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Merge pull request BBVA#82 from aalda/new_client
New advanced client
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,120 @@ | ||
| /* | ||
| Copyright 2018 Banco Bilbao Vizcaya Argentaria, S.A. | ||
| 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. | ||
| */ | ||
|
|
||
| package client | ||
|
|
||
| import ( | ||
| "math" | ||
| "math/rand" | ||
| "sync" | ||
| "time" | ||
| ) | ||
|
|
||
| // BackoffF specifies the signature of a function that returns the | ||
| // time to wait before the next call to a resource. To stop retrying | ||
| // return false in the 2nd return value. | ||
| type BackoffF func(attempt int) (time.Duration, bool) | ||
|
|
||
| // Backoff allows callers to implement their own Backoff strategy. | ||
| type Backoff interface { | ||
| // Next implements a BackoffF. | ||
| Next(attempt int) (time.Duration, bool) | ||
| } | ||
|
|
||
| // StopBackoff is a fixed backoff policy that always returns false for | ||
| // Next(), meaning that the operation should never be retried. | ||
| type StopBackoff struct{} | ||
|
|
||
| // NewStopBackoff returns a new StopBackoff. | ||
| func NewStopBackoff() *StopBackoff { | ||
| return &StopBackoff{} | ||
| } | ||
|
|
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| // Next implements BackoffF for StopBackoff. | ||
| func (b StopBackoff) Next(attempt int) (time.Duration, bool) { | ||
| return 0, false | ||
| } | ||
|
|
||
| // ConstantBackoff is a backoff policy that always returns the same delay. | ||
| type ConstantBackoff struct { | ||
| interval time.Duration | ||
| } | ||
|
|
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| // NewConstantBackoff returns a new ConstantBackoff. | ||
| func NewConstantBackoff(interval time.Duration) *ConstantBackoff { | ||
| return &ConstantBackoff{interval: interval} | ||
| } | ||
|
|
||
| // Next implements BackoffF for ConstantBackoff. | ||
| func (b *ConstantBackoff) Next(attempt int) (time.Duration, bool) { | ||
| return b.interval, true | ||
| } | ||
|
|
||
| // SimpleBackoff takes a list of fixed values for backoff intervals. | ||
| // Each call to Next returns the next value from that fixed list. | ||
| // After each value is returned, subsequent calls to Next will only return | ||
| // the last element. | ||
| type SimpleBackoff struct { | ||
| sync.Mutex | ||
| ticks []int | ||
| } | ||
|
|
||
| // NewSimpleBackoff creates a SimpleBackoff algorithm with the specified | ||
| // list of fixed intervals in milliseconds. | ||
| func NewSimpleBackoff(ticks ...int) *SimpleBackoff { | ||
| return &SimpleBackoff{ticks: ticks} | ||
| } | ||
|
|
||
| // Next implements BackoffF for SimpleBackoff. | ||
| func (b *SimpleBackoff) Next(attempt int) (time.Duration, bool) { | ||
| b.Lock() | ||
| defer b.Unlock() | ||
| if attempt >= len(b.ticks) { | ||
| return 0, false | ||
| } | ||
| ms := b.ticks[attempt] | ||
| return time.Duration(ms) * time.Millisecond, true | ||
| } | ||
|
|
||
| // ExponentialBackoff implements the simple exponential backoff described by | ||
| // Douglas Thain at http://dthain.blogspot.de/2009/02/exponential-backoff-in-distributed.html. | ||
| type ExponentialBackoff struct { | ||
| t float64 // initial timeout (in msec) | ||
| f float64 // exponential factor (e.g. 2) | ||
| m float64 // maximum timeout (in msec) | ||
| } | ||
|
|
||
| // NewExponentialBackoff returns a ExponentialBackoff backoff policy. | ||
| // Use initialTimeout to set the first/minimal interval | ||
| // and maxTimeout to set the maximum wait interval. | ||
| func NewExponentialBackoff(initialTimeout, maxTimeout time.Duration) *ExponentialBackoff { | ||
| return &ExponentialBackoff{ | ||
| t: float64(int64(initialTimeout / time.Millisecond)), | ||
| f: 2.0, | ||
| m: float64(int64(maxTimeout / time.Millisecond)), | ||
| } | ||
| } | ||
|
|
||
| // Next implements BackoffF for ExponentialBackoff. | ||
| func (b *ExponentialBackoff) Next(attempt int) (time.Duration, bool) { | ||
| r := 1.0 + rand.Float64() // random number in [1..2] | ||
| m := math.Min(r*b.t*math.Pow(b.f, float64(attempt)), b.m) | ||
| if m >= b.m { | ||
| return 0, false | ||
| } | ||
| d := time.Duration(int64(m)) * time.Millisecond | ||
| return d, true | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,112 @@ | ||
| /* | ||
| Copyright 2018 Banco Bilbao Vizcaya Argentaria, S.A. | ||
| 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. | ||
| */ | ||
|
|
||
| package client | ||
|
|
||
| import ( | ||
| "math/rand" | ||
| "testing" | ||
| "time" | ||
|
|
||
| "github.com/stretchr/testify/require" | ||
| ) | ||
|
|
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| func TestStopBackoff(t *testing.T) { | ||
| b := NewStopBackoff() | ||
| _, ok := b.Next(0) | ||
| require.False(t, ok) | ||
| } | ||
|
|
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| func TestConstantBackoff(t *testing.T) { | ||
| b := NewConstantBackoff(time.Second) | ||
| d, ok := b.Next(0) | ||
| require.True(t, ok) | ||
| require.Equal(t, time.Second, d) | ||
| } | ||
|
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| func TestSimpleBackoff(t *testing.T) { | ||
|
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| testCases := []struct { | ||
| Duration time.Duration | ||
| Continue bool | ||
| }{ | ||
| { | ||
| Duration: 1 * time.Millisecond, | ||
| Continue: true, | ||
| }, | ||
| { | ||
| Duration: 2 * time.Millisecond, | ||
| Continue: true, | ||
| }, | ||
| { | ||
| Duration: 7 * time.Millisecond, | ||
| Continue: true, | ||
| }, | ||
| { | ||
| Duration: 0, | ||
| Continue: false, | ||
| }, | ||
| { | ||
| Duration: 0, | ||
| Continue: false, | ||
| }, | ||
| } | ||
|
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| b := NewSimpleBackoff(1, 2, 7) | ||
|
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| for i, c := range testCases { | ||
| d, ok := b.Next(i) | ||
| require.Equalf(t, c.Continue, ok, "The continue value should match for test case %d", i) | ||
| require.Equalf(t, c.Duration, d, "The duration value should match for test case %d", i) | ||
| } | ||
| } | ||
|
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| func TestExponentialBackoff(t *testing.T) { | ||
|
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| rand.Seed(time.Now().UnixNano()) | ||
|
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| min := time.Duration(8) * time.Millisecond | ||
| max := time.Duration(256) * time.Millisecond | ||
| b := NewExponentialBackoff(min, max) | ||
|
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| between := func(value time.Duration, a, b int) bool { | ||
| x := int(value / time.Millisecond) | ||
| return a <= x && x <= b | ||
| } | ||
|
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| d, ok := b.Next(0) | ||
| require.True(t, ok) | ||
| require.True(t, between(d, 8, 256)) | ||
|
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| d, ok = b.Next(1) | ||
| require.True(t, ok) | ||
| require.True(t, between(d, 8, 256)) | ||
|
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| d, ok = b.Next(3) | ||
| require.True(t, ok) | ||
| require.True(t, between(d, 8, 256)) | ||
|
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| d, ok = b.Next(4) | ||
| require.True(t, ok) | ||
| require.True(t, between(d, 8, 256)) | ||
|
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| _, ok = b.Next(5) | ||
| require.False(t, ok) | ||
|
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| _, ok = b.Next(6) | ||
| require.False(t, ok) | ||
|
|
||
| } |
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