Add interfaces to Polly

Adds interfaces to Polly.  Delivers App-vNext#257

src/Polly.Shared/Bulkhead/BulkheadPolicy.cs

@@ -13,7 +13,7 @@ namespace Polly.Bulkhead
     /// <summary>
     /// A bulkhead-isolation policy which can be applied to delegates.
     /// </summary>
-    public partial class BulkheadPolicy : Policy, IDisposable
+    public partial class BulkheadPolicy : Policy, IBulkheadPolicy
     {
         private readonly SemaphoreSlim _maxParallelizationSemaphore;
         private readonly SemaphoreSlim _maxQueuedActionsSemaphore;
@@ -58,7 +58,7 @@ public void Dispose()
     /// <summary>
     /// A bulkhead-isolation policy which can be applied to delegates returning a value of type <typeparamref name="TResult"/>.
     /// </summary>
-    public partial class BulkheadPolicy<TResult> : Policy<TResult>, IDisposable
+    public partial class BulkheadPolicy<TResult> : Policy<TResult>, IBulkheadPolicy<TResult>
     {
         private readonly SemaphoreSlim _maxParallelizationSemaphore;
         private readonly SemaphoreSlim _maxQueuedActionsSemaphore;

src/Polly.Shared/Bulkhead/BulkheadPolicyAsync.cs

@@ -11,7 +11,7 @@
 
 namespace Polly.Bulkhead
 {
-    public partial class BulkheadPolicy
+    public partial class BulkheadPolicy : IBulkheadPolicy
     {
         internal BulkheadPolicy(Func<Func<Context, CancellationToken, Task>, Context, CancellationToken, bool, Task> asyncExceptionPolicy,
             int maxParallelization,
@@ -27,7 +27,7 @@ internal BulkheadPolicy(Func<Func<Context, CancellationToken, Task>, Context, Ca
         }
     }
 
-    public partial class BulkheadPolicy<TResult>
+    public partial class BulkheadPolicy<TResult> : IBulkheadPolicy<TResult>
     {
         internal BulkheadPolicy(
             Func<Func<Context, CancellationToken, Task<TResult>>, Context, CancellationToken, bool, Task<TResult>> asyncExecutionPolicy,

src/Polly.Shared/Bulkhead/IBulkheadPolicy.cs

@@ -0,0 +1,29 @@
+using System;
+
+namespace Polly.Bulkhead
+{
+    /// <summary>
+    /// Defines properties and methods common to all bulkhead policies.
+    /// </summary>
+
+    public interface IBulkheadPolicy : IsPolicy, IDisposable
+    {
+        /// <summary>
+        /// Gets the number of slots currently available for executing actions through the bulkhead.
+        /// </summary>
+        int BulkheadAvailableCount { get; }
+
+        /// <summary>
+        /// Gets the number of slots currently available for queuing actions for execution through the bulkhead.
+        /// </summary>
+        int QueueAvailableCount { get; }
+    }
+
+    /// <summary>
+    /// Defines properties and methods common to all bulkhead policies generic-typed for executions returning results of type <typeparamref name="TResult"/>.
+    /// </summary>
+    public interface IBulkheadPolicy<TResult> : IBulkheadPolicy
+    {
+
+    }
+}

src/Polly.Shared/CircuitBreaker/CircuitBreakerPolicy.cs

@@ -8,7 +8,7 @@ namespace Polly.CircuitBreaker
     /// <summary>
     /// A circuit-breaker policy that can be applied to delegates.
     /// </summary>
-    public partial class CircuitBreakerPolicy : Policy
+    public partial class CircuitBreakerPolicy : Policy, ICircuitBreakerPolicy
     {
         internal readonly ICircuitController<EmptyStruct> _breakerController;
 
@@ -58,7 +58,7 @@ public void Reset()
     /// <summary>
     /// A circuit-breaker policy that can be applied to delegates returning a value of type <typeparamref name="TResult"/>.
     /// </summary>
-    public partial class CircuitBreakerPolicy<TResult> : Policy<TResult>
+    public partial class CircuitBreakerPolicy<TResult> : Policy<TResult>, ICircuitBreakerPolicy<TResult>
     {
         internal readonly ICircuitController<TResult> _breakerController;
 

src/Polly.Shared/CircuitBreaker/CircuitBreakerPolicyAsync.cs

@@ -7,7 +7,7 @@
 
 namespace Polly.CircuitBreaker
 {
-    public partial class CircuitBreakerPolicy
+    public partial class CircuitBreakerPolicy : ICircuitBreakerPolicy
     {
         internal CircuitBreakerPolicy(
             Func<Func<Context, CancellationToken, Task>, Context, CancellationToken, bool, Task> asyncExceptionPolicy, 
@@ -19,7 +19,7 @@ ICircuitController<EmptyStruct> breakerController
         }
     }
 
-    public partial class CircuitBreakerPolicy<TResult>
+    public partial class CircuitBreakerPolicy<TResult> : ICircuitBreakerPolicy<TResult>
     {
         internal CircuitBreakerPolicy(
             Func<Func<Context, CancellationToken, Task<TResult>>, Context, CancellationToken, bool, Task<TResult>> asyncExecutionPolicy, 

src/Polly.Shared/CircuitBreaker/ICircuitBreakerPolicy.cs

@@ -0,0 +1,43 @@
+using System;
+
+namespace Polly.CircuitBreaker
+{
+    /// <summary>
+    /// Defines properties and methods common to all circuit-breaker policies.
+    /// </summary>
+    public interface ICircuitBreakerPolicy : IsPolicy
+    {
+        /// <summary>
+        /// Gets the state of the underlying circuit.
+        /// </summary>
+        CircuitState CircuitState { get; }
+
+        /// <summary>
+        /// Gets the last exception handled by the circuit-breaker.
+        /// <remarks>This will be null if no exceptions have been handled by the circuit-breaker since the circuit last closed.</remarks>
+        /// </summary>
+        Exception LastException { get; }
+
+        /// <summary>
+        /// Isolates (opens) the circuit manually, and holds it in this state until a call to <see cref="CircuitBreakerPolicy.Reset"/> is made.
+        /// </summary>
+        void Isolate();
+
+        /// <summary>
+        /// Closes the circuit, and resets any statistics controlling automated circuit-breaking.
+        /// </summary>
+        void Reset();
+    }
+
+    /// <summary>
+    /// Defines properties and methods common to all circuit-breaker policies generic-typed for executions returning results of type <typeparamref name="TResult"/>.
+    /// </summary>
+    public interface ICircuitBreakerPolicy<TResult> : ICircuitBreakerPolicy
+    {
+        /// <summary>
+        /// Gets the last result returned from a user delegate which the circuit-breaker handled.
+        /// <remarks>This will be default(<typeparamref name="TResult"/>) if no results have been handled by the circuit-breaker since the circuit last closed, or if the last event handled by the circuit was an exception.</remarks>
+        /// </summary>
+        TResult LastHandledResult { get; }
+    }
+}

src/Polly.Shared/Fallback/FallbackPolicy.cs

@@ -7,7 +7,7 @@ namespace Polly.Fallback
     /// <summary>
     /// A fallback policy that can be applied to delegates.
     /// </summary>
-    public partial class FallbackPolicy : Policy
+    public partial class FallbackPolicy : Policy, IFallbackPolicy
     {
         internal FallbackPolicy(Action<Action<Context, CancellationToken>, Context, CancellationToken> exceptionPolicy, IEnumerable<ExceptionPredicate> exceptionPredicates)
             : base(exceptionPolicy, exceptionPredicates)
@@ -18,7 +18,7 @@ internal FallbackPolicy(Action<Action<Context, CancellationToken>, Context, Canc
     /// <summary>
     /// A fallback policy that can be applied to delegates returning a value of type <typeparamref name="TResult"/>.
     /// </summary>
-    public partial class FallbackPolicy<TResult> : Policy<TResult>
+    public partial class FallbackPolicy<TResult> : Policy<TResult>, IFallbackPolicy<TResult>
     {
         internal FallbackPolicy(
             Func<Func<Context, CancellationToken, TResult>, Context, CancellationToken, TResult> executionPolicy,

src/Polly.Shared/Fallback/FallbackPolicyAsync.cs

@@ -5,15 +5,15 @@
 
 namespace Polly.Fallback
 {
-    public partial class FallbackPolicy
+    public partial class FallbackPolicy : IFallbackPolicy
     {
         internal FallbackPolicy(Func<Func<Context, CancellationToken, Task>, Context, CancellationToken, bool, Task> asyncExceptionPolicy, IEnumerable<ExceptionPredicate> exceptionPredicates)
            : base(asyncExceptionPolicy, exceptionPredicates)
         {
         }
     }
 
-    public partial class FallbackPolicy<TResult>
+    public partial class FallbackPolicy<TResult> : IFallbackPolicy<TResult>
     {
         internal FallbackPolicy(
             Func<Func<Context, CancellationToken, Task<TResult>>, Context, CancellationToken, bool, Task<TResult>> asyncExecutionPolicy,

src/Polly.Shared/Fallback/IFallbackPolicy.cs

@@ -0,0 +1,18 @@
+namespace Polly.Fallback
+{
+    /// <summary>
+    /// Defines properties and methods common to all Fallback policies.
+    /// </summary>
+
+    public interface IFallbackPolicy : IsPolicy
+    {
+    }
+
+    /// <summary>
+    /// Defines properties and methods common to all Fallback policies generic-typed for executions returning results of type <typeparamref name="TResult"/>.
+    /// </summary>
+    public interface IFallbackPolicy<TResult> : IFallbackPolicy
+    {
+
+    }
+}