* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/* MT safe */
#include <string.h>
#include <errno.h>
-#ifdef HAVE_UNISTD_H
+#ifdef G_OS_UNIX
#include <unistd.h> /* sysconf() */
#endif
#ifdef G_OS_WIN32
#include "gthread.h"
#include "glib_trace.h"
+#include "valgrind.h"
+
+/**
+ * SECTION:memory_slices
+ * @title: Memory Slices
+ * @short_description: efficient way to allocate groups of equal-sized
+ * chunks of memory
+ *
+ * Memory slices provide a space-efficient and multi-processing scalable
+ * way to allocate equal-sized pieces of memory, just like the original
+ * #GMemChunks (from GLib 2.8), while avoiding their excessive
+ * memory-waste, scalability and performance problems.
+ *
+ * To achieve these goals, the slice allocator uses a sophisticated,
+ * layered design that has been inspired by Bonwick's slab allocator
+ * ([Bonwick94](http://citeseer.ist.psu.edu/bonwick94slab.html)
+ * Jeff Bonwick, The slab allocator: An object-caching kernel
+ * memory allocator. USENIX 1994, and
+ * [Bonwick01](http://citeseer.ist.psu.edu/bonwick01magazines.html)
+ * Bonwick and Jonathan Adams, Magazines and vmem: Extending the
+ * slab allocator to many cpu's and arbitrary resources. USENIX 2001)
+ *
+ * It uses posix_memalign() to optimize allocations of many equally-sized
+ * chunks, and has per-thread free lists (the so-called magazine layer)
+ * to quickly satisfy allocation requests of already known structure sizes.
+ * This is accompanied by extra caching logic to keep freed memory around
+ * for some time before returning it to the system. Memory that is unused
+ * due to alignment constraints is used for cache colorization (random
+ * distribution of chunk addresses) to improve CPU cache utilization. The
+ * caching layer of the slice allocator adapts itself to high lock contention
+ * to improve scalability.
+ *
+ * The slice allocator can allocate blocks as small as two pointers, and
+ * unlike malloc(), it does not reserve extra space per block. For large block
+ * sizes, g_slice_new() and g_slice_alloc() will automatically delegate to the
+ * system malloc() implementation. For newly written code it is recommended
+ * to use the new `g_slice` API instead of g_malloc() and
+ * friends, as long as objects are not resized during their lifetime and the
+ * object size used at allocation time is still available when freeing.
+ *
+ * Here is an example for using the slice allocator:
+ * |[<!-- language="C" -->
+ * gchar *mem[10000];
+ * gint i;
+ *
+ * // Allocate 10000 blocks.
+ * for (i = 0; i < 10000; i++)
+ * {
+ * mem[i] = g_slice_alloc (50);
+ *
+ * // Fill in the memory with some junk.
+ * for (j = 0; j < 50; j++)
+ * mem[i][j] = i * j;
+ * }
+ *
+ * // Now free all of the blocks.
+ * for (i = 0; i < 10000; i++)
+ * g_slice_free1 (50, mem[i]);
+ * ]|
+ *
+ * And here is an example for using the using the slice allocator
+ * with data structures:
+ * |[<!-- language="C" -->
+ * GRealArray *array;
+ *
+ * // Allocate one block, using the g_slice_new() macro.
+ * array = g_slice_new (GRealArray);
+
+ * // We can now use array just like a normal pointer to a structure.
+ * array->data = NULL;
+ * array->len = 0;
+ * array->alloc = 0;
+ * array->zero_terminated = (zero_terminated ? 1 : 0);
+ * array->clear = (clear ? 1 : 0);
+ * array->elt_size = elt_size;
+ *
+ * // We can free the block, so it can be reused.
+ * g_slice_free (GRealArray, array);
+ * ]|
+ */
+
/* the GSlice allocator is split up into 4 layers, roughly modelled after the slab
* allocator and magazine extensions as outlined in:
* + [Bonwick94] Jeff Bonwick, The slab allocator: An object-caching kernel
}
}
-static const gchar *
-getenv_nomalloc (const gchar *variable,
- gchar buffer[1024])
-{
- const gchar *retval = getenv (variable);
- if (retval && retval[0])
- {
- gint l = strlen (retval);
- if (l < 1024)
- {
- strncpy (buffer, retval, l);
- buffer[l] = 0;
- return buffer;
- }
- }
- return NULL;
-}
-
static void
slice_config_init (SliceConfig *config)
{
- /* don't use g_malloc/g_message here */
- gchar buffer[1024];
- const gchar *val = getenv_nomalloc ("G_SLICE", buffer);
- const GDebugKey keys[] = {
- { "always-malloc", 1 << 0 },
- { "debug-blocks", 1 << 1 },
- };
- gint flags = !val ? 0 : g_parse_debug_string (val, keys, G_N_ELEMENTS (keys));
+ const gchar *val;
+
*config = slice_config;
- if (flags & (1 << 0)) /* always-malloc */
- config->always_malloc = TRUE;
- if (flags & (1 << 1)) /* debug-blocks */
- config->debug_blocks = TRUE;
+
+ val = getenv ("G_SLICE");
+ if (val != NULL)
+ {
+ gint flags;
+ const GDebugKey keys[] = {
+ { "always-malloc", 1 << 0 },
+ { "debug-blocks", 1 << 1 },
+ };
+
+ flags = g_parse_debug_string (val, keys, G_N_ELEMENTS (keys));
+ if (flags & (1 << 0))
+ config->always_malloc = TRUE;
+ if (flags & (1 << 1))
+ config->debug_blocks = TRUE;
+ }
+ else
+ {
+ /* G_SLICE was not specified, so check if valgrind is running and
+ * disable ourselves if it is.
+ *
+ * This way it's possible to force gslice to be enabled under
+ * valgrind just by setting G_SLICE to the empty string.
+ */
+ if (RUNNING_ON_VALGRIND)
+ config->always_malloc = TRUE;
+ }
}
static void
* fit less than 8 times (see [4]) into 4KB pages.
* we allow very small page sizes here, to reduce wastage in
* threads if only small allocations are required (this does
- * bear the risk of incresing allocation times and fragmentation
+ * bear the risk of increasing allocation times and fragmentation
* though).
*/
allocator->min_page_size = MAX (allocator->min_page_size, 4096);
allocator->slab_stack = g_new0 (SlabInfo*, MAX_SLAB_INDEX (allocator));
}
- g_mutex_init (&allocator->magazine_mutex);
allocator->mutex_counter = 0;
allocator->stamp_counter = MAX_STAMP_COUNTER; /* force initial update */
allocator->last_stamp = 0;
- g_mutex_init (&allocator->slab_mutex);
allocator->color_accu = 0;
magazine_cache_update_stamp();
/* values cached for performance reasons */
}
/* --- API functions --- */
+
+/**
+ * g_slice_new:
+ * @type: the type to allocate, typically a structure name
+ *
+ * A convenience macro to allocate a block of memory from the
+ * slice allocator.
+ *
+ * It calls g_slice_alloc() with `sizeof (@type)` and casts the
+ * returned pointer to a pointer of the given type, avoiding a type
+ * cast in the source code. Note that the underlying slice allocation
+ * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
+ * environment variable.
+ *
+ * Returns: a pointer to the allocated block, cast to a pointer to @type
+ *
+ * Since: 2.10
+ */
+
+/**
+ * g_slice_new0:
+ * @type: the type to allocate, typically a structure name
+ *
+ * A convenience macro to allocate a block of memory from the
+ * slice allocator and set the memory to 0.
+ *
+ * It calls g_slice_alloc0() with `sizeof (@type)`
+ * and casts the returned pointer to a pointer of the given type,
+ * avoiding a type cast in the source code.
+ * Note that the underlying slice allocation mechanism can
+ * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
+ * environment variable.
+ *
+ * Since: 2.10
+ */
+
+/**
+ * g_slice_dup:
+ * @type: the type to duplicate, typically a structure name
+ * @mem: the memory to copy into the allocated block
+ *
+ * A convenience macro to duplicate a block of memory using
+ * the slice allocator.
+ *
+ * It calls g_slice_copy() with `sizeof (@type)`
+ * and casts the returned pointer to a pointer of the given type,
+ * avoiding a type cast in the source code.
+ * Note that the underlying slice allocation mechanism can
+ * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
+ * environment variable.
+ *
+ * Returns: a pointer to the allocated block, cast to a pointer to @type
+ *
+ * Since: 2.14
+ */
+
+/**
+ * g_slice_free:
+ * @type: the type of the block to free, typically a structure name
+ * @mem: a pointer to the block to free
+ *
+ * A convenience macro to free a block of memory that has
+ * been allocated from the slice allocator.
+ *
+ * It calls g_slice_free1() using `sizeof (type)`
+ * as the block size.
+ * Note that the exact release behaviour can be changed with the
+ * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
+ * [`G_SLICE`][G_SLICE] for related debugging options.
+ *
+ * Since: 2.10
+ */
+
+/**
+ * g_slice_free_chain:
+ * @type: the type of the @mem_chain blocks
+ * @mem_chain: a pointer to the first block of the chain
+ * @next: the field name of the next pointer in @type
+ *
+ * Frees a linked list of memory blocks of structure type @type.
+ * The memory blocks must be equal-sized, allocated via
+ * g_slice_alloc() or g_slice_alloc0() and linked together by
+ * a @next pointer (similar to #GSList). The name of the
+ * @next field in @type is passed as third argument.
+ * Note that the exact release behaviour can be changed with the
+ * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
+ * [`G_SLICE`][G_SLICE] for related debugging options.
+ *
+ * Since: 2.10
+ */
+
+/**
+ * g_slice_alloc:
+ * @block_size: the number of bytes to allocate
+ *
+ * Allocates a block of memory from the slice allocator.
+ * The block adress handed out can be expected to be aligned
+ * to at least 1 * sizeof (void*),
+ * though in general slices are 2 * sizeof (void*) bytes aligned,
+ * if a malloc() fallback implementation is used instead,
+ * the alignment may be reduced in a libc dependent fashion.
+ * Note that the underlying slice allocation mechanism can
+ * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
+ * environment variable.
+ *
+ * Returns: a pointer to the allocated memory block
+ *
+ * Since: 2.10
+ */
gpointer
g_slice_alloc (gsize mem_size)
{
return mem;
}
+/**
+ * g_slice_alloc0:
+ * @block_size: the number of bytes to allocate
+ *
+ * Allocates a block of memory via g_slice_alloc() and initializes
+ * the returned memory to 0. Note that the underlying slice allocation
+ * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
+ * environment variable.
+ *
+ * Returns: a pointer to the allocated block
+ *
+ * Since: 2.10
+ */
gpointer
g_slice_alloc0 (gsize mem_size)
{
return mem;
}
+/**
+ * g_slice_copy:
+ * @block_size: the number of bytes to allocate
+ * @mem_block: the memory to copy
+ *
+ * Allocates a block of memory from the slice allocator
+ * and copies @block_size bytes into it from @mem_block.
+ *
+ * Returns: a pointer to the allocated memory block
+ *
+ * Since: 2.14
+ */
gpointer
g_slice_copy (gsize mem_size,
gconstpointer mem_block)
return mem;
}
+/**
+ * g_slice_free1:
+ * @block_size: the size of the block
+ * @mem_block: a pointer to the block to free
+ *
+ * Frees a block of memory.
+ *
+ * The memory must have been allocated via g_slice_alloc() or
+ * g_slice_alloc0() and the @block_size has to match the size
+ * specified upon allocation. Note that the exact release behaviour
+ * can be changed with the [`G_DEBUG=gc-friendly`][G_DEBUG] environment
+ * variable, also see [`G_SLICE`][G_SLICE] for related debugging options.
+ *
+ * Since: 2.10
+ */
void
g_slice_free1 (gsize mem_size,
gpointer mem_block)
TRACE (GLIB_SLICE_FREE((void*)mem_block, mem_size));
}
+/**
+ * g_slice_free_chain_with_offset:
+ * @block_size: the size of the blocks
+ * @mem_chain: a pointer to the first block of the chain
+ * @next_offset: the offset of the @next field in the blocks
+ *
+ * Frees a linked list of memory blocks of structure type @type.
+ *
+ * The memory blocks must be equal-sized, allocated via
+ * g_slice_alloc() or g_slice_alloc0() and linked together by a
+ * @next pointer (similar to #GSList). The offset of the @next
+ * field in each block is passed as third argument.
+ * Note that the exact release behaviour can be changed with the
+ * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
+ * [`G_SLICE`][G_SLICE] for related debugging options.
+ *
+ * Since: 2.10
+ */
void
g_slice_free_chain_with_offset (gsize mem_size,
gpointer mem_chain,
guint i;
if (!mem)
{
- const gchar *syserr = "unknown error";
-#if HAVE_STRERROR
- syserr = strerror (errno);
-#endif
+ const gchar *syserr = strerror (errno);
mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
(guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr);
}
/* --- g-slice memory checker tree implementation --- */
#define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */
#define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */
-#define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key adress space per trunk, should distribute uniformly across BRANCH_COUNT */
+#define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key address space per trunk, should distribute uniformly across BRANCH_COUNT */
#define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */
#define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT)
static void
smc_tree_abort (int errval)
{
- const char *syserr = "unknown error";
-#if HAVE_STRERROR
- syserr = strerror (errval);
-#endif
+ const char *syserr = strerror (errval);
mem_error ("MemChecker: failure in debugging tree: %s", syserr);
}
if (!branch->entries)
smc_tree_abort (errno);
entry = branch->entries + index;
- g_memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
+ memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
branch->n_entries += 1;
return entry;
}
{
unsigned int i = entry - smc_tree_root[ix0][ix1].entries;
smc_tree_root[ix0][ix1].n_entries -= 1;
- g_memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0]));
+ memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0]));
if (!smc_tree_root[ix0][ix1].n_entries)
{
/* avoid useless pressure on the memory system */
projects / platform / upstream / glib.git / blobdiff