util: import the slab allocator from gallium

There are also some cosmetic changes.

src/util/Makefile.sources

@@ -25,6 +25,8 @@ MESA_UTIL_FILES :=	\
 	set.c \
 	set.h \
 	simple_list.h \
+	slab.c \
+	slab.h \
 	strndup.c \
 	strndup.h \
 	strtod.c \

src/util/slab.c

@@ -0,0 +1,180 @@
+/*
+ * Copyright 2010 Marek Olšák <maraeo@gmail.com>
+ * Copyright 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
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, 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 "slab.h"
+#include "macros.h"
+#include "simple_list.h"
+#include <stdbool.h>
+#include <string.h>
+
+#define ALIGN(value, align) (((value) + (align) - 1) & ~((align) - 1))
+
+#ifdef DEBUG
+#define SLAB_MAGIC 0xcafe4321
+#define SET_MAGIC(element)   (element)->magic = SLAB_MAGIC
+#define CHECK_MAGIC(element) assert((element)->magic == SLAB_MAGIC)
+#else
+#define SET_MAGIC(element)
+#define CHECK_MAGIC(element)
+#endif
+
+/* One array element within a big buffer. */
+struct slab_element_header {
+   /* The next free element. */
+   struct slab_element_header *next_free;
+
+#ifdef DEBUG
+   /* Use intptr_t to keep the header aligned to a pointer size. */
+   intptr_t magic;
+#endif
+};
+
+static struct slab_element_header *
+slab_get_element(struct slab_mempool *pool,
+                 struct slab_page_header *page, unsigned index)
+{
+   return (struct slab_element_header*)
+          ((uint8_t*)&page[1] + (pool->element_size * index));
+}
+
+static bool
+slab_add_new_page(struct slab_mempool *pool)
+{
+   struct slab_page_header *page;
+   struct slab_element_header *element;
+   unsigned i;
+
+   page = malloc(sizeof(struct slab_page_header) +
+                 pool->num_elements * pool->element_size);
+   if (!page)
+      return false;
+
+   if (!pool->list.prev)
+      make_empty_list(&pool->list);
+
+   insert_at_tail(&pool->list, page);
+
+   /* Mark all elements as free. */
+   for (i = 0; i < pool->num_elements-1; i++) {
+      element = slab_get_element(pool, page, i);
+      element->next_free = slab_get_element(pool, page, i + 1);
+      SET_MAGIC(element);
+   }
+
+   element = slab_get_element(pool, page, pool->num_elements - 1);
+   element->next_free = pool->first_free;
+   SET_MAGIC(element);
+   pool->first_free = slab_get_element(pool, page, 0);
+   return true;
+}
+
+/**
+ * Allocate an object from the slab. Single-threaded (no mutex).
+ */
+void *
+slab_alloc_st(struct slab_mempool *pool)
+{
+   struct slab_element_header *element;
+
+   /* Allocate a new page. */
+   if (!pool->first_free &&
+       !slab_add_new_page(pool))
+      return NULL;
+
+   element = pool->first_free;
+   CHECK_MAGIC(element);
+   pool->first_free = element->next_free;
+   return &element[1];
+}
+
+/**
+ * Free an object allocated from the slab. Single-threaded (no mutex).
+ */
+void
+slab_free_st(struct slab_mempool *pool, void *ptr)
+{
+   struct slab_element_header *element =
+      ((struct slab_element_header*)ptr - 1);
+
+   CHECK_MAGIC(element);
+   element->next_free = pool->first_free;
+   pool->first_free = element;
+}
+
+/**
+ * Allocate an object from the slab. Thread-safe.
+ */
+void *
+slab_alloc_mt(struct slab_mempool *pool)
+{
+   void *mem;
+
+   mtx_lock(&pool->mutex);
+   mem = slab_alloc_st(pool);
+   mtx_unlock(&pool->mutex);
+   return mem;
+}
+
+/**
+ * Free an object allocated from the slab. Thread-safe.
+ */
+void
+slab_free_mt(struct slab_mempool *pool, void *ptr)
+{
+   mtx_lock(&pool->mutex);
+   slab_free_st(pool, ptr);
+   mtx_unlock(&pool->mutex);
+}
+
+void
+slab_destroy(struct slab_mempool *pool)
+{
+   struct slab_page_header *page, *temp;
+
+   if (pool->list.next) {
+      foreach_s(page, temp, &pool->list) {
+         remove_from_list(page);
+         free(page);
+      }
+   }
+
+   mtx_destroy(&pool->mutex);
+}
+
+/**
+ * Create an allocator for same-sized objects.
+ *
+ * \param item_size     Size of one object.
+ * \param num_items     Number of objects to allocate at once.
+ */
+void
+slab_create(struct slab_mempool *pool,
+            unsigned item_size,
+            unsigned num_items)
+{
+   mtx_init(&pool->mutex, mtx_plain);
+   pool->element_size = ALIGN(sizeof(struct slab_element_header) + item_size,
+                              sizeof(intptr_t));
+   pool->num_elements = num_items;
+   pool->first_free = NULL;
+}

src/util/slab.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2010 Marek Olšák <maraeo@gmail.com>
+ * Copyright 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
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, 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. */
+
+/**
+ * Slab allocator for equally sized memory allocations.
+ * The thread-safe path ("*_mt" functions) is usually slower than malloc/free.
+ * The single-threaded path ("*_st" functions) is faster than malloc/free.
+ */
+
+#ifndef SLAB_H
+#define SLAB_H
+
+#include "c11/threads.h"
+
+/* The page is an array of allocations in one block. */
+struct slab_page_header {
+   /* The header (linked-list pointers). */
+   struct slab_page_header *prev, *next;
+
+   /* Memory after the last member is dedicated to the page itself.
+    * The allocated size is always larger than this structure.
+    */
+};
+
+struct slab_mempool {
+   mtx_t mutex;
+   unsigned element_size;
+   unsigned num_elements;
+   struct slab_element_header *first_free;
+   struct slab_page_header list;
+};
+
+void slab_create(struct slab_mempool *pool,
+                 unsigned item_size,
+                 unsigned num_items);
+void slab_destroy(struct slab_mempool *pool);
+void *slab_alloc_st(struct slab_mempool *pool);
+void slab_free_st(struct slab_mempool *pool, void *ptr);
+void *slab_alloc_mt(struct slab_mempool *pool);
+void slab_free_mt(struct slab_mempool *pool, void *ptr);
+
+#endif