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Diffstat (limited to 'vendor/google.golang.org/grpc/internal/backoff/backoff.go')
-rw-r--r-- | vendor/google.golang.org/grpc/internal/backoff/backoff.go | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/internal/backoff/backoff.go b/vendor/google.golang.org/grpc/internal/backoff/backoff.go new file mode 100644 index 0000000..1bd0cce --- /dev/null +++ b/vendor/google.golang.org/grpc/internal/backoff/backoff.go | |||
@@ -0,0 +1,78 @@ | |||
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 | "google.golang.org/grpc/internal/grpcrand" | ||
29 | ) | ||
30 | |||
31 | // Strategy defines the methodology for backing off after a grpc connection | ||
32 | // failure. | ||
33 | // | ||
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 | const ( | ||
41 | // baseDelay is the amount of time to wait before retrying after the first | ||
42 | // failure. | ||
43 | baseDelay = 1.0 * time.Second | ||
44 | // factor is applied to the backoff after each retry. | ||
45 | factor = 1.6 | ||
46 | // jitter provides a range to randomize backoff delays. | ||
47 | jitter = 0.2 | ||
48 | ) | ||
49 | |||
50 | // Exponential implements exponential backoff algorithm as defined in | ||
51 | // https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md. | ||
52 | type Exponential struct { | ||
53 | // MaxDelay is the upper bound of backoff delay. | ||
54 | MaxDelay time.Duration | ||
55 | } | ||
56 | |||
57 | // Backoff returns the amount of time to wait before the next retry given the | ||
58 | // number of retries. | ||
59 | func (bc Exponential) Backoff(retries int) time.Duration { | ||
60 | if retries == 0 { | ||
61 | return baseDelay | ||
62 | } | ||
63 | backoff, max := float64(baseDelay), float64(bc.MaxDelay) | ||
64 | for backoff < max && retries > 0 { | ||
65 | backoff *= factor | ||
66 | retries-- | ||
67 | } | ||
68 | if backoff > max { | ||
69 | backoff = max | ||
70 | } | ||
71 | // Randomize backoff delays so that if a cluster of requests start at | ||
72 | // the same time, they won't operate in lockstep. | ||
73 | backoff *= 1 + jitter*(grpcrand.Float64()*2-1) | ||
74 | if backoff < 0 { | ||
75 | return 0 | ||
76 | } | ||
77 | return time.Duration(backoff) | ||
78 | } | ||