From d032458875bb5a053e41f2cb90c92dfd085ac901 Mon Sep 17 00:00:00 2001
From: GrosQuildu <e2.8a.95@gmail.com>
Date: Wed, 10 Apr 2024 15:52:30 +0200
Subject: [PATCH] improve performance

---
 go/hanging-goroutine.go   | 49 ++++++++++++++++++++++++++++++++++++---
 go/hanging-goroutine.yaml | 16 ++++++++++++-
 2 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/go/hanging-goroutine.go b/go/hanging-goroutine.go
index 58b4d24..16533d3 100644
--- a/go/hanging-goroutine.go
+++ b/go/hanging-goroutine.go
@@ -11,9 +11,9 @@ var (
 )
 
 func main() {
-	req3(1)
-	fmt.Println(result)
-	fmt.Println(runtime.NumGoroutine())
+	req5_FP(1)
+	fmt.Println("Result: ", result)
+	fmt.Println("Goroutines (must be 1 for FPs):", runtime.NumGoroutine())
 }
 
 func req1(timeout time.Duration) string {
@@ -110,6 +110,49 @@ func req3_FP(timeout time.Duration) {
 	fmt.Println("finished req3")
 }
 
+func req4_FP(timeout time.Duration) string {
+	ch := make(chan string)
+	// ok: hanging-goroutine
+	go func() {
+		newData := test()
+		ch <- newData // block
+	}()
+	select {
+	case result = <- ch:
+		fmt.Println("case result")
+		return result
+	case <- time.After(timeout):
+		result = <- ch
+		fmt.Println("case time.Afer")
+		return ""
+	}
+}
+
+func req5_FP(timeout time.Duration) {
+	ch := make(chan string)
+	tick := time.Tick(100 * time.Millisecond)
+	quit := time.After(2 * time.Second)
+	// ok: hanging-goroutine
+	go func() {
+		newData := test()
+		ch <- newData // block
+	}()
+	for {
+		select {
+			case <-tick:
+				fmt.Print("|")
+			case <-quit:
+				result = <- ch
+				fmt.Println("\nquit")
+				return
+			default:
+				fmt.Print(".")
+				time.Sleep(50 * time.Millisecond)
+		}
+	}
+}
+
+
 func test() string {
 	time.Sleep(time.Second * 2)
 	return "very important data"
diff --git a/go/hanging-goroutine.yaml b/go/hanging-goroutine.yaml
index d3c9c02..2517bdf 100644
--- a/go/hanging-goroutine.yaml
+++ b/go/hanging-goroutine.yaml
@@ -123,15 +123,29 @@ rules:
       - pattern-not-inside: |
           $CHANNEL := make(..., $T)
           ...
+
+      # heuristics to limit FPs, we may miss some leaks because of these
       - pattern-not: |
+          go func(...){
+            ...
+            $CHANNEL <- $X
+            ...
+          }(...)
+          ...
           select {
           case ...
           case ...: 
             ...
-            ... =<- $CHANNEL
+            ... = <- $CHANNEL
             ...
           }
       - pattern-not: |
+          go func(...){
+            ...
+            $CHANNEL <- $X
+            ...
+          }(...)
+          ...
           select {
           case ...
           case ...: