/
ratelimiter.go
139 lines (122 loc) · 3.61 KB
/
ratelimiter.go
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package core
import (
"context"
"encoding/json"
"errors"
"io"
"sync"
"github.com/go-redis/redis_rate/v10"
"github.com/redis/go-redis/v9"
"github.com/wundergraph/graphql-go-tools/v2/pkg/engine/resolve"
)
var (
ErrRateLimitExceeded = errors.New("rate limit exceeded")
)
type CosmoRateLimiterOptions struct {
RedisClient *redis.Client
Debug bool
}
func NewCosmoRateLimiter(opts *CosmoRateLimiterOptions) *CosmoRateLimiter {
limiter := redis_rate.NewLimiter(opts.RedisClient)
return &CosmoRateLimiter{
client: opts.RedisClient,
limiter: limiter,
debug: opts.Debug,
}
}
type CosmoRateLimiter struct {
client *redis.Client
limiter *redis_rate.Limiter
debug bool
}
func (c *CosmoRateLimiter) RateLimitPreFetch(ctx *resolve.Context, info *resolve.FetchInfo, input json.RawMessage) (result *resolve.RateLimitDeny, err error) {
if c.isIntrospectionQuery(info.RootFields) {
return nil, nil
}
requestRate := c.calculateRate()
limit := redis_rate.Limit{
Rate: ctx.RateLimitOptions.Rate,
Burst: ctx.RateLimitOptions.Burst,
Period: ctx.RateLimitOptions.Period,
}
allow, err := c.limiter.AllowN(ctx.Context(), ctx.RateLimitOptions.RateLimitKey, limit, requestRate)
if err != nil {
return nil, err
}
c.setRateLimitStats(ctx, requestRate, allow.Remaining, allow.RetryAfter.Milliseconds(), allow.ResetAfter.Milliseconds())
if allow.Allowed >= requestRate {
return nil, nil
}
if ctx.RateLimitOptions.RejectExceedingRequests {
return nil, ErrRateLimitExceeded
}
return &resolve.RateLimitDeny{}, nil
}
type RateLimitStats struct {
RequestRate int `json:"requestRate"`
Remaining int `json:"remaining"`
RetryAfterMilliseconds int64 `json:"retryAfterMs"`
ResetAfterMilliseconds int64 `json:"resetAfterMs"`
}
func (c *CosmoRateLimiter) RenderResponseExtension(ctx *resolve.Context, out io.Writer) error {
data, err := c.statsJSON(ctx)
if err != nil {
return err
}
_, err = out.Write(data)
return err
}
func (c *CosmoRateLimiter) isIntrospectionQuery(rootFields []resolve.GraphCoordinate) bool {
if len(rootFields) != 1 {
return false
}
if rootFields[0].TypeName == "Query" {
return rootFields[0].FieldName == "__schema" || rootFields[0].FieldName == "__type"
}
if rootFields[0].TypeName == "__Type" {
return true
}
return false
}
func (c *CosmoRateLimiter) calculateRate() int {
return 1
}
func (c *CosmoRateLimiter) statsJSON(ctx *resolve.Context) ([]byte, error) {
stats := c.getRateLimitStats(ctx)
if c.debug {
stats.ResetAfterMilliseconds = 1234
stats.RetryAfterMilliseconds = 1234
}
return json.Marshal(stats)
}
func (c *CosmoRateLimiter) setRateLimitStats(ctx *resolve.Context, requestRate, remaining int, retryAfter, resetAfter int64) {
v := ctx.Context().Value(rateLimitStatsCtxKey{})
if v == nil {
return
}
statsCtx := v.(*rateLimitStatsCtx)
statsCtx.mux.Lock()
statsCtx.stats.RequestRate = statsCtx.stats.RequestRate + requestRate
statsCtx.stats.Remaining = remaining
statsCtx.stats.RetryAfterMilliseconds = retryAfter
statsCtx.stats.ResetAfterMilliseconds = resetAfter
statsCtx.mux.Unlock()
}
func (c *CosmoRateLimiter) getRateLimitStats(ctx *resolve.Context) RateLimitStats {
v := ctx.Context().Value(rateLimitStatsCtxKey{})
if v == nil {
return RateLimitStats{}
}
statsCtx := v.(*rateLimitStatsCtx)
return statsCtx.stats
}
type rateLimitStatsCtx struct {
stats RateLimitStats
mux sync.Mutex
}
type rateLimitStatsCtxKey struct{}
func WithRateLimiterStats(ctx *resolve.Context) *resolve.Context {
stats := &rateLimitStatsCtx{}
withStats := context.WithValue(ctx.Context(), rateLimitStatsCtxKey{}, stats)
return ctx.WithContext(withStats)
}