/// <summary>
/// Initializes a new instance of the <see cref="ExecuteDynamicsServiceCall"/> class.
/// </summary>
/// <param name="logger">The logger<see cref="ILogger{ExecuteDynamicsServiceCall}"/></param>
/// <param name="odataService">The odataService<see cref="IOdataService"/></param>
public ExecuteDynamicsServiceCall(ILogger <ExecuteDynamicsServiceCall> logger, IOdataService odataService)
{
this.logger = logger;
this.odataService = odataService;
circuitBreakerStateCollection = new ConcurrentDictionary <string, CircuitBreakerState>();
defaultCircuitBreakerStateCollection = new CircuitBreakerState
{
ExceptionsCounter = 0,
ODataExceptionsCounter = 0,
IsClosed = true,
LastExceptionOccuredTime = DateTime.MinValue.Ticks,
TimespanDifferenceBetweenExceptions = CircuitBreakerPatternConstants.InitialTimespanDifference
};
}
/// <summary>
/// The ExecuteServiceCall
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="func">The func<see cref="Func{Task{T}}"/></param>
/// <param name="serviceName">The serviceName<see cref="string"/></param>
/// <returns>The <see cref="Task{T}"/></returns>
public async Task <T> ExecuteServiceCall <T>(Func <Task <T> > func, string serviceName = null)
{
try
{
if (serviceName == null)
{
return(await this.TryWebCallWithRetry(func));
}
else
{
CircuitBreakerState circuitBreakerState;
this.circuitBreakerStateCollection.TryGetValue(serviceName, out circuitBreakerState);
if (circuitBreakerState == null)
{
circuitBreakerStateCollection.TryAdd(serviceName, defaultCircuitBreakerStateCollection);
this.circuitBreakerStateCollection.TryGetValue(serviceName, out circuitBreakerState);
}
CircuitBreakerState newCircuitBreakerState = new CircuitBreakerState
{
ExceptionsCounter = circuitBreakerState.ExceptionsCounter,
ODataExceptionsCounter = circuitBreakerState.ODataExceptionsCounter,
IsClosed = circuitBreakerState.IsClosed,
LastExceptionOccuredTime = circuitBreakerState.LastExceptionOccuredTime,
TimespanDifferenceBetweenExceptions = circuitBreakerState.TimespanDifferenceBetweenExceptions
};
if (newCircuitBreakerState.IsClosed)
{
try
{
return(await this.TryWebCallWithRetry(func));
}
catch (Microsoft.OData.ODataException oDataException)
{
this.logger.LogError(oDataException, $"{serviceName} has thrown an OData Exception");
newCircuitBreakerState.ODataExceptionsCounter += 1;
this.UpdateCircuitBreakerState(newCircuitBreakerState);
///TODO - In case we want to clear metadata cache after 4 failures for ANY api, we need to refactor the below dictionary entry to separately save a metadata cache exception state.
if (newCircuitBreakerState.TimespanDifferenceBetweenExceptions > CircuitBreakerPatternConstants.MaximumTimeDifferenceToResetCircuitBreaker)
{
newCircuitBreakerState.ODataExceptionsCounter = 0;
this.circuitBreakerStateCollection.TryUpdate(serviceName, newCircuitBreakerState, circuitBreakerState);
throw;
}
else if (newCircuitBreakerState.ODataExceptionsCounter > CircuitBreakerPatternConstants.MinimumExceptionCounterToOpenCircuit)
{
this.logger.LogError(oDataException, $"{serviceName} {ErrorMessages.MethodInOpenState}");
this.odataService.ResetOdataCache();
newCircuitBreakerState.IsClosed = false;
}
else
{
this.circuitBreakerStateCollection.TryUpdate(serviceName, newCircuitBreakerState, circuitBreakerState);
throw;
}
}
catch (Exception ex)
{
this.logger.LogError(ex, $"{serviceName} {ErrorMessages.MethodThrewAnException}", ex.Message);
newCircuitBreakerState.ExceptionsCounter += 1;
this.UpdateCircuitBreakerState(newCircuitBreakerState);
if (newCircuitBreakerState.TimespanDifferenceBetweenExceptions > CircuitBreakerPatternConstants.MaximumTimeDifferenceToResetCircuitBreaker)
{
newCircuitBreakerState.ExceptionsCounter = 0;
this.circuitBreakerStateCollection.TryUpdate(serviceName, newCircuitBreakerState, circuitBreakerState);
throw;
}
else if (newCircuitBreakerState.ExceptionsCounter > CircuitBreakerPatternConstants.MinimumExceptionCounterToOpenCircuit)
{
this.logger.LogError(ex, $"{serviceName} {ErrorMessages.MethodInOpenState}");
newCircuitBreakerState.IsClosed = false;
}
else
{
this.circuitBreakerStateCollection.TryUpdate(serviceName, newCircuitBreakerState, circuitBreakerState);
throw;
}
}
}
else
{
if (DateTime.UtcNow.Ticks - newCircuitBreakerState.LastExceptionOccuredTime > CircuitBreakerPatternConstants.MinimumTimeToTryClosingCircuit)
{
this.logger.LogInformation($"{serviceName} {ErrorMessages.MethodInHalfOpenState}");
try
{
var result = await this.TryWebCallWithRetry(func, 1);
newCircuitBreakerState.ExceptionsCounter = 0;
newCircuitBreakerState.ODataExceptionsCounter = 0;
newCircuitBreakerState.IsClosed = true;
this.circuitBreakerStateCollection.TryUpdate(serviceName, newCircuitBreakerState, circuitBreakerState);
this.logger.LogInformation($"{serviceName} {ErrorMessages.MethodReturnToClosedState}");
return(result);
}
catch (Exception ex)
{
this.logger.LogError(ex, $"{serviceName} {ErrorMessages.MethodReturnToOpenState}", ex.Message);
newCircuitBreakerState.ExceptionsCounter += 1;
newCircuitBreakerState.ODataExceptionsCounter += 1;
newCircuitBreakerState.TimespanDifferenceBetweenExceptions = DateTime.UtcNow.Ticks - newCircuitBreakerState.LastExceptionOccuredTime;
newCircuitBreakerState.LastExceptionOccuredTime = DateTime.UtcNow.Ticks;
}
}
else
{
this.logger.LogError($"{serviceName} {ErrorMessages.MethodRunningInOpenState}");
}
}
this.circuitBreakerStateCollection.TryUpdate(serviceName, newCircuitBreakerState, circuitBreakerState);
}
}
catch (InvalidOperationException ex) //For catching dictionary exceptions in case of threading issues (concurrent read/write operations)
{
this.logger.LogError(ex, $"{serviceName} {ErrorMessages.InvalidOperationException}", ex.Message);
throw;
}
catch (Exception ex)
{
this.logger.LogError(ex, $"{serviceName} {ErrorMessages.GeneralException}", ex.Message);
throw;
}
throw new CircuitBreakerException();
}
/// <summary>
/// The UpdateCircuitBreakerState
/// </summary>
/// <param name="newCircuitBreakerState">The newCircuitBreakerState<see cref="CircuitBreakerState"/></param>
private void UpdateCircuitBreakerState(CircuitBreakerState newCircuitBreakerState)
{
newCircuitBreakerState.TimespanDifferenceBetweenExceptions = DateTime.UtcNow.Ticks - newCircuitBreakerState.LastExceptionOccuredTime;
newCircuitBreakerState.LastExceptionOccuredTime = DateTime.UtcNow.Ticks;
}