README
¶
requestdedup
Request deduplication middleware for fh. Prevents duplicate processing of identical requests within a configurable time window.
Why
In distributed systems, clients may accidentally or maliciously send the same request multiple times due to retries, network duplicates, or UI double-clicks. Without deduplication, this causes duplicate charges, duplicate orders, duplicate email sends, and other side effects.
Features
- SHA-256 based dedup keys (method + URL + body)
- Configurable time window and max key count
- Automatic LRU eviction when capacity is reached
- Custom key function support
- Returns 409 Conflict with original request metadata on duplicates
Usage
import "github.com/oarkflow/fh/mw/requestdedup"
app := fh.New()
dedup := requestdedup.New(requestdedup.Config{
Window: 10 * time.Second,
MaxKeys: 5000,
})
app.Post("/payments", dedup.Handler(), func(c fh.Ctx) error {
// Only processes once per dedup window
return c.JSON(fh.Map{"status": "success"})
})
Config
| Field | Type | Default | Description |
|---|---|---|---|
| Window | time.Duration |
5s | Time window for dedup detection |
| MaxKeys | int |
10000 | Max tracked keys before LRU eviction |
| KeyFunc | func(Ctx) string |
SHA-256(method+URL+body) | Custom key extraction |
| OnDuplicate | func(Ctx, *Entry) error |
409 Conflict JSON | Custom duplicate handler |
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func NewMiddleware ¶
func NewMiddleware(cfg ...Config) fh.HandlerFunc
New is a convenience function that creates and returns middleware.
Types ¶
type Config ¶
type Config struct {
// Window is the time window during which duplicate requests are detected.
// Default: 5 seconds.
Window time.Duration
// MaxKeys is the maximum number of dedup keys stored before eviction.
// Default: 10000.
MaxKeys int
// KeyFunc extracts the dedup key from the request. The default computes
// SHA-256(method + path + body).
KeyFunc func(fh.Ctx) string
// OnDuplicate is called when a duplicate request is detected. The default
// returns 409 Conflict with the original request's response.
OnDuplicate func(fh.Ctx, *Entry) error
}
Config controls deduplication behavior.
type Deduplicator ¶
type Deduplicator struct {
// contains filtered or unexported fields
}
Deduplicator tracks in-flight requests and deduplicates within a window.
func New ¶
func New(cfg ...Config) *Deduplicator
New creates a deduplicator. If cfg is zero, defaults are applied.
func (*Deduplicator) Handler ¶
func (d *Deduplicator) Handler() fh.HandlerFunc
Handler returns middleware that deduplicates requests within the configured window.
func (*Deduplicator) Stats ¶
func (d *Deduplicator) Stats() (active int, evictions int)
Stats returns current deduplication statistics.
Source Files