util/hash_table: add _mesa_hash_table_clear (v4)

v4: coding style change (Matt Turner)

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com> (v3)

src/util/hash_table.c

@@ -163,6 +163,32 @@ _mesa_hash_table_destroy(struct hash_table *ht,
    ralloc_free(ht);
 }
 
+/**
+ * Deletes all entries of the given hash table without deleting the table
+ * itself or changing its structure.
+ *
+ * If delete_function is passed, it gets called on each entry present.
+ */
+void
+_mesa_hash_table_clear(struct hash_table *ht,
+                       void (*delete_function)(struct hash_entry *entry))
+{
+   struct hash_entry *entry;
+
+   for (entry = ht->table; entry != ht->table + ht->size; entry++) {
+      if (entry->key == NULL)
+         continue;
+
+      if (delete_function != NULL && entry->key != ht->deleted_key)
+         delete_function(entry);
+
+      entry->key = NULL;
+   }
+
+   ht->entries = 0;
+   ht->deleted_entries = 0;
+}
+
 /** Sets the value of the key pointer used for deleted entries in the table.
  *
  * The assumption is that usually keys are actual pointers, so we use a

src/util/hash_table.h

@@ -64,6 +64,8 @@ _mesa_hash_table_create(void *mem_ctx,
                                                     const void *b));
 void _mesa_hash_table_destroy(struct hash_table *ht,
                               void (*delete_function)(struct hash_entry *entry));
+void _mesa_hash_table_clear(struct hash_table *ht,
+                            void (*delete_function)(struct hash_entry *entry));
 void _mesa_hash_table_set_deleted_key(struct hash_table *ht,
                                       const void *deleted_key);
 

src/util/tests/hash_table/Makefile.am

@@ -29,6 +29,7 @@ LDADD = \
 	$(DLOPEN_LIBS)
 
 TESTS = \
+	clear \
 	collision \
 	delete_and_lookup \
 	delete_management \

src/util/tests/hash_table/clear.c

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "hash_table.h"
+
+static void *make_key(uint32_t i)
+{
+      return (void *)(uintptr_t)(1 + i);
+}
+
+static uint32_t key_id(const void *key)
+{
+   return (uintptr_t)key - 1;
+}
+
+static uint32_t key_hash(const void *key)
+{
+   return (uintptr_t)key;
+}
+
+static bool key_equal(const void *a, const void *b)
+{
+   return a == b;
+}
+
+static void delete_function(struct hash_entry *entry)
+{
+   bool *deleted = (bool *)entry->data;
+   assert(!*deleted);
+   *deleted = true;
+}
+
+int main()
+{
+   struct hash_table *ht;
+   struct hash_entry *entry;
+   const uint32_t size = 1000;
+   bool flags[size];
+   uint32_t i;
+
+   ht = _mesa_hash_table_create(NULL, key_hash, key_equal);
+
+   for (i = 0; i < size; ++i) {
+      flags[i] = false;
+      _mesa_hash_table_insert(ht, make_key(i), &flags[i]);
+   }
+
+   _mesa_hash_table_clear(ht, delete_function);
+   assert(_mesa_hash_table_next_entry(ht, NULL) == NULL);
+
+   /* Check that delete_function was called and that repopulating the table
+    * works. */
+   for (i = 0; i < size; ++i) {
+      assert(flags[i]);
+      flags[i] = false;
+      _mesa_hash_table_insert(ht, make_key(i), &flags[i]);
+   }
+
+   /* Check that exactly the right set of entries is in the table. */
+   for (i = 0; i < size; ++i) {
+      assert(_mesa_hash_table_search(ht, make_key(i)));
+   }
+
+   hash_table_foreach(ht, entry) {
+      assert(key_id(entry->key) < size);
+   }
+
+   _mesa_hash_table_destroy(ht, NULL);
+
+   return 0;
+}