*this == référence valide dans un destructeur ?
Bonjour,
J'ai une classe qui joue un rôle d'observateur et qui possède une liste d'observables (pour pouvoir être notifié par plusieurs sources). Dans le destructeur de cette classe, je parcours la liste et pour chaque observable, je demande à ce que mon objet soit retiré de la liste des observateurs. Le code est comme ceci :
(observateur)
Code:
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| MultipleDefaultObserver::~MultipleDefaultObserver() {
for (auto& detector : detectors_m) {
if (detector != nullptr) {
detector->removeObserver(*this);
}
}
} |
(observable)
Code:
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| void DefaultDetector::removeObserver(DefaultObserver& observer) {
for (auto& slot : observers_m) {
if (slot == &observer) {
slot = nullptr;
break;
}
}
} |
Comme je ne fais pas d'allocation dynamique, detectors_m et observers_m sont des std::array de pointeurs.
J'ai écris ce code, donc il me parait OK, sinon j'aurais fait autrement. Valgrind n'est pas de mon avis et me signalent des invalid read/write of size 4 dans le destructeur. En commentant la ligne detector->removeObserver(*this);, les erreurs disparaissent. Un exemple de message de Valgrind :
Citation:
==1687== Invalid read of size 4
==1687== at 0x12E5A9: supervisor::DefaultDetector::removeObserver(supervisor::DefaultObserver&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x12E917: supervisor::MultipleDefaultObserver::~MultipleDefaultObserver() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x26A6F3: ____C_A_T_C_H____T_E_S_T____8() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x181BD2: Catch::RunContext::invokeActiveTestCase() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1933D0: Catch::RunContext::runCurrentTest(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1A4FF0: Catch::RunContext::runTest(Catch::TestCase const&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1A58FC: Catch::(anonymous namespace)::runTests(std::shared_ptr<Catch::Config> const&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1AA01D: Catch::Session::runInternal() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1AA160: Catch::Session::run() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x114FD3: main (in /media/sf_shared/Common/cmake-debug/common)
==1687== Address 0x4dcfb90 is 0 bytes inside a block of size 440 free'd
==1687== at 0x48318D7: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1687== by 0x26A6D7: ____C_A_T_C_H____T_E_S_T____8() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x181BD2: Catch::RunContext::invokeActiveTestCase() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1933D0: Catch::RunContext::runCurrentTest(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1A4FF0: Catch::RunContext::runTest(Catch::TestCase const&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1A58FC: Catch::(anonymous namespace)::runTests(std::shared_ptr<Catch::Config> const&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1AA01D: Catch::Session::runInternal() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1AA160: Catch::Session::run() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x114FD3: main (in /media/sf_shared/Common/cmake-debug/common)
==1687== Block was alloc'd at
==1687== at 0x483087B: operator new(unsigned int) (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1687== by 0x26A458: ____C_A_T_C_H____T_E_S_T____8() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x181BD2: Catch::RunContext::invokeActiveTestCase() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1933D0: Catch::RunContext::runCurrentTest(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1A4FF0: Catch::RunContext::runTest(Catch::TestCase const&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1A58FC: Catch::(anonymous namespace)::runTests(std::shared_ptr<Catch::Config> const&) (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1AA01D: Catch::Session::runInternal() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x1AA160: Catch::Session::run() (in /media/sf_shared/Common/cmake-debug/common)
==1687== by 0x114FD3: main (in /media/sf_shared/Common/cmake-debug/common)
Vu que j'utilise un auto-range for, je ne pense pas dépasser des tableaux. La seule hypothèse qui me vient à l'esprit est que *this n'est plus une référence valide à ce moment là. Vous pouvez confirmer ? Comment faire pour que ça fonctionne correctement ?
Merci d'avance !
