin(); iter != slots_.end(); ) { > > if (match(iter)) { > > Object *object = (*iter)->object(); > > @@ -47,6 +64,7 @@ void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) > > > > SignalBase::SlotList SignalBase::slots() > > { > > + MutexLocker locker(signalsLock); > > return slots_; > > } > > > > @@ -99,23 +117,31 @@ SignalBase::SlotList SignalBase::slots() > > * disconnected from the \a func slot of \a object when \a object is destroyed. > > * Otherwise the caller shall disconnect signals manually before destroying \a > > * object. > > + * > > + * \context This function is \threadsafe. > > */ > > > > /** > > * \fn Signal::connect(R (*func)(Args...)) > > * \brief Connect the signal to a static function slot > > * \param[in] func The slot static function > > + * > > + * \context This function is \threadsafe. > > */ > > > > /** > > * \fn Signal::disconnect() > > * \brief Disconnect the signal from all slots > > + * > > + * \context This function is \threadsafe. > > */ > > > > /** > > * \fn Signal::disconnect(T *object) > > * \brief Disconnect the signal from all slots of the \a object > > * \param[in] object The object pointer whose slots to disconnect > > + * > > + * \context This function is \threadsafe. > > */ > > > > /** > > @@ -123,12 +149,16 @@ SignalBase::SlotList SignalBase::slots() > > * \brief Disconnect the signal from the \a object slot member function \a func > > * \param[in] object The object pointer whose slots to disconnect > > * \param[in] func The slot member function to disconnect > > + * > > + * \context This function is \threadsafe. > > */ > > > > /** > > * \fn Signal::disconnect(R (*func)(Args...)) > > * \brief Disconnect the signal from the slot static function \a func > > * \param[in] func The slot static function to disconnect > > + * > > + * \context This function is \threadsafe. > > */ > > > > /** > > @@ -141,6 +171,9 @@ SignalBase::SlotList SignalBase::slots() > > * function are passed to the slot functions unchanged. If a slot modifies one > > * of the arguments (when passed by pointer or reference), the modification is > > * thus visible to all subsequently called slots. > > + * > > + * This function is not \threadsafe, but thread-safety is guaranteed against > > + * concurrent connect() and disconnect() calls. > > */ > > > > } /* namespace libcamera */ > > -- > > Regards, > > > > Laurent Pinchart > > > > _______________________________________________ > > libcamera-devel mailing list > > libcamera-devel@lists.libcamera.org > > https://lists.libcamera.org/listinfo/libcamera-devel
Hi Laurent, Thanks for your work. On 2020-01-20 02:24:30 +0200, Laurent Pinchart wrote: > Make the signal connection and disconnection thread-safe, and document > them as such. This is required to make objects connectable from > different threads. > > The connect(), disconnect() and emit() methods are now all protected by > a global mutex, which may generate a high lock contention. This could be > improved with finer-grained locks or with a pool of mutexes. > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> > --- > src/libcamera/signal.cpp | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/src/libcamera/signal.cpp b/src/libcamera/signal.cpp > index 9bb7eca8ed6e..6eab1fa74d42 100644 > --- a/src/libcamera/signal.cpp > +++ b/src/libcamera/signal.cpp > @@ -7,6 +7,8 @@ > > #include <libcamera/signal.h> > > +#include "thread.h" > + > /** > * \file signal.h > * \brief Signal & slot implementation > @@ -14,8 +16,21 @@ > > namespace libcamera { > > +namespace { > + > +/* > + * Mutex to protect the SignalBase::slots_ and Object::signals_ lists. If lock > + * contention needs to be decreased, this could be replaced with locks in > + * Object and SignalBase, or with a mutex pool. > + */ > +Mutex signalsLock; > + > +} /* namespace */ > + > void SignalBase::connect(BoundMethodBase *slot) > { > + MutexLocker locker(signalsLock); > + > Object *object = slot->object(); > if (object) > object->connect(this); > @@ -31,6 +46,8 @@ void SignalBase::disconnect(Object *object) > > void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) > { > + MutexLocker locker(signalsLock); > + > for (auto iter = slots_.begin(); iter != slots_.end(); ) { > if (match(iter)) { > Object *object = (*iter)->object(); > @@ -47,6 +64,7 @@ void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) > > SignalBase::SlotList SignalBase::slots() > { > + MutexLocker locker(signalsLock); > return slots_; > } > > @@ -99,23 +117,31 @@ SignalBase::SlotList SignalBase::slots() > * disconnected from the \a func slot of \a object when \a object is destroyed. > * Otherwise the caller shall disconnect signals manually before destroying \a > * object. > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::connect(R (*func)(Args...)) > * \brief Connect the signal to a static function slot > * \param[in] func The slot static function > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::disconnect() > * \brief Disconnect the signal from all slots > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::disconnect(T *object) > * \brief Disconnect the signal from all slots of the \a object > * \param[in] object The object pointer whose slots to disconnect > + * > + * \context This function is \threadsafe. > */ > > /** > @@ -123,12 +149,16 @@ SignalBase::SlotList SignalBase::slots() > * \brief Disconnect the signal from the \a object slot member function \a func > * \param[in] object The object pointer whose slots to disconnect > * \param[in] func The slot member function to disconnect > + * > + * \context This function is \threadsafe. > */ > > /** > * \fn Signal::disconnect(R (*func)(Args...)) > * \brief Disconnect the signal from the slot static function \a func > * \param[in] func The slot static function to disconnect > + * > + * \context This function is \threadsafe. > */ > > /** > @@ -141,6 +171,9 @@ SignalBase::SlotList SignalBase::slots() > * function are passed to the slot functions unchanged. If a slot modifies one > * of the arguments (when passed by pointer or reference), the modification is > * thus visible to all subsequently called slots. > + * > + * This function is not \threadsafe, but thread-safety is guaranteed against > + * concurrent connect() and disconnect() calls. > */ > > } /* namespace libcamera */ > -- > Regards, > > Laurent Pinchart > > _______________________________________________ > libcamera-devel mailing list > libcamera-devel@lists.libcamera.org > https://lists.libcamera.org/listinfo/libcamera-devel
diff --git a/src/libcamera/signal.cpp b/src/libcamera/signal.cpp index 9bb7eca8ed6e..6eab1fa74d42 100644 --- a/src/libcamera/signal.cpp +++ b/src/libcamera/signal.cpp @@ -7,6 +7,8 @@ #include <libcamera/signal.h> +#include "thread.h" + /** * \file signal.h * \brief Signal & slot implementation @@ -14,8 +16,21 @@ namespace libcamera { +namespace { + +/* + * Mutex to protect the SignalBase::slots_ and Object::signals_ lists. If lock + * contention needs to be decreased, this could be replaced with locks in + * Object and SignalBase, or with a mutex pool. + */ +Mutex signalsLock; + +} /* namespace */ + void SignalBase::connect(BoundMethodBase *slot) { + MutexLocker locker(signalsLock); + Object *object = slot->object(); if (object) object->connect(this); @@ -31,6 +46,8 @@ void SignalBase::disconnect(Object *object) void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) { + MutexLocker locker(signalsLock); + for (auto iter = slots_.begin(); iter != slots_.end(); ) { if (match(iter)) { Object *object = (*iter)->object(); @@ -47,6 +64,7 @@ void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match) SignalBase::SlotList SignalBase::slots() { + MutexLocker locker(signalsLock); return slots_; } @@ -99,23 +117,31 @@ SignalBase::SlotList SignalBase::slots() * disconnected from the \a func slot of \a object when \a object is destroyed. * Otherwise the caller shall disconnect signals manually before destroying \a * object. + * + * \context This function is \threadsafe. */ /** * \fn Signal::connect(R (*func)(Args...)) * \brief Connect the signal to a static function slot * \param[in] func The slot static function + * + * \context This function is \threadsafe. */ /** * \fn Signal::disconnect() * \brief Disconnect the signal from all slots + * + * \context This function is \threadsafe. */ /** * \fn Signal::disconnect(T *object) * \brief Disconnect the signal from all slots of the \a object * \param[in] object The object pointer whose slots to disconnect + * + * \context This function is \threadsafe. */ /** @@ -123,12 +149,16 @@ SignalBase::SlotList SignalBase::slots() * \brief Disconnect the signal from the \a object slot member function \a func * \param[in] object The object pointer whose slots to disconnect * \param[in] func The slot member function to disconnect + * + * \context This function is \threadsafe. */ /** * \fn Signal::disconnect(R (*func)(Args...)) * \brief Disconnect the signal from the slot static function \a func * \param[in] func The slot static function to disconnect + * + * \context This function is \threadsafe. */ /** @@ -141,6 +171,9 @@ SignalBase::SlotList SignalBase::slots() * function are passed to the slot functions unchanged. If a slot modifies one * of the arguments (when passed by pointer or reference), the modification is * thus visible to all subsequently called slots. + * + * This function is not \threadsafe, but thread-safety is guaranteed against + * concurrent connect() and disconnect() calls. */ } /* namespace libcamera */
Make the signal connection and disconnection thread-safe, and document them as such. This is required to make objects connectable from different threads. The connect(), disconnect() and emit() methods are now all protected by a global mutex, which may generate a high lock contention. This could be improved with finer-grained locks or with a pool of mutexes. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- src/libcamera/signal.cpp | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)