From e80e401c7eca20fa2c13abc85306f55c94b5c4d1 Mon Sep 17 00:00:00 2001
From: Alessandro Arzilli <alessandro.arzilli@gmail.com>
Date: Tue, 26 Dec 2023 19:16:52 +0100
Subject: [PATCH] service/dap: fix close on closed channel (#3609)

This fixes an infrequent close on closed channel panic in service/dap
caused by a race condition with closing a channel.
---
 service/dap/server.go | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/service/dap/server.go b/service/dap/server.go
index e3f2dbbb..98467634 100644
--- a/service/dap/server.go
+++ b/service/dap/server.go
@@ -181,26 +181,22 @@ type Config struct {
 }
 
 type connection struct {
+	mu     sync.Mutex
+	closed bool
 	io.ReadWriteCloser
-	closed chan struct{}
 }
 
 func (c *connection) Close() error {
-	select {
-	case <-c.closed:
-	default:
-		close(c.closed)
-	}
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.closed = true
 	return c.ReadWriteCloser.Close()
 }
 
 func (c *connection) isClosed() bool {
-	select {
-	case <-c.closed:
-		return true
-	default:
-		return false
-	}
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.closed
 }
 
 type process struct {
@@ -339,7 +335,7 @@ func NewSession(conn io.ReadWriteCloser, config *Config, debugger *debugger.Debu
 	return &Session{
 		config:            config,
 		id:                sessionCount,
-		conn:              &connection{conn, make(chan struct{})},
+		conn:              &connection{ReadWriteCloser: conn},
 		stackFrameHandles: newHandlesMap(),
 		variableHandles:   newVariablesHandlesMap(),
 		args:              defaultArgs,