util: hash: Introduce virHashForEachSorted

Iterate the hash elements sorted by key. This is useful to provide a
stable ordering such as in cases when the output is checked in tests.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Matt Coleman <matt@datto.com>

src/libvirt_private.syms

@@ -2207,6 +2207,7 @@ virHashAtomicSteal;
 virHashAtomicUpdate;
 virHashEqual;
 virHashForEach;
+virHashForEachSorted;
 virHashFree;
 virHashGetItems;
 virHashHasEntry;

src/util/virhash.c

@@ -481,14 +481,25 @@ virHashRemoveEntry(virHashTablePtr table, const char *name)
 
 
 /**
- * virHashForEach
+ * virHashForEach, virHashForEachSorted
  * @table: the hash table to process
  * @iter: callback to process each element
  * @opaque: opaque data to pass to the iterator
  *
- * Iterates over every element in the hash table, invoking the
- * 'iter' callback. The callback is allowed to remove the current element
- * using virHashRemoveEntry but calling other virHash* functions is prohibited.
+ * Iterates over every element in the hash table, invoking the 'iter' callback.
+ *
+ * The elements are iterated in arbitrary order.
+ *
+ * virHashForEach allows the callback to remove the current
+ * element using virHashRemoveEntry but calling other virHash* functions is
+ * prohibited. Note that removing the entry invalidates @key and @payload in
+ * the callback.
+ *
+ * virHashForEachSorted iterates the elements in order by sorted key.
+ *
+ * virHashForEachSorted is more computationally
+ * expensive than virHashForEach.
+ *
  * If @iter fails and returns a negative value, the evaluation is stopped and -1
  * is returned.
  *
@@ -520,6 +531,26 @@ virHashForEach(virHashTablePtr table, virHashIterator iter, void *opaque)
 }
 
 
+int
+virHashForEachSorted(virHashTablePtr table,
+                     virHashIterator iter,
+                     void *opaque)
+{
+    g_autofree virHashKeyValuePairPtr items = virHashGetItems(table, NULL, true);
+    size_t i;
+
+    if (!items)
+        return -1;
+
+    for (i = 0; items[i].key; i++) {
+        if (iter((void *)items[i].value, items[i].key, opaque) < 0)
+            return -1;
+    }
+
+    return 0;
+}
+
+
 /**
  * virHashRemoveSet
  * @table: the hash table to process

src/util/virhash.h

@@ -136,6 +136,7 @@ bool virHashEqual(const virHashTable *table1,
  * Iterators
  */
 int virHashForEach(virHashTablePtr table, virHashIterator iter, void *opaque);
+int virHashForEachSorted(virHashTablePtr table, virHashIterator iter, void *opaque);
 ssize_t virHashRemoveSet(virHashTablePtr table, virHashSearcher iter, const void *opaque);
 void *virHashSearch(const virHashTable *table, virHashSearcher iter,
                     const void *opaque, char **name);