# Class RetryExtensions

OptimaJet.Workflow.Core.RetryExtensions

Provides extension methods for retrying asynchronous operations created by task factories.

Namespace: [OptimaJet.Workflow.Core](https://api.workflowengine.io/core/OptimaJet.Workflow.Core/)

```csharp
public static class RetryExtensions
```

## Methods

`public static Task<T> RetryAsync<T>(this Func<Task<T>> taskFactory, int retries, TimeSpan delay, CancellationToken cancellationToken = default, Func<Exception, bool> isRetryAllowed = null, bool progressiveDelay = true)` 

Executes the asynchronous operation produced by `taskFactory` and retries it when it faults.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `taskFactory` | `Func<Task<T>>` | A delegate that creates a new [Task<TResult>](https://learn.microsoft.com/dotnet/api/system.threading.tasks.task-1) for each retry attempt. |
| `retries` | `Int32` | The number of additional attempts allowed after the first failed attempt. |
| `delay` | `TimeSpan` | The delay before the first retry attempt. |
| `cancellationToken` | `CancellationToken` | A token observed after each attempt and while waiting between attempts. It is not passed to `taskFactory`. |
| `isRetryAllowed` | `Func<Exception, Boolean>` | Optional predicate that decides whether a failed attempt can be retried. The predicate receives the [AggregateException](https://learn.microsoft.com/dotnet/api/system.aggregateexception) from the failed attempt. |
| `progressiveDelay` | `Boolean` | [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) to set the next delay to [TimeSpan.FromTicks(long)](https://learn.microsoft.com/dotnet/api/system.timespan.fromticks)(2 \* `delay`.Ticks); [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) to reuse `delay`. |

### Returns

| Type | Description |
| --- | --- |
| `Task<T>` | The value returned by a successful operation attempt. |

### Exceptions

| Type | Description |
| --- | --- |
| `AggregateException` | Thrown when a fault is not eligible for another attempt or the retry limit is reached. |
| `OperationCanceledException` | Thrown when `cancellationToken` is canceled. |

`public static Task<T> RetryWithDefaultRetryAllowedChecker<T>(this Func<Task<T>> taskFactory, int retries, TimeSpan delay, CancellationToken cancellationToken = default)` 

Executes the asynchronous operation produced by `taskFactory` and retries it when it faults.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `taskFactory` | `Func<Task<T>>` | A delegate that creates a new [Task<TResult>](https://learn.microsoft.com/dotnet/api/system.threading.tasks.task-1) for each retry attempt. |
| `retries` | `Int32` | The number of additional attempts allowed after the first failed attempt. |
| `delay` | `TimeSpan` | The delay before the first retry attempt. |
| `cancellationToken` | `CancellationToken` | A token observed after each attempt and while waiting between attempts. It is not passed to `taskFactory`. |

### Returns

| Type | Description |
| --- | --- |
| `Task<T>` | A task that completes with the successful result of `taskFactory` or fails when retries are exhausted. |

### Remarks

Retries only when the exception itself or its [Exception.InnerException](https://learn.microsoft.com/dotnet/api/system.exception.innerexception) chain contains a [PersistenceProviderQueryException](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Fault/PersistenceProviderQueryException/) whose [PersistenceProviderQueryException.IsRetryAllowed](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Fault/PersistenceProviderQueryException/) property is [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool).

`public static Task RetryAsync(this Func<Task> taskFactory, int retries, TimeSpan delay, CancellationToken cancellationToken = default, Func<Exception, bool> isRetryAllowed = null, bool progressiveDelay = true)` 

Executes the asynchronous operation produced by `taskFactory` and retries it when it faults.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `taskFactory` | `Func<Task>` | A delegate that creates a new [Task](https://learn.microsoft.com/dotnet/api/system.threading.tasks.task) for each retry attempt. |
| `retries` | `Int32` | The number of additional attempts allowed after the first failed attempt. |
| `delay` | `TimeSpan` | The delay before the first retry attempt. |
| `cancellationToken` | `CancellationToken` | A token observed after each attempt and while waiting between attempts. It is not passed to `taskFactory`. |
| `isRetryAllowed` | `Func<Exception, Boolean>` | Optional predicate that decides whether a failed attempt can be retried. The predicate receives the [AggregateException](https://learn.microsoft.com/dotnet/api/system.aggregateexception) from the failed attempt. |
| `progressiveDelay` | `Boolean` | [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) to set the next delay from twice the [TimeSpan.Milliseconds](https://learn.microsoft.com/dotnet/api/system.timespan.milliseconds) component of `delay`; [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) to reuse `delay`. |

### Returns

| Type | Description |
| --- | --- |
| `Task` | A task that represents the full retry sequence. |

### Exceptions

| Type | Description |
| --- | --- |
| `AggregateException` | Thrown when a fault is not eligible for another attempt or the retry limit is reached. |
| `OperationCanceledException` | Thrown when `cancellationToken` is canceled. |

`public static Task RetryWithDefaultRetryAllowedChecker(this Func<Task> taskFactory, int retries, TimeSpan delay, CancellationToken cancellationToken = default)` 

Executes the asynchronous operation produced by `taskFactory` and retries it when it faults.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `taskFactory` | `Func<Task>` | A delegate that creates a new [Task](https://learn.microsoft.com/dotnet/api/system.threading.tasks.task) for each retry attempt. |
| `retries` | `Int32` | The number of additional attempts allowed after the first failed attempt. |
| `delay` | `TimeSpan` | The delay before the first retry attempt. |
| `cancellationToken` | `CancellationToken` | A token observed after each attempt and while waiting between attempts. It is not passed to `taskFactory`. |

### Returns

| Type | Description |
| --- | --- |
| `Task` | A task that represents the retry sequence. |

### Remarks

Retries only when the exception itself or its [Exception.InnerException](https://learn.microsoft.com/dotnet/api/system.exception.innerexception) chain contains a [PersistenceProviderQueryException](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Fault/PersistenceProviderQueryException/) whose [PersistenceProviderQueryException.IsRetryAllowed](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Fault/PersistenceProviderQueryException/) property is [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool).

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