Add test coverage for sinks; prevent panic on nil channels

server/sink.go

@@ -52,10 +52,12 @@ func (p *sinkPool) Off(c chan []byte) {
 		copy(sinks[i:], sinks[i+1:])
 		sinks[len(sinks)-1] = nil
 		sinks = sinks[:len(sinks)-1]
-
-		// Update our tracked sinks, and close the matched channel.
 		p.sinks = sinks
+
+		// Avoid a panic if the sink channel is nil at this point.
+		if c != nil {
 			close(c)
+		}
 
 		return
 	}
@@ -68,8 +70,10 @@ func (p *sinkPool) Destroy() {
 	defer p.mu.Unlock()
 
 	for _, c := range p.sinks {
+		if c != nil {
 			close(c)
 		}
+	}
 
 	p.sinks = nil
 }
@@ -77,10 +81,15 @@ func (p *sinkPool) Destroy() {
 // Push sends a given message to each of the channels registered in the pool.
 func (p *sinkPool) Push(data []byte) {
 	p.mu.RLock()
+	// Attempt to send the data over to the channels. If the channel buffer is full,
+	// or otherwise blocked for some reason (such as being a nil channel), just discard
+	// the event data and move on to the next channel in the slice. If you don't
+	// implement the "default" on the select you'll block execution until the channel
+	// becomes unblocked, which is not what we want to do here.
 	for _, c := range p.sinks {
 		select {
-		// Send the event data over to the channels.
 		case c <- data:
+		default:
 		}
 	}
 	p.mu.RUnlock()

server/sink_test.go

@@ -0,0 +1,189 @@
+package server
+
+import (
+	"reflect"
+	"sync"
+	"testing"
+
+	. "github.com/franela/goblin"
+)
+
+func MutexLocked(m *sync.RWMutex) bool {
+	v := reflect.ValueOf(m).Elem()
+
+	state := v.FieldByName("w").FieldByName("state")
+
+	return state.Int()&1 == 1 || v.FieldByName("readerCount").Int() > 0
+}
+
+func Test(t *testing.T) {
+	g := Goblin(t)
+
+	g.Describe("SinkPool#On", func() {
+		g.It("pushes additional channels to a sink", func() {
+			pool := &sinkPool{}
+
+			g.Assert(pool.sinks).IsZero()
+
+			c1 := make(chan []byte, 1)
+			pool.On(c1)
+
+			g.Assert(len(pool.sinks)).Equal(1)
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+	})
+
+	g.Describe("SinkPool#Off", func() {
+		var pool *sinkPool
+		g.BeforeEach(func() {
+			pool = &sinkPool{}
+		})
+
+		g.It("works when no sinks are registered", func() {
+			ch := make(chan []byte, 1)
+
+			g.Assert(pool.sinks).IsZero()
+			pool.Off(ch)
+
+			g.Assert(pool.sinks).IsZero()
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+
+		g.It("does not remove any sinks when the channel does not match", func() {
+			ch := make(chan []byte, 1)
+			ch2 := make(chan []byte, 1)
+
+			pool.On(ch)
+			g.Assert(len(pool.sinks)).Equal(1)
+
+			pool.Off(ch2)
+			g.Assert(len(pool.sinks)).Equal(1)
+			g.Assert(pool.sinks[0]).Equal(ch)
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+
+		g.It("removes a channel and maintains the order", func() {
+			channels := make([]chan []byte, 8)
+            for i := 0; i < len(channels); i++ {
+				channels[i] = make(chan []byte, 1)
+                pool.On(channels[i])
+            }
+
+			g.Assert(len(pool.sinks)).Equal(8)
+
+			pool.Off(channels[2])
+			g.Assert(len(pool.sinks)).Equal(7)
+			g.Assert(pool.sinks[1]).Equal(channels[1])
+			g.Assert(pool.sinks[2]).Equal(channels[3])
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+
+		g.It("does not panic if a nil channel is provided", func() {
+			ch := make([]chan []byte, 1)
+
+			defer func () {
+				if r := recover(); r != nil {
+                    g.Fail("removing a nil channel should not cause a panic")
+                }
+			}()
+
+			pool.On(ch[0])
+			pool.Off(ch[0])
+
+			g.Assert(len(pool.sinks)).Equal(0)
+		})
+	})
+
+	g.Describe("SinkPool#Push", func() {
+		var pool *sinkPool
+		g.BeforeEach(func() {
+			pool = &sinkPool{}
+		})
+
+		g.It("works when no sinks are registered", func() {
+			g.Assert(len(pool.sinks)).IsZero()
+			pool.Push([]byte("test"))
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+
+		g.It("sends data to every registered sink", func() {
+			ch1 := make(chan []byte, 1)
+			ch2 := make(chan []byte, 1)
+
+			pool.On(ch1)
+			pool.On(ch2)
+
+			g.Assert(len(pool.sinks)).Equal(2)
+			b := []byte("test")
+			pool.Push(b)
+
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+			g.Assert(<-ch1).Equal(b)
+			g.Assert(<-ch2).Equal(b)
+			g.Assert(len(pool.sinks)).Equal(2)
+		})
+
+		g.It("does not block if a channel is nil or otherwise full", func() {
+			ch := make([]chan []byte, 2)
+			ch[1] = make(chan []byte, 1)
+			ch[1] <- []byte("test")
+
+			pool.On(ch[0])
+			pool.On(ch[1])
+
+			pool.Push([]byte("testing"))
+
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+			g.Assert(<-ch[1]).Equal([]byte("test"))
+
+			pool.Push([]byte("test2"))
+			g.Assert(<-ch[1]).Equal([]byte("test2"))
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+	})
+
+	g.Describe("SinkPool#Destroy", func() {
+		var pool *sinkPool
+		g.BeforeEach(func() {
+			pool = &sinkPool{}
+		})
+
+		g.It("works if no sinks are registered", func() {
+			pool.Destroy()
+
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+
+		g.It("closes all channels fully", func() {
+			ch1 := make(chan []byte, 1)
+			ch2 := make(chan []byte, 1)
+
+			pool.On(ch1)
+			pool.On(ch2)
+
+			g.Assert(len(pool.sinks)).Equal(2)
+			pool.Destroy()
+			g.Assert(pool.sinks).IsZero()
+
+			defer func() {
+				r := recover()
+
+				g.Assert(r).IsNotNil()
+				g.Assert(r.(error).Error()).Equal("send on closed channel")
+			}()
+
+			ch1 <- []byte("test")
+		})
+
+		g.It("works when a sink channel is nil", func() {
+			ch := make([]chan []byte, 2)
+
+			pool.On(ch[0])
+			pool.On(ch[1])
+
+			pool.Destroy()
+
+			g.Assert(MutexLocked(&pool.mu)).IsFalse()
+		})
+	})
+}