private void KeySpaceNotificationHandler(string target, string operation)
{
if (key != target)
{
return;
}
switch (operation)
{
case "expired":
{
Task.Run(() => Transition(
null,
JsonConvert.SerializeObject(
new CircuitBreakerStateDescriptor(CircuitBreakerState.HalfOpen, Clock.Current.Now()),
JsonSerializationSettings), true));
}
break;
default:
ReadDescriptor().ContinueWith(task =>
{
var desc = task.Result;
stateDescriptor = desc;
lastSerializedState = JsonConvert.SerializeObject(stateDescriptor, JsonSerializationSettings);
foreach (var observer in subscribers)
{
observer(desc);
}
});
break;
}
}
private async Task TransitionStateTo(CircuitBreakerStateDescriptor targetState, TimeSpan?expiry = null)
{
var shoudLogEvent = IsNullOrWhiteSpace(lastSerializedState) || targetState.State == CircuitBreakerState.Open || stateDescriptor?.State != targetState.State;
var serialized = JsonConvert.SerializeObject(targetState, JsonSerializationSettings);
var stateExpiry = targetState.State == CircuitBreakerState.Open && expiry == null
? TimeSpan.FromMinutes(1)
: expiry;
await Transition(lastSerializedState, serialized, shoudLogEvent, stateExpiry);
}
public async Task SignalSuccessAsync()
{
var target = CircuitBreakerState.Closed;
if (stateDescriptor?.State == CircuitBreakerState.Open)
{
target = CircuitBreakerState.HalfOpen;
}
var targetState = new CircuitBreakerStateDescriptor(target, Clock.Current.Now());
await TransitionStateTo(targetState);
}
private async Task <CircuitBreakerStateDescriptor> ReadDescriptor()
{
var desc = new CircuitBreakerStateDescriptor(CircuitBreakerState.Closed, Clock.Now());
var src = await db.StringGetAsync(key);
if (!src.IsNullOrEmpty && !IsNullOrWhiteSpace(src))
{
desc = JsonConvert.DeserializeObject <CircuitBreakerStateDescriptor>(src, JsonSerializationSettings);
}
return(desc);
}
public async Task <CircuitBreakerStateDescriptor> GetLastStateAsync()
{
var serialised = await db.StringGetAsync(key);
lastSerializedState = serialised.HasValue ? serialised.ToString() : Empty;
if (IsNullOrWhiteSpace(serialised))
{
var newState = new CircuitBreakerStateDescriptor(CircuitBreakerState.Closed, Clock.Current.Now(),
TimeSpan.FromMinutes(1));
lastSerializedState = await Transition(lastSerializedState,
JsonConvert.SerializeObject(newState, JsonSerializationSettings), true);
}
return(TryDeserialise(lastSerializedState));
}
public async Task SignalFailureAsync(TimeSpan expiry)
{
var openState = new CircuitBreakerStateDescriptor(CircuitBreakerState.Open, Clock.Current.Now(), expiry);
await TransitionStateTo(openState, expiry);
}
