gitee.com/ks-custle/core-gm@v0.0.0-20230922171213-b83bdd97b62c/grpc/internal/backoff/backoff.go (about)

     1  /*
     2   *
     3   * Copyright 2017 gRPC authors.
     4   *
     5   * Licensed under the Apache License, Version 2.0 (the "License");
     6   * you may not use this file except in compliance with the License.
     7   * You may obtain a copy of the License at
     8   *
     9   *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   */
    18  
    19  // Package backoff implement the backoff strategy for gRPC.
    20  //
    21  // This is kept in internal until the gRPC project decides whether or not to
    22  // allow alternative backoff strategies.
    23  package backoff
    24  
    25  import (
    26  	"time"
    27  
    28  	grpcbackoff "gitee.com/ks-custle/core-gm/grpc/backoff"
    29  	"gitee.com/ks-custle/core-gm/grpc/internal/grpcrand"
    30  )
    31  
    32  // Strategy defines the methodology for backing off after a grpc connection
    33  // failure.
    34  type Strategy interface {
    35  	// Backoff returns the amount of time to wait before the next retry given
    36  	// the number of consecutive failures.
    37  	Backoff(retries int) time.Duration
    38  }
    39  
    40  // DefaultExponential is an exponential backoff implementation using the
    41  // default values for all the configurable knobs defined in
    42  // https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.
    43  var DefaultExponential = Exponential{Config: grpcbackoff.DefaultConfig}
    44  
    45  // Exponential implements exponential backoff algorithm as defined in
    46  // https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.
    47  type Exponential struct {
    48  	// Config contains all options to configure the backoff algorithm.
    49  	Config grpcbackoff.Config
    50  }
    51  
    52  // Backoff returns the amount of time to wait before the next retry given the
    53  // number of retries.
    54  func (bc Exponential) Backoff(retries int) time.Duration {
    55  	if retries == 0 {
    56  		return bc.Config.BaseDelay
    57  	}
    58  	backoff, max := float64(bc.Config.BaseDelay), float64(bc.Config.MaxDelay)
    59  	for backoff < max && retries > 0 {
    60  		backoff *= bc.Config.Multiplier
    61  		retries--
    62  	}
    63  	if backoff > max {
    64  		backoff = max
    65  	}
    66  	// Randomize backoff delays so that if a cluster of requests start at
    67  	// the same time, they won't operate in lockstep.
    68  	backoff *= 1 + bc.Config.Jitter*(grpcrand.Float64()*2-1)
    69  	if backoff < 0 {
    70  		return 0
    71  	}
    72  	return time.Duration(backoff)
    73  }