48ddfef89f
ThreadLocal should not own the pointer it is managing because the use case in Mapbox GL is to keep a pointer to a stack allocated object, like: ``` MyObject foo; threadLocal.set(&foo); ``` To keep consistency, it is required that we clear the managed object before ThreadLocal gets destroyed by setting it to `nullptr`.
67 lines
1.5 KiB
C++
67 lines
1.5 KiB
C++
#include <mbgl/util/thread_local.hpp>
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#include <mbgl/map/backend_scope.hpp>
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#include <mbgl/util/logging.hpp>
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#include <mbgl/util/run_loop.hpp>
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#include <stdexcept>
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#include <cassert>
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#include <pthread.h>
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namespace mbgl {
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namespace util {
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template <class T>
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class ThreadLocal<T>::Impl {
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public:
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pthread_key_t key;
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};
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template <class T>
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ThreadLocal<T>::ThreadLocal() : impl(std::make_unique<Impl>()) {
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int ret = pthread_key_create(&impl->key, [](void *) {});
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if (ret) {
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throw std::runtime_error("Failed to init local storage key.");
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}
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}
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template <class T>
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ThreadLocal<T>::~ThreadLocal() {
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// ThreadLocal will not take ownership
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// of the pointer it is managing. The pointer
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// needs to be explicitly cleared before we
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// destroy this object.
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assert(!get());
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if (pthread_key_delete(impl->key)) {
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Log::Error(Event::General, "Failed to delete local storage key.");
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assert(false);
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}
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}
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template <class T>
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T* ThreadLocal<T>::get() {
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auto* ret = reinterpret_cast<T*>(pthread_getspecific(impl->key));
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if (!ret) {
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return nullptr;
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}
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return ret;
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}
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template <class T>
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void ThreadLocal<T>::set(T* ptr) {
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if (pthread_setspecific(impl->key, ptr)) {
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throw std::runtime_error("Failed to set local storage.");
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}
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}
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template class ThreadLocal<RunLoop>;
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template class ThreadLocal<BackendScope>;
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template class ThreadLocal<int>; // For unit tests
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} // namespace util
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} // namespace mbgl
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