add countdown latch implementation using glib mutexes to use in improving tests

Author: DenverM80

test/countdown_latch.c

@@ -0,0 +1,54 @@
+
+#include <glib.h>
+#include "countdown_latch.h"
+
+struct _countdown_latch {
+    guint initial_count;
+    volatile guint count;
+    GCond waiters;
+    GMutex lock;
+};
+
+countdown_latch* countdown_latch_new(guint count) {
+    countdown_latch* latch = g_new0(countdown_latch, 1);
+    latch->initial_count = count;
+    latch->count = count;
+    g_mutex_init(&(latch->lock));
+    g_cond_init(&(latch->waiters));
+    return latch;
+}
+
+void countdownlatch_free(countdown_latch* latch) {
+    g_cond_clear(&(latch->waiters));
+    g_mutex_clear(&(latch->lock));
+    g_free(latch);
+}
+
+void countdownlatch_wait(countdown_latch* latch) {
+    g_mutex_lock(&(latch->lock));
+    while(latch->count > 0) {
+        g_cond_wait(&(latch->waiters), &(latch->lock));
+    }
+    g_mutex_unlock(&(latch->lock));
+}
+
+void countdownlatch_count_down(countdown_latch* latch) {
+    g_mutex_lock(&(latch->lock));
+    (latch->count)--;
+    if(latch->count == 0) {
+        g_cond_broadcast(&(latch->waiters));
+    }
+    g_mutex_unlock(&(latch->lock));
+}
+
+void countdownlatch_count_down_wait(countdown_latch* latch) {
+    g_mutex_lock(&(latch->lock));
+    (latch->count)--;
+    if(latch->count == 0) {
+        g_cond_broadcast(&(latch->waiters));
+    } else {
+        g_cond_wait(&(latch->waiters), &(latch->lock));
+    }
+    g_mutex_unlock(&(latch->lock));
+}
+

test/countdown_latch.h

@@ -0,0 +1,14 @@
+#ifndef COUNTDOWN_LATCH_H_
+#define COUNTDOWN_LATCH_H_
+
+typedef struct _countdown_latch countdown_latch;
+
+countdown_latch* countdown_latch_new(guint count);
+void countdown_latch_free(countdown_latch* latch);
+
+void countdown_latch_wait(countdown_latch* latch);
+void countdown_latch_count_down(countdown_latch* latch);
+void countdown_latch_count_down_and_wait(countdown_latch* latch);
+
+#endif /* COUNTDOWN_LATCH_H_ */
+#endif