145 lines
3.5 KiB
Go
145 lines
3.5 KiB
Go
package discordgo
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import (
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"net/http"
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"strconv"
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"sync"
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"sync/atomic"
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"time"
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)
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// RateLimiter holds all ratelimit buckets
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type RateLimiter struct {
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sync.Mutex
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global *int64
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buckets map[string]*Bucket
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globalRateLimit time.Duration
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}
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// NewRatelimiter returns a new RateLimiter
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func NewRatelimiter() *RateLimiter {
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return &RateLimiter{
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buckets: make(map[string]*Bucket),
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global: new(int64),
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}
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}
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// getBucket retrieves or creates a bucket
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func (r *RateLimiter) getBucket(key string) *Bucket {
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r.Lock()
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defer r.Unlock()
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if bucket, ok := r.buckets[key]; ok {
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return bucket
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}
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b := &Bucket{
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remaining: 1,
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Key: key,
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global: r.global,
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}
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r.buckets[key] = b
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return b
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}
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// LockBucket Locks until a request can be made
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func (r *RateLimiter) LockBucket(bucketID string) *Bucket {
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b := r.getBucket(bucketID)
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b.Lock()
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// If we ran out of calls and the reset time is still ahead of us
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// then we need to take it easy and relax a little
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if b.remaining < 1 && b.reset.After(time.Now()) {
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time.Sleep(b.reset.Sub(time.Now()))
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}
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// Check for global ratelimits
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sleepTo := time.Unix(0, atomic.LoadInt64(r.global))
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if now := time.Now(); now.Before(sleepTo) {
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time.Sleep(sleepTo.Sub(now))
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}
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b.remaining--
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return b
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}
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// Bucket represents a ratelimit bucket, each bucket gets ratelimited individually (-global ratelimits)
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type Bucket struct {
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sync.Mutex
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Key string
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remaining int
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limit int
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reset time.Time
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global *int64
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}
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// Release unlocks the bucket and reads the headers to update the buckets ratelimit info
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// and locks up the whole thing in case if there's a global ratelimit.
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func (b *Bucket) Release(headers http.Header) error {
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defer b.Unlock()
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if headers == nil {
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return nil
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}
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remaining := headers.Get("X-RateLimit-Remaining")
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reset := headers.Get("X-RateLimit-Reset")
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global := headers.Get("X-RateLimit-Global")
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retryAfter := headers.Get("Retry-After")
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// Update global and per bucket reset time if the proper headers are available
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// If global is set, then it will block all buckets until after Retry-After
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// If Retry-After without global is provided it will use that for the new reset
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// time since it's more accurate than X-RateLimit-Reset.
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// If Retry-After after is not proided, it will update the reset time from X-RateLimit-Reset
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if retryAfter != "" {
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parsedAfter, err := strconv.ParseInt(retryAfter, 10, 64)
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if err != nil {
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return err
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}
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resetAt := time.Now().Add(time.Duration(parsedAfter) * time.Millisecond)
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// Lock either this single bucket or all buckets
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if global != "" {
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atomic.StoreInt64(b.global, resetAt.UnixNano())
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} else {
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b.reset = resetAt
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}
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} else if reset != "" {
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// Calculate the reset time by using the date header returned from discord
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discordTime, err := http.ParseTime(headers.Get("Date"))
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if err != nil {
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return err
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}
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unix, err := strconv.ParseInt(reset, 10, 64)
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if err != nil {
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return err
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}
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// Calculate the time until reset and add it to the current local time
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// some extra time is added because without it i still encountered 429's.
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// The added amount is the lowest amount that gave no 429's
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// in 1k requests
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delta := time.Unix(unix, 0).Sub(discordTime) + time.Millisecond*250
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b.reset = time.Now().Add(delta)
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}
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// Udpate remaining if header is present
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if remaining != "" {
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parsedRemaining, err := strconv.ParseInt(remaining, 10, 32)
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if err != nil {
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return err
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}
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b.remaining = int(parsedRemaining)
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}
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return nil
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}
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