ydb/util/system/condvar.cpp

#include "event.h"
#include "mutex.h"
#include "yassert.h"
#include "condvar.h"
#include "datetime.h"
#include "spinlock.h"

#include <util/generic/ylimits.h>
#include <util/generic/intrlist.h>
#include <util/generic/yexception.h>

#include <cstdlib>

#if defined(_unix_)
    #include <sys/time.h>
    #include <pthread.h>
    #include <cerrno>
#endif

namespace {
    class TCondVarImpl {
        using TLock = TAdaptiveLock;

        struct TWaitEvent: public TIntrusiveListItem<TWaitEvent>, public TSystemEvent {
        };

        using TWaitEvents = TIntrusiveList<TWaitEvent>;

    public:
        inline ~TCondVarImpl() {
            Y_ASSERT(Events_.Empty());
        }

        inline void Signal() noexcept {
            with_lock (Lock_) {
                if (!Events_.Empty()) {
                    Events_.PopFront()->Signal();
                }
            }
        }

        inline void BroadCast() noexcept {
            with_lock (Lock_) {
                //TODO
                while (!Events_.Empty()) {
                    Events_.PopFront()->Signal();
                }
            }
        }

        inline bool WaitD(TMutex& m, TInstant deadLine) noexcept {
            TWaitEvent event;

            with_lock (Lock_) {
                Events_.PushBack(&event);
            }

            m.Release();

            const bool signalled = event.WaitD(deadLine);

            m.Acquire();

            with_lock (Lock_) {
                event.Unlink();
            }

            return signalled;
        }

    private:
        TWaitEvents Events_;
        TLock Lock_;
    };
}

#if defined(_win_)
class TCondVar::TImpl: public TCondVarImpl {
};
#else
class TCondVar::TImpl {
public:
    inline TImpl() {
        if (pthread_cond_init(&Cond_, nullptr)) {
            ythrow yexception() << "can not create condvar(" << LastSystemErrorText() << ")";
        }
    }

    inline ~TImpl() {
        int ret = pthread_cond_destroy(&Cond_);
        Y_VERIFY(ret == 0, "pthread_cond_destroy failed: %s", LastSystemErrorText(ret));
    }

    inline void Signal() noexcept {
        int ret = pthread_cond_signal(&Cond_);
        Y_VERIFY(ret == 0, "pthread_cond_signal failed: %s", LastSystemErrorText(ret));
    }

    inline bool WaitD(TMutex& lock, TInstant deadLine) noexcept {
        if (deadLine == TInstant::Max()) {
            int ret = pthread_cond_wait(&Cond_, (pthread_mutex_t*)lock.Handle());
            Y_VERIFY(ret == 0, "pthread_cond_wait failed: %s", LastSystemErrorText(ret));
            return true;
        } else {
            struct timespec spec;

            Zero(spec);

            spec.tv_sec = deadLine.Seconds();
            spec.tv_nsec = deadLine.NanoSecondsOfSecond();

            int ret = pthread_cond_timedwait(&Cond_, (pthread_mutex_t*)lock.Handle(), &spec);

            Y_VERIFY(ret == 0 || ret == ETIMEDOUT, "pthread_cond_timedwait failed: %s", LastSystemErrorText(ret));

            return ret == 0;
        }
    }

    inline void BroadCast() noexcept {
        int ret = pthread_cond_broadcast(&Cond_);
        Y_VERIFY(ret == 0, "pthread_cond_broadcast failed: %s", LastSystemErrorText(ret));
    }

private:
    pthread_cond_t Cond_;
};
#endif

TCondVar::TCondVar()
    : Impl_(new TImpl)
{
}

TCondVar::~TCondVar() = default;

void TCondVar::BroadCast() noexcept {
    Impl_->BroadCast();
}

void TCondVar::Signal() noexcept {
    Impl_->Signal();
}

bool TCondVar::WaitD(TMutex& mutex, TInstant deadLine) noexcept {
    return Impl_->WaitD(mutex, deadLine);
}