replace zxq.co/ripple/hanayo

vendor/zxq.co/ripple/rippleapi/limit/limit.go

@@ -0,0 +1,122 @@
+package limit
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+// Request is a Request with DefaultLimiter.
+func Request(u string, perMinute int) { DefaultLimiter.Request(u, perMinute) }
+
+// NonBlockingRequest is a NonBlockingRequest with DefaultLimiter.
+func NonBlockingRequest(u string, perMinute int) bool {
+	return DefaultLimiter.NonBlockingRequest(u, perMinute)
+}
+
+// DefaultLimiter is the RateLimiter used by the package-level
+// Request and NonBlockingRequest.
+var DefaultLimiter = &RateLimiter{
+	Map:   make(map[string]chan struct{}),
+	Mutex: &sync.RWMutex{},
+}
+
+// RateLimiter is a simple rate limiter.
+type RateLimiter struct {
+	Map   map[string]chan struct{}
+	Mutex *sync.RWMutex
+}
+
+// Request is a simple request. Blocks until it can make the request.
+func (s *RateLimiter) Request(u string, perMinute int) {
+	s.request(u, perMinute, true)
+}
+
+// NonBlockingRequest checks if it can do a request. If it can't, it returns
+// false, else it returns true if the request succeded.
+func (s *RateLimiter) NonBlockingRequest(u string, perMinute int) bool {
+	return s.request(u, perMinute, false)
+}
+
+func (s *RateLimiter) request(u string, perMinute int, blocking bool) bool {
+	s.check()
+	s.Mutex.RLock()
+	c, exists := s.Map[u]
+	s.Mutex.RUnlock()
+	if !exists {
+		c = makePrefilledChan(perMinute)
+		s.Mutex.Lock()
+		// Now that we have exclusive read and write-access, we want to
+		// make sure we don't overwrite an existing channel. Otherwise,
+		// race conditions and panic happen.
+		if cNew, exists := s.Map[u]; exists {
+			c = cNew
+			s.Mutex.Unlock()
+		} else {
+			s.Map[u] = c
+			s.Mutex.Unlock()
+			<-c
+			go s.filler(u, perMinute)
+		}
+	}
+	return rcv(c, blocking)
+}
+
+// rcv receives from a channel, but if blocking is true it waits til something
+// is received and always returns true, otherwise if it can't receive it
+// returns false.
+func rcv(c chan struct{}, blocking bool) bool {
+	if blocking {
+		<-c
+		return true
+	}
+	select {
+	case <-c:
+		return true
+	default:
+		return false
+	}
+}
+
+func (s *RateLimiter) filler(el string, perMinute int) {
+	defer func() {
+		r := recover()
+		if r != nil {
+			fmt.Println(r)
+		}
+	}()
+
+	s.Mutex.RLock()
+	c := s.Map[el]
+	s.Mutex.RUnlock()
+	for {
+		select {
+		case c <- struct{}{}:
+			time.Sleep(time.Minute / time.Duration(perMinute))
+		default: // c is full
+			s.Mutex.Lock()
+			close(c)
+			delete(s.Map, el)
+			s.Mutex.Unlock()
+			return
+		}
+	}
+}
+
+// check makes sure the map and the mutex are properly initialised.
+func (s *RateLimiter) check() {
+	if s.Map == nil {
+		s.Map = make(map[string]chan struct{})
+	}
+	if s.Mutex == nil {
+		s.Mutex = new(sync.RWMutex)
+	}
+}
+
+func makePrefilledChan(l int) chan struct{} {
+	c := make(chan struct{}, l)
+	for i := 0; i < l; i++ {
+		c <- struct{}{}
+	}
+	return c
+}