Switch back go upstream bwmarrin/discordgo

Commit ffa9956c9b got merged in.

vendor/github.com/bwmarrin/discordgo/ratelimit.go

@@ -0,0 +1,194 @@
+package discordgo
+
+import (
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// customRateLimit holds information for defining a custom rate limit
+type customRateLimit struct {
+	suffix   string
+	requests int
+	reset    time.Duration
+}
+
+// RateLimiter holds all ratelimit buckets
+type RateLimiter struct {
+	sync.Mutex
+	global           *int64
+	buckets          map[string]*Bucket
+	globalRateLimit  time.Duration
+	customRateLimits []*customRateLimit
+}
+
+// NewRatelimiter returns a new RateLimiter
+func NewRatelimiter() *RateLimiter {
+
+	return &RateLimiter{
+		buckets: make(map[string]*Bucket),
+		global:  new(int64),
+		customRateLimits: []*customRateLimit{
+			&customRateLimit{
+				suffix:   "//reactions//",
+				requests: 1,
+				reset:    200 * time.Millisecond,
+			},
+		},
+	}
+}
+
+// GetBucket retrieves or creates a bucket
+func (r *RateLimiter) GetBucket(key string) *Bucket {
+	r.Lock()
+	defer r.Unlock()
+
+	if bucket, ok := r.buckets[key]; ok {
+		return bucket
+	}
+
+	b := &Bucket{
+		Remaining: 1,
+		Key:       key,
+		global:    r.global,
+	}
+
+	// Check if there is a custom ratelimit set for this bucket ID.
+	for _, rl := range r.customRateLimits {
+		if strings.HasSuffix(b.Key, rl.suffix) {
+			b.customRateLimit = rl
+			break
+		}
+	}
+
+	r.buckets[key] = b
+	return b
+}
+
+// GetWaitTime returns the duration you should wait for a Bucket
+func (r *RateLimiter) GetWaitTime(b *Bucket, minRemaining int) time.Duration {
+	// If we ran out of calls and the reset time is still ahead of us
+	// then we need to take it easy and relax a little
+	if b.Remaining < minRemaining && b.reset.After(time.Now()) {
+		return b.reset.Sub(time.Now())
+	}
+
+	// Check for global ratelimits
+	sleepTo := time.Unix(0, atomic.LoadInt64(r.global))
+	if now := time.Now(); now.Before(sleepTo) {
+		return sleepTo.Sub(now)
+	}
+
+	return 0
+}
+
+// LockBucket Locks until a request can be made
+func (r *RateLimiter) LockBucket(bucketID string) *Bucket {
+	return r.LockBucketObject(r.GetBucket(bucketID))
+}
+
+// LockBucketObject Locks an already resolved bucket until a request can be made
+func (r *RateLimiter) LockBucketObject(b *Bucket) *Bucket {
+	b.Lock()
+
+	if wait := r.GetWaitTime(b, 1); wait > 0 {
+		time.Sleep(wait)
+	}
+
+	b.Remaining--
+	return b
+}
+
+// Bucket represents a ratelimit bucket, each bucket gets ratelimited individually (-global ratelimits)
+type Bucket struct {
+	sync.Mutex
+	Key       string
+	Remaining int
+	limit     int
+	reset     time.Time
+	global    *int64
+
+	lastReset       time.Time
+	customRateLimit *customRateLimit
+	Userdata        interface{}
+}
+
+// Release unlocks the bucket and reads the headers to update the buckets ratelimit info
+// and locks up the whole thing in case if there's a global ratelimit.
+func (b *Bucket) Release(headers http.Header) error {
+	defer b.Unlock()
+
+	// Check if the bucket uses a custom ratelimiter
+	if rl := b.customRateLimit; rl != nil {
+		if time.Now().Sub(b.lastReset) >= rl.reset {
+			b.Remaining = rl.requests - 1
+			b.lastReset = time.Now()
+		}
+		if b.Remaining < 1 {
+			b.reset = time.Now().Add(rl.reset)
+		}
+		return nil
+	}
+
+	if headers == nil {
+		return nil
+	}
+
+	remaining := headers.Get("X-RateLimit-Remaining")
+	reset := headers.Get("X-RateLimit-Reset")
+	global := headers.Get("X-RateLimit-Global")
+	retryAfter := headers.Get("Retry-After")
+
+	// Update global and per bucket reset time if the proper headers are available
+	// If global is set, then it will block all buckets until after Retry-After
+	// If Retry-After without global is provided it will use that for the new reset
+	// time since it's more accurate than X-RateLimit-Reset.
+	// If Retry-After after is not proided, it will update the reset time from X-RateLimit-Reset
+	if retryAfter != "" {
+		parsedAfter, err := strconv.ParseInt(retryAfter, 10, 64)
+		if err != nil {
+			return err
+		}
+
+		resetAt := time.Now().Add(time.Duration(parsedAfter) * time.Millisecond)
+
+		// Lock either this single bucket or all buckets
+		if global != "" {
+			atomic.StoreInt64(b.global, resetAt.UnixNano())
+		} else {
+			b.reset = resetAt
+		}
+	} else if reset != "" {
+		// Calculate the reset time by using the date header returned from discord
+		discordTime, err := http.ParseTime(headers.Get("Date"))
+		if err != nil {
+			return err
+		}
+
+		unix, err := strconv.ParseInt(reset, 10, 64)
+		if err != nil {
+			return err
+		}
+
+		// Calculate the time until reset and add it to the current local time
+		// some extra time is added because without it i still encountered 429's.
+		// The added amount is the lowest amount that gave no 429's
+		// in 1k requests
+		delta := time.Unix(unix, 0).Sub(discordTime) + time.Millisecond*250
+		b.reset = time.Now().Add(delta)
+	}
+
+	// Udpate remaining if header is present
+	if remaining != "" {
+		parsedRemaining, err := strconv.ParseInt(remaining, 10, 32)
+		if err != nil {
+			return err
+		}
+		b.Remaining = int(parsedRemaining)
+	}
+
+	return nil
+}