implab/ImplabNet Commit - r19:e3935fdf59a2

Promise is rewritten to use interlocked operations instead of locks

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r19:e3935fdf59a2 promises

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r19:e3935fdf59a2

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Implab.Test/AsyncTests.cs +2 -2

             using System;
             using Microsoft.VisualStudio.TestTools.UnitTesting;
             using System.Reflection;
             using System.Threading;
             using Implab.Parallels;
             namespace Implab.Test {
                 [TestClass]
                 public class AsyncTests {
                     [TestMethod]
                     public void ResolveTest() {
                         int res = -1;
                         var p = new Promise<int>();
                         p.Then(x => res = x);
                         p.Resolve(100);
-                        Assert.AreEqual(res, 100);
+                        Assert.AreEqual(100, res);
                     }
                     [TestMethod]
                     public void RejectTest() {
                         int res = -1;
                         Exception err = null;
                         var p = new Promise<int>();
                         p.Then(x => res = x, e => err = e);
                         p.Reject(new ApplicationException("error"));
                         Assert.AreEqual(res, -1);
                         Assert.AreEqual(err.Message, "error");
                     }
                     [TestMethod]
                     public void JoinSuccessTest() {
                         var p = new Promise<int>();
                         p.Resolve(100);
                         Assert.AreEqual(p.Join(), 100);
                     }
                     [TestMethod]
                     public void JoinFailTest() {
                         var p = new Promise<int>();
                         p.Reject(new ApplicationException("failed"));
                         try {
                             p.Join();
                             throw new ApplicationException("WRONG!");
                         } catch (TargetInvocationException err) {
                             Assert.AreEqual(err.InnerException.Message, "failed");
                         } catch {
                             Assert.Fail("Got wrong excaption");
                         }
                     }
                     [TestMethod]
                     public void MapTest() {
                         var p = new Promise<int>();
                         var p2 = p.Map(x => x.ToString());
                         p.Resolve(100);
                         Assert.AreEqual(p2.Join(), "100");
                     }
                     [TestMethod]
                     public void FixErrorTest() {
                         var p = new Promise<int>();
                         var p2 = p.Error(e => 101);
                         p.Reject(new Exception());
                         Assert.AreEqual(p2.Join(), 101);
                     }
                     [TestMethod]
                     public void ChainTest() {
                         var p1 = new Promise<int>();
                         var p3 = p1.Chain(x => {
                             var p2 = new Promise<string>();
                             p2.Resolve(x.ToString());
                             return p2;
                         });
                         p1.Resolve(100);
                         Assert.AreEqual(p3.Join(), "100");
                     }
                     [TestMethod]
                     public void PoolTest() {
                         var pid = Thread.CurrentThread.ManagedThreadId;
                         var p = AsyncPool.Invoke(() => Thread.CurrentThread.ManagedThreadId);
                         Assert.AreNotEqual(pid, p.Join());
                     }
                     [TestMethod]
                     public void WorkerPoolSizeTest() {
                         var pool = new WorkerPool(5, 10, 0);
                         Assert.AreEqual(5, pool.ThreadCount);
                         pool.Invoke(() => { Thread.Sleep(1000000); return 10; });
                         pool.Invoke(() => { Thread.Sleep(1000000); return 10; });
                         pool.Invoke(() => { Thread.Sleep(1000000); return 10; });
                         Assert.AreEqual(5, pool.ThreadCount);
                         for (int i = 0; i < 100; i++)
                             pool.Invoke(() => { Thread.Sleep(1000000); return 10; });
                         Thread.Sleep(100);
                         Assert.AreEqual(10, pool.ThreadCount);
                         pool.Dispose();
                     }
                     [TestMethod]
                     public void WorkerPoolCorrectTest() {
                         var pool = new WorkerPool(0,1000,100);
                         int iterations = 1000;
                         int pending = iterations;
                         var stop = new ManualResetEvent(false);
                         var count = 0;
                         for (int i = 0; i < iterations; i++) {
                             pool
                                 .Invoke(() => 1)
                                 .Then(x => Interlocked.Add(ref count, x))
                                 .Then(x => Math.Log10(x))
                                 .Anyway(() => {
                                     Interlocked.Decrement(ref pending);
                                     if (pending == 0)
                                         stop.Set();
                                 });
                         }
                         stop.WaitOne();
                         Assert.AreEqual(iterations, count);
                         Console.WriteLine("Max threads: {0}", pool.MaxRunningThreads);
                         pool.Dispose();
                     }
                     [TestMethod]
                     public void WorkerPoolDisposeTest() {
                         var pool = new WorkerPool(5, 20);
                         Assert.AreEqual(5, pool.ThreadCount);
                         pool.Dispose();
                         Thread.Sleep(100);
                         Assert.AreEqual(0, pool.ThreadCount);
                         pool.Dispose();
                     }
                     [TestMethod]
                     public void MTQueueTest() {
                         var queue = new MTQueue<int>();
                         int res;
                         queue.Enqueue(10);
                         Assert.IsTrue(queue.TryDequeue(out res));
                         Assert.AreEqual(10, res);
                         Assert.IsFalse(queue.TryDequeue(out res));
                         for (int i = 0; i < 1000; i++)
                             queue.Enqueue(i);
                         for (int i = 0; i < 1000; i++) {
                             queue.TryDequeue(out res);
                             Assert.AreEqual(i, res);
                         }
                         int writers = 0;
                         int readers = 0;
                         var stop = new ManualResetEvent(false);
                         int total = 0;
                         int itemsPerWriter = 1000;
                         int writersCount = 3;
                         for (int i = 0; i < writersCount; i++) {
                             Interlocked.Increment(ref writers);
                             var wn = i;
                             AsyncPool
                                 .InvokeNewThread(() => {
                                     for (int ii = 0; ii < itemsPerWriter; ii++) {
                                         queue.Enqueue(1);
                                     }
                                     return 1;
                                 })
                                 .Anyway(() => Interlocked.Decrement(ref writers));
                         }
                         for (int i = 0; i < 10; i++) {
                             Interlocked.Increment(ref readers);
                             var wn = i;
                             AsyncPool
                                 .InvokeNewThread(() => {
                                     int t;
                                     do {
                                         while (queue.TryDequeue(out t))
                                             Interlocked.Add(ref total, t);
                                     } while (writers > 0);
                                     return 1;
                                 })
                                 .Anyway(() => {
                                     Interlocked.Decrement(ref readers);
                                     if (readers == 0)
                                         stop.Set();
                                 });
                         }
                         stop.WaitOne();
                         Assert.AreEqual(itemsPerWriter * writersCount, total);
                     }
                     [TestMethod]
                     public void ParallelMapTest() {
                         int count = 100000;
                         double[] args = new double[count];
                         var rand = new Random();
                         for (int i = 0; i < count; i++)
                             args[i] = rand.NextDouble();
                         var t = Environment.TickCount;
                         var res = args.ParallelMap(x => Math.Sin(x*x), 4).Join();
                         Console.WriteLine("Map complete in {0} ms", Environment.TickCount - t);
                         t = Environment.TickCount;
                         for (int i = 0; i < count; i++)
                             Assert.AreEqual(Math.Sin(args[i] * args[i]), res[i]);
                         Console.WriteLine("Verified in {0} ms", Environment.TickCount - t);
                     }
                     [TestMethod]
                     public void ChainedMapTest() {
-                        using (var pool = new WorkerPool(8,100,0)) {
+                        using (var pool = new WorkerPool(4,4,0)) {
                             int count = 10000;
                             double[] args = new double[count];
                             var rand = new Random();
                             for (int i = 0; i < count; i++)
                                 args[i] = rand.NextDouble();
                             var t = Environment.TickCount;
                             var res = args
                                 .ChainedMap(
                                     x => pool.Invoke(
                                         () => Math.Sin(x * x)
                                     ),
                                 )
                                 .Join();
                             Console.WriteLine("Map complete in {0} ms", Environment.TickCount - t);
                             t = Environment.TickCount;
                             for (int i = 0; i < count; i++)
                                 Assert.AreEqual(Math.Sin(args[i] * args[i]), res[i]);
                             Console.WriteLine("Verified in {0} ms", Environment.TickCount - t);
                             Console.WriteLine("Max workers: {0}", pool.MaxRunningThreads);
                         }
                     }
                     [TestMethod]
                     public void ParallelForEachTest() {
                         int count = 100000;
                         int[] args = new int[count];
                         var rand = new Random();
                         for (int i = 0; i < count; i++)
                             args[i] = (int)(rand.NextDouble() * 100);
                         int result = 0;
                         var t = Environment.TickCount;
                         args.ParallelForEach(x => Interlocked.Add(ref result, x), 4).Join();
                         Console.WriteLine("Iteration complete in {0} ms, result: {1}", Environment.TickCount - t, result);
                         int result2 = 0;
                         t = Environment.TickCount;
                         for (int i = 0; i < count; i++)
                             result2 += args[i];
                         Assert.AreEqual(result2, result);
                         Console.WriteLine("Verified in {0} ms", Environment.TickCount - t);
                     }
                     [TestMethod]
                     public void ComplexCase1Test() {
                         var flags = new bool[3];
                         // op1 (aync 200ms) => op2 (async 200ms) => op3 (sync map)
                         var p = PromiseHelper
                             .Sleep(200, "Alan")
                             .Cancelled(() => flags[0] = true)
                             .Chain(x =>
                                 PromiseHelper
                                     .Sleep(200, "Hi, " + x)
                                     .Map(y => y)
                                     .Cancelled(() => flags[1] = true)
                             )
                             .Cancelled(() => flags[2] = true);
                         Thread.Sleep(300);
                         p.Cancel();
                         try {
                             Assert.AreEqual(p.Join(), "Hi, Alan");
                             Assert.Fail("Shouldn't get here");
                         } catch (OperationCanceledException) {
                         }
                         Assert.IsFalse(flags[0]);
                         Assert.IsTrue(flags[1]);
                         Assert.IsTrue(flags[2]);
                     }
                 }
             }

Implab.v11.suo binary modified 0 0

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Implab/IPromise.cs 0 -13

             using System;
             using System.Collections.Generic;
             using System.Linq;
             using System.Text;
             namespace Implab
             {
                 public interface IPromise: ICancellable
                 {
                     /// <summary>
                     /// Check whereather the promise has no more than one dependent promise.
                     /// </summary>
                     bool IsExclusive
                     {
                         get;
                     }
-                    /// <summary>
-                    /// The current state of the promise.
-                    /// </summary>
-                    PromiseState State
-                        get;
-                    /// <summary>
-                    /// Registers handler for the case when the promise is cencelled. If the promise already cancelled the
-                    /// handler will be invoked immediatelly.
-                    /// </summary>
-                    /// <param name="handler">The handler</param>
-                    void HandleCancelled(Action handler);
                 }
             }

Implab/Parallels/ArrayTraits.cs +1 -1

             using System;
             using System.Collections.Generic;
             using System.Diagnostics;
             using System.Linq;
             using System.Text;
             using System.Threading;
             namespace Implab.Parallels {
                 public static class ArrayTraits {
                     class ArrayIterator<TSrc> : DispatchPool<int> {
                         readonly Action<TSrc> m_action;
                         readonly TSrc[] m_source;
                         readonly Promise<int> m_promise = new Promise<int>();
                         int m_pending;
                         int m_next;
                         public ArrayIterator(TSrc[] source, Action<TSrc> action, int threads)
                             : base(threads) {
                             Debug.Assert(source != null);
                             Debug.Assert(action != null);
                             m_next = 0;
                             m_source = source;
                             m_pending = source.Length;
                             m_action = action;
                             m_promise.Anyway(() => Dispose());
                             m_promise.Cancelled(() => Dispose());
                             InitPool();
                         }
                         public Promise<int> Promise {
                             get {
                                 return m_promise;
                             }
                         }
                         protected override bool TryDequeue(out int unit) {
                             unit = Interlocked.Increment(ref m_next) - 1;
                             return unit >= m_source.Length ? false : true;
                         }
                         protected override void InvokeUnit(int unit) {
                             try {
                                 m_action(m_source[unit]);
                                 var pending = Interlocked.Decrement(ref m_pending);
                                 if (pending == 0)
                                     m_promise.Resolve(m_source.Length);
                             } catch (Exception e) {
                                 m_promise.Reject(e);
                             }
                         }
                     }
                     class ArrayMapper<TSrc, TDst>: DispatchPool<int> {
                         readonly Func<TSrc, TDst> m_transform;
                         readonly TSrc[] m_source;
                         readonly TDst[] m_dest;
                         readonly Promise<TDst[]> m_promise = new Promise<TDst[]>();
                         int m_pending;
                         int m_next;
                         public ArrayMapper(TSrc[] source, Func<TSrc, TDst> transform, int threads)
                             : base(threads) {
                             Debug.Assert (source != null);
                             Debug.Assert( transform != null);
                             m_next = 0;
                             m_source = source;
                             m_dest = new TDst[source.Length];
                             m_pending = source.Length;
                             m_transform = transform;
                             m_promise.Anyway(() => Dispose());
                             m_promise.Cancelled(() => Dispose());
                             InitPool();
                         }
                         public Promise<TDst[]> Promise {
                             get {
                                 return m_promise;
                             }
                         }
                         protected override bool TryDequeue(out int unit) {
                             unit = Interlocked.Increment(ref m_next) - 1;
                             return unit >= m_source.Length ? false : true;
                         }
                         protected override void InvokeUnit(int unit) {
                             try {
                                 m_dest[unit] = m_transform(m_source[unit]);
                                 var pending = Interlocked.Decrement(ref m_pending);
                                 if (pending == 0)
                                     m_promise.Resolve(m_dest);
                             } catch (Exception e) {
                                 m_promise.Reject(e);
                             }
                         }
                     }
                     public static Promise<TDst[]> ParallelMap<TSrc, TDst> (this TSrc[] source, Func<TSrc,TDst> transform, int threads) {
                         if (source == null)
                             throw new ArgumentNullException("source");
                         if (transform == null)
                             throw new ArgumentNullException("transform");
                         var mapper = new ArrayMapper<TSrc, TDst>(source, transform, threads);
                         return mapper.Promise;
                     }
                     public static Promise<int> ParallelForEach<TSrc>(this TSrc[] source, Action<TSrc> action, int threads) {
                         if (source == null)
                             throw new ArgumentNullException("source");
                         if (action == null)
                             throw new ArgumentNullException("action");
                         var iter = new ArrayIterator<TSrc>(source, action, threads);
                         return iter.Promise;
                     }
                     public static Promise<TDst[]> ChainedMap<TSrc, TDst>(this TSrc[] source, ChainedOperation<TSrc, TDst> transform, int threads) {
                         if (source == null)
                             throw new ArgumentNullException("source");
                         if (transform == null)
                             throw new ArgumentNullException("transform");
                         if (threads <= 0)
                             throw new ArgumentOutOfRangeException("Threads number must be greater then zero");
                         var promise = new Promise<TDst[]>();
                         var res = new TDst[source.Length];
                         var pending = source.Length;
                         var semaphore = new Semaphore(threads, threads);
                         AsyncPool.InvokeNewThread(() => {
                             for (int i = 0; i < source.Length; i++) {
-                                if(promise.State != PromiseState.Unresolved)
+                                if(promise.IsResolved)
                                     break; // stop processing in case of error or cancellation
                                 var idx = i;
                                 semaphore.WaitOne();
                                 try {
                                     var p1 = transform(source[i]);
                                     p1.Anyway(() => semaphore.Release());
                                     p1.Cancelled(() => semaphore.Release());
                                     p1.Then(
                                         x => {
                                             res[idx] = x;
                                             var left = Interlocked.Decrement(ref pending);
                                             if (left == 0)
                                                 promise.Resolve(res);
                                         },
                                         e => promise.Reject(e)
                                     );
                                 } catch (Exception e) {
                                     promise.Reject(e);
                                 }
                             }
                             return 0;
                         });
                         return promise.Anyway(() => semaphore.Dispose());
                     }
                 }
             }

Implab/Parallels/MTQueue.cs +4 -3

             using System;
             using System.Collections.Generic;
             using System.Linq;
             using System.Text;
             using System.Threading;
             namespace Implab.Parallels {
                 public class MTQueue<T> {
                     class Node {
                         public Node(T value) {
                             this.value = value;
                         }
                         public readonly T value;
                         public Node next;
                     }
                     Node m_first;
                     Node m_last;
                     public void Enqueue(T value) {
                         var last = m_last;
                         var next = new Node(value);
                         while (last != Interlocked.CompareExchange(ref m_last, next, last))
                             last = m_last;
                         if (last != null)
                             last.next = next;
                         else
                             m_first = next;
                     }
                     public bool TryDequeue(out T value) {
                         Node first;
                         Node next = null;
                         value = default(T);
                         do {
                             first = m_first;
                             if (first == null)
                                 return false;
                             next = first.next;
                             if (next == null) {
                                 // this is the last element,
-                                // then try to update tail
+                                // then try to update the tail
                                 if (first != Interlocked.CompareExchange(ref m_last, null, first)) {
-                                    // this is inconsistent situation which means that the queue is empty
+                                    // this is a ace condition
                                     if (m_last == null)
+                                        // the queue is empty
                                         return false;
-                                    // tail has been changed, that means that we need to restart
+                                    // tail has been changed, than we need to restart
                                     continue;
                                 }
                                 // tail succesfully updated and first.next will never be changed
                                 // other readers will fail due to inconsistency m_last != m_fist, but m_first.next == null
                                 // but the writer may update the m_first since the m_last is null
                                 // so we need to fix inconsistency by setting m_first to null, but if it already has been
                                 // updated by a writer then we should just give up
                                 Interlocked.CompareExchange(ref m_first, null, first);
                                 break;
                             } else {
                                     if (first == Interlocked.CompareExchange(ref m_first, next, first))
                                         // head succesfully updated
                                         break;
                             }
                         } while (true);
                         value = first.value;
                         return true;
                     }
                 }
             }

Implab/Promise.cs +201 -186

             using System;
             using System.Collections.Generic;
             using System.Reflection;
             using System.Diagnostics;
             using System.Threading;
+            using Implab.Parallels;
             namespace Implab {
                 public delegate void ErrorHandler(Exception e);
                 public delegate T ErrorHandler<out T>(Exception e);
                 public delegate void ResultHandler<in T>(T result);
                 public delegate TNew ResultMapper<in TSrc, out TNew>(TSrc result);
                 public delegate Promise<TNew> ChainedOperation<in TSrc, TNew>(TSrc result);
                 /// <summary>
                 /// Класс для асинхронного получения результатов. Так называемое "обещание".
                 /// </summary>
                 /// <typeparam name="T">Тип получаемого результата</typeparam>
                 /// <remarks>
                 /// <para>Сервис при обращении к его методу дает обещаиние о выполнении операции,
                 /// клиент получив такое обещание может установить ряд обратных вызово для получения
                 /// событий выполнения обещания, тоесть завершения операции и предоставлении результатов.</para>
                 /// <para>
                 /// Обещение может быть как выполнено, так и выполнено с ошибкой. Для подписки на
                 /// данные события клиент должен использовать методы <c>Then</c>.
                 /// </para>
                 /// <para>
                 /// Сервис, в свою очередь, по окончанию выполнения операции (возможно с ошибкой),
                 /// использует методы <c>Resolve</c> либо <c>Reject</c> для оповещения клиетна о
                 /// выполнении обещания.
                 /// </para>
                 /// <para>
                 /// Если сервер успел выполнить обещание еще до того, как клиент на него подписался,
                 /// то в момент подписки клиента будут вызваны соответсвующие события в синхронном
                 /// режиме и клиент будет оповещен в любом случае. Иначе, обработчики добавляются в
                 /// список в порядке подписания и в этом же порядке они будут вызваны при выполнении
                 /// обещания.
                 /// </para>
                 /// <para>
                 /// Обрабатывая результаты обещания можно преобразовывать результаты либо инициировать
                 /// связанные асинхронные операции, которые также возвращают обещания. Для этого следует
                 /// использовать соответствующую форму методе <c>Then</c>.
                 /// </para>
                 /// <para>
                 /// Также хорошим правилом является то, что <c>Resolve</c> и <c>Reject</c> должен вызывать
                 /// только инициатор обещания иначе могут возникнуть противоречия.
                 /// </para>
                 /// </remarks>
                 public class Promise<T> : IPromise {
-                    struct ResultHandlerInfo {
+                    struct HandlerDescriptor {
                         public ResultHandler<T> resultHandler;
                         public ErrorHandler errorHandler;
+                        public Action cancellHandler;
+                        public void Resolve(T result) {
+                            if (resultHandler != null)
+                                try {
+                                    resultHandler(result);
+                                } catch (Exception e) {
+                                    Reject(e);
+                                }
+                        }
+                        public void Reject(Exception err) {
+                            if (errorHandler != null)
+                                try {
+                                    errorHandler(err);
+                                } catch {
+                                }
+                        }
+                        public void Cancel() {
+                            if (cancellHandler != null)
+                                try {
+                                    cancellHandler();
+                                } catch {
+                                }
+                        }
                     }
+                    const int UnresolvedSate = 0;
+                    const int TransitionalState = 1;
+                    const int ResolvedState = 2;
+                    const int RejectedState = 3;
+                    const int CancelledState = 4;
                     readonly IPromise m_parent;
+                    readonly bool m_cancellable;
-                    LinkedList<ResultHandlerInfo> m_resultHandlers = new LinkedList<ResultHandlerInfo>();
-                    LinkedList<Action> m_cancelHandlers = new LinkedList<Action>();
-                    readonly object m_lock = new Object();
-                    readonly bool m_cancellable;
                     int m_childrenCount = 0;
+                    int m_state;
-                    PromiseState m_state;
                     T m_result;
                     Exception m_error;
+                    readonly MTQueue<HandlerDescriptor> m_handlers = new MTQueue<HandlerDescriptor>();
                     public Promise() {
                         m_cancellable = true;
                     }
                     public Promise(IPromise parent, bool cancellable) {
                         m_cancellable = cancellable;
                         m_parent = parent;
-                        if (parent != null)
-                            parent.HandleCancelled(InternalCancel);
                     }
                     void InternalCancel() {
                         // don't try to cancel parent :)
                         Cancel(false);
                     }
+                    bool BeginTransit() {
+                        return UnresolvedSate == Interlocked.CompareExchange(ref m_state, TransitionalState, UnresolvedSate);
+                    }
+                    void CompleteTransit(int state) {
+                        if (TransitionalState != Interlocked.CompareExchange(ref m_state, state, TransitionalState))
+                            throw new InvalidOperationException("Can't complete transition when the object isn't in the transitional state");
+                    }
+                    public bool IsResolved {
+                        get {
+                            return m_state > 1;
+                        }
+                    }
+                    public bool IsCancelled {
+                        get {
+                            return m_state == CancelledState;
+                        }
+                    }
                     /// <summary>
                     /// Выполняет обещание, сообщая об успешном выполнении.
                     /// </summary>
                     /// <param name="result">Результат выполнения.</param>
                     /// <exception cref="InvalidOperationException">Данное обещание уже выполнено</exception>
                     public void Resolve(T result) {
-                        lock (m_lock) {
+                        if (BeginTransit()) {
-                            if (m_state == PromiseState.Cancelled)
-                                return;
-                            if (m_state != PromiseState.Unresolved)
-                                throw new InvalidOperationException("The promise is already resolved");
                             m_result = result;
-                            m_state = PromiseState.Resolved;
+                            CompleteTransit(ResolvedState);
+                            OnStateChanged();
+                        } else if (m_state != CancelledState)
-                        OnStateChanged();
+                            throw new InvalidOperationException("The promise is already resolved");
                     }
                     /// <summary>
                     /// Выполняет обещание, сообщая об ошибке
                     /// </summary>
                     /// <remarks>
                     /// Поскольку обещание должно работать в многопточной среде, при его выполнении сразу несколько потоков
                     /// могу вернуть ошибку, при этом только первая будет использована в качестве результата, остальные
                     /// будут проигнорированы.
                     /// </remarks>
                     /// <param name="error">Исключение возникшее при выполнении операции</param>
                     /// <exception cref="InvalidOperationException">Данное обещание уже выполнено</exception>
                     public void Reject(Exception error) {
-                        lock (m_lock) {
+                        if (BeginTransit()) {
-                            if (m_state == PromiseState.Cancelled || m_state == PromiseState.Rejected)
-                                return;
-                            if (m_state != PromiseState.Unresolved)
-                                throw new InvalidOperationException("The promise is already resolved");
                             m_error = error;
-                            m_state = PromiseState.Rejected;
+                            CompleteTransit(RejectedState);
+                            OnStateChanged();
+                        } else if (m_state == ResolvedState)
-                        OnStateChanged();
+                            throw new InvalidOperationException("The promise is already resolved");
                     }
                     /// <summary>
                     /// Отменяет операцию, если это возможно.
                     /// </summary>
                     /// <returns><c>true</c> Операция была отменена, обработчики не будут вызваны.<c>false</c> отмена не возможна, поскольку обещание уже выполнено и обработчики отработали.</returns>
                     public bool Cancel() {
                         return Cancel(true);
                     }
                     /// <summary>
                     /// Adds new handlers to this promise.
                     /// </summary>
                     /// <param name="success">The handler of the successfully completed operation.
                     /// This handler will recieve an operation result as a parameter.</param>
                     /// <param name="error">Handles an exception that may occur during the operation.</param>
                     /// <returns>The new promise chained to this one.</returns>
                     public Promise<T> Then(ResultHandler<T> success, ErrorHandler error) {
                         if (success == null && error == null)
                             return this;
                         var medium = new Promise<T>(this, true);
-                        var handlerInfo = new ResultHandlerInfo();
+                        ResultHandler<T> resultHandler;
                         if (success != null)
-                            handlerInfo.resultHandler = x => {
+                            resultHandler = x => {
                                 success(x);
                                 medium.Resolve(x);
                             };
                         else
-                            handlerInfo.resultHandler = medium.Resolve;
+                            resultHandler = medium.Resolve;
+                        ErrorHandler errorHandler;
                         if (error != null)
-                            handlerInfo.errorHandler = x => {
+                            errorHandler = x => {
                                 try {
                                     error(x);
                                 } catch { }
                                 medium.Reject(x);
                             };
                         else
-                            handlerInfo.errorHandler = medium.Reject;
+                            errorHandler = medium.Reject;
-                        AddHandler(handlerInfo);
+                        AddHandler(resultHandler, errorHandler, medium.InternalCancel);
                         return medium;
                     }
                     /// <summary>
                     /// Adds new handlers to this promise.
                     /// </summary>
                     /// <param name="success">The handler of the successfully completed operation.
                     /// This handler will recieve an operation result as a parameter.</param>
                     /// <param name="error">Handles an exception that may occur during the operation and returns the value which will be used as the result of the operation.</param>
                     /// <returns>The new promise chained to this one.</returns>
                     public Promise<T> Then(ResultHandler<T> success, ErrorHandler<T> error) {
                         if (success == null && error == null)
                             return this;
                         var medium = new Promise<T>(this, true);
-                        var handlerInfo = new ResultHandlerInfo();
+                        ResultHandler<T> resultHandler;
+                        ErrorHandler errorHandler;
                         if (success != null)
-                            handlerInfo.resultHandler = x => {
+                            resultHandler = x => {
                                 success(x);
                                 medium.Resolve(x);
                             };
                         else
-                            handlerInfo.resultHandler = medium.Resolve;
+                            resultHandler = medium.Resolve;
                         if (error != null)
-                            handlerInfo.errorHandler = x => {
+                            errorHandler = x => {
                                 try {
                                     medium.Resolve(error(x));
                                 } catch { }
                                 medium.Reject(x);
                             };
                         else
-                            handlerInfo.errorHandler = medium.Reject;
+                            errorHandler = medium.Reject;
-                        AddHandler(handlerInfo);
+                        AddHandler(resultHandler, errorHandler, medium.InternalCancel);
                         return medium;
                     }
                     public Promise<T> Then(ResultHandler<T> success) {
                         if (success == null)
                             return this;
                         var medium = new Promise<T>(this, true);
-                        var handlerInfo = new ResultHandlerInfo();
+                        ResultHandler<T> resultHandler;
                         if (success != null)
-                            handlerInfo.resultHandler = x => {
+                            resultHandler = x => {
                                 success(x);
                                 medium.Resolve(x);
                             };
                         else
-                            handlerInfo.resultHandler = medium.Resolve;
+                            resultHandler = medium.Resolve;
-                        handlerInfo.errorHandler = medium.Reject;
+                        AddHandler(resultHandler, medium.Reject, medium.InternalCancel);
-                        AddHandler(handlerInfo);
                         return medium;
                     }
                     public Promise<T> Error(ErrorHandler error) {
                         return Then(null, error);
                     }
                     /// <summary>
                     /// Handles error and allows to keep the promise.
                     /// </summary>
                     /// <remarks>
                     /// If the specified handler throws an exception, this exception will be used to reject the promise.
                     /// </remarks>
                     /// <param name="handler">The error handler which returns the result of the promise.</param>
                     /// <returns>New promise.</returns>
                     public Promise<T> Error(ErrorHandler<T> handler) {
                         if (handler == null)
                             return this;
                         var medium = new Promise<T>(this, true);
-                        AddHandler(new ResultHandlerInfo {
+                        AddHandler(
-                            errorHandler = e => {
+                            null,
+                            e => {
                                 try {
                                     medium.Resolve(handler(e));
                                 } catch (Exception e2) {
                                     medium.Reject(e2);
                                 }
+                            },
-                        });
+                            medium.InternalCancel
+                        );
                         return medium;
                     }
                     public Promise<T> Anyway(Action handler) {
                         if (handler == null)
                             return this;
                         var medium = new Promise<T>();
-                        AddHandler(new ResultHandlerInfo {
+                        AddHandler(
-                            resultHandler = x => {
+                            x => {
                                 // to avoid handler being called multiple times we handle exception by ourselfs
                                 try {
                                     handler();
                                     medium.Resolve(x);
                                 } catch (Exception e) {
                                     medium.Reject(e);
                                 }
                             },
-                            errorHandler = x => {
+                            e => {
                                 try {
                                     handler();
                                 } catch { }
-                                medium.Reject(x);
+                                medium.Reject(e);
+                            },
-                        });
+                            medium.InternalCancel
+                        );
                         return medium;
                     }
                     /// <summary>
                     /// Позволяет преобразовать результат выполения операции к новому типу.
                     /// </summary>
                     /// <typeparam name="TNew">Новый тип результата.</typeparam>
                     /// <param name="mapper">Преобразование результата к новому типу.</param>
                     /// <param name="error">Обработчик ошибки. Данный обработчик получит
                     /// исключение возникшее при выполнении операции.</param>
                     /// <returns>Новое обещание, которое будет выполнено при выполнении исходного обещания.</returns>
                     public Promise<TNew> Map<TNew>(ResultMapper<T, TNew> mapper, ErrorHandler error) {
                         if (mapper == null)
                             throw new ArgumentNullException("mapper");
                         // создаем прицепленное обещание
                         var chained = new Promise<TNew>();
-                        AddHandler(new ResultHandlerInfo() {
+                        ResultHandler<T> resultHandler = result => chained.Resolve(mapper(result));
-                            resultHandler = result => chained.Resolve(mapper(result)),
+                        ErrorHandler errorHandler = delegate(Exception e) {
-                            errorHandler = delegate(Exception e) {
+                            if (error != null)
-                                if (error != null)
+                                try {
-                                    try {
+                                    error(e);
-                                        error(e);
+                                } catch { }
-                                    } catch { }
+                            // в случае ошибки нужно передать исключение дальше по цепочке
-                                // в случае ошибки нужно передать исключение дальше по цепочке
+                            chained.Reject(e);
-                                chained.Reject(e);
+                        };
-                        });
+                        AddHandler(
+                            resultHandler,
+                            errorHandler,
+                            chained.InternalCancel
+                        );
                         return chained;
                     }
                     public Promise<TNew> Map<TNew>(ResultMapper<T, TNew> mapper) {
                         return Map(mapper, null);
                     }
                     /// <summary>
                     /// Сцепляет несколько аснхронных операций. Указанная асинхронная операция будет вызвана после
                     /// выполнения текущей, а результат текущей операции может быть использован для инициализации
                     /// новой операции.
                     /// </summary>
                     /// <typeparam name="TNew">Тип результата указанной асинхронной операции.</typeparam>
                     /// <param name="chained">Асинхронная операция, которая должна будет начаться после выполнения текущей.</param>
                     /// <param name="error">Обработчик ошибки. Данный обработчик получит
                     /// исключение возникшее при выполнении текуещй операции.</param>
                     /// <returns>Новое обещание, которое будет выполнено по окончанию указанной аснхронной операции.</returns>
                     public Promise<TNew> Chain<TNew>(ChainedOperation<T, TNew> chained, ErrorHandler error) {
                         // проблема в том, что на момент связывания еще не начата асинхронная операция, поэтому нужно
                         // создать посредника, к которому будут подвызяваться следующие обработчики.
                         // когда будет выполнена реальная асинхронная операция, она обратиться к посреднику, чтобы
                         // передать через него результаты работы.
                         var medium = new Promise<TNew>(this, true);
-                        AddHandler(new ResultHandlerInfo {
+                        ResultHandler<T> resultHandler = delegate(T result) {
-                            resultHandler = delegate(T result) {
+                            if (medium.IsCancelled)
-                                if (medium.State == PromiseState.Cancelled)
+                                return;
-                                    return;
-                                var promise = chained(result);
+                            var promise = chained(result);
-                                // notify chained operation that it's not needed
+                            // notify chained operation that it's not needed
-                                medium.Cancelled(() => promise.Cancel());
+                            medium.Cancelled(() => promise.Cancel());
-                                promise.Then(
+                            promise.Then(
-                                    x => medium.Resolve(x),
+                                x => medium.Resolve(x),
-                                    e => medium.Reject(e)
+                                e => medium.Reject(e)
-                                );
+                            );
-                            },
+                        };
-                            errorHandler = delegate(Exception e) {
-                                if (error != null)
+                        ErrorHandler errorHandler = delegate(Exception e) {
-                                    error(e);
+                            if (error != null)
-                                // в случае ошибки нужно передать исключение дальше по цепочке
+                                error(e);
-                                medium.Reject(e);
+                            // в случае ошибки нужно передать исключение дальше по цепочке
+                            medium.Reject(e);
-                        });
+                        };
+                        AddHandler(
+                            resultHandler,
+                            errorHandler,
+                            medium.InternalCancel
+                        );
                         return medium;
                     }
                     public Promise<TNew> Chain<TNew>(ChainedOperation<T, TNew> chained) {
                         return Chain(chained, null);
                     }
                     public Promise<T> Cancelled(Action handler) {
-                        if (handler == null)
+                        AddHandler(null, null, handler);
-                            return this;
-                        lock (m_lock) {
-                            if (m_state == PromiseState.Unresolved)
-                                m_cancelHandlers.AddLast(handler);
-                            else if (m_state == PromiseState.Cancelled)
-                                handler();
                         return this;
                     }
-                    public void HandleCancelled(Action handler) {
+                    public Promise<T> Finally(Action handler) {
-                        Cancelled(handler);
+                        if (handler == null)
+                            throw new ArgumentNullException("handler");
+                        AddHandler(
+                            x => handler(),
+                            e => handler(),
+                            handler
+                        );
+                        return this;
                     }
                     /// <summary>
                     /// Дожидается отложенного обещания и в случае успеха, возвращает
                     /// его, результат, в противном случае бросает исключение.
                     /// </summary>
                     /// <remarks>
                     /// <para>
                     /// Если ожидание обещания было прервано по таймауту, это не значит,
                     /// что обещание было отменено или что-то в этом роде, это только
                     /// означает, что мы его не дождались, однако все зарегистрированные
                     /// обработчики, как были так остались и они будут вызваны, когда
                     /// обещание будет выполнено.
                     /// </para>
                     /// <para>
                     /// Такое поведение вполне оправдано поскольку таймаут может истечь
                     /// в тот момент, когда началась обработка цепочки обработчиков, и
                     /// к тому же текущее обещание может стоять в цепочке обещаний и его
                     /// отклонение может привести к непрогнозируемому результату.
                     /// </para>
                     /// </remarks>
                     /// <param name="timeout">Время ожидания</param>
                     /// <returns>Результат выполнения обещания</returns>
                     public T Join(int timeout) {
                         var evt = new ManualResetEvent(false);
                         Anyway(() => evt.Set());
                         Cancelled(() => evt.Set());
                         if (!evt.WaitOne(timeout, true))
                             throw new TimeoutException();
-                        switch (State) {
+                        switch (m_state) {
-                            case PromiseState.Resolved:
+                            case ResolvedState:
                                 return m_result;
-                            case PromiseState.Cancelled:
+                            case CancelledState:
                                 throw new OperationCanceledException();
-                            case PromiseState.Rejected:
+                            case RejectedState:
                                 throw new TargetInvocationException(m_error);
                             default:
-                                throw new ApplicationException(String.Format("Invalid promise state {0}", State));
+                                throw new ApplicationException(String.Format("Invalid promise state {0}", m_state));
                         }
                     }
                     public T Join() {
                         return Join(Timeout.Infinite);
                     }
-                    void AddHandler(ResultHandlerInfo handler) {
+                    void AddHandler(ResultHandler<T> success, ErrorHandler error, Action cancel) {
-                        bool invokeRequired = false;
+                        Interlocked.Increment(ref m_childrenCount);
+                        HandlerDescriptor handler = new HandlerDescriptor {
+                            resultHandler = success,
+                            errorHandler = error,
+                            cancellHandler = cancel
+                        };
-                        lock (m_lock) {
+                        bool queued;
-                            m_childrenCount++;
-                            if (m_state == PromiseState.Unresolved) {
+                        if (!IsResolved) {
-                                m_resultHandlers.AddLast(handler);
+                            m_handlers.Enqueue(handler);
-                            } else
+                            queued = true;
-                                invokeRequired = true;
+                        } else {
+                            // the promise is in resolved state, just invoke the handled with minimum overhead
+                            queued = false;
+                            InvokeHandler(handler);
                         }
-                        // обработчики не должны блокировать сам объект
+                        if (queued && IsResolved && m_handlers.TryDequeue(out handler))
-                        if (invokeRequired)
+                            // if the promise have been resolved while we was adding handler to the queue
+                            // we can't guarantee that someone is still processing it
+                            // therefore we will fetch a handler from the queue and execute it
+                            // note that fetched handler may be not the one we have added
                             InvokeHandler(handler);
                     }
-                    void InvokeHandler(ResultHandlerInfo handler) {
+                    void InvokeHandler(HandlerDescriptor handler) {
                         switch (m_state) {
-                            case PromiseState.Resolved:
+                            case ResolvedState:
-                                try {
+                                handler.Resolve(m_result);
-                                    if (handler.resultHandler != null)
-                                        handler.resultHandler(m_result);
-                                } catch (Exception e) {
-                                    try {
-                                        if (handler.errorHandler != null)
-                                            handler.errorHandler(e);
-                                    } catch { }
                                 break;
-                            case PromiseState.Rejected:
+                            case RejectedState:
-                                try {
+                                handler.Reject(m_error);
-                                    if (handler.errorHandler != null)
+                                break;
-                                        handler.errorHandler(m_error);
+                            case CancelledState:
-                                } catch { }
+                                handler.Cancel();
                                 break;
                             default:
                                 // do nothing
                                 return;
                         }
                     }
                     protected virtual void OnStateChanged() {
-                        switch (m_state) {
+                        HandlerDescriptor handler;
-                            case PromiseState.Resolved:
+                        while (m_handlers.TryDequeue(out handler))
-                                foreach (var resultHandlerInfo in m_resultHandlers)
+                            InvokeHandler(handler);
-                                    try {
-                                        if (resultHandlerInfo.resultHandler != null)
-                                            resultHandlerInfo.resultHandler(m_result);
-                                    } catch (Exception e) {
-                                        try {
-                                            if (resultHandlerInfo.errorHandler != null)
-                                                resultHandlerInfo.errorHandler(e);
-                                        } catch { }
-                                break;
-                            case PromiseState.Cancelled:
-                                foreach (var cancelHandler in m_cancelHandlers)
-                                    cancelHandler();
-                                break;
-                            case PromiseState.Rejected:
-                                foreach (var resultHandlerInfo in m_resultHandlers)
-                                    try {
-                                        if (resultHandlerInfo.errorHandler != null)
-                                            resultHandlerInfo.errorHandler(m_error);
-                                    } catch { }
-                                break;
-                            default:
-                                throw new InvalidOperationException(String.Format("Promise entered an invalid state {0}", m_state));
-                        m_resultHandlers = null;
-                        m_cancelHandlers = null;
                     }
                     public bool IsExclusive {
                         get {
-                            lock (m_lock) {
+                            return m_childrenCount <= 1;
-                                return m_childrenCount <= 1;
-                    public PromiseState State {
-                        get {
-                            lock (m_lock) {
-                                return m_state;
                         }
                     }
                     protected bool Cancel(bool dependencies) {
-                        bool result;
+                        if (BeginTransit()) {
+                            CompleteTransit(CancelledState);
-                        lock (m_lock) {
-                            if (m_state == PromiseState.Unresolved) {
-                                m_state = PromiseState.Cancelled;
-                                result = true;
-                            } else {
-                                result = false;
-                        if (result)
                             OnStateChanged();
-                        if (dependencies && m_parent != null && m_parent.IsExclusive) {
+                            if (dependencies && m_parent != null && m_parent.IsExclusive)
-                            m_parent.Cancel();
+                                m_parent.Cancel();
+                            return true;
+                        } else {
+                            return false;
                         }
-                        return result;
                     }
                 }
             }

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