scount: change the signal API to return count

This is useful for the caller to track the state of the waiting thread; count =
0 means the target thread is no longer waiting

src/cond/zm_scount.c

@@ -27,21 +27,20 @@ int zm_scount_wait(struct zm_scount *C, zm_lock_t *L) {
     return 0;
 }
 
-int zm_scount_signal(struct zm_scount *C) {
+int zm_scount_signal(struct zm_scount *C, int *out_count) {
     int ret = 0;
     if(C->count > 0) {
         C->count--;
         if(C->count == 0)
             ret = zm_ccond_signal(&C->cvar);
     }
+    *out_count = C->count;
     return ret;
 }
 
 /* Forced wake up regardless of the counter */
 int zm_scond_signalf(struct zm_scount *C) {
     int ret = 0;
-    if(C->count > 0)
-        C->count--;
     /* wakeup signal regardless of the counter value */
     ret = zm_ccond_signal(&C->cvar);
 

src/include/cond/zm_scount.h

@@ -11,7 +11,7 @@
 int zm_scount_init(struct zm_scount *C, int);
 int zm_scount_destroy(struct zm_scount *C);
 int zm_scount_wait(struct zm_scount *C, zm_lock_t *L);
-int zm_scount_signal(struct zm_scount *C);
+int zm_scount_signal(struct zm_scount *C, int*);
 int zm_scount_signalf(struct zm_scount *C);
 
 #endif /* _ZM_SCOND_H */

test/regres/cond/prio_chain.c

@@ -44,7 +44,8 @@ static void* run(void *arg) {
         counter++;
         for(int i = 1; i<TEST_NTHREADS; i++) {
             int trg = (tid + i) % TEST_NTHREADS;
-            zm_scount_signal(&scounts[trg]);
+            int out_count; /* ignored */
+            zm_scount_signal(&scounts[trg], &out_count);
         }
 
         zm_lock_release(&glock);   /* Release the lock */