Add function to log thread state loops (once)

Add sinsp_threadinfo::note_parent_state_loop(), which logs that a loop
in parent state was found. It only does so once, though, using
m_parent_loop_detected to only log the first occurence.

The *logic* for detecting a loop is outside this function, though.

userspace/libsinsp/threadinfo.cpp

@@ -86,6 +86,7 @@ void sinsp_threadinfo::init()
 	m_program_hash = 0;
 	m_program_hash_falco = 0;
 	m_lastevent_data = NULL;
+	m_parent_loop_detected = false;
 }
 
 sinsp_threadinfo::~sinsp_threadinfo()
@@ -767,6 +768,20 @@ uint64_t sinsp_threadinfo::get_fd_limit()
 	return get_main_thread()->m_fdlimit;
 }
 
+void sinsp_threadinfo::note_parent_state_loop()
+{
+	// In debug mode, we trigger an assertion.
+	ASSERT(false);
+
+	// Note we only log a loop once for a given main thread, to avoid flooding logs.
+	if(!m_parent_loop_detected)
+	{
+		g_logger.log(string("Loop in parent thread state detected for pid ") +
+			     std::to_string(m_pid), sinsp_logger::SEV_WARNING);
+		m_parent_loop_detected = true;
+	}
+}
+
 sinsp_threadinfo* sinsp_threadinfo::lookup_thread()
 {
 	return m_inspector->get_thread(m_pid, true, true);

userspace/libsinsp/threadinfo.h

@@ -198,6 +198,11 @@ class SINSP_PUBLIC sinsp_threadinfo
 	*/
 	uint64_t get_fd_limit();
 
+	//
+	// Note that this thread has a loop in parent state, and possibly log the loop.
+	//
+	void note_parent_state_loop();
+
 	//
 	// Core state
 	//
@@ -325,6 +330,7 @@ VISIBILITY_PRIVATE
 	uint16_t m_lastevent_type;
 	uint16_t m_lastevent_cpuid;
 	sinsp_evt::category m_lastevent_category;
+	bool m_parent_loop_detected;
 
 	friend class sinsp;
 	friend class sinsp_parser;