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PromiseT.cs
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cin
Promises rewritten, added improved version of AsyncQueue
 r119 using System;
using System.Diagnostics;
namespace Implab {
/// <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> : AbstractPromise<IDeferred<T>>, IPromise<T>, IDeferred<T> {
class StubDeferred : IDeferred<T> {
public static readonly StubDeferred instance = new StubDeferred();
StubDeferred() {
}
#region IDeferred implementation
public void Resolve(T value) {
}
public void Reject(Exception error) {
}
#endregion
#region ICancellable implementation
public void Cancel() {
}
#endregion
}
class RemapDescriptor<T2> : IDeferred<T> {
readonly Func<T,T2> m_remap;
readonly Func<Exception,T2> m_failed;
readonly Func<T2> m_cancel;
readonly IDeferred<T2> m_deferred;
public RemapDescriptor(Func<T,T2> remap, Func<Exception,T2> failed, Func<T2> cancel, IDeferred<T2> deferred ) {
Debug.Assert(deferred != null);
m_remap = remap;
m_failed = failed;
m_cancel = cancel;
m_deferred = deferred;
}
#region IDeferred implementation
public void Resolve(T value) {
if (m_remap != null) {
try {
m_deferred.Resolve(m_remap(value));
} catch (Exception ex) {
Reject(ex);
}
}
}
public void Reject(Exception error) {
if (m_failed != null) {
try {
m_deferred.Resolve(m_failed(error));
} catch (Exception ex) {
m_deferred.Reject(ex);
}
} else {
m_deferred.Reject(error);
}
}
#endregion
#region ICancellable implementation
public void Cancel() {
if (m_cancel != null) {
try {
m_deferred.Resolve(m_cancel());
} catch (Exception ex) {
Reject(ex);
}
} else {
m_deferred.Cancel();
}
}
#endregion
}
class ListenerDescriptor : IDeferred<T> {
readonly Action m_handler;
readonly PromiseEventType m_events;
public ListenerDescriptor(Action handler, PromiseEventType events) {
Debug.Assert(handler != null);
m_handler = handler;
m_events = events;
}
#region IDeferred implementation
public void Resolve(T value) {
if (m_events.HasFlag(PromiseEventType.Success)) {
try {
m_handler();
// Analysis disable once EmptyGeneralCatchClause
} catch {
}
}
}
public void Reject(Exception error) {
if (m_events.HasFlag(PromiseEventType.Error)){
try {
m_handler();
// Analysis disable once EmptyGeneralCatchClause
} catch {
}
}
}
#endregion
#region ICancellable implementation
public void Cancel() {
if (m_events.HasFlag(PromiseEventType.Cancelled)){
try {
m_handler();
// Analysis disable once EmptyGeneralCatchClause
} catch {
}
}
}
#endregion
}
class ValueEventDescriptor : IDeferred<T> {
readonly Action<T> m_success;
readonly Action<Exception> m_failed;
readonly Action m_cancelled;
readonly IDeferred<T> m_deferred;
public ValueEventDescriptor(Action<T> success, Action<Exception> failed, Action cancelled, IDeferred<T> deferred) {
Debug.Assert(deferred != null);
m_success = success;
m_failed = failed;
m_cancelled = cancelled;
m_deferred = deferred;
}
#region IDeferred implementation
public void Resolve(T value) {
if (m_success != null) {
try {
m_success(value);
m_deferred.Resolve(value);
} catch (Exception ex) {
Reject(ex);
}
}
}
public void Reject(Exception error) {
if (m_failed != null) {
try {
m_failed(error);
m_deferred.Resolve(default(T));
} catch(Exception ex) {
m_deferred.Reject(ex);
}
} else {
m_deferred.Reject(error);
}
}
#endregion
#region ICancellable implementation
public void Cancel() {
if (m_cancelled != null) {
try {
m_cancelled();
m_deferred.Resolve(default(T));
} catch(Exception ex) {
Reject(ex);
}
} else {
m_deferred.Cancel();
}
}
#endregion
}
public class EventDescriptor : IDeferred<T> {
readonly Action m_success;
readonly Action<Exception> m_failed;
readonly Action m_cancelled;
readonly IDeferred<T> m_deferred;
public EventDescriptor(Action success, Action<Exception> failed, Action cancelled, IDeferred<T> deferred) {
Debug.Assert(deferred != null);
m_success = success;
m_failed = failed;
m_cancelled = cancelled;
m_deferred = deferred;
}
#region IDeferred implementation
public void Resolve(T value) {
if (m_success != null) {
try {
m_success();
m_deferred.Resolve(value);
} catch (Exception ex) {
Reject(ex);
}
}
}
public void Reject(Exception error) {
if (m_failed != null) {
try {
m_failed(error);
m_deferred.Resolve(default(T));
}catch (Exception ex)
{
m_deferred.Reject(ex);
}
} else {
m_deferred.Reject(error);
}
}
#endregion
#region ICancellable implementation
public void Cancel() {
if (m_cancelled != null) {
try {
m_cancelled();
m_deferred.Resolve(default(T));
} catch (Exception ex) {
Reject(ex);
}
} else {
m_deferred.Cancel();
}
}
#endregion
}
T m_result;
public virtual void Resolve(T value) {
cin
fixed Resove method bug when calling it on already cancelled promise
 r130 if (BeginSetResult()) {
m_result = value;
EndSetResult();
}
cin
Promises rewritten, added improved version of AsyncQueue
 r119 }
public void Reject(Exception error) {
SetError(error);
}
public Type PromiseType {
get {
return typeof(T);
}
}
public new T Join() {
WaitResult(-1);
return m_result;
}
public new T Join(int timeout) {
WaitResult(timeout);
return m_result;
}
public IPromise<T> On(Action<T> success, Action<Exception> error, Action cancel) {
AddHandler(new ValueEventDescriptor(success, error, cancel, StubDeferred.instance));
return this;
}
public IPromise<T> On(Action<T> success, Action<Exception> error) {
AddHandler(new ValueEventDescriptor(success, error, null, StubDeferred.instance));
return this;
}
public IPromise<T> On(Action<T> success) {
AddHandler(new ValueEventDescriptor(success, null, null, StubDeferred.instance));
return this;
}
public IPromise<T> On(Action handler, PromiseEventType events) {
Listen(events, handler);
return this;
}
public IPromise<T2> Then<T2>(Func<T, T2> mapper, Func<Exception, T2> error, Func<T2> cancel) {
var promise = new Promise<T2>();
AddHandler(new RemapDescriptor<T2>(mapper, error, cancel, promise));
return promise;
}
public IPromise<T2> Then<T2>(Func<T, T2> mapper, Func<Exception, T2> error) {
var promise = new Promise<T2>();
AddHandler(new RemapDescriptor<T2>(mapper, error, null, promise));
return promise;
}
public IPromise<T2> Then<T2>(Func<T, T2> mapper) {
var promise = new Promise<T2>();
AddHandler(new RemapDescriptor<T2>(mapper, null, null, promise));
return promise;
}
public IPromise<T2> Chain<T2>(Func<T, IPromise<T2>> chained, Func<Exception, IPromise<T2>> error, Func<IPromise<T2>> cancel) {
// this promise will be resolved when an asyc operation is started
var promise = new Promise<IPromise<T2>>();
AddHandler(new RemapDescriptor<IPromise<T2>>(
chained,
error,
cancel,
promise
));
var medium = new Promise<T2>();
if (chained != null)
medium.On(Cancel, PromiseEventType.Cancelled);
// we need to connect started async operation with the medium
// if the async operation hasn't been started by the some reason
// report is to the medium
promise.On(
result => ConnectPromise<T2>(result, medium),
medium.Reject,
medium.Cancel
);
return medium;
}
static void ConnectPromise<T2>(IPromise<T2> result, Promise<T2> medium) {
if (result != null) {
result.On(
medium.Resolve,
medium.Reject,
() => medium.Reject(new OperationCanceledException())
);
medium.On(result.Cancel, PromiseEventType.Cancelled);
} else {
medium.Reject(
new NullReferenceException(
"The chained asynchronous operation returned" +
" 'null' where the promise instance is expected"
)
);
}
}
public IPromise<T2> Chain<T2>(Func<T, IPromise<T2>> chained, Func<Exception, IPromise<T2>> error) {
return Chain(chained, error, null);
}
public IPromise<T2> Chain<T2>(Func<T, IPromise<T2>> chained) {
return Chain(chained, null, null);
}
public IPromise<T2> Error<T2>(Func<Exception, T2> error) {
var promise = new Promise<T2>();
if (error != null)
On(
(Action<T>)null,
ex => {
try {
promise.Resolve(error(ex));
} catch (Exception ex2) {
promise.Reject(ex2);
}
}
);
else
Listen(PromiseEventType.Error, () => promise.Resolve(default(T2)));
return promise;
}
public IPromise<T2> Cancelled<T2>(Func<T2> handler) {
var promise = new Promise<T2>();
if (handler != null)
On(
(Action<T>)null,
null,
() => {
try {
promise.Resolve(handler());
} catch (Exception ex) {
promise.Reject(ex);
}
});
else
Listen(PromiseEventType.Cancelled, () => promise.Resolve(default(T2)));
return promise;
}
public IPromise Then(Action success, Action<Exception> error, Action cancel) {
var promise = new Promise<T>();
if (success != null)
promise.On(Cancel, PromiseEventType.Cancelled);
AddHandler(new EventDescriptor(success, error, cancel, promise));
return promise;
}
public IPromise Then(Action success, Action<Exception> error) {
return Then(success, error, null);
}
public IPromise Then(Action success) {
return Then(success, null, null);
}
public IPromise Chain(Func<IPromise> chained, Func<Exception, IPromise> error, Func<IPromise> cancel) {
var promise = new Promise<IPromise>();
AddHandler(
new RemapDescriptor<IPromise>(
x => chained(),
error,
cancel,
promise
)
);
var medium = new Promise();
if (chained != null)
medium.On(Cancel, PromiseEventType.Cancelled);
promise.On(
result => ConnectPromise(result, medium),
medium.Reject,
medium.Cancel
);
return medium;
}
static void ConnectPromise(IPromise result, Promise medium) {
if (result != null) {
result.On(
medium.Resolve,
medium.Reject,
() => medium.Reject(new OperationCanceledException())
);
medium.On(result.Cancel, PromiseEventType.Cancelled);
} else {
medium.Reject(
new NullReferenceException(
"The chained asynchronous operation returned" +
" 'null' where the promise instance is expected"
)
);
}
}
public IPromise Chain(Func<IPromise> chained, Func<Exception, IPromise> error) {
return Chain(chained, error, null);
}
public IPromise Chain(Func<IPromise> chained) {
return Chain(chained, null, null);
}
public IPromise On(Action success, Action<Exception> error, Action cancel) {
AddHandler(new EventDescriptor(success,error,cancel, StubDeferred.instance));
return this;
}
public IPromise On(Action success, Action<Exception> error) {
AddHandler(new EventDescriptor(success, error, null, StubDeferred.instance));
return this;
}
public IPromise On(Action success) {
Listen(PromiseEventType.Success, success);
return this;
}
IPromise IPromise.On(Action handler, PromiseEventType events) {
Listen(events,handler);
return this;
}
public IPromise Error(Action<Exception> error) {
var promise = new Promise();
if (error != null)
On(
(Action<T>)null,
ex => {
try {
error(ex);
promise.Resolve();
} catch (Exception ex2) {
promise.Reject(ex2);
}
});
else
Listen(PromiseEventType.Error, promise.Resolve);
return promise;
}
public IPromise Cancelled(Action handler) {
var promise = new Promise();
if (handler != null)
On(
(Action<T>)null,
null,
() => {
try {
handler();
promise.Resolve();
} catch (Exception ex) {
promise.Reject(ex);
}
});
else
Listen(PromiseEventType.Cancelled, promise.Resolve);
return promise;
}
public IPromise<T2> Cast<T2>() {
return (IPromise<T2>)this;
}
#region implemented abstract members of AbstractPromise
protected override void SignalSuccess(IDeferred<T> handler) {
handler.Resolve(m_result);
}
protected override void SignalError(IDeferred<T> handler, Exception error) {
handler.Reject(error);
}
protected override void SignalCancelled(IDeferred<T> handler) {
handler.Cancel();
}
protected override void Listen(PromiseEventType events, Action handler) {
if (handler != null)
AddHandler(new ListenerDescriptor(handler, events));
}
#endregion
public static IPromise<T> ResultToPromise(T value) {
var p = new Promise<T>();
p.Resolve(value);
return p;
}
public static IPromise<T> ExceptionToPromise(Exception error) {
var p = new Promise<T>();
p.Reject(error);
return p;
}
}
}