[Mesa-dev] [PATCH 3/6] ralloc: a new MIT-licensed recursive memory allocator.
Kenneth Graunke
kenneth at whitecape.org
Mon Jan 24 11:07:26 PST 2011
---
src/glsl/ralloc.c | 306 +++++++++++++++++++++++++++++++++++++++++++++++------
src/glsl/ralloc.h | 9 ++-
2 files changed, 280 insertions(+), 35 deletions(-)
diff --git a/src/glsl/ralloc.c b/src/glsl/ralloc.c
index 5f030ac..e92f433 100644
--- a/src/glsl/ralloc.c
+++ b/src/glsl/ralloc.c
@@ -27,7 +27,6 @@
#include <stdio.h>
#include <string.h>
#include <stdint.h>
-#include <talloc.h>
#include "ralloc.h"
@@ -39,28 +38,123 @@
#define unlikely(x) !!(x)
#endif
+#define CANARY 0x5A1106
+
+struct ralloc_header
+{
+ /* A canary value used to determine whether a pointer is ralloc'd. */
+ unsigned canary;
+
+ struct ralloc_header *parent;
+
+ /* The first child (head of a linked list) */
+ struct ralloc_header *child;
+
+ /* Linked list of siblings */
+ struct ralloc_header *prev;
+ struct ralloc_header *next;
+
+ void (*destructor)(void *);
+};
+
+typedef struct ralloc_header ralloc_header;
+
+static void unlink_block(ralloc_header *info);
+static void unsafe_free(ralloc_header *info);
+
+static ralloc_header *
+get_header(const void *ptr)
+{
+ ralloc_header *info = (ralloc_header *) (((char *) ptr) -
+ sizeof(ralloc_header));
+ assert(info->canary == CANARY);
+ return info;
+}
+
+#define PTR_FROM_HEADER(info) (((char *) info) + sizeof(ralloc_header))
+
+static void
+add_child(ralloc_header *parent, ralloc_header *info)
+{
+ if (parent != NULL) {
+ info->parent = parent;
+ info->next = parent->child;
+ parent->child = info;
+
+ if (info->next != NULL)
+ info->next->prev = info;
+ }
+}
+
void *
ralloc_context(const void *ctx)
{
- return talloc_new(ctx);
+ return ralloc_size(ctx, 0);
}
void *
ralloc_size(const void *ctx, size_t size)
{
- return talloc_size(ctx, size);
+ void *block = calloc(1, size + sizeof(ralloc_header));
+
+ ralloc_header *info = (ralloc_header *) block;
+ ralloc_header *parent = ctx != NULL ? get_header(ctx) : NULL;
+
+ add_child(parent, info);
+
+ info->canary = CANARY;
+
+ return PTR_FROM_HEADER(info);
}
void *
rzalloc_size(const void *ctx, size_t size)
{
- return talloc_zero_size(ctx, size);
+ void *ptr = ralloc_size(ctx, size);
+ if (likely(ptr != NULL))
+ memset(ptr, 0, size);
+ return ptr;
+}
+
+/* helper function - assumes ptr != NULL */
+static void *
+resize(void *ptr, size_t size)
+{
+ ralloc_header *child, *old, *info;
+
+ old = get_header(ptr);
+ info = realloc(old, size + sizeof(ralloc_header));
+
+ if (info == NULL)
+ return NULL;
+
+ /* Update parent and sibling's links to the reallocated node. */
+ if (info != old && info->parent != NULL) {
+ if (info->parent->child == old)
+ info->parent->child = info;
+
+ if (info->prev != NULL)
+ info->prev->next = info;
+
+ if (info->next != NULL)
+ info->next->prev = info;
+ }
+
+ /* Update child->parent links for all children */
+ for (child = info->child; child != NULL; child = child->next)
+ child->parent = info;
+
+ return PTR_FROM_HEADER(info);
}
void *
reralloc_size(const void *ctx, void *ptr, size_t size)
{
- return talloc_realloc_size(ctx, ptr, size);
+ if (unlikely(ptr == NULL))
+ return ralloc_size(ctx, size);
+
+ assert(ralloc_parent(ptr) == ctx);
+ return resize(ptr, size);
}
void *
@@ -69,7 +163,7 @@ ralloc_array_size(const void *ctx, size_t size, unsigned count)
if (count > SIZE_MAX/size)
return NULL;
- return talloc_array_size(ctx, size, count);
+ return ralloc_size(ctx, size * count);
}
void *
@@ -85,7 +179,7 @@ void *
reralloc_array_size(const void *ctx, void *ptr, size_t size, unsigned count)
{
if (count > SIZE_MAX/size)
- return false;
+ return NULL;
return reralloc_size(ctx, ptr, size * count);
}
@@ -93,71 +187,177 @@ reralloc_array_size(const void *ctx, void *ptr, size_t size, unsigned count)
void
ralloc_free(void *ptr)
{
- talloc_free(ptr);
+ ralloc_header *info;
+
+ if (ptr == NULL)
+ return;
+
+ info = get_header(ptr);
+ unlink_block(info);
+ unsafe_free(info);
+}
+
+static void
+unlink_block(ralloc_header *info)
+{
+ /* Unlink from parent & siblings */
+ if (info->parent != NULL) {
+ if (info->parent->child == info)
+ info->parent->child = info->next;
+
+ if (info->prev != NULL)
+ info->prev->next = info->next;
+
+ if (info->next != NULL)
+ info->next->prev = info->prev;
+ }
+ info->parent = NULL;
+ info->prev = NULL;
+ info->next = NULL;
+}
+
+static void
+unsafe_free(ralloc_header *info)
+{
+ /* Recursively free any children...don't waste time unlinking them. */
+ ralloc_header *temp;
+ while (info->child != NULL) {
+ temp = info->child;
+ info->child = temp->next;
+ unsafe_free(temp);
+ }
+
+ /* Free the block itself. Call the destructor first, if any. */
+ if (info->destructor != NULL)
+ info->destructor(PTR_FROM_HEADER(info));
+
+ free(info);
}
void
ralloc_steal(const void *new_ctx, void *ptr)
{
- talloc_steal(new_ctx, ptr);
+ ralloc_header *info, *parent;
+
+ if (unlikely(ptr == NULL))
+ return;
+
+ info = get_header(ptr);
+ parent = get_header(new_ctx);
+
+ unlink_block(info);
+
+ add_child(parent, info);
}
void *
ralloc_parent(const void *ptr)
{
- return talloc_parent(ptr);
+ ralloc_header *info;
+
+ if (unlikely(ptr == NULL))
+ return NULL;
+
+ info = get_header(ptr);
+ return PTR_FROM_HEADER(info->parent);
+}
+
+static void *autofree_context = NULL;
+
+static void
+autofree(void)
+{
+ ralloc_free(autofree_context);
}
void *
ralloc_autofree_context(void)
{
- return talloc_autofree_context();
+ if (unlikely(autofree_context == NULL)) {
+ autofree_context = ralloc_context(NULL);
+ atexit(autofree);
+ }
+ return autofree_context;
}
void
ralloc_set_destructor(const void *ptr, void(*destructor)(void *))
{
- talloc_set_destructor(ptr, (int(*)(void *)) destructor);
+ ralloc_header *info = get_header(ptr);
+ info->destructor = destructor;
}
char *
ralloc_strdup(const void *ctx, const char *str)
{
- return talloc_strdup(ctx, str);
+ size_t n;
+ char *ptr;
+
+ if (unlikely(str == NULL))
+ return NULL;
+
+ n = strlen(str);
+ ptr = ralloc_array(ctx, char, n + 1);
+ memcpy(ptr, str, n);
+ ptr[n] = '\0';
+ return ptr;
}
char *
ralloc_strndup(const void *ctx, const char *str, size_t max)
{
- return talloc_strndup(ctx, str, max);
+ size_t n;
+ char *ptr;
+
+ if (unlikely(str == NULL))
+ return NULL;
+
+ n = strlen(str);
+ if (n > max)
+ n = max;
+
+ ptr = ralloc_array(ctx, char, n + 1);
+ memcpy(ptr, str, n);
+ ptr[n] = '\0';
+ return ptr;
}
-bool
-ralloc_strcat(char **dest, const char *str)
+/* helper routine for strcat/strncat - n is the exact amount to copy */
+static bool
+cat(char **dest, const char *str, size_t n)
{
- void *ptr;
- assert(dest != NULL);
- ptr = talloc_strdup_append(*dest, str);
+ char *both;
+ size_t existing_length;
+ assert(dest != NULL && *dest != NULL);
- if (unlikely(ptr == NULL))
+ existing_length = strlen(*dest);
+ both = resize(*dest, existing_length + n + 1);
+ if (unlikely(both == NULL))
return false;
- *dest = ptr;
+ memcpy(both + existing_length, str, n);
+ both[existing_length + n] = '\0';
+
+ *dest = both;
return true;
}
+
bool
-ralloc_strncat(char **dest, const char *str, size_t n)
+ralloc_strcat(char **dest, const char *str)
{
- void *ptr;
- assert(dest != NULL);
- ptr = talloc_strndup_append(*dest, str, n);
+ return cat(dest, str, strlen(str));
+}
- if (unlikely(ptr == NULL))
- return false;
+bool
+ralloc_strncat(char **dest, const char *str, size_t n)
+{
+ /* Clamp n to the string length */
+ size_t str_length = strlen(str);
+ if (str_length < n)
+ n = str_length;
- *dest = ptr;
- return true;
+ return cat(dest, str, n);
}
char *
@@ -171,32 +371,70 @@ ralloc_asprintf(const void *ctx, const char *fmt, ...)
return ptr;
}
+/* Return the length of the string that would be generated by a printf-style
+ * format and argument list, not including the \0 byte.
+ */
+static size_t
+printf_length(const char *fmt, va_list untouched_args)
+{
+ int size;
+ char junk;
+
+ /* Make a copy of the va_list so the original caller can still use it */
+ va_list args;
+ va_copy(args, untouched_args);
+
+ size = vsnprintf(&junk, 1, fmt, args);
+ assert(size >= 0);
+
+ return size;
+}
+
char *
ralloc_vasprintf(const void *ctx, const char *fmt, va_list args)
{
- return talloc_vasprintf(ctx, fmt, args);
+ size_t size = printf_length(fmt, args) + 1;
+
+ char *ptr = ralloc_size(ctx, size);
+ if (ptr != NULL)
+ vsnprintf(ptr, size, fmt, args);
+
+ return ptr;
}
bool
ralloc_asprintf_append(char **str, const char *fmt, ...)
{
+ bool success;
va_list args;
-
va_start(args, fmt);
- return ralloc_vasprintf_append(str, fmt, args);
+ success = ralloc_vasprintf_append(str, fmt, args);
va_end(args);
+ return success;
}
bool
ralloc_vasprintf_append(char **str, const char *fmt, va_list args)
{
- void *ptr;
+ size_t existing_length, new_length;
+ char *ptr;
+
assert(str != NULL);
- ptr = talloc_vasprintf_append(*str, fmt, args);
+ if (unlikely(*str == NULL)) {
+ // Assuming a NULL context is probably bad, but it's expected behavior.
+ *str = ralloc_vasprintf(NULL, fmt, args);
+ return true;
+ }
+
+ existing_length = strlen(*str);
+ new_length = printf_length(fmt, args);
+
+ ptr = resize(*str, existing_length + new_length + 1);
if (unlikely(ptr == NULL))
return false;
+ vsnprintf(ptr + existing_length, new_length + 1, fmt, args);
*str = ptr;
return true;
}
diff --git a/src/glsl/ralloc.h b/src/glsl/ralloc.h
index 57e8c7a..d533815 100644
--- a/src/glsl/ralloc.h
+++ b/src/glsl/ralloc.h
@@ -34,7 +34,14 @@
* ralloc_free on any particular object to free it and all of its
* children.
*
- * This is currently a wrapper around talloc, but that will change.
+ * The conceptual working of ralloc was directly inspired by Andrew
+ * Tridgell's talloc, but ralloc is an independent implementation
+ * released under the MIT license and tuned for Mesa.
+ *
+ * The talloc implementation is available under the GNU Lesser
+ * General Public License (GNU LGPL), version 3 or later. It is
+ * more sophisticated than ralloc in that it includes reference
+ * counting and debugging features. See: http://talloc.samba.org/
*/
#ifndef RALLOC_H
--
1.7.3.5
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