Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

https://github.com/sony/gobreaker

Circuit Breaker implemented in Go
https://github.com/sony/gobreaker

circuit-breaker golang microservice

Last synced: 11 days ago
JSON representation

Circuit Breaker implemented in Go

Lists

README

        

gobreaker
=========

[![GoDoc](https://godoc.org/github.com/sony/gobreaker?status.svg)](https://godoc.org/github.com/sony/gobreaker)

[gobreaker][repo-url] implements the [Circuit Breaker pattern](https://msdn.microsoft.com/en-us/library/dn589784.aspx) in Go.

Installation
------------

```
go get github.com/sony/gobreaker/v2
```

Usage
-----

The struct `CircuitBreaker` is a state machine to prevent sending requests that are likely to fail.
The function `NewCircuitBreaker` creates a new `CircuitBreaker`.
The type parameter `T` specifies the return type of requests.

```go
func NewCircuitBreaker[T any](st Settings) *CircuitBreaker[T]
```

You can configure `CircuitBreaker` by the struct `Settings`:

```go
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)
IsSuccessful func(err error) bool
}
```

- `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, `CircuitBreaker` allows only 1 request.

- `Interval` is the cyclic period of the closed state
for `CircuitBreaker` to clear the internal `Counts`, described later in this section.
If `Interval` is 0, `CircuitBreaker` doesn't clear the internal `Counts` during the closed state.

- `Timeout` is the period of the open state,
after which the state of `CircuitBreaker` becomes half-open.
If `Timeout` is 0, the timeout value of `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, `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 `CircuitBreaker` changes.

- `IsSuccessful` is called with the error returned from a request.
If `IsSuccessful` returns true, the error is counted as a success.
Otherwise the error is counted as a failure.
If `IsSuccessful` is nil, default `IsSuccessful` is used, which returns false for all non-nil errors.

The struct `Counts` holds the numbers of requests and their successes/failures:

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

`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.

`CircuitBreaker` can wrap any function to send a request:

```go
func (cb *CircuitBreaker[T]) Execute(req func() (T, error)) (T, error)
```

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

Example
-------

```go
var cb *gobreaker.CircuitBreaker[[]byte]

func Get(url string) ([]byte, error) {
body, err := cb.Execute(func() ([]byte, error) {
resp, err := http.Get(url)
if err != nil {
return nil, err
}

defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
return nil, err
}

return body, nil
})
if err != nil {
return nil, err
}

return body, nil
}
```

See [example](https://github.com/sony/gobreaker/blob/master/v2/example) for details.

License
-------

The MIT License (MIT)

See [LICENSE](https://github.com/sony/gobreaker/blob/master/LICENSE) for details.

[repo-url]: https://github.com/sony/gobreaker