[glib/wip/kalev/recursive-mutex-locker: 21/22] Add GRecMutexLocker

[Kalev Lember <klember src gnome org>]

commit 10ed2d926f5f770261ce76fc08f53599b295b100
Author: Kalev Lember <klember redhat com>
Date:   Wed Dec 12 12:03:13 2018 +0100

    Add GRecMutexLocker
    
    This is the same as GMutexLocker, just for recursive mutexes.

 docs/reference/glib/glib-sections.txt |  5 +++
 glib/glib-autocleanups.h              |  1 +
 glib/gthread.h                        | 69 +++++++++++++++++++++++++++++++++++
 glib/tests/autoptr.c                  | 43 ++++++++++++++++++++++
 4 files changed, 118 insertions(+)
---
diff --git a/docs/reference/glib/glib-sections.txt b/docs/reference/glib/glib-sections.txt
index 1369012ce..20dd4cc41 100644
--- a/docs/reference/glib/glib-sections.txt
+++ b/docs/reference/glib/glib-sections.txt
@@ -730,6 +730,11 @@ g_rec_mutex_lock
 g_rec_mutex_trylock
 g_rec_mutex_unlock
 
+<SUBSECTION>
+GRecMutexLocker
+g_rec_mutex_locker_new
+g_rec_mutex_locker_free
+
 <SUBSECTION>
 GRWLock
 g_rw_lock_init
diff --git a/glib/glib-autocleanups.h b/glib/glib-autocleanups.h
index ce1690b78..d89c8d2fe 100644
--- a/glib/glib-autocleanups.h
+++ b/glib/glib-autocleanups.h
@@ -75,6 +75,7 @@ G_DEFINE_AUTOPTR_CLEANUP_FUNC(GStringChunk, g_string_chunk_free)
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GThread, g_thread_unref)
 G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GMutex, g_mutex_clear)
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMutexLocker, g_mutex_locker_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GRecMutexLocker, g_rec_mutex_locker_free)
 G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GCond, g_cond_clear)
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTimer, g_timer_destroy)
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTimeZone, g_time_zone_unref)
diff --git a/glib/gthread.h b/glib/gthread.h
index 3d765c2c2..80b0ef99b 100644
--- a/glib/gthread.h
+++ b/glib/gthread.h
@@ -336,6 +336,75 @@ g_mutex_locker_free (GMutexLocker *locker)
   g_mutex_unlock ((GMutex *) locker);
 }
 
+/**
+ * GRecMutexLocker:
+ *
+ * Opaque type. See g_rec_mutex_locker_new() for details.
+ * Since: 2.60
+ */
+typedef void GRecMutexLocker;
+
+/**
+ * g_rec_mutex_locker_new:
+ * @rec_mutex: a recursive mutex to lock
+ *
+ * Lock @rec_mutex and return a new #GRecMutexLocker. Unlock with
+ * g_rec_mutex_locker_free(). Using g_rec_mutex_unlock() on @rec_mutex
+ * while a #GRecMutexLocker exists can lead to undefined behaviour.
+ *
+ * This is intended to be used with g_autoptr().  Note that g_autoptr()
+ * is only available when using GCC or clang, so the following example
+ * will only work with those compilers:
+ * |[
+ * typedef struct
+ * {
+ *   ...
+ *   GRecMutex rec_mutex;
+ *   ...
+ * } MyObject;
+ *
+ * static void
+ * my_object_do_stuff (MyObject *self)
+ * {
+ *   g_autoptr(GRecMutexLocker) locker = g_rec_mutex_locker_new (&self->rec_mutex);
+ *
+ *   // Code with rec_mutex locked here
+ *
+ *   if (cond)
+ *     // No need to unlock
+ *     return;
+ *
+ *   // Optionally early unlock
+ *   g_clear_pointer (&locker, g_rec_mutex_locker_free);
+ *
+ *   // Code with rec_mutex unlocked here
+ * }
+ * ]|
+ *
+ * Returns: a #GRecMutexLocker
+ * Since: 2.60
+ */
+static inline GRecMutexLocker *
+g_rec_mutex_locker_new (GRecMutex *rec_mutex)
+{
+  g_rec_mutex_lock (rec_mutex);
+  return (GRecMutexLocker *) rec_mutex;
+}
+
+/**
+ * g_rec_mutex_locker_free:
+ * @locker: a GRecMutexLocker
+ *
+ * Unlock @locker's recursive mutex. See g_rec_mutex_locker_new() for details.
+ *
+ * Since: 2.60
+ */
+static inline void
+g_rec_mutex_locker_free (GRecMutexLocker *locker)
+{
+  g_rec_mutex_unlock ((GRecMutex *) locker);
+}
+
 G_END_DECLS
 
 #endif /* __G_THREAD_H__ */
diff --git a/glib/tests/autoptr.c b/glib/tests/autoptr.c
index 5b3bce71c..076acced7 100644
--- a/glib/tests/autoptr.c
+++ b/glib/tests/autoptr.c
@@ -344,6 +344,48 @@ test_g_mutex_locker (void)
     }
 }
 
+/* Thread function to check that a recursive mutex given in @data is locked */
+static gpointer
+rec_mutex_locked_thread (gpointer data)
+{
+  GRecMutex *rec_mutex = (GRecMutex *) data;
+  g_assert_false (g_rec_mutex_trylock (rec_mutex));
+  return NULL;
+}
+
+/* Thread function to check that a recursive mutex given in @data is unlocked */
+static gpointer
+rec_mutex_unlocked_thread (gpointer data)
+{
+  GRecMutex *rec_mutex = (GRecMutex *) data;
+  g_assert_true (g_rec_mutex_trylock (rec_mutex));
+  return NULL;
+}
+
+static void
+test_g_rec_mutex_locker (void)
+{
+  GRecMutex rec_mutex;
+  GThread *thread;
+
+  g_rec_mutex_init (&rec_mutex);
+
+  if (TRUE)
+    {
+      g_autoptr(GRecMutexLocker) val = g_rec_mutex_locker_new (&rec_mutex);
+
+      g_assert_nonnull (val);
+
+      /* Verify that the mutex is actually locked */
+      thread = g_thread_new ("rec mutex locked", rec_mutex_locked_thread, &rec_mutex);
+      g_thread_join (thread);
+    }
+
+    /* Verify that the mutex is unlocked again */
+    thread = g_thread_new ("rec mutex unlocked", rec_mutex_unlocked_thread, &rec_mutex);
+    g_thread_join (thread);
+}
+
 static void
 test_g_cond (void)
 {
@@ -536,6 +578,7 @@ main (int argc, gchar *argv[])
   g_test_add_func ("/autoptr/g_thread", test_g_thread);
   g_test_add_func ("/autoptr/g_mutex", test_g_mutex);
   g_test_add_func ("/autoptr/g_mutex_locker", test_g_mutex_locker);
+  g_test_add_func ("/autoptr/g_rec_mutex_locker", test_g_rec_mutex_locker);
   g_test_add_func ("/autoptr/g_cond", test_g_cond);
   g_test_add_func ("/autoptr/g_timer", test_g_timer);
   g_test_add_func ("/autoptr/g_time_zone", test_g_time_zone);