README
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backoff
Calculate delays for retries, polling, and reconnect loops. This package does not wait, execute operations, or manage cancellation. Its Go version is specified in go.mod.
go get github.com/alextanhongpin/core/sync/backoff
import (
"time"
"github.com/alextanhongpin/core/sync/backoff"
)
policy := backoff.NewExponential(100*time.Millisecond, 2*time.Second)
delay := policy.At(1) // Full jitter: 0 <= delay < 200ms.
NewConstant(period)returns the same delay for every index; nonpositive periods return zero.NewLinear(period)returnsperiod * index, saturated at the maximum duration. Nonpositive periods or indices return zero.NewExponential(base, cap)returns full jitter in[0, min(base * 2^index, cap)), with overflow capped. Negative indices use zero; indices above 62 use 62. Nonpositive base or cap returns zero.
Indices are supplied by the caller. The retry package uses index 1 for its first retry, giving exponential backoff an initial upper bound of twice the base.
The strategies implement Backoff, which requires At(int) time.Duration. Exported fields support struct literals and adjustment before use. Zero-valued strategies return zero. Concurrent calls are safe when fields are not mutated concurrently. Exponential calls sample a new random delay each time.
Use a context-aware timer when waiting. The caller decides when to stop and whether an operation is safe to repeat. See the runnable example in backoff_test.go.
Documentation
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Overview ¶
Package backoff calculates delays; callers own waiting and cancellation.
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Backoff ¶
Backoff calculates a delay for an attempt index. Retry uses index 1 for its first retry.
type Constant ¶
Constant returns a fixed delay; nonpositive periods produce zero. Concurrent calls are safe provided exported fields are not mutated concurrently.
func NewConstant ¶
NewConstant constructs a Constant delay policy.
type Exponential ¶
Exponential returns full jitter below min(Base * 2^index, Cap). Negative indices use zero; indices above 62 use 62. Nonpositive Base or Cap produces zero. Concurrent calls are safe provided exported fields are not mutated concurrently.
func NewExponential ¶
func NewExponential(base, cap time.Duration) *Exponential
NewExponential constructs a Exponential delay policy.
type Linear ¶
Linear returns Period times the index, saturated at the maximum duration. Nonpositive periods or indices produce zero. Concurrent calls are safe provided exported fields are not mutated concurrently.
func (*Linear) At ¶
At calculates the delay without waiting.
Example ¶
package main
import (
"fmt"
"time"
"github.com/alextanhongpin/core/sync/backoff"
)
func main() {
policy := backoff.NewLinear(100 * time.Millisecond)
for index := 1; index <= 3; index++ {
fmt.Println(policy.At(index))
}
}
Output: 100ms 200ms 300ms
Source Files