[PATCH v2] erofs-utils: lib: name worker threads erofs_compress

[Nithurshen]

Set a specific thread name for the multi-threaded workqueue workers
to make debugging, profiling, and process monitoring significantly
easier.

Previously, worker threads inherited the name of the parent process
(e.g., mkfs.erofs), making it difficult to distinguish them from the
main thread in tools like `top`, `htop`, or `ps`.

This utilizes `prctl(PR_SET_NAME)` on Linux and `pthread_setname_np`
on macOS to explicitly label these threads as "erofs_compress" upon
initialization.

Signed-off-by: Nithurshen <nithurshen.dev at gmail.com>
---
 lib/workqueue.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/workqueue.c b/lib/workqueue.c
index 18ee0f9..860e403 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -2,6 +2,9 @@
 #include <pthread.h>
 #include <stdlib.h>
 #include "erofs/workqueue.h"
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
 
 static void *worker_thread(void *arg)
 {
@@ -9,6 +12,12 @@ static void *worker_thread(void *arg)
 	struct erofs_work *work;
 	void *tlsp = NULL;
 
+#if defined(__linux__)
+	prctl(PR_SET_NAME, "erofs_compress");
+#elif defined(__APPLE__)
+	pthread_setname_np("erofs_compress");
+#endif
+
 	if (wq->on_start)
 		tlsp = (wq->on_start)(wq, NULL);
 
-- 
2.51.0