/// <summary>
/// <para> Builds a <see cref="Policy"/> that will function like a Circuit Breaker.</para>
/// <para>The circuit will break if, within any timeslice of duration <paramref name="samplingDuration"/>, the proportion of actions resulting in a handled exception exceeds <paramref name="failureThreshold"/>, provided also that the number of actions through the circuit in the timeslice is at least <paramref name="minimumThroughput" />. </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="failureThreshold">The failure threshold at which the circuit will break (a number between 0 and 1; eg 0.5 represents breaking if 50% or more of actions result in a handled failure.</param>
/// <param name="samplingDuration">The duration of the timeslice over which failure ratios are assessed.</param>
/// <param name="minimumThroughput">The minimum throughput: this many actions or more must pass through the circuit in the timeslice, for statistics to be considered significant and the circuit-breaker to come into action.</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="ArgumentOutOfRangeException">failureThreshold;Value must be greater than zero</exception>
/// <exception cref="ArgumentOutOfRangeException">failureThreshold;Value must be less than or equal to one</exception>
/// <exception cref="ArgumentOutOfRangeException">samplingDuration;Value must be equal to or greater than the minimum resolution of the CircuitBreaker timer</exception>
/// <exception cref="ArgumentOutOfRangeException">minimumThroughput;Value must be greater than one</exception>
/// <exception cref="ArgumentOutOfRangeException">durationOfBreak;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 AdvancedCircuitBreakerAsync(this PolicyBuilder policyBuilder, double failureThreshold, TimeSpan samplingDuration, int minimumThroughput, TimeSpan durationOfBreak, Action<Exception, TimeSpan, Context> onBreak, Action<Context> onReset, Action onHalfOpen)
{
var resolutionOfCircuit = TimeSpan.FromTicks(AdvancedCircuitController<EmptyStruct>.ResolutionOfCircuitTimer);
if (failureThreshold <= 0) throw new ArgumentOutOfRangeException("failureThreshold", "Value must be greater than zero.");
if (failureThreshold > 1) throw new ArgumentOutOfRangeException("failureThreshold", "Value must be less than or equal to one.");
if (samplingDuration < resolutionOfCircuit) throw new ArgumentOutOfRangeException("samplingDuration", String.Format("Value must be equal to or greater than {0} milliseconds. This is the minimum resolution of the CircuitBreaker timer.", resolutionOfCircuit.TotalMilliseconds));
if (minimumThroughput <= 1) throw new ArgumentOutOfRangeException("minimumThroughput", "Value must be greater than one.");
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 AdvancedCircuitController<EmptyStruct>(
failureThreshold,
samplingDuration,
minimumThroughput,
durationOfBreak,
(outcome, timespan, context) => onBreak(outcome.Exception, timespan, context),
onReset,
onHalfOpen);
return new CircuitBreakerPolicy(
(action, context, cancellationToken, continueOnCapturedContext) => CircuitBreakerEngine.ImplementationAsync<EmptyStruct>(
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 if, within any timeslice of duration <paramref name="samplingDuration"/>, the proportion of actions resulting in a handled exception exceeds <paramref name="failureThreshold"/>, provided also that the number of actions through the circuit in the timeslice is at least <paramref name="minimumThroughput" />. </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="failureThreshold">The failure threshold at which the circuit will break (a number between 0 and 1; eg 0.5 represents breaking if 50% or more of actions result in a handled failure.</param>
/// <param name="samplingDuration">The duration of the timeslice over which failure ratios are assessed.</param>
/// <param name="minimumThroughput">The minimum throughput: this many actions or more must pass through the circuit in the timeslice, for statistics to be considered significant and the circuit-breaker to come into action.</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>
/// <exception cref="System.ArgumentOutOfRangeException">exceptionsAllowedBeforeBreaking;Value must be greater than zero.</exception>
/// <exception cref="System.ArgumentNullException">
/// onBreak
/// or
/// onReset
/// or
/// onHalfOpen
/// </exception>
/// <exception cref="ArgumentNullException">exceptionsAllowedBeforeBreaking;Value must be greater than zero.</exception>
/// <exception cref="ArgumentNullException">onBreak</exception>
/// <exception cref="ArgumentNullException">onReset</exception>
/// <remarks>(see "Release It!" by Michael T. Nygard fi)</remarks>
public static CircuitBreakerPolicy AdvancedCircuitBreaker(this PolicyBuilder policyBuilder, double failureThreshold, TimeSpan samplingDuration, int minimumThroughput, TimeSpan durationOfBreak, Action<Exception, TimeSpan, Context> onBreak, Action<Context> onReset, Action onHalfOpen)
{
var resolutionOfCircuit = TimeSpan.FromTicks(AdvancedCircuitController.ResolutionOfCircuitTimer);
if (failureThreshold <= 0) throw new ArgumentOutOfRangeException("failureThreshold", "Value must be greater than zero.");
if (failureThreshold > 1) throw new ArgumentOutOfRangeException("failureThreshold", "Value must be less than or equal to one.");
if (samplingDuration < resolutionOfCircuit) throw new ArgumentOutOfRangeException("samplingDuration", String.Format("Value must be equal to or greater than {0} milliseconds. This is the minimum resolution of the CircuitBreaker timer.", resolutionOfCircuit.TotalMilliseconds));
if (minimumThroughput <= 1) throw new ArgumentOutOfRangeException("minimumThroughput", "Value must be greater than one.");
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 AdvancedCircuitController(failureThreshold, samplingDuration, minimumThroughput, durationOfBreak, onBreak, onReset, onHalfOpen);
return new CircuitBreakerPolicy(
(action, context) => CircuitBreakerEngine.Implementation(action, context, policyBuilder.ExceptionPredicates, breakerController),
policyBuilder.ExceptionPredicates,
breakerController
);
}