gobreaker: github.com/sony/gobreaker Index | Files | Directories

package gobreaker

import "github.com/sony/gobreaker"

Package gobreaker implements the Circuit Breaker pattern. See https://msdn.microsoft.com/en-us/library/dn589784.aspx.

Index

Package Files

gobreaker.go

Variables

var (
    // ErrTooManyRequests is returned when the CB state is half open and the requests count is over the cb maxRequests
    ErrTooManyRequests = errors.New("too many requests")
    // ErrOpenState is returned when the CB state is open
    ErrOpenState = errors.New("circuit breaker is open")
)

type CircuitBreaker Uses

type CircuitBreaker struct {
    // contains filtered or unexported fields
}

CircuitBreaker is a state machine to prevent sending requests that are likely to fail.

func NewCircuitBreaker Uses

func NewCircuitBreaker(st Settings) *CircuitBreaker

NewCircuitBreaker returns a new CircuitBreaker configured with the given Settings.

func (*CircuitBreaker) Execute Uses

func (cb *CircuitBreaker) Execute(req func() (interface{}, error)) (interface{}, error)

Execute runs the given request if the CircuitBreaker accepts it. Execute returns an error instantly if the CircuitBreaker rejects the request. Otherwise, Execute returns the result of the request. If a panic occurs in the request, the CircuitBreaker handles it as an error and causes the same panic again.

func (*CircuitBreaker) Name Uses

func (cb *CircuitBreaker) Name() string

Name returns the name of the CircuitBreaker.

func (*CircuitBreaker) State Uses

func (cb *CircuitBreaker) State() State

State returns the current state of the CircuitBreaker.

type Counts Uses

type Counts struct {
    Requests             uint32
    TotalSuccesses       uint32
    TotalFailures        uint32
    ConsecutiveSuccesses uint32
    ConsecutiveFailures  uint32
}

Counts holds the numbers of requests and their successes/failures. CircuitBreaker clears the internal Counts either on the change of the state or at the closed-state intervals. Counts ignores the results of the requests sent before clearing.

type Settings Uses

type Settings struct {
    Name          string
    MaxRequests   uint32
    Interval      time.Duration
    Timeout       time.Duration
    ReadyToTrip   func(counts Counts) bool
    OnStateChange func(name string, from State, to State)
}

Settings configures CircuitBreaker:

Name is the name of the CircuitBreaker.

MaxRequests is the maximum number of requests allowed to pass through when the CircuitBreaker is half-open. If MaxRequests is 0, the CircuitBreaker allows only 1 request.

Interval is the cyclic period of the closed state for the CircuitBreaker to clear the internal Counts. If Interval is 0, the CircuitBreaker doesn't clear internal Counts during the closed state.

Timeout is the period of the open state, after which the state of the CircuitBreaker becomes half-open. If Timeout is 0, the timeout value of the CircuitBreaker is set to 60 seconds.

ReadyToTrip is called with a copy of Counts whenever a request fails in the closed state. If ReadyToTrip returns true, the CircuitBreaker will be placed into the open state. If ReadyToTrip is nil, default ReadyToTrip is used. Default ReadyToTrip returns true when the number of consecutive failures is more than 5.

OnStateChange is called whenever the state of the CircuitBreaker changes.

type State Uses

type State int

State is a type that represents a state of CircuitBreaker.

const (
    StateClosed State = iota
    StateHalfOpen
    StateOpen
)

These constants are states of CircuitBreaker.

func (State) String Uses

func (s State) String() string

String implements stringer interface.

type TwoStepCircuitBreaker Uses

type TwoStepCircuitBreaker struct {
    // contains filtered or unexported fields
}

TwoStepCircuitBreaker is like CircuitBreaker but instead of surrounding a function with the breaker functionality, it only checks whether a request can proceed and expects the caller to report the outcome in a separate step using a callback.

func NewTwoStepCircuitBreaker Uses

func NewTwoStepCircuitBreaker(st Settings) *TwoStepCircuitBreaker

NewTwoStepCircuitBreaker returns a new TwoStepCircuitBreaker configured with the given Settings.

func (*TwoStepCircuitBreaker) Allow Uses

func (tscb *TwoStepCircuitBreaker) Allow() (done func(success bool), err error)

Allow checks if a new request can proceed. It returns a callback that should be used to register the success or failure in a separate step. If the circuit breaker doesn't allow requests, it returns an error.

func (*TwoStepCircuitBreaker) Name Uses

func (tscb *TwoStepCircuitBreaker) Name() string

Name returns the name of the TwoStepCircuitBreaker.

func (*TwoStepCircuitBreaker) State Uses

func (tscb *TwoStepCircuitBreaker) State() State

State returns the current state of the TwoStepCircuitBreaker.

Directories

PathSynopsis
example

Package gobreaker imports 4 packages (graph) and is imported by 130 packages. Updated 2019-05-28. Refresh now. Tools for package owners.