-- import "github.com/mwitkow/go-grpc-middleware/retry"
grpc_retry provides client-side request retry logic for gRPC.
It allows for automatic retry, inside the generated gRPC code of requests based on the gRPC status of the reply. It supports unary (1:1), and server stream (1:n) requests.
By default the interceptors are disabled, preventing accidental use of
retries. You can easily override the number of retries (setting them to more
than 0) with a grpc.ClientOption, e.g.:
myclient.Ping(ctx, goodPing, grpc_retry.WithMax(5))
Other default options are: retry on ResourceExhausted and Unavailable gRPC
codes, use a 50ms linear backoff with 10% jitter.
Please see examples for more advanced use.
const (
AttemptMetadataKey = "x-retry-attempty"
)var (
// DefaultRetriableCodes is a set of well known types gRPC codes that should be retri-able.
//
// `ResourceExhausted` means that the user quota, e.g. per-RPC limits, have been reached.
// `Unavailable` means that system is currently unavailable and the client should retry again.
DefaultRetriableCodes = []codes.Code{codes.ResourceExhausted, codes.Unavailable}
)func StreamClientInterceptor(optFuncs ...CallOption) grpc.StreamClientInterceptorStreamClientInterceptor returns a new retrying stream client interceptor for server side streaming calls.
The default configuration of the interceptor is to not retry at all. This behaviour can be changed through options (e.g. WithMax) on creation of the interceptor or on call (through grpc.CallOptions).
Retry logic is available only for ServerStreams, i.e. 1:n streams, as the internal logic needs to buffer the messages sent by the client. If retry is enabled on any other streams (ClientStreams, BidiStreams), the retry interceptor will fail the call.
func UnaryClientInterceptor(optFuncs ...CallOption) grpc.UnaryClientInterceptorUnaryClientInterceptor returns a new retrying unary client interceptor.
The default configuration of the interceptor is to not retry at all. This behaviour can be changed through options (e.g. WithMax) on creation of the interceptor or on call (through grpc.CallOptions).
type BackoffFunc func(attempt uint) time.DurationBackoffFunc denotes a family of functions that controll the backoff duration between call retries.
They are called with an identifier of the attempt, and should return a time the
system client should hold off for. If the time returned is longer than the
context.Context.Deadline of the request the deadline of the request takes
precedence and the wait will be interrupted before proceeding with the next
iteration.
func BackoffLinear(waitBetween time.Duration) BackoffFuncBackoffLinear is very simple: it waits for a fixed period of time between calls.
func BackoffLinearWithJitter(waitBetween time.Duration, jitterFraction float64) BackoffFuncBackoffLinearWithJitter waits a set period of time, allowing for jitter (fractional adjustment).
For example waitBetween=1s and jitter=0.10 can generate waits between 900ms and 1100ms.
type CallOption struct {
grpc.CallOption // anonymously implement it, without knowing the private fields.
}callOption is a grpc.CallOption that is local to grpc_retry.
func Disable() CallOptionDisable disables the retry behaviour on this call, or this interceptor.
Its semantically the same to WithMax
func WithBackoff(bf BackoffFunc) CallOptionWithBackoff sets the BackoffFunc used to control time between retries.
func WithCodes(retryCodes ...codes.Code) CallOptionWithCodes sets which codes should be retried.
Please use with care, as you may be retrying non-idempotend calls.
You cannot automatically retry on Cancelled and Deadline, please use
WithPerRetryTimeout for these.
func WithMax(maxRetries uint) CallOptionWithMax sets the maximum number of retries on this call, or this interceptor.
func WithPerRetryTimeout(timeout time.Duration) CallOptionWithPerRetryTimeout sets the RPC timeout per call (including initial call) on this call, or this interceptor.
The context.Deadline of the call takes precedence and sets the maximum time the whole invocation will take, but WithPerCallTimeout can be used to limit the RPC time per each call.
For example, with context.Deadline = now + 10s, and WithPerCallTimeout(3 * time.Seconds), each of the retry calls (including the initial one) will have a deadline of now + 3s.
A value of 0 disables the timeout overrides completely and returns to each retry
call using the parent context.Deadline.