Module io.helidon.faulttolerance

Package io.helidon.faulttolerance

Class FaultTolerance

java.lang.Object

io.helidon.faulttolerance.FaultTolerance

public final class FaultTolerance
extends Object

System-wide fault tolerance configuration and access to a customized sequence of fault tolerance handlers.

Fault tolerance provides the following features:

• Bulkhead - limit number of parallel requests to a resource
• CircuitBreaker - stop trying to request a failing resource until it becomes available
• Fallback - fall back to another supplier of result in case the usual one fails
• Retry - try to call a supplier again if invocation fails
• Timeout - time out a request if it takes too long

See Also:

• config(io.helidon.config.Config)
• executor()
• builder()

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	FaultTolerance.Builder	A builder used for setting up a customized list of fault tolerance handlers.
static class	FaultTolerance.TypedBuilder<T>	A builder used for fault tolerance handlers that require a specific type to be used, such as Fallback.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	FT_METRICS_DEFAULT_ENABLED	Config key to enable metrics in Fault Tolerance.

Method Summary

Modifier and Type	Method	Description
static FaultTolerance.Builder	builder()	A builder to configure a customized sequence of fault tolerance handlers.
static void	config(Config config)	Configure Helidon wide defaults from a config instance.
static void	executor(Supplier<? extends ExecutorService> executor)	Configure Helidon wide executor service for Fault Tolerance.
static <T> Callable<T>	toDelayedCallable(Callable<T> callable, long millis)	Converts a Callable into another that sleeps for millis before executing.
static Runnable	toDelayedRunnable(Runnable runnable, long millis)	Converts a Runnable into another that sleeps for millis before executing.
static <T> FaultTolerance.TypedBuilder<T>	typedBuilder()	A typed builder to configure a customized sequence of fault tolerance handlers.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

FT_METRICS_DEFAULT_ENABLED

public static final String FT_METRICS_DEFAULT_ENABLED

Config key to enable metrics in Fault Tolerance. This flag can be overridden by each FT command builder. See for example BulkheadConfigBlueprint.enableMetrics(). All metrics are disabled by default.

See Also:

• Constant Field Values

Method Details

config

public static void config(Config config)

Configure Helidon wide defaults from a config instance.

Parameters:

config - config to read fault tolerance configuration

executor

public static void executor(Supplier<? extends ExecutorService> executor)

Configure Helidon wide executor service for Fault Tolerance.

Parameters:

executor - executor service to use

builder

public static FaultTolerance.Builder builder()

A builder to configure a customized sequence of fault tolerance handlers.

Returns:

a new builder

typedBuilder

public static <T> FaultTolerance.TypedBuilder<T> typedBuilder()

A typed builder to configure a customized sequence of fault tolerance handlers.

Type Parameters:

T - type of result

Returns:

a new builder

toDelayedRunnable

public static Runnable toDelayedRunnable(Runnable runnable,
 long millis)

Converts a Runnable into another that sleeps for millis before executing. Simulates a scheduled executor when using VTs.

Parameters:

runnable - the runnable

millis - the time to sleep

Returns:

the new runnable

toDelayedCallable

public static <T> Callable<T> toDelayedCallable(Callable<T> callable,
 long millis)

Converts a Callable into another that sleeps for millis before executing. Simulates a scheduled executor when using VTs.

Type Parameters:

T - type of value returned

Parameters:

callable - the callable

millis - the time to sleep

Returns:

the new callable