Breaker

The Breaker is a sealed class that implements the circuit breaker pattern. It is a live object; create it and share it across the calls you intend to protect.

Member	Description
Breaker(BreakerSettings? settings = null)	Creates a new breaker. This constructor validates the settings and throws a ResilienceConfigurationException if they are invalid.
Name	An init-only property used for diagnostics and health endpoints.
Settings	The BreakerSettings used to configure the breaker.
State	The current state of the breaker. If a breaker is open but the break duration has elapsed, it reports HalfOpen because the next call will be treated as a probe. Reading this property does not consume a probe slot.
OpenedAt	The timestamp of when the breaker last opened, or null if it is currently closed.
Isolate()	Forces the breaker into the Isolated state. An isolated breaker does not self-heal.
Reset()	Closes the breaker and clears its failure history.

Isolate and Reset do not raise events because they are administrative actions and not triggered by a specific call.

BreakerState

The BreakerState enum defines the possible states of the circuit breaker:

Value	Description
Closed	The breaker is operating normally. Calls pass through, and outcomes are sampled.
Open	The breaker has tripped. Calls are refused until the break duration expires.
HalfOpen	The break duration has expired. A limited number of trial calls (probes) are allowed through.
Isolated	The breaker has been forced open via the Isolate method.

BreakerSettings

BreakerSettings is a sealed record used to configure the breaker's trip and reset logic. All properties are init-only.

Property	Default	Description
ConsecutiveFailures	5	The number of consecutive failures required to trip the breaker.
FailureRatio	null	An optional rate-based trip threshold in the range (0, 1]. This is evaluated alongside the consecutive failure counter.
MinimumCalls	20	The minimum number of sampled calls in the window before a rate-based trip is evaluated.
Window	30 s	The sliding window duration over which rates are measured.
SlowCallThreshold	null	The duration above which an attempt is considered "slow," even if it succeeded.
SlowCallRatio	0.5	The proportion of slow calls in the window that will trip the breaker.
BreakDuration	15 s	The duration of the first break.
MaxBreakDuration	2 min	The maximum break duration. The break duration doubles with each consecutive trip up to this limit. Set this equal to BreakDuration to disable growth.
HalfOpenProbes	1	The number of concurrent trial calls allowed while in the HalfOpen state.
ProbeSuccesses	2	The number of successful probes required to return the breaker to the Closed state.
Time	TimeProvider.System	The clock used for timing. The breaker maintains its own clock so its state can be read by health endpoints that do not have access to a policy.
Validate()	N/A	Validates the settings and throws a ResilienceConfigurationException listing all found problems.

Implementation details

• Evaluation: Rate-based trips (including the SlowCallThreshold) are not evaluated until MinimumCalls have occurred within the window.
• Resource Efficiency: Window arrays are only allocated if a rate-based trip is configured. A breaker relying solely on consecutive failures requires no arrays.
• Sampling: The breaker samples individual attempts. Only Transient outcomes are counted as evidence of failure.

For a detailed explanation of the logic, see Breaker internals.