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#include "at_fork.h"
#include <library/cpp/yt/memory/leaky_singleton.h>
#include <library/cpp/yt/assert/assert.h>
#ifdef _unix_
#include <pthread.h>
#endif
#include <atomic>
#include <array>
namespace NYT::NThreading {
////////////////////////////////////////////////////////////////////////////////
class TAtForkManager
{
public:
static TAtForkManager* Get()
{
return LeakySingleton<TAtForkManager>();
}
void RegisterAtForkHandlers(
TAtForkHandler prepare,
TAtForkHandler parent,
TAtForkHandler child)
{
int index = AtForkHandlerCount_++;
Y_VERIFY(index < MaxAtForkHandlerSets);
auto& set = AtForkHandlerSets_[index];
set.Prepare = std::move(prepare);
set.Parent = std::move(parent);
set.Child = std::move(child);
set.Initialized.store(true);
}
TReaderWriterSpinLock* GetForkLock()
{
return &ForkLock_;
}
private:
DECLARE_LEAKY_SINGLETON_FRIEND()
TReaderWriterSpinLock ForkLock_;
struct TAtForkHandlerSet
{
TAtForkHandler Prepare;
TAtForkHandler Parent;
TAtForkHandler Child;
std::atomic<bool> Initialized;
};
static constexpr int MaxAtForkHandlerSets = 8;
std::array<TAtForkHandlerSet, MaxAtForkHandlerSets> AtForkHandlerSets_;
std::atomic<int> AtForkHandlerCount_ = 0;
TAtForkManager()
{
#ifdef _unix_
pthread_atfork(
[] { Get()->OnPrepare(); },
[] { Get()->OnParent(); },
[] { Get()->OnChild(); });
#endif
}
void OnPrepare()
{
IterateAtForkHandlerSets([] (const TAtForkHandlerSet& set) {
if (set.Prepare) {
set.Prepare();
}
});
ForkLock_.AcquireWriter();
}
void OnParent()
{
ForkLock_.ReleaseWriter();
IterateAtForkHandlerSets([] (const TAtForkHandlerSet& set) {
if (set.Parent) {
set.Parent();
}
});
}
void OnChild()
{
ForkLock_.ReleaseWriter();
IterateAtForkHandlerSets([] (const TAtForkHandlerSet& set) {
if (set.Child) {
set.Child();
}
});
}
template <class F>
void IterateAtForkHandlerSets(F func)
{
for (const auto& set : AtForkHandlerSets_) {
if (set.Initialized.load()) {
func(set);
}
}
}
};
////////////////////////////////////////////////////////////////////////////////
static void* AtForkManagerInitializer = [] { return TAtForkManager::Get(); }();
////////////////////////////////////////////////////////////////////////////////
void RegisterAtForkHandlers(
TAtForkHandler prepare,
TAtForkHandler parent,
TAtForkHandler child)
{
return TAtForkManager::Get()->RegisterAtForkHandlers(
std::move(prepare),
std::move(parent),
std::move(child));
}
TReaderWriterSpinLock* GetForkLock()
{
return TAtForkManager::Get()->GetForkLock();
}
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT::NThreading
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