avoid close 'nil' panics if any (#18890)

brings a generic implementation that
prints a stack trace for 'nil' channel
closes(), if not safely closes it.

internal/grid/connection.go

@@ -40,6 +40,7 @@ import (
 	"github.com/gobwas/ws/wsutil"
 	"github.com/google/uuid"
 	"github.com/minio/madmin-go/v3"
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 	"github.com/minio/minio/internal/pubsub"
 	"github.com/tinylib/msgp/msgp"
@@ -449,7 +450,7 @@ func (c *Connection) WaitForConnect(ctx context.Context) error {
 	defer cancel()
 	changed := make(chan State, 1)
 	go func() {
-		defer close(changed)
+		defer xioutil.SafeClose(changed)
 		for {
 			c.connChange.Wait()
 			newState := c.State()

internal/grid/debug.go

@@ -26,6 +26,7 @@ import (
 	"sync"
 	"time"
 
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/mux"
 )
 
@@ -98,7 +99,7 @@ func SetupTestGrid(n int) (*TestGrid, error) {
 		res.Listeners = append(res.Listeners, listeners[i])
 		res.Mux = append(res.Mux, m)
 	}
-	close(ready)
+	xioutil.SafeClose(ready)
 	for _, m := range res.Managers {
 		for _, remote := range m.Targets() {
 			if err := m.Connection(remote).WaitForConnect(ctx); err != nil {

internal/grid/handlers.go

@@ -26,6 +26,7 @@ import (
 	"sync"
 
 	"github.com/minio/minio/internal/hash/sha256"
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 	"github.com/tinylib/msgp/msgp"
 )
@@ -579,7 +580,7 @@ func (h *StreamTypeHandler[Payload, Req, Resp]) register(m *Manager, handle func
 				// Don't add extra buffering
 				inT = make(chan Req)
 				go func() {
-					defer close(inT)
+					defer xioutil.SafeClose(inT)
 					for {
 						select {
 						case <-ctx.Done():
@@ -607,7 +608,7 @@ func (h *StreamTypeHandler[Payload, Req, Resp]) register(m *Manager, handle func
 			outT := make(chan Resp)
 			outDone := make(chan struct{})
 			go func() {
-				defer close(outDone)
+				defer xioutil.SafeClose(outDone)
 				dropOutput := false
 				for v := range outT {
 					if dropOutput {
@@ -629,7 +630,7 @@ func (h *StreamTypeHandler[Payload, Req, Resp]) register(m *Manager, handle func
 				}
 			}()
 			rErr := handle(ctx, plT, inT, outT)
-			close(outT)
+			xioutil.SafeClose(outT)
 			<-outDone
 			return rErr
 		}, OutCapacity: h.OutCapacity, InCapacity: h.InCapacity, Subroute: strings.Join(subroute, "/"),
@@ -695,7 +696,7 @@ func (h *StreamTypeHandler[Payload, Req, Resp]) Call(ctx context.Context, c Stre
 			return nil, fmt.Errorf("internal error: stream request channel nil")
 		}
 		go func() {
-			defer close(stream.Requests)
+			defer xioutil.SafeClose(stream.Requests)
 			for req := range reqT {
 				b, err := req.MarshalMsg(GetByteBuffer()[:0])
 				if err != nil {
@@ -706,7 +707,7 @@ func (h *StreamTypeHandler[Payload, Req, Resp]) Call(ctx context.Context, c Stre
 			}
 		}()
 	} else if stream.Requests != nil {
-		close(stream.Requests)
+		xioutil.SafeClose(stream.Requests)
 	}
 
 	return &TypedStream[Req, Resp]{responses: stream, newResp: h.NewResponse, Requests: reqT}, nil

internal/grid/muxclient.go

@@ -26,6 +26,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 	"github.com/zeebo/xxh3"
 )
@@ -267,7 +268,7 @@ func (m *muxClient) handleOneWayStream(start time.Time, respHandler chan<- Respo
 			fmt.Println("Mux", m.MuxID, "Request took", time.Since(start).Round(time.Millisecond))
 		}()
 	}
-	defer close(respHandler)
+	defer xioutil.SafeClose(respHandler)
 	var pingTimer <-chan time.Time
 	if m.deadline == 0 || m.deadline > clientPingInterval {
 		ticker := time.NewTicker(clientPingInterval)
@@ -324,7 +325,7 @@ func (m *muxClient) handleOneWayStream(start time.Time, respHandler chan<- Respo
 
 func (m *muxClient) handleTwowayResponses(responseCh chan Response, responses chan Response) {
 	defer m.parent.deleteMux(false, m.MuxID)
-	defer close(responseCh)
+	defer xioutil.SafeClose(responseCh)
 	for resp := range responses {
 		responseCh <- resp
 		m.send(message{Op: OpUnblockSrvMux, MuxID: m.MuxID})
@@ -534,7 +535,7 @@ func (m *muxClient) closeLocked() {
 		return
 	}
 	if m.respWait != nil {
-		close(m.respWait)
+		xioutil.SafeClose(m.respWait)
 		m.respWait = nil
 	}
 	m.closed = true

internal/grid/muxserver.go

@@ -26,6 +26,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 )
 
@@ -117,7 +118,7 @@ func newMuxStream(ctx context.Context, msg message, c *Connection, handler Strea
 		m.inbound = make(chan []byte, inboundCap)
 		handlerIn = make(chan []byte, 1)
 		go func(inbound <-chan []byte) {
-			defer close(handlerIn)
+			defer xioutil.SafeClose(handlerIn)
 			// Send unblocks when we have delivered the message to the handler.
 			for in := range inbound {
 				handlerIn <- in
@@ -146,7 +147,7 @@ func newMuxStream(ctx context.Context, msg message, c *Connection, handler Strea
 			if debugPrint {
 				fmt.Println("muxServer: Mux", m.ID, "Returned with", handlerErr)
 			}
-			close(send)
+			xioutil.SafeClose(send)
 		}()
 		// handlerErr is guarded by 'send' channel.
 		handlerErr = handler.Handle(ctx, msg.Payload, handlerIn, send)
@@ -247,7 +248,7 @@ func (m *muxServer) message(msg message) {
 			logger.LogIf(m.ctx, fmt.Errorf("muxServer: EOF message with payload"))
 		}
 		if m.inbound != nil {
-			close(m.inbound)
+			xioutil.SafeClose(m.inbound)
 			m.inbound = nil
 		}
 		return
@@ -324,12 +325,9 @@ func (m *muxServer) close() {
 	m.cancel()
 	m.recvMu.Lock()
 	defer m.recvMu.Unlock()
-	if m.inbound != nil {
-		close(m.inbound)
-		m.inbound = nil
-	}
-	if m.outBlock != nil {
-		close(m.outBlock)
-		m.outBlock = nil
-	}
+	xioutil.SafeClose(m.inbound)
+	m.inbound = nil
+
+	xioutil.SafeClose(m.outBlock)
+	m.outBlock = nil
 }