/// <summary>
/// <para> Builds a <see cref="Policy"/> that will function like a Circuit Breaker.</para>
/// <para>The circuit will break after <paramref name="exceptionsAllowedBeforeBreaking"/>
/// exceptions that are handled by this policy are raised. </para>
/// <para>The circuit will stay broken for the <paramref name="durationOfBreak"/>. Any attempt to execute this policy
/// while the circuit is broken, will immediately throw a <see cref="BrokenCircuitException"/> containing the exception
/// that broke the circuit.
/// </para>
/// <para>If the first action after the break duration period results in a handled exception, the circuit will break
/// again for another <paramref name="durationOfBreak"/>; if no exception is thrown, the circuit will reset.
/// </para>
/// </summary>
/// <param name="policyBuilder">The policy builder.</param>
/// <param name="exceptionsAllowedBeforeBreaking">The number of exceptions that are allowed before opening the circuit.</param>
/// <param name="durationOfBreak">The duration the circuit will stay open before resetting.</param>
/// <param name="onBreak">The action to call when the circuit transitions to an <see cref="CircuitState.Open"/> state.</param>
/// <param name="onReset">The action to call when the circuit resets to a <see cref="CircuitState.Closed"/> state.</param>
/// <param name="onHalfOpen">The action to call when the circuit transitions to <see cref="CircuitState.HalfOpen"/> state, ready to try action executions again. </param>
/// <returns>The policy instance.</returns>
/// <remarks>(see "Release It!" by Michael T. Nygard fi)</remarks>
/// <exception cref="System.ArgumentOutOfRangeException">exceptionsAllowedBeforeBreaking;Value must be greater than zero.</exception>
/// <exception cref="ArgumentNullException">onBreak</exception>
/// <exception cref="ArgumentNullException">onReset</exception>
/// <exception cref="ArgumentNullException">onHalfOpen</exception>
public static CircuitBreakerPolicy CircuitBreakerAsync(this PolicyBuilder policyBuilder, int exceptionsAllowedBeforeBreaking, TimeSpan durationOfBreak, Action<Exception, TimeSpan, Context> onBreak, Action<Context> onReset, Action onHalfOpen)
{
if (exceptionsAllowedBeforeBreaking <= 0) throw new ArgumentOutOfRangeException("exceptionsAllowedBeforeBreaking", "Value must be greater than zero.");
if (durationOfBreak < TimeSpan.Zero) throw new ArgumentOutOfRangeException("durationOfBreak", "Value must be greater than zero.");
if (onBreak == null) throw new ArgumentNullException("onBreak");
if (onReset == null) throw new ArgumentNullException("onReset");
if (onHalfOpen == null) throw new ArgumentNullException("onHalfOpen");
var breakerController = new ConsecutiveCountCircuitController<EmptyStruct>(
exceptionsAllowedBeforeBreaking,
durationOfBreak,
(outcome, timespan, context) => onBreak(outcome.Exception, timespan, context),
onReset,
onHalfOpen);
return new CircuitBreakerPolicy(
(action, context, cancellationToken, continueOnCapturedContext) =>
CircuitBreakerEngine.ImplementationAsync(
async ct => { await action(ct).ConfigureAwait(continueOnCapturedContext); return EmptyStruct.Instance; },
context,
policyBuilder.ExceptionPredicates,
Enumerable.Empty<ResultPredicate<EmptyStruct>>(),
breakerController,
cancellationToken,
continueOnCapturedContext),
policyBuilder.ExceptionPredicates,
breakerController
);
}
/// <summary>
/// <para> Builds a <see cref="Policy"/> that will function like a Circuit Breaker.</para>
/// <para>The circuit will break after <paramref name="exceptionsAllowedBeforeBreaking"/>
/// exceptions that are handled by this policy are raised. </para>
/// <para>The circuit will stay broken for the <paramref name="durationOfBreak"/>. Any attempt to execute this policy
/// while the circuit is broken, will immediately throw a <see cref="BrokenCircuitException"/> containing the exception
/// that broke the circuit.
/// </para>
/// <para>If the first action after the break duration period results in a handled exception, the circuit will break
/// again for another <paramref name="durationOfBreak"/>; if no exception is thrown, the circuit will reset.
/// </para>
/// </summary>
/// <param name="policyBuilder">The policy builder.</param>
/// <param name="exceptionsAllowedBeforeBreaking">The number of exceptions that are allowed before opening the circuit.</param>
/// <param name="durationOfBreak">The duration the circuit will stay open before resetting.</param>
/// <param name="onBreak">The action to call when the circuit transitions to an <see cref="CircuitState.Open"/> state.</param>
/// <param name="onReset">The action to call when the circuit resets to a <see cref="CircuitState.Closed"/> state.</param>
/// <param name="onHalfOpen">The action to call when the circuit transitions to <see cref="CircuitState.HalfOpen"/> state, ready to try action executions again. </param>
/// <returns>The policy instance.</returns>
/// <remarks>(see "Release It!" by Michael T. Nygard fi)</remarks>
/// <exception cref="System.ArgumentOutOfRangeException">exceptionsAllowedBeforeBreaking;Value must be greater than zero.</exception>
/// <exception cref="ArgumentNullException">onBreak</exception>
/// <exception cref="ArgumentNullException">onReset</exception>
/// <exception cref="ArgumentNullException">onHalfOpen</exception>
public static CircuitBreakerPolicy CircuitBreakerAsync(this PolicyBuilder policyBuilder, int exceptionsAllowedBeforeBreaking, TimeSpan durationOfBreak, Action<Exception, TimeSpan, Context> onBreak, Action<Context> onReset, Action onHalfOpen)
{
if (exceptionsAllowedBeforeBreaking <= 0) throw new ArgumentOutOfRangeException("exceptionsAllowedBeforeBreaking", "Value must be greater than zero.");
if (durationOfBreak < TimeSpan.Zero) throw new ArgumentOutOfRangeException("durationOfBreak", "Value must be greater than zero.");
if (onBreak == null) throw new ArgumentNullException("onBreak");
if (onReset == null) throw new ArgumentNullException("onReset");
if (onHalfOpen == null) throw new ArgumentNullException("onHalfOpen");
var breakerController = new ConsecutiveCountCircuitController(exceptionsAllowedBeforeBreaking, durationOfBreak, onBreak, onReset, onHalfOpen);
return new CircuitBreakerPolicy(
(action, context, cancellationToken, continueOnCapturedContext) => CircuitBreakerEngine.ImplementationAsync(action, context, policyBuilder.ExceptionPredicates, breakerController, cancellationToken, continueOnCapturedContext),
policyBuilder.ExceptionPredicates,
breakerController
);
}