重试

可配置重试策略，支持固定/指数/线性退避与 jitter。

go get github.com/LingByte/ling-base/common/retry

以下为 common/retry 包 README 全文。

A flexible retry framework with configurable backoff strategies, max attempts, timeouts, and retryable-error filtering.

Features

Backoff strategies: exponential backoff (with jitter), fixed interval, no delay
Custom backoff: implement the Backoff interface for custom strategies
Max attempts: fixed count or unlimited (bounded by context/timeout)
Overall timeout: deadline across all attempts combined
Retryable errors: filter which errors should be retried via WithRetryIf
Callbacks: OnRetry, OnSuccess, OnError hooks for observability
Decorator pattern: wrap any function to produce a retried version
Context-aware: respects context cancellation and deadlines
Zero dependencies: only uses the standard library

Quick start

import "github.com/LingByte/ling-base/common/retry"

// Basic retry with exponential backoff
err := retry.Do(ctx, func(ctx context.Context) error {
    return callRemoteAPI(ctx)
},
    retry.WithMaxAttempts(5),
    retry.WithExponentialBackoff(100*time.Millisecond, 10*time.Second, 2.0, true),
)

// Only retry on transient errors
err := retry.Do(ctx, op,
    retry.WithMaxAttempts(3),
    retry.WithFixedInterval(500*time.Millisecond),
    retry.WithRetryIf(func(err error) bool {
        var netErr net.Error
        return errors.As(err, &netErr) && netErr.Timeout()
    }),
)

Backoff strategies

Exponential backoff

retry.WithExponentialBackoff(
    base:     100*time.Millisecond,  // initial delay
    maxDelay: 10*time.Second,        // upper bound (0 = no cap)
    factor:   2.0,                   // growth multiplier
    jitter:   true,                  // ±25% random jitter
)

Delay = base * factor^attempt, capped at maxDelay. With jitter enabled, a random ±25% offset is added to avoid thundering-herd.

Fixed interval

retry.WithFixedInterval(500 * time.Millisecond)

Constant delay between every attempt.

No backoff

retry.WithNoBackoff()

Retry immediately with zero delay.

Custom backoff

type LinearBackoff struct{ Step time.Duration }
func (l LinearBackoff) NextDelay(attempt int) time.Duration {
    return l.Step * time.Duration(attempt+1)
}

retry.WithBackoff(LinearBackoff{Step: 100 * time.Millisecond})

Decorator pattern

Wrap any function to produce a retried version:

retriedGet := retry.Decorate(
    func(ctx context.Context, url string) (*http.Response, error) {
        return http.Get(url)
    },
    retry.WithMaxAttempts(3),
    retry.WithFixedInterval(500*time.Millisecond),
)
resp, err := retriedGet(ctx, "https://example.com")

For functions with no arguments:

retriedFn := retry.Decorate0(
    func(ctx context.Context) error { return doWork(ctx) },
    retry.WithMaxAttempts(5),
)
err := retriedFn(ctx)

Options

Option	Description
`WithMaxAttempts(n)`	Total attempts including first (default: 3, `<0` = unlimited)
`WithTimeout(d)`	Overall deadline for all attempts (0 = no timeout)
`WithBackoff(b)`	Custom backoff strategy
`WithExponentialBackoff(...)`	Convenience: exponential backoff
`WithFixedInterval(d)`	Convenience: fixed interval
`WithNoBackoff()`	Convenience: retry immediately
`WithRetryIf(fn)`	Predicate to filter retryable errors
`WithOnRetry(fn)`	Callback before each retry
`WithOnSuccess(fn)`	Callback after success
`WithOnError(fn)`	Callback when all attempts exhausted

License

MIT

重试

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