vendor/go.etcd.io/etcd/clientv3/retry_interceptor.go - voltha-go - Gitiles

 // Copyright 2016 The etcd Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 // Based on github.com/grpc-ecosystem/go-grpc-middleware/retry, but modified to support the more
 // fine grained error checking required by write-at-most-once retry semantics of etcd.

 package clientv3

 import (
 	"context"
 	"io"
 	"sync"
 	"time"

 	"go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes"
 	"go.uber.org/zap"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
 )

 // unaryClientInterceptor 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).
 func (c *Client) unaryClientInterceptor(logger *zap.Logger, optFuncs ...retryOption) grpc.UnaryClientInterceptor {
 	intOpts := reuseOrNewWithCallOptions(defaultOptions, optFuncs)
 	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
 		grpcOpts, retryOpts := filterCallOptions(opts)
 		callOpts := reuseOrNewWithCallOptions(intOpts, retryOpts)
 		// short circuit for simplicity, and avoiding allocations.
 		if callOpts.max == 0 {
 			return invoker(ctx, method, req, reply, cc, grpcOpts...)
 		}
 		var lastErr error
 		for attempt := uint(0); attempt < callOpts.max; attempt++ {
 			if err := waitRetryBackoff(ctx, attempt, callOpts); err != nil {
 				return err
 			}
 			logger.Info(
 				"retrying of unary invoker",
 				zap.String("target", cc.Target()),
 				zap.Uint("attempt", attempt),
 			)
 			lastErr = invoker(ctx, method, req, reply, cc, grpcOpts...)
 			if lastErr == nil {
 				return nil
 			}
 			logger.Warn(
 				"retrying of unary invoker failed",
 				zap.String("target", cc.Target()),
 				zap.Uint("attempt", attempt),
 				zap.Error(lastErr),
 			)
 			if isContextError(lastErr) {
 				if ctx.Err() != nil {
 					// its the context deadline or cancellation.
 					return lastErr
 				}
 				// its the callCtx deadline or cancellation, in which case try again.
 				continue
 			}
 			if callOpts.retryAuth && rpctypes.Error(lastErr) == rpctypes.ErrInvalidAuthToken {
 				gterr := c.getToken(ctx)
 				if gterr != nil {
 					logger.Warn(
 						"retrying of unary invoker failed to fetch new auth token",
 						zap.String("target", cc.Target()),
 						zap.Error(gterr),
 					)
 					return lastErr // return the original error for simplicity
 				}
 				continue
 			}
 			if !isSafeRetry(c.lg, lastErr, callOpts) {
 				return lastErr
 			}
 		}
 		return lastErr
 	}
 }

 // streamClientInterceptor 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 (c *Client) streamClientInterceptor(logger *zap.Logger, optFuncs ...retryOption) grpc.StreamClientInterceptor {
 	intOpts := reuseOrNewWithCallOptions(defaultOptions, optFuncs)
 	return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
 		grpcOpts, retryOpts := filterCallOptions(opts)
 		callOpts := reuseOrNewWithCallOptions(intOpts, retryOpts)
 		// short circuit for simplicity, and avoiding allocations.
 		if callOpts.max == 0 {
 			return streamer(ctx, desc, cc, method, grpcOpts...)
 		}
 		if desc.ClientStreams {
 			return nil, grpc.Errorf(codes.Unimplemented, "clientv3/retry_interceptor: cannot retry on ClientStreams, set Disable()")
 		}
 		newStreamer, err := streamer(ctx, desc, cc, method, grpcOpts...)
 		logger.Info("retry stream intercept", zap.Error(err))
 		if err != nil {
 			// TODO(mwitkow): Maybe dial and transport errors should be retriable?
 			return nil, err
 		}
 		retryingStreamer := &serverStreamingRetryingStream{
 			client:       c,
 			ClientStream: newStreamer,
 			callOpts:     callOpts,
 			ctx:          ctx,
 			streamerCall: func(ctx context.Context) (grpc.ClientStream, error) {
 				return streamer(ctx, desc, cc, method, grpcOpts...)
 			},
 		}
 		return retryingStreamer, nil
 	}
 }

 // type serverStreamingRetryingStream is the implementation of grpc.ClientStream that acts as a
 // proxy to the underlying call. If any of the RecvMsg() calls fail, it will try to reestablish
 // a new ClientStream according to the retry policy.
 type serverStreamingRetryingStream struct {
 	grpc.ClientStream
 	client        *Client
 	bufferedSends []interface{} // single message that the client can sen
 	receivedGood  bool          // indicates whether any prior receives were successful
 	wasClosedSend bool          // indicates that CloseSend was closed
 	ctx           context.Context
 	callOpts      *options
 	streamerCall  func(ctx context.Context) (grpc.ClientStream, error)
 	mu            sync.RWMutex
 }

 func (s *serverStreamingRetryingStream) setStream(clientStream grpc.ClientStream) {
 	s.mu.Lock()
 	s.ClientStream = clientStream
 	s.mu.Unlock()
 }

 func (s *serverStreamingRetryingStream) getStream() grpc.ClientStream {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
 	return s.ClientStream
 }

 func (s *serverStreamingRetryingStream) SendMsg(m interface{}) error {
 	s.mu.Lock()
 	s.bufferedSends = append(s.bufferedSends, m)
 	s.mu.Unlock()
 	return s.getStream().SendMsg(m)
 }

 func (s *serverStreamingRetryingStream) CloseSend() error {
 	s.mu.Lock()
 	s.wasClosedSend = true
 	s.mu.Unlock()
 	return s.getStream().CloseSend()
 }

 func (s *serverStreamingRetryingStream) Header() (metadata.MD, error) {
 	return s.getStream().Header()
 }

 func (s *serverStreamingRetryingStream) Trailer() metadata.MD {
 	return s.getStream().Trailer()
 }

 func (s *serverStreamingRetryingStream) RecvMsg(m interface{}) error {
 	attemptRetry, lastErr := s.receiveMsgAndIndicateRetry(m)
 	if !attemptRetry {
 		return lastErr // success or hard failure
 	}
 	// We start off from attempt 1, because zeroth was already made on normal SendMsg().
 	for attempt := uint(1); attempt < s.callOpts.max; attempt++ {
 		if err := waitRetryBackoff(s.ctx, attempt, s.callOpts); err != nil {
 			return err
 		}
 		newStream, err := s.reestablishStreamAndResendBuffer(s.ctx)
 		if err != nil {
 			// TODO(mwitkow): Maybe dial and transport errors should be retriable?
 			return err
 		}
 		s.setStream(newStream)
 		attemptRetry, lastErr = s.receiveMsgAndIndicateRetry(m)
 		//fmt.Printf("Received message and indicate: %v  %v\n", attemptRetry, lastErr)
 		if !attemptRetry {
 			return lastErr
 		}
 	}
 	return lastErr
 }

 func (s *serverStreamingRetryingStream) receiveMsgAndIndicateRetry(m interface{}) (bool, error) {
 	s.mu.RLock()
 	wasGood := s.receivedGood
 	s.mu.RUnlock()
 	err := s.getStream().RecvMsg(m)
 	if err == nil || err == io.EOF {
 		s.mu.Lock()
 		s.receivedGood = true
 		s.mu.Unlock()
 		return false, err
 	} else if wasGood {
 		// previous RecvMsg in the stream succeeded, no retry logic should interfere
 		return false, err
 	}
 	if isContextError(err) {
 		if s.ctx.Err() != nil {
 			return false, err
 		}
 		// its the callCtx deadline or cancellation, in which case try again.
 		return true, err
 	}
 	if s.callOpts.retryAuth && rpctypes.Error(err) == rpctypes.ErrInvalidAuthToken {
 		gterr := s.client.getToken(s.ctx)
 		if gterr != nil {
 			s.client.lg.Info("retry failed to fetch new auth token", zap.Error(gterr))
 			return false, err // return the original error for simplicity
 		}
 		return true, err

 	}
 	return isSafeRetry(s.client.lg, err, s.callOpts), err
 }

 func (s *serverStreamingRetryingStream) reestablishStreamAndResendBuffer(callCtx context.Context) (grpc.ClientStream, error) {
 	s.mu.RLock()
 	bufferedSends := s.bufferedSends
 	s.mu.RUnlock()
 	newStream, err := s.streamerCall(callCtx)
 	if err != nil {
 		return nil, err
 	}
 	for _, msg := range bufferedSends {
 		if err := newStream.SendMsg(msg); err != nil {
 			return nil, err
 		}
 	}
 	if err := newStream.CloseSend(); err != nil {
 		return nil, err
 	}
 	return newStream, nil
 }

 func waitRetryBackoff(ctx context.Context, attempt uint, callOpts *options) error {
 	waitTime := time.Duration(0)
 	if attempt > 0 {
 		waitTime = callOpts.backoffFunc(attempt)
 	}
 	if waitTime > 0 {
 		timer := time.NewTimer(waitTime)
 		select {
 		case <-ctx.Done():
 			timer.Stop()
 			return contextErrToGrpcErr(ctx.Err())
 		case <-timer.C:
 		}
 	}
 	return nil
 }

 // isSafeRetry returns "true", if request is safe for retry with the given error.
 func isSafeRetry(lg *zap.Logger, err error, callOpts *options) bool {
 	if isContextError(err) {
 		return false
 	}
 	switch callOpts.retryPolicy {
 	case repeatable:
 		return isSafeRetryImmutableRPC(err)
 	case nonRepeatable:
 		return isSafeRetryMutableRPC(err)
 	default:
 		lg.Warn("unrecognized retry policy", zap.String("retryPolicy", callOpts.retryPolicy.String()))
 		return false
 	}
 }

 func isContextError(err error) bool {
 	return grpc.Code(err) == codes.DeadlineExceeded || grpc.Code(err) == codes.Canceled
 }

 func contextErrToGrpcErr(err error) error {
 	switch err {
 	case context.DeadlineExceeded:
 		return grpc.Errorf(codes.DeadlineExceeded, err.Error())
 	case context.Canceled:
 		return grpc.Errorf(codes.Canceled, err.Error())
 	default:
 		return grpc.Errorf(codes.Unknown, err.Error())
 	}
 }

 var (
 	defaultOptions = &options{
 		retryPolicy: nonRepeatable,
 		max:         0, // disable
 		backoffFunc: backoffLinearWithJitter(50*time.Millisecond /*jitter*/, 0.10),
 		retryAuth:   true,
 	}
 )

 // backoffFunc denotes a family of functions that control 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.
 type backoffFunc func(attempt uint) time.Duration

 // withRetryPolicy sets the retry policy of this call.
 func withRetryPolicy(rp retryPolicy) retryOption {
 	return retryOption{applyFunc: func(o *options) {
 		o.retryPolicy = rp
 	}}
 }

 // withAuthRetry sets enables authentication retries.
 func withAuthRetry(retryAuth bool) retryOption {
 	return retryOption{applyFunc: func(o *options) {
 		o.retryAuth = retryAuth
 	}}
 }

 // withMax sets the maximum number of retries on this call, or this interceptor.
 func withMax(maxRetries uint) retryOption {
 	return retryOption{applyFunc: func(o *options) {
 		o.max = maxRetries
 	}}
 }

 // WithBackoff sets the `BackoffFunc `used to control time between retries.
 func withBackoff(bf backoffFunc) retryOption {
 	return retryOption{applyFunc: func(o *options) {
 		o.backoffFunc = bf
 	}}
 }

 type options struct {
 	retryPolicy retryPolicy
 	max         uint
 	backoffFunc backoffFunc
 	retryAuth   bool
 }

 // retryOption is a grpc.CallOption that is local to clientv3's retry interceptor.
 type retryOption struct {
 	grpc.EmptyCallOption // make sure we implement private after() and before() fields so we don't panic.
 	applyFunc            func(opt *options)
 }

 func reuseOrNewWithCallOptions(opt *options, retryOptions []retryOption) *options {
 	if len(retryOptions) == 0 {
 		return opt
 	}
 	optCopy := &options{}
 	*optCopy = *opt
 	for _, f := range retryOptions {
 		f.applyFunc(optCopy)
 	}
 	return optCopy
 }

 func filterCallOptions(callOptions []grpc.CallOption) (grpcOptions []grpc.CallOption, retryOptions []retryOption) {
 	for _, opt := range callOptions {
 		if co, ok := opt.(retryOption); ok {
 			retryOptions = append(retryOptions, co)
 		} else {
 			grpcOptions = append(grpcOptions, opt)
 		}
 	}
 	return grpcOptions, retryOptions
 }

 // BackoffLinearWithJitter 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.
 func backoffLinearWithJitter(waitBetween time.Duration, jitterFraction float64) backoffFunc {
 	return func(attempt uint) time.Duration {
 		return jitterUp(waitBetween, jitterFraction)
 	}
 }
	// Copyright 2016 The etcd Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	// Based on github.com/grpc-ecosystem/go-grpc-middleware/retry, but modified to support the more
	// fine grained error checking required by write-at-most-once retry semantics of etcd.

	package clientv3

	import (
	"context"
	"io"
	"sync"
	"time"

	"go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes"
	"go.uber.org/zap"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
	)

	// unaryClientInterceptor 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).
	func (c Client) unaryClientInterceptor(logger zap.Logger, optFuncs ...retryOption) grpc.UnaryClientInterceptor {
	intOpts := reuseOrNewWithCallOptions(defaultOptions, optFuncs)
	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
	grpcOpts, retryOpts := filterCallOptions(opts)
	callOpts := reuseOrNewWithCallOptions(intOpts, retryOpts)
	// short circuit for simplicity, and avoiding allocations.
	if callOpts.max == 0 {
	return invoker(ctx, method, req, reply, cc, grpcOpts...)
	}
	var lastErr error
	for attempt := uint(0); attempt < callOpts.max; attempt++ {
	if err := waitRetryBackoff(ctx, attempt, callOpts); err != nil {
	return err
	}
	logger.Info(
	"retrying of unary invoker",
	zap.String("target", cc.Target()),
	zap.Uint("attempt", attempt),
	)
	lastErr = invoker(ctx, method, req, reply, cc, grpcOpts...)
	if lastErr == nil {
	return nil
	}
	logger.Warn(
	"retrying of unary invoker failed",
	zap.String("target", cc.Target()),
	zap.Uint("attempt", attempt),
	zap.Error(lastErr),
	)
	if isContextError(lastErr) {
	if ctx.Err() != nil {
	// its the context deadline or cancellation.
	return lastErr
	}
	// its the callCtx deadline or cancellation, in which case try again.
	continue
	}
	if callOpts.retryAuth && rpctypes.Error(lastErr) == rpctypes.ErrInvalidAuthToken {
	gterr := c.getToken(ctx)
	if gterr != nil {
	logger.Warn(
	"retrying of unary invoker failed to fetch new auth token",
	zap.String("target", cc.Target()),
	zap.Error(gterr),
	)
	return lastErr // return the original error for simplicity
	}
	continue
	}
	if !isSafeRetry(c.lg, lastErr, callOpts) {
	return lastErr
	}
	}
	return lastErr
	}
	}

	// streamClientInterceptor 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 (c Client) streamClientInterceptor(logger zap.Logger, optFuncs ...retryOption) grpc.StreamClientInterceptor {
	intOpts := reuseOrNewWithCallOptions(defaultOptions, optFuncs)
	return func(ctx context.Context, desc grpc.StreamDesc, cc grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
	grpcOpts, retryOpts := filterCallOptions(opts)
	callOpts := reuseOrNewWithCallOptions(intOpts, retryOpts)
	// short circuit for simplicity, and avoiding allocations.
	if callOpts.max == 0 {
	return streamer(ctx, desc, cc, method, grpcOpts...)
	}
	if desc.ClientStreams {
	return nil, grpc.Errorf(codes.Unimplemented, "clientv3/retry_interceptor: cannot retry on ClientStreams, set Disable()")
	}
	newStreamer, err := streamer(ctx, desc, cc, method, grpcOpts...)
	logger.Info("retry stream intercept", zap.Error(err))
	if err != nil {
	// TODO(mwitkow): Maybe dial and transport errors should be retriable?
	return nil, err
	}
	retryingStreamer := &serverStreamingRetryingStream{
	client: c,
	ClientStream: newStreamer,
	callOpts: callOpts,
	ctx: ctx,
	streamerCall: func(ctx context.Context) (grpc.ClientStream, error) {
	return streamer(ctx, desc, cc, method, grpcOpts...)
	},
	}
	return retryingStreamer, nil
	}
	}

	// type serverStreamingRetryingStream is the implementation of grpc.ClientStream that acts as a
	// proxy to the underlying call. If any of the RecvMsg() calls fail, it will try to reestablish
	// a new ClientStream according to the retry policy.
	type serverStreamingRetryingStream struct {
	grpc.ClientStream
	client *Client
	bufferedSends []interface{} // single message that the client can sen
	receivedGood bool // indicates whether any prior receives were successful
	wasClosedSend bool // indicates that CloseSend was closed
	ctx context.Context
	callOpts *options
	streamerCall func(ctx context.Context) (grpc.ClientStream, error)
	mu sync.RWMutex
	}

	func (s *serverStreamingRetryingStream) setStream(clientStream grpc.ClientStream) {
	s.mu.Lock()
	s.ClientStream = clientStream
	s.mu.Unlock()
	}

	func (s *serverStreamingRetryingStream) getStream() grpc.ClientStream {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.ClientStream
	}

	func (s *serverStreamingRetryingStream) SendMsg(m interface{}) error {
	s.mu.Lock()
	s.bufferedSends = append(s.bufferedSends, m)
	s.mu.Unlock()
	return s.getStream().SendMsg(m)
	}

	func (s *serverStreamingRetryingStream) CloseSend() error {
	s.mu.Lock()
	s.wasClosedSend = true
	s.mu.Unlock()
	return s.getStream().CloseSend()
	}

	func (s *serverStreamingRetryingStream) Header() (metadata.MD, error) {
	return s.getStream().Header()
	}

	func (s *serverStreamingRetryingStream) Trailer() metadata.MD {
	return s.getStream().Trailer()
	}

	func (s *serverStreamingRetryingStream) RecvMsg(m interface{}) error {
	attemptRetry, lastErr := s.receiveMsgAndIndicateRetry(m)
	if !attemptRetry {
	return lastErr // success or hard failure
	}
	// We start off from attempt 1, because zeroth was already made on normal SendMsg().
	for attempt := uint(1); attempt < s.callOpts.max; attempt++ {
	if err := waitRetryBackoff(s.ctx, attempt, s.callOpts); err != nil {
	return err
	}
	newStream, err := s.reestablishStreamAndResendBuffer(s.ctx)
	if err != nil {
	// TODO(mwitkow): Maybe dial and transport errors should be retriable?
	return err
	}
	s.setStream(newStream)
	attemptRetry, lastErr = s.receiveMsgAndIndicateRetry(m)
	//fmt.Printf("Received message and indicate: %v %v\n", attemptRetry, lastErr)
	if !attemptRetry {
	return lastErr
	}
	}
	return lastErr
	}

	func (s *serverStreamingRetryingStream) receiveMsgAndIndicateRetry(m interface{}) (bool, error) {
	s.mu.RLock()
	wasGood := s.receivedGood
	s.mu.RUnlock()
	err := s.getStream().RecvMsg(m)
	if err == nil \|\| err == io.EOF {
	s.mu.Lock()
	s.receivedGood = true
	s.mu.Unlock()
	return false, err
	} else if wasGood {
	// previous RecvMsg in the stream succeeded, no retry logic should interfere
	return false, err
	}
	if isContextError(err) {
	if s.ctx.Err() != nil {
	return false, err
	}
	// its the callCtx deadline or cancellation, in which case try again.
	return true, err
	}
	if s.callOpts.retryAuth && rpctypes.Error(err) == rpctypes.ErrInvalidAuthToken {
	gterr := s.client.getToken(s.ctx)
	if gterr != nil {
	s.client.lg.Info("retry failed to fetch new auth token", zap.Error(gterr))
	return false, err // return the original error for simplicity
	}
	return true, err

	}
	return isSafeRetry(s.client.lg, err, s.callOpts), err
	}

	func (s *serverStreamingRetryingStream) reestablishStreamAndResendBuffer(callCtx context.Context) (grpc.ClientStream, error) {
	s.mu.RLock()
	bufferedSends := s.bufferedSends
	s.mu.RUnlock()
	newStream, err := s.streamerCall(callCtx)
	if err != nil {
	return nil, err
	}
	for _, msg := range bufferedSends {
	if err := newStream.SendMsg(msg); err != nil {
	return nil, err
	}
	}
	if err := newStream.CloseSend(); err != nil {
	return nil, err
	}
	return newStream, nil
	}

	func waitRetryBackoff(ctx context.Context, attempt uint, callOpts *options) error {
	waitTime := time.Duration(0)
	if attempt > 0 {
	waitTime = callOpts.backoffFunc(attempt)
	}
	if waitTime > 0 {
	timer := time.NewTimer(waitTime)
	select {
	case <-ctx.Done():
	timer.Stop()
	return contextErrToGrpcErr(ctx.Err())
	case <-timer.C:
	}
	}
	return nil
	}

	// isSafeRetry returns "true", if request is safe for retry with the given error.
	func isSafeRetry(lg zap.Logger, err error, callOpts options) bool {
	if isContextError(err) {
	return false
	}
	switch callOpts.retryPolicy {
	case repeatable:
	return isSafeRetryImmutableRPC(err)
	case nonRepeatable:
	return isSafeRetryMutableRPC(err)
	default:
	lg.Warn("unrecognized retry policy", zap.String("retryPolicy", callOpts.retryPolicy.String()))
	return false
	}
	}

	func isContextError(err error) bool {
	return grpc.Code(err) == codes.DeadlineExceeded \|\| grpc.Code(err) == codes.Canceled
	}

	func contextErrToGrpcErr(err error) error {
	switch err {
	case context.DeadlineExceeded:
	return grpc.Errorf(codes.DeadlineExceeded, err.Error())
	case context.Canceled:
	return grpc.Errorf(codes.Canceled, err.Error())
	default:
	return grpc.Errorf(codes.Unknown, err.Error())
	}
	}

	var (
	defaultOptions = &options{
	retryPolicy: nonRepeatable,
	max: 0, // disable
	backoffFunc: backoffLinearWithJitter(50time.Millisecond /jitter*/, 0.10),
	retryAuth: true,
	}
	)

	// backoffFunc denotes a family of functions that control 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.
	type backoffFunc func(attempt uint) time.Duration

	// withRetryPolicy sets the retry policy of this call.
	func withRetryPolicy(rp retryPolicy) retryOption {
	return retryOption{applyFunc: func(o *options) {
	o.retryPolicy = rp
	}}
	}

	// withAuthRetry sets enables authentication retries.
	func withAuthRetry(retryAuth bool) retryOption {
	return retryOption{applyFunc: func(o *options) {
	o.retryAuth = retryAuth
	}}
	}

	// withMax sets the maximum number of retries on this call, or this interceptor.
	func withMax(maxRetries uint) retryOption {
	return retryOption{applyFunc: func(o *options) {
	o.max = maxRetries
	}}
	}

	// WithBackoff sets the `BackoffFunc `used to control time between retries.
	func withBackoff(bf backoffFunc) retryOption {
	return retryOption{applyFunc: func(o *options) {
	o.backoffFunc = bf
	}}
	}

	type options struct {
	retryPolicy retryPolicy
	max uint
	backoffFunc backoffFunc
	retryAuth bool
	}

	// retryOption is a grpc.CallOption that is local to clientv3's retry interceptor.
	type retryOption struct {
	grpc.EmptyCallOption // make sure we implement private after() and before() fields so we don't panic.
	applyFunc func(opt *options)
	}

	func reuseOrNewWithCallOptions(opt options, retryOptions []retryOption) options {
	if len(retryOptions) == 0 {
	return opt
	}
	optCopy := &options{}
	optCopy = opt
	for _, f := range retryOptions {
	f.applyFunc(optCopy)
	}
	return optCopy
	}

	func filterCallOptions(callOptions []grpc.CallOption) (grpcOptions []grpc.CallOption, retryOptions []retryOption) {
	for _, opt := range callOptions {
	if co, ok := opt.(retryOption); ok {
	retryOptions = append(retryOptions, co)
	} else {
	grpcOptions = append(grpcOptions, opt)
	}
	}
	return grpcOptions, retryOptions
	}

	// BackoffLinearWithJitter 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.
	func backoffLinearWithJitter(waitBetween time.Duration, jitterFraction float64) backoffFunc {
	return func(attempt uint) time.Duration {
	return jitterUp(waitBetween, jitterFraction)
	}
	}