Report thread names in stackusage output (#6)

stackusage reports the function pointer of each thread.
It can be unclear to users what each thread really is.

This change makes stackusage also report the thread name.
Applications can set a thread name using POSIX API
pthread_setname_np(). When not set, the thread name is
the program name.

Example of output (notice the "name" last column which is added
by this change):

stackusage log at 2019-10-31 11:12:41 ----------------------------------------
  pid  id    tid  requested     actual     maxuse  max%    dur               funcP name
...
 2254  15  22272    8388608    8388608      74676     0     14      0x7f9228afe890 Fts
...
22254  19  22273    8388608    8388608      15328     0      1      0x7f9228afe890 FtsGetRemoteCat
...
22254  42  22313    8388608    8388608      10664     0      1      0x7f9228afe890 FtsAsyncInitial
22254  43  22314    8388608    8388608      46584     0      1      0x7f9228afe890 FtsLocalSearchA

I've only checked on Linux x86_64. I don't have access
to other platforms.

Author: dpelle

src/sumain.c

@@ -81,6 +81,7 @@ typedef struct su_threadinfo_s
   time_t time_stop;
   int time_duration;
   void *func_ptr;
+  char thread_name[16];
   struct su_threadinfo_s *next;
 } su_threadinfo_t;
 
@@ -147,7 +148,7 @@ void __attribute__ ((destructor)) su_fini(void)
 {
   if(su_inited == 1)
   {
-    /* Unegister main thread */
+    /* Unregister main thread */
     su_thread_fini(NULL);
 
     /* Log stack usage in process */
@@ -364,6 +365,8 @@ static void su_thread_init(su_threadtype_t threadtype, pthread_attr_t *rattr,
   threadinfo->threadtype = threadtype;
   threadinfo->pthread = pthread_self();
   threadinfo->func_ptr = func_ptr;
+  threadinfo->thread_name[0] = '\0';
+
 #ifdef __linux__
   threadinfo->tid = syscall(SYS_gettid);
 #endif
@@ -513,7 +516,7 @@ static void su_log_stack_usage(void)
   SU_LOG("%s log at %s ----------------------------------------\n",
          su_name, timestamp);
   SU_LOG("  pid  id    tid  requested     actual     maxuse  max%%    dur"
-         "  funcP\n");
+         "               funcP name\n");
   while(threadinfo_it)
   {
     int usage_percent = 0;
@@ -524,7 +527,7 @@ static void su_log_stack_usage(void)
         (int) threadinfo_it->stack_req_size;
     }
 
-    SU_LOG("%5d %3d  %5d  %9d  %9d  %9d   %3d  %5d  %p\n",
+    SU_LOG("%5d %3d  %5d  %9d  %9d  %9d   %3d  %5d  %18p %s\n",
            getpid(),
            threadinfo_it->id, 
            threadinfo_it->tid,
@@ -533,7 +536,8 @@ static void su_log_stack_usage(void)
            (int) threadinfo_it->stack_max_usage,
            (int) usage_percent,
            threadinfo_it->time_duration,
-           threadinfo_it->func_ptr
+           threadinfo_it->func_ptr,
+           threadinfo_it->thread_name
           );
 
     threadinfo_it = threadinfo_it->next;
@@ -608,6 +612,9 @@ static void su_thread_fini(void *key)
   /* Update its stack usage info */
   su_get_stack_usage(threadinfo);
 
+  /* Record the thread name */
+  pthread_getname_np(threadinfo->pthread, threadinfo->thread_name, 16);
+
   /* Store stop time and calculate duration */
   if(time(&(threadinfo->time_stop)) != ((time_t)-1))
   {