Continentis/Assets/Plugins/UniRx/Scripts/Operators/RefCount.cs

using System;

namespace UniRx.Operators
{
    internal class RefCountObservable<T> : OperatorObservableBase<T>
    {
        private readonly object gate = new();
        private readonly IConnectableObservable<T> source;
        private IDisposable connection;
        private int refCount;

        public RefCountObservable(IConnectableObservable<T> source)
            : base(source.IsRequiredSubscribeOnCurrentThread())
        {
            this.source = source;
        }

        protected override IDisposable SubscribeCore(IObserver<T> observer, IDisposable cancel)
        {
            return new RefCount(this, observer, cancel).Run();
        }

        private class RefCount : OperatorObserverBase<T, T>
        {
            private readonly RefCountObservable<T> parent;

            public RefCount(RefCountObservable<T> parent, IObserver<T> observer, IDisposable cancel) : base(observer,
                cancel)
            {
                this.parent = parent;
            }

            public IDisposable Run()
            {
                var subcription = parent.source.Subscribe(this);

                lock (parent.gate)
                {
                    if (++parent.refCount == 1) parent.connection = parent.source.Connect();
                }

                return Disposable.Create(() =>
                {
                    subcription.Dispose();

                    lock (parent.gate)
                    {
                        if (--parent.refCount == 0) parent.connection.Dispose();
                    }
                });
            }

            public override void OnNext(T value)
            {
                observer.OnNext(value);
            }

            public override void OnError(Exception error)
            {
                try
                {
                    observer.OnError(error);
                }
                finally
                {
                    Dispose();
                }
            }

            public override void OnCompleted()
            {
                try
                {
                    observer.OnCompleted();
                }
                finally
                {
                    Dispose();
                }
            }
        }
    }
}