shim improvements for docs, clean quit, and slow readers (#7452)

plugins/inputs/execd/shim/goshim_posix.go

@@ -0,0 +1,23 @@
+// +build !windows
+
+package shim
+
+import (
+	"context"
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+func listenForCollectMetricsSignals(ctx context.Context, collectMetricsPrompt chan os.Signal) {
+	// just listen to all the signals.
+	signal.Notify(collectMetricsPrompt, syscall.SIGHUP, syscall.SIGUSR1, syscall.SIGUSR2)
+
+	go func() {
+		select {
+		case <-ctx.Done():
+			// context done. stop to signals to avoid pushing messages to a closed channel
+			signal.Stop(collectMetricsPrompt)
+		}
+	}()
+}