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glib/glib/gslice.c
Philip Withnall 25a7c817d3 glib: Add missing (nullable) and (optional) annotations 
Add various (nullable) and (optional) annotations which were missing
from a variety of functions. Also port a couple of existing (allow-none)
annotations in the same files to use (nullable) and (optional) as
appropriate instead.

Secondly, add various (not nullable) annotations as needed by the new
default in gobject-introspection of marking gpointers as (nullable). See
https://bugzilla.gnome.org/show_bug.cgi?id=729660.

This includes adding some stub documentation comments for the
assertion macro error functions, which weren’t previously documented.
The new comments are purely to allow for annotations, and hence are
marked as (skip) to prevent the symbols appearing in the GIR file.

https://bugzilla.gnome.org/show_bug.cgi?id=719966
2015-11-07 10:48:32 +01:00

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/* GLIB sliced memory - fast concurrent memory chunk allocator
* Copyright (C) 2005 Tim Janik
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* 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, see <http://www.gnu.org/licenses/>.
*/
/* MT safe */
#include "config.h"
#include "glibconfig.h"
#if defined HAVE_POSIX_MEMALIGN && defined POSIX_MEMALIGN_WITH_COMPLIANT_ALLOCS
# define HAVE_COMPLIANT_POSIX_MEMALIGN 1
#endif
#if defined(HAVE_COMPLIANT_POSIX_MEMALIGN) && !defined(_XOPEN_SOURCE)
#define _XOPEN_SOURCE 600 /* posix_memalign() */
#endif
#include <stdlib.h> /* posix_memalign() */
#include <string.h>
#include <errno.h>
#ifdef G_OS_UNIX
#include <unistd.h> /* sysconf() */
#endif
#ifdef G_OS_WIN32
#include <windows.h>
#include <process.h>
#endif
#include <stdio.h> /* fputs/fprintf */
#include "gslice.h"
#include "gmain.h"
#include "gmem.h" /* gslice.h */
#include "gstrfuncs.h"
#include "gutils.h"
#include "gtrashstack.h"
#include "gtestutils.h"
#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
* memory allocator. USENIX 1994, http://citeseer.ist.psu.edu/bonwick94slab.html
* + [Bonwick01] Bonwick and Jonathan Adams, Magazines and vmem: Extending the
* slab allocator to many cpu's and arbitrary resources.
* USENIX 2001, http://citeseer.ist.psu.edu/bonwick01magazines.html
* the layers are:
* - the thread magazines. for each (aligned) chunk size, a magazine (a list)
* of recently freed and soon to be allocated chunks is maintained per thread.
* this way, most alloc/free requests can be quickly satisfied from per-thread
* free lists which only require one g_private_get() call to retrive the
* thread handle.
* - the magazine cache. allocating and freeing chunks to/from threads only
* occours at magazine sizes from a global depot of magazines. the depot
* maintaines a 15 second working set of allocated magazines, so full
* magazines are not allocated and released too often.
* the chunk size dependent magazine sizes automatically adapt (within limits,
* see [3]) to lock contention to properly scale performance across a variety
* of SMP systems.
* - the slab allocator. this allocator allocates slabs (blocks of memory) close
* to the system page size or multiples thereof which have to be page aligned.
* the blocks are divided into smaller chunks which are used to satisfy
* allocations from the upper layers. the space provided by the reminder of
* the chunk size division is used for cache colorization (random distribution
* of chunk addresses) to improve processor cache utilization. multiple slabs
* with the same chunk size are kept in a partially sorted ring to allow O(1)
* freeing and allocation of chunks (as long as the allocation of an entirely
* new slab can be avoided).
* - the page allocator. on most modern systems, posix_memalign(3) or
* memalign(3) should be available, so this is used to allocate blocks with
* system page size based alignments and sizes or multiples thereof.
* if no memalign variant is provided, valloc() is used instead and
* block sizes are limited to the system page size (no multiples thereof).
* as a fallback, on system without even valloc(), a malloc(3)-based page
* allocator with alloc-only behaviour is used.
*
* NOTES:
* [1] some systems memalign(3) implementations may rely on boundary tagging for
* the handed out memory chunks. to avoid excessive page-wise fragmentation,
* we reserve 2 * sizeof (void*) per block size for the systems memalign(3),
* specified in NATIVE_MALLOC_PADDING.
* [2] using the slab allocator alone already provides for a fast and efficient
* allocator, it doesn't properly scale beyond single-threaded uses though.
* also, the slab allocator implements eager free(3)-ing, i.e. does not
* provide any form of caching or working set maintenance. so if used alone,
* it's vulnerable to trashing for sequences of balanced (alloc, free) pairs
* at certain thresholds.
* [3] magazine sizes are bound by an implementation specific minimum size and
* a chunk size specific maximum to limit magazine storage sizes to roughly
* 16KB.
* [4] allocating ca. 8 chunks per block/page keeps a good balance between
* external and internal fragmentation (<= 12.5%). [Bonwick94]
*/
/* --- macros and constants --- */
#define LARGEALIGNMENT (256)
#define P2ALIGNMENT (2 * sizeof (gsize)) /* fits 2 pointers (assumed to be 2 * GLIB_SIZEOF_SIZE_T below) */
#define ALIGN(size, base) ((base) * (gsize) (((size) + (base) - 1) / (base)))
#define NATIVE_MALLOC_PADDING P2ALIGNMENT /* per-page padding left for native malloc(3) see [1] */
#define SLAB_INFO_SIZE P2ALIGN (sizeof (SlabInfo) + NATIVE_MALLOC_PADDING)
#define MAX_MAGAZINE_SIZE (256) /* see [3] and allocator_get_magazine_threshold() for this */
#define MIN_MAGAZINE_SIZE (4)
#define MAX_STAMP_COUNTER (7) /* distributes the load of gettimeofday() */
#define MAX_SLAB_CHUNK_SIZE(al) (((al)->max_page_size - SLAB_INFO_SIZE) / 8) /* we want at last 8 chunks per page, see [4] */
#define MAX_SLAB_INDEX(al) (SLAB_INDEX (al, MAX_SLAB_CHUNK_SIZE (al)) + 1)
#define SLAB_INDEX(al, asize) ((asize) / P2ALIGNMENT - 1) /* asize must be P2ALIGNMENT aligned */
#define SLAB_CHUNK_SIZE(al, ix) (((ix) + 1) * P2ALIGNMENT)
#define SLAB_BPAGE_SIZE(al,csz) (8 * (csz) + SLAB_INFO_SIZE)
/* optimized version of ALIGN (size, P2ALIGNMENT) */
#if GLIB_SIZEOF_SIZE_T * 2 == 8 /* P2ALIGNMENT */
#define P2ALIGN(size) (((size) + 0x7) & ~(gsize) 0x7)
#elif GLIB_SIZEOF_SIZE_T * 2 == 16 /* P2ALIGNMENT */
#define P2ALIGN(size) (((size) + 0xf) & ~(gsize) 0xf)
#else
#define P2ALIGN(size) ALIGN (size, P2ALIGNMENT)
#endif
/* special helpers to avoid gmessage.c dependency */
static void mem_error (const char *format, ...) G_GNUC_PRINTF (1,2);
#define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0)
/* --- structures --- */
typedef struct _ChunkLink ChunkLink;
typedef struct _SlabInfo SlabInfo;
typedef struct _CachedMagazine CachedMagazine;
struct _ChunkLink {
ChunkLink *next;
ChunkLink *data;
};
struct _SlabInfo {
ChunkLink *chunks;
guint n_allocated;
SlabInfo *next, *prev;
};
typedef struct {
ChunkLink *chunks;
gsize count; /* approximative chunks list length */
} Magazine;
typedef struct {
Magazine *magazine1; /* array of MAX_SLAB_INDEX (allocator) */
Magazine *magazine2; /* array of MAX_SLAB_INDEX (allocator) */
} ThreadMemory;
typedef struct {
gboolean always_malloc;
gboolean bypass_magazines;
gboolean debug_blocks;
gsize working_set_msecs;
guint color_increment;
} SliceConfig;
typedef struct {
/* const after initialization */
gsize min_page_size, max_page_size;
SliceConfig config;
gsize max_slab_chunk_size_for_magazine_cache;
/* magazine cache */
GMutex magazine_mutex;
ChunkLink **magazines; /* array of MAX_SLAB_INDEX (allocator) */
guint *contention_counters; /* array of MAX_SLAB_INDEX (allocator) */
gint mutex_counter;
guint stamp_counter;
guint last_stamp;
/* slab allocator */
GMutex slab_mutex;
SlabInfo **slab_stack; /* array of MAX_SLAB_INDEX (allocator) */
guint color_accu;
} Allocator;
/* --- g-slice prototypes --- */
static gpointer slab_allocator_alloc_chunk (gsize chunk_size);
static void slab_allocator_free_chunk (gsize chunk_size,
gpointer mem);
static void private_thread_memory_cleanup (gpointer data);
static gpointer allocator_memalign (gsize alignment,
gsize memsize);
static void allocator_memfree (gsize memsize,
gpointer mem);
static inline void magazine_cache_update_stamp (void);
static inline gsize allocator_get_magazine_threshold (Allocator *allocator,
guint ix);
/* --- g-slice memory checker --- */
static void smc_notify_alloc (void *pointer,
size_t size);
static int smc_notify_free (void *pointer,
size_t size);
/* --- variables --- */
static GPrivate private_thread_memory = G_PRIVATE_INIT (private_thread_memory_cleanup);
static gsize sys_page_size = 0;
static Allocator allocator[1] = { { 0, }, };
static SliceConfig slice_config = {
FALSE, /* always_malloc */
FALSE, /* bypass_magazines */
FALSE, /* debug_blocks */
15 * 1000, /* working_set_msecs */
1, /* color increment, alt: 0x7fffffff */
};
static GMutex smc_tree_mutex; /* mutex for G_SLICE=debug-blocks */
/* --- auxiliary funcitons --- */
void
g_slice_set_config (GSliceConfig ckey,
gint64 value)
{
g_return_if_fail (sys_page_size == 0);
switch (ckey)
{
case G_SLICE_CONFIG_ALWAYS_MALLOC:
slice_config.always_malloc = value != 0;
break;
case G_SLICE_CONFIG_BYPASS_MAGAZINES:
slice_config.bypass_magazines = value != 0;
break;
case G_SLICE_CONFIG_WORKING_SET_MSECS:
slice_config.working_set_msecs = value;
break;
case G_SLICE_CONFIG_COLOR_INCREMENT:
slice_config.color_increment = value;
default: ;
}
}
gint64
g_slice_get_config (GSliceConfig ckey)
{
switch (ckey)
{
case G_SLICE_CONFIG_ALWAYS_MALLOC:
return slice_config.always_malloc;
case G_SLICE_CONFIG_BYPASS_MAGAZINES:
return slice_config.bypass_magazines;
case G_SLICE_CONFIG_WORKING_SET_MSECS:
return slice_config.working_set_msecs;
case G_SLICE_CONFIG_CHUNK_SIZES:
return MAX_SLAB_INDEX (allocator);
case G_SLICE_CONFIG_COLOR_INCREMENT:
return slice_config.color_increment;
default:
return 0;
}
}
gint64*
g_slice_get_config_state (GSliceConfig ckey,
gint64 address,
guint *n_values)
{
guint i = 0;
g_return_val_if_fail (n_values != NULL, NULL);
*n_values = 0;
switch (ckey)
{
gint64 array[64];
case G_SLICE_CONFIG_CONTENTION_COUNTER:
array[i++] = SLAB_CHUNK_SIZE (allocator, address);
array[i++] = allocator->contention_counters[address];
array[i++] = allocator_get_magazine_threshold (allocator, address);
*n_values = i;
return g_memdup (array, sizeof (array[0]) * *n_values);
default:
return NULL;
}
}
static void
slice_config_init (SliceConfig *config)
{
const gchar *val;
*config = slice_config;
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
g_slice_init_nomessage (void)
{
/* we may not use g_error() or friends here */
mem_assert (sys_page_size == 0);
mem_assert (MIN_MAGAZINE_SIZE >= 4);
#ifdef G_OS_WIN32
{
SYSTEM_INFO system_info;
GetSystemInfo (&system_info);
sys_page_size = system_info.dwPageSize;
}
#else
sys_page_size = sysconf (_SC_PAGESIZE); /* = sysconf (_SC_PAGE_SIZE); = getpagesize(); */
#endif
mem_assert (sys_page_size >= 2 * LARGEALIGNMENT);
mem_assert ((sys_page_size & (sys_page_size - 1)) == 0);
slice_config_init (&allocator->config);
allocator->min_page_size = sys_page_size;
#if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN
/* allow allocation of pages up to 8KB (with 8KB alignment).
* this is useful because many medium to large sized structures
* 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 increasing allocation times and fragmentation
* though).
*/
allocator->min_page_size = MAX (allocator->min_page_size, 4096);
allocator->max_page_size = MAX (allocator->min_page_size, 8192);
allocator->min_page_size = MIN (allocator->min_page_size, 128);
#else
/* we can only align to system page size */
allocator->max_page_size = sys_page_size;
#endif
if (allocator->config.always_malloc)
{
allocator->contention_counters = NULL;
allocator->magazines = NULL;
allocator->slab_stack = NULL;
}
else
{
allocator->contention_counters = g_new0 (guint, MAX_SLAB_INDEX (allocator));
allocator->magazines = g_new0 (ChunkLink*, MAX_SLAB_INDEX (allocator));
allocator->slab_stack = g_new0 (SlabInfo*, MAX_SLAB_INDEX (allocator));
}
allocator->mutex_counter = 0;
allocator->stamp_counter = MAX_STAMP_COUNTER; /* force initial update */
allocator->last_stamp = 0;
allocator->color_accu = 0;
magazine_cache_update_stamp();
/* values cached for performance reasons */
allocator->max_slab_chunk_size_for_magazine_cache = MAX_SLAB_CHUNK_SIZE (allocator);
if (allocator->config.always_malloc || allocator->config.bypass_magazines)
allocator->max_slab_chunk_size_for_magazine_cache = 0; /* non-optimized cases */
}
static inline guint
allocator_categorize (gsize aligned_chunk_size)
{
/* speed up the likely path */
if (G_LIKELY (aligned_chunk_size && aligned_chunk_size <= allocator->max_slab_chunk_size_for_magazine_cache))
return 1; /* use magazine cache */
if (!allocator->config.always_malloc &&
aligned_chunk_size &&
aligned_chunk_size <= MAX_SLAB_CHUNK_SIZE (allocator))
{
if (allocator->config.bypass_magazines)
return 2; /* use slab allocator, see [2] */
return 1; /* use magazine cache */
}
return 0; /* use malloc() */
}
static inline void
g_mutex_lock_a (GMutex *mutex,
guint *contention_counter)
{
gboolean contention = FALSE;
if (!g_mutex_trylock (mutex))
{
g_mutex_lock (mutex);
contention = TRUE;
}
if (contention)
{
allocator->mutex_counter++;
if (allocator->mutex_counter >= 1) /* quickly adapt to contention */
{
allocator->mutex_counter = 0;
*contention_counter = MIN (*contention_counter + 1, MAX_MAGAZINE_SIZE);
}
}
else /* !contention */
{
allocator->mutex_counter--;
if (allocator->mutex_counter < -11) /* moderately recover magazine sizes */
{
allocator->mutex_counter = 0;
*contention_counter = MAX (*contention_counter, 1) - 1;
}
}
}
static inline ThreadMemory*
thread_memory_from_self (void)
{
ThreadMemory *tmem = g_private_get (&private_thread_memory);
if (G_UNLIKELY (!tmem))
{
static GMutex init_mutex;
guint n_magazines;
g_mutex_lock (&init_mutex);
if G_UNLIKELY (sys_page_size == 0)
g_slice_init_nomessage ();
g_mutex_unlock (&init_mutex);
n_magazines = MAX_SLAB_INDEX (allocator);
tmem = g_malloc0 (sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
tmem->magazine1 = (Magazine*) (tmem + 1);
tmem->magazine2 = &tmem->magazine1[n_magazines];
g_private_set (&private_thread_memory, tmem);
}
return tmem;
}
static inline ChunkLink*
magazine_chain_pop_head (ChunkLink **magazine_chunks)
{
/* magazine chains are linked via ChunkLink->next.
* each ChunkLink->data of the toplevel chain may point to a subchain,
* linked via ChunkLink->next. ChunkLink->data of the subchains just
* contains uninitialized junk.
*/
ChunkLink *chunk = (*magazine_chunks)->data;
if (G_UNLIKELY (chunk))
{
/* allocating from freed list */
(*magazine_chunks)->data = chunk->next;
}
else
{
chunk = *magazine_chunks;
*magazine_chunks = chunk->next;
}
return chunk;
}
#if 0 /* useful for debugging */
static guint
magazine_count (ChunkLink *head)
{
guint count = 0;
if (!head)
return 0;
while (head)
{
ChunkLink *child = head->data;
count += 1;
for (child = head->data; child; child = child->next)
count += 1;
head = head->next;
}
return count;
}
#endif
static inline gsize
allocator_get_magazine_threshold (Allocator *allocator,
guint ix)
{
/* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE,
* which is required by the implementation. also, for moderately sized chunks
* (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number
* of chunks available per page/2 to avoid excessive traffic in the magazine
* cache for small to medium sized structures.
* the upper bound of the magazine size is effectively provided by
* MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that
* the content of a single magazine doesn't exceed ca. 16KB.
*/
gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
guint threshold = MAX (MIN_MAGAZINE_SIZE, allocator->max_page_size / MAX (5 * chunk_size, 5 * 32));
guint contention_counter = allocator->contention_counters[ix];
if (G_UNLIKELY (contention_counter)) /* single CPU bias */
{
/* adapt contention counter thresholds to chunk sizes */
contention_counter = contention_counter * 64 / chunk_size;
threshold = MAX (threshold, contention_counter);
}
return threshold;
}
/* --- magazine cache --- */
static inline void
magazine_cache_update_stamp (void)
{
if (allocator->stamp_counter >= MAX_STAMP_COUNTER)
{
GTimeVal tv;
g_get_current_time (&tv);
allocator->last_stamp = tv.tv_sec * 1000 + tv.tv_usec / 1000; /* milli seconds */
allocator->stamp_counter = 0;
}
else
allocator->stamp_counter++;
}
static inline ChunkLink*
magazine_chain_prepare_fields (ChunkLink *magazine_chunks)
{
ChunkLink *chunk1;
ChunkLink *chunk2;
ChunkLink *chunk3;
ChunkLink *chunk4;
/* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */
/* ensure a magazine with at least 4 unused data pointers */
chunk1 = magazine_chain_pop_head (&magazine_chunks);
chunk2 = magazine_chain_pop_head (&magazine_chunks);
chunk3 = magazine_chain_pop_head (&magazine_chunks);
chunk4 = magazine_chain_pop_head (&magazine_chunks);
chunk4->next = magazine_chunks;
chunk3->next = chunk4;
chunk2->next = chunk3;
chunk1->next = chunk2;
return chunk1;
}
/* access the first 3 fields of a specially prepared magazine chain */
#define magazine_chain_prev(mc) ((mc)->data)
#define magazine_chain_stamp(mc) ((mc)->next->data)
#define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data)
#define magazine_chain_next(mc) ((mc)->next->next->data)
#define magazine_chain_count(mc) ((mc)->next->next->next->data)
static void
magazine_cache_trim (Allocator *allocator,
guint ix,
guint stamp)
{
/* g_mutex_lock (allocator->mutex); done by caller */
/* trim magazine cache from tail */
ChunkLink *current = magazine_chain_prev (allocator->magazines[ix]);
ChunkLink *trash = NULL;
while (ABS (stamp - magazine_chain_uint_stamp (current)) >= allocator->config.working_set_msecs)
{
/* unlink */
ChunkLink *prev = magazine_chain_prev (current);
ChunkLink *next = magazine_chain_next (current);
magazine_chain_next (prev) = next;
magazine_chain_prev (next) = prev;
/* clear special fields, put on trash stack */
magazine_chain_next (current) = NULL;
magazine_chain_count (current) = NULL;
magazine_chain_stamp (current) = NULL;
magazine_chain_prev (current) = trash;
trash = current;
/* fixup list head if required */
if (current == allocator->magazines[ix])
{
allocator->magazines[ix] = NULL;
break;
}
current = prev;
}
g_mutex_unlock (&allocator->magazine_mutex);
/* free trash */
if (trash)
{
const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
g_mutex_lock (&allocator->slab_mutex);
while (trash)
{
current = trash;
trash = magazine_chain_prev (current);
magazine_chain_prev (current) = NULL; /* clear special field */
while (current)
{
ChunkLink *chunk = magazine_chain_pop_head (&current);
slab_allocator_free_chunk (chunk_size, chunk);
}
}
g_mutex_unlock (&allocator->slab_mutex);
}
}
static void
magazine_cache_push_magazine (guint ix,
ChunkLink *magazine_chunks,
gsize count) /* must be >= MIN_MAGAZINE_SIZE */
{
ChunkLink *current = magazine_chain_prepare_fields (magazine_chunks);
ChunkLink *next, *prev;
g_mutex_lock (&allocator->magazine_mutex);
/* add magazine at head */
next = allocator->magazines[ix];
if (next)
prev = magazine_chain_prev (next);
else
next = prev = current;
magazine_chain_next (prev) = current;
magazine_chain_prev (next) = current;
magazine_chain_prev (current) = prev;
magazine_chain_next (current) = next;
magazine_chain_count (current) = (gpointer) count;
/* stamp magazine */
magazine_cache_update_stamp();
magazine_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp);
allocator->magazines[ix] = current;
/* free old magazines beyond a certain threshold */
magazine_cache_trim (allocator, ix, allocator->last_stamp);
/* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */
}
static ChunkLink*
magazine_cache_pop_magazine (guint ix,
gsize *countp)
{
g_mutex_lock_a (&allocator->magazine_mutex, &allocator->contention_counters[ix]);
if (!allocator->magazines[ix])
{
guint magazine_threshold = allocator_get_magazine_threshold (allocator, ix);
gsize i, chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
ChunkLink *chunk, *head;
g_mutex_unlock (&allocator->magazine_mutex);
g_mutex_lock (&allocator->slab_mutex);
head = slab_allocator_alloc_chunk (chunk_size);
head->data = NULL;
chunk = head;
for (i = 1; i < magazine_threshold; i++)
{
chunk->next = slab_allocator_alloc_chunk (chunk_size);
chunk = chunk->next;
chunk->data = NULL;
}
chunk->next = NULL;
g_mutex_unlock (&allocator->slab_mutex);
*countp = i;
return head;
}
else
{
ChunkLink *current = allocator->magazines[ix];
ChunkLink *prev = magazine_chain_prev (current);
ChunkLink *next = magazine_chain_next (current);
/* unlink */
magazine_chain_next (prev) = next;
magazine_chain_prev (next) = prev;
allocator->magazines[ix] = next == current ? NULL : next;
g_mutex_unlock (&allocator->magazine_mutex);
/* clear special fields and hand out */
*countp = (gsize) magazine_chain_count (current);
magazine_chain_prev (current) = NULL;
magazine_chain_next (current) = NULL;
magazine_chain_count (current) = NULL;
magazine_chain_stamp (current) = NULL;
return current;
}
}
/* --- thread magazines --- */
static void
private_thread_memory_cleanup (gpointer data)
{
ThreadMemory *tmem = data;
const guint n_magazines = MAX_SLAB_INDEX (allocator);
guint ix;
for (ix = 0; ix < n_magazines; ix++)
{
Magazine *mags[2];
guint j;
mags[0] = &tmem->magazine1[ix];
mags[1] = &tmem->magazine2[ix];
for (j = 0; j < 2; j++)
{
Magazine *mag = mags[j];
if (mag->count >= MIN_MAGAZINE_SIZE)
magazine_cache_push_magazine (ix, mag->chunks, mag->count);
else
{
const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
g_mutex_lock (&allocator->slab_mutex);
while (mag->chunks)
{
ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
slab_allocator_free_chunk (chunk_size, chunk);
}
g_mutex_unlock (&allocator->slab_mutex);
}
}
}
g_free (tmem);
}
static void
thread_memory_magazine1_reload (ThreadMemory *tmem,
guint ix)
{
Magazine *mag = &tmem->magazine1[ix];
mem_assert (mag->chunks == NULL); /* ensure that we may reset mag->count */
mag->count = 0;
mag->chunks = magazine_cache_pop_magazine (ix, &mag->count);
}
static void
thread_memory_magazine2_unload (ThreadMemory *tmem,
guint ix)
{
Magazine *mag = &tmem->magazine2[ix];
magazine_cache_push_magazine (ix, mag->chunks, mag->count);
mag->chunks = NULL;
mag->count = 0;
}
static inline void
thread_memory_swap_magazines (ThreadMemory *tmem,
guint ix)
{
Magazine xmag = tmem->magazine1[ix];
tmem->magazine1[ix] = tmem->magazine2[ix];
tmem->magazine2[ix] = xmag;
}
static inline gboolean
thread_memory_magazine1_is_empty (ThreadMemory *tmem,
guint ix)
{
return tmem->magazine1[ix].chunks == NULL;
}
static inline gboolean
thread_memory_magazine2_is_full (ThreadMemory *tmem,
guint ix)
{
return tmem->magazine2[ix].count >= allocator_get_magazine_threshold (allocator, ix);
}
static inline gpointer
thread_memory_magazine1_alloc (ThreadMemory *tmem,
guint ix)
{
Magazine *mag = &tmem->magazine1[ix];
ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
if (G_LIKELY (mag->count > 0))
mag->count--;
return chunk;
}
static inline void
thread_memory_magazine2_free (ThreadMemory *tmem,
guint ix,
gpointer mem)
{
Magazine *mag = &tmem->magazine2[ix];
ChunkLink *chunk = mem;
chunk->data = NULL;
chunk->next = mag->chunks;
mag->chunks = chunk;
mag->count++;
}
/* --- 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.
*
* This can never return %NULL as the minimum allocation size from
* `sizeof (@type)` is 1 byte.
*
* Returns: (not nullable): 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.
*
* This can never return %NULL as the minimum allocation size from
* `sizeof (@type)` is 1 byte.
*
* Returns: (not nullable): a pointer to the allocated block, cast to a pointer
* to @type
*
* Since: 2.10
*/
/**
* g_slice_dup:
* @type: the type to duplicate, typically a structure name
* @mem: (not nullable): 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.
*
* This can never return %NULL.
*
* Returns: (not nullable): 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.
*
* If @mem is %NULL, this macro does nothing.
*
* 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.
*
* If @mem_chain is %NULL, this function does nothing.
*
* 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, which will be %NULL if and
* only if @mem_size is 0
*
* Since: 2.10
*/
gpointer
g_slice_alloc (gsize mem_size)
{
ThreadMemory *tmem;
gsize chunk_size;
gpointer mem;
guint acat;
/* This gets the private structure for this thread. If the private
* structure does not yet exist, it is created.
*
* This has a side effect of causing GSlice to be initialised, so it
* must come first.
*/
tmem = thread_memory_from_self ();
chunk_size = P2ALIGN (mem_size);
acat = allocator_categorize (chunk_size);
if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
{
guint ix = SLAB_INDEX (allocator, chunk_size);
if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
{
thread_memory_swap_magazines (tmem, ix);
if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
thread_memory_magazine1_reload (tmem, ix);
}
mem = thread_memory_magazine1_alloc (tmem, ix);
}
else if (acat == 2) /* allocate through slab allocator */
{
g_mutex_lock (&allocator->slab_mutex);
mem = slab_allocator_alloc_chunk (chunk_size);
g_mutex_unlock (&allocator->slab_mutex);
}
else /* delegate to system malloc */
mem = g_malloc (mem_size);
if (G_UNLIKELY (allocator->config.debug_blocks))
smc_notify_alloc (mem, mem_size);
TRACE (GLIB_SLICE_ALLOC((void*)mem, 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, which will be %NULL if and only
* if @mem_size is 0
*
* Since: 2.10
*/
gpointer
g_slice_alloc0 (gsize mem_size)
{
gpointer mem = g_slice_alloc (mem_size);
if (mem)
memset (mem, 0, 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.
*
* @mem_block must be non-%NULL if @block_size is non-zero.
*
* Returns: a pointer to the allocated memory block, which will be %NULL if and
* only if @mem_size is 0
*
* Since: 2.14
*/
gpointer
g_slice_copy (gsize mem_size,
gconstpointer mem_block)
{
gpointer mem = g_slice_alloc (mem_size);
if (mem)
memcpy (mem, mem_block, mem_size);
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.
*
* If @mem_block is %NULL, this function does nothing.
*
* Since: 2.10
*/
void
g_slice_free1 (gsize mem_size,
gpointer mem_block)
{
gsize chunk_size = P2ALIGN (mem_size);
guint acat = allocator_categorize (chunk_size);
if (G_UNLIKELY (!mem_block))
return;
if (G_UNLIKELY (allocator->config.debug_blocks) &&
!smc_notify_free (mem_block, mem_size))
abort();
if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
{
ThreadMemory *tmem = thread_memory_from_self();
guint ix = SLAB_INDEX (allocator, chunk_size);
if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
{
thread_memory_swap_magazines (tmem, ix);
if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
thread_memory_magazine2_unload (tmem, ix);
}
if (G_UNLIKELY (g_mem_gc_friendly))
memset (mem_block, 0, chunk_size);
thread_memory_magazine2_free (tmem, ix, mem_block);
}
else if (acat == 2) /* allocate through slab allocator */
{
if (G_UNLIKELY (g_mem_gc_friendly))
memset (mem_block, 0, chunk_size);
g_mutex_lock (&allocator->slab_mutex);
slab_allocator_free_chunk (chunk_size, mem_block);
g_mutex_unlock (&allocator->slab_mutex);
}
else /* delegate to system malloc */
{
if (G_UNLIKELY (g_mem_gc_friendly))
memset (mem_block, 0, mem_size);
g_free (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.
*
* If @mem_chain is %NULL, this function does nothing.
*
* Since: 2.10
*/
void
g_slice_free_chain_with_offset (gsize mem_size,
gpointer mem_chain,
gsize next_offset)
{
gpointer slice = mem_chain;
/* while the thread magazines and the magazine cache are implemented so that
* they can easily be extended to allow for free lists containing more free
* lists for the first level nodes, which would allow O(1) freeing in this
* function, the benefit of such an extension is questionable, because:
* - the magazine size counts will become mere lower bounds which confuses
* the code adapting to lock contention;
* - freeing a single node to the thread magazines is very fast, so this
* O(list_length) operation is multiplied by a fairly small factor;
* - memory usage histograms on larger applications seem to indicate that
* the amount of released multi node lists is negligible in comparison
* to single node releases.
* - the major performance bottle neck, namely g_private_get() or
* g_mutex_lock()/g_mutex_unlock() has already been moved out of the
* inner loop for freeing chained slices.
*/
gsize chunk_size = P2ALIGN (mem_size);
guint acat = allocator_categorize (chunk_size);
if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
{
ThreadMemory *tmem = thread_memory_from_self();
guint ix = SLAB_INDEX (allocator, chunk_size);
while (slice)
{
guint8 *current = slice;
slice = *(gpointer*) (current + next_offset);
if (G_UNLIKELY (allocator->config.debug_blocks) &&
!smc_notify_free (current, mem_size))
abort();
if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
{
thread_memory_swap_magazines (tmem, ix);
if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
thread_memory_magazine2_unload (tmem, ix);
}
if (G_UNLIKELY (g_mem_gc_friendly))
memset (current, 0, chunk_size);
thread_memory_magazine2_free (tmem, ix, current);
}
}
else if (acat == 2) /* allocate through slab allocator */
{
g_mutex_lock (&allocator->slab_mutex);
while (slice)
{
guint8 *current = slice;
slice = *(gpointer*) (current + next_offset);
if (G_UNLIKELY (allocator->config.debug_blocks) &&
!smc_notify_free (current, mem_size))
abort();
if (G_UNLIKELY (g_mem_gc_friendly))
memset (current, 0, chunk_size);
slab_allocator_free_chunk (chunk_size, current);
}
g_mutex_unlock (&allocator->slab_mutex);
}
else /* delegate to system malloc */
while (slice)
{
guint8 *current = slice;
slice = *(gpointer*) (current + next_offset);
if (G_UNLIKELY (allocator->config.debug_blocks) &&
!smc_notify_free (current, mem_size))
abort();
if (G_UNLIKELY (g_mem_gc_friendly))
memset (current, 0, mem_size);
g_free (current);
}
}
/* --- single page allocator --- */
static void
allocator_slab_stack_push (Allocator *allocator,
guint ix,
SlabInfo *sinfo)
{
/* insert slab at slab ring head */
if (!allocator->slab_stack[ix])
{
sinfo->next = sinfo;
sinfo->prev = sinfo;
}
else
{
SlabInfo *next = allocator->slab_stack[ix], *prev = next->prev;
next->prev = sinfo;
prev->next = sinfo;
sinfo->next = next;
sinfo->prev = prev;
}
allocator->slab_stack[ix] = sinfo;
}
static gsize
allocator_aligned_page_size (Allocator *allocator,
gsize n_bytes)
{
gsize val = 1 << g_bit_storage (n_bytes - 1);
val = MAX (val, allocator->min_page_size);
return val;
}
static void
allocator_add_slab (Allocator *allocator,
guint ix,
gsize chunk_size)
{
ChunkLink *chunk;
SlabInfo *sinfo;
gsize addr, padding, n_chunks, color = 0;
gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
/* allocate 1 page for the chunks and the slab */
gpointer aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING);
guint8 *mem = aligned_memory;
guint i;
if (!mem)
{
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);
}
/* mask page address */
addr = ((gsize) mem / page_size) * page_size;
/* assert alignment */
mem_assert (aligned_memory == (gpointer) addr);
/* basic slab info setup */
sinfo = (SlabInfo*) (mem + page_size - SLAB_INFO_SIZE);
sinfo->n_allocated = 0;
sinfo->chunks = NULL;
/* figure cache colorization */
n_chunks = ((guint8*) sinfo - mem) / chunk_size;
padding = ((guint8*) sinfo - mem) - n_chunks * chunk_size;
if (padding)
{
color = (allocator->color_accu * P2ALIGNMENT) % padding;
allocator->color_accu += allocator->config.color_increment;
}
/* add chunks to free list */
chunk = (ChunkLink*) (mem + color);
sinfo->chunks = chunk;
for (i = 0; i < n_chunks - 1; i++)
{
chunk->next = (ChunkLink*) ((guint8*) chunk + chunk_size);
chunk = chunk->next;
}
chunk->next = NULL; /* last chunk */
/* add slab to slab ring */
allocator_slab_stack_push (allocator, ix, sinfo);
}
static gpointer
slab_allocator_alloc_chunk (gsize chunk_size)
{
ChunkLink *chunk;
guint ix = SLAB_INDEX (allocator, chunk_size);
/* ensure non-empty slab */
if (!allocator->slab_stack[ix] || !allocator->slab_stack[ix]->chunks)
allocator_add_slab (allocator, ix, chunk_size);
/* allocate chunk */
chunk = allocator->slab_stack[ix]->chunks;
allocator->slab_stack[ix]->chunks = chunk->next;
allocator->slab_stack[ix]->n_allocated++;
/* rotate empty slabs */
if (!allocator->slab_stack[ix]->chunks)
allocator->slab_stack[ix] = allocator->slab_stack[ix]->next;
return chunk;
}
static void
slab_allocator_free_chunk (gsize chunk_size,
gpointer mem)
{
ChunkLink *chunk;
gboolean was_empty;
guint ix = SLAB_INDEX (allocator, chunk_size);
gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
gsize addr = ((gsize) mem / page_size) * page_size;
/* mask page address */
guint8 *page = (guint8*) addr;
SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE);
/* assert valid chunk count */
mem_assert (sinfo->n_allocated > 0);
/* add chunk to free list */
was_empty = sinfo->chunks == NULL;
chunk = (ChunkLink*) mem;
chunk->next = sinfo->chunks;
sinfo->chunks = chunk;
sinfo->n_allocated--;
/* keep slab ring partially sorted, empty slabs at end */
if (was_empty)
{
/* unlink slab */
SlabInfo *next = sinfo->next, *prev = sinfo->prev;
next->prev = prev;
prev->next = next;
if (allocator->slab_stack[ix] == sinfo)
allocator->slab_stack[ix] = next == sinfo ? NULL : next;
/* insert slab at head */
allocator_slab_stack_push (allocator, ix, sinfo);
}
/* eagerly free complete unused slabs */
if (!sinfo->n_allocated)
{
/* unlink slab */
SlabInfo *next = sinfo->next, *prev = sinfo->prev;
next->prev = prev;
prev->next = next;
if (allocator->slab_stack[ix] == sinfo)
allocator->slab_stack[ix] = next == sinfo ? NULL : next;
/* free slab */
allocator_memfree (page_size, page);
}
}
/* --- memalign implementation --- */
#ifdef HAVE_MALLOC_H
#include <malloc.h> /* memalign() */
#endif
/* from config.h:
* define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
* define HAVE_COMPLIANT_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works for sizes != 2^n, <stdlib.h>
* define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
* define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
* if none is provided, we implement malloc(3)-based alloc-only page alignment
*/
#if !(HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
static GTrashStack *compat_valloc_trash = NULL;
#endif
static gpointer
allocator_memalign (gsize alignment,
gsize memsize)
{
gpointer aligned_memory = NULL;
gint err = ENOMEM;
#if HAVE_COMPLIANT_POSIX_MEMALIGN
err = posix_memalign (&aligned_memory, alignment, memsize);
#elif HAVE_MEMALIGN
errno = 0;
aligned_memory = memalign (alignment, memsize);
err = errno;
#elif HAVE_VALLOC
errno = 0;
aligned_memory = valloc (memsize);
err = errno;
#else
/* simplistic non-freeing page allocator */
mem_assert (alignment == sys_page_size);
mem_assert (memsize <= sys_page_size);
if (!compat_valloc_trash)
{
const guint n_pages = 16;
guint8 *mem = malloc (n_pages * sys_page_size);
err = errno;
if (mem)
{
gint i = n_pages;
guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size);
if (amem != mem)
i--; /* mem wasn't page aligned */
while (--i >= 0)
g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size);
}
}
aligned_memory = g_trash_stack_pop (&compat_valloc_trash);
#endif
if (!aligned_memory)
errno = err;
return aligned_memory;
}
static void
allocator_memfree (gsize memsize,
gpointer mem)
{
#if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC
free (mem);
#else
mem_assert (memsize <= sys_page_size);
g_trash_stack_push (&compat_valloc_trash, mem);
#endif
}
static void
mem_error (const char *format,
...)
{
const char *pname;
va_list args;
/* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */
fputs ("\n***MEMORY-ERROR***: ", stderr);
pname = g_get_prgname();
fprintf (stderr, "%s[%ld]: GSlice: ", pname ? pname : "", (long)getpid());
va_start (args, format);
vfprintf (stderr, format, args);
va_end (args);
fputs ("\n", stderr);
abort();
_exit (1);
}
/* --- g-slice memory checker tree --- */
typedef size_t SmcKType; /* key type */
typedef size_t SmcVType; /* value type */
typedef struct {
SmcKType key;
SmcVType value;
} SmcEntry;
static void smc_tree_insert (SmcKType key,
SmcVType value);
static gboolean smc_tree_lookup (SmcKType key,
SmcVType *value_p);
static gboolean smc_tree_remove (SmcKType key);
/* --- g-slice memory checker implementation --- */
static void
smc_notify_alloc (void *pointer,
size_t size)
{
size_t adress = (size_t) pointer;
if (pointer)
smc_tree_insert (adress, size);
}
#if 0
static void
smc_notify_ignore (void *pointer)
{
size_t adress = (size_t) pointer;
if (pointer)
smc_tree_remove (adress);
}
#endif
static int
smc_notify_free (void *pointer,
size_t size)
{
size_t adress = (size_t) pointer;
SmcVType real_size;
gboolean found_one;
if (!pointer)
return 1; /* ignore */
found_one = smc_tree_lookup (adress, &real_size);
if (!found_one)
{
fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
return 0;
}
if (real_size != size && (real_size || size))
{
fprintf (stderr, "GSlice: MemChecker: attempt to release block with invalid size: %p size=%" G_GSIZE_FORMAT " invalid-size=%" G_GSIZE_FORMAT "\n", pointer, real_size, size);
return 0;
}
if (!smc_tree_remove (adress))
{
fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
return 0;
}
return 1; /* all fine */
}
/* --- 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 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)
typedef struct {
SmcEntry *entries;
unsigned int n_entries;
} SmcBranch;
static SmcBranch **smc_tree_root = NULL;
static void
smc_tree_abort (int errval)
{
const char *syserr = strerror (errval);
mem_error ("MemChecker: failure in debugging tree: %s", syserr);
}
static inline SmcEntry*
smc_tree_branch_grow_L (SmcBranch *branch,
unsigned int index)
{
unsigned int old_size = branch->n_entries * sizeof (branch->entries[0]);
unsigned int new_size = old_size + sizeof (branch->entries[0]);
SmcEntry *entry;
mem_assert (index <= branch->n_entries);
branch->entries = (SmcEntry*) realloc (branch->entries, new_size);
if (!branch->entries)
smc_tree_abort (errno);
entry = branch->entries + index;
memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
branch->n_entries += 1;
return entry;
}
static inline SmcEntry*
smc_tree_branch_lookup_nearest_L (SmcBranch *branch,
SmcKType key)
{
unsigned int n_nodes = branch->n_entries, offs = 0;
SmcEntry *check = branch->entries;
int cmp = 0;
while (offs < n_nodes)
{
unsigned int i = (offs + n_nodes) >> 1;
check = branch->entries + i;
cmp = key < check->key ? -1 : key != check->key;
if (cmp == 0)
return check; /* return exact match */
else if (cmp < 0)
n_nodes = i;
else /* (cmp > 0) */
offs = i + 1;
}
/* check points at last mismatch, cmp > 0 indicates greater key */
return cmp > 0 ? check + 1 : check; /* return insertion position for inexact match */
}
static void
smc_tree_insert (SmcKType key,
SmcVType value)
{
unsigned int ix0, ix1;
SmcEntry *entry;
g_mutex_lock (&smc_tree_mutex);
ix0 = SMC_TRUNK_HASH (key);
ix1 = SMC_BRANCH_HASH (key);
if (!smc_tree_root)
{
smc_tree_root = calloc (SMC_TRUNK_COUNT, sizeof (smc_tree_root[0]));
if (!smc_tree_root)
smc_tree_abort (errno);
}
if (!smc_tree_root[ix0])
{
smc_tree_root[ix0] = calloc (SMC_BRANCH_COUNT, sizeof (smc_tree_root[0][0]));
if (!smc_tree_root[ix0])
smc_tree_abort (errno);
}
entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
if (!entry || /* need create */
entry >= smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries || /* need append */
entry->key != key) /* need insert */
entry = smc_tree_branch_grow_L (&smc_tree_root[ix0][ix1], entry - smc_tree_root[ix0][ix1].entries);
entry->key = key;
entry->value = value;
g_mutex_unlock (&smc_tree_mutex);
}
static gboolean
smc_tree_lookup (SmcKType key,
SmcVType *value_p)
{
SmcEntry *entry = NULL;
unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
gboolean found_one = FALSE;
*value_p = 0;
g_mutex_lock (&smc_tree_mutex);
if (smc_tree_root && smc_tree_root[ix0])
{
entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
if (entry &&
entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
entry->key == key)
{
found_one = TRUE;
*value_p = entry->value;
}
}
g_mutex_unlock (&smc_tree_mutex);
return found_one;
}
static gboolean
smc_tree_remove (SmcKType key)
{
unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
gboolean found_one = FALSE;
g_mutex_lock (&smc_tree_mutex);
if (smc_tree_root && smc_tree_root[ix0])
{
SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
if (entry &&
entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
entry->key == key)
{
unsigned int i = entry - smc_tree_root[ix0][ix1].entries;
smc_tree_root[ix0][ix1].n_entries -= 1;
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 */
free (smc_tree_root[ix0][ix1].entries);
smc_tree_root[ix0][ix1].entries = NULL;
}
found_one = TRUE;
}
}
g_mutex_unlock (&smc_tree_mutex);
return found_one;
}
#ifdef G_ENABLE_DEBUG
void
g_slice_debug_tree_statistics (void)
{
g_mutex_lock (&smc_tree_mutex);
if (smc_tree_root)
{
unsigned int i, j, t = 0, o = 0, b = 0, su = 0, ex = 0, en = 4294967295u;
double tf, bf;
for (i = 0; i < SMC_TRUNK_COUNT; i++)
if (smc_tree_root[i])
{
t++;
for (j = 0; j < SMC_BRANCH_COUNT; j++)
if (smc_tree_root[i][j].n_entries)
{
b++;
su += smc_tree_root[i][j].n_entries;
en = MIN (en, smc_tree_root[i][j].n_entries);
ex = MAX (ex, smc_tree_root[i][j].n_entries);
}
else if (smc_tree_root[i][j].entries)
o++; /* formerly used, now empty */
}
en = b ? en : 0;
tf = MAX (t, 1.0); /* max(1) to be a valid divisor */
bf = MAX (b, 1.0); /* max(1) to be a valid divisor */
fprintf (stderr, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t, b, o);
fprintf (stderr, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n",
b / tf,
100.0 - (SMC_BRANCH_COUNT - b / tf) / (0.01 * SMC_BRANCH_COUNT));
fprintf (stderr, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n",
su / bf, en, ex);
}
else
fprintf (stderr, "GSlice: MemChecker: root=NULL\n");
g_mutex_unlock (&smc_tree_mutex);
/* sample statistics (beast + GSLice + 24h scripted core & GUI activity):
* PID %CPU %MEM VSZ RSS COMMAND
* 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse
* $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages
* 114017 103714 2354 344 0 108676 0
* $ cat /proc/8887/status
* Name: beast-0.7.1
* VmSize: 456068 kB
* VmLck: 0 kB
* VmRSS: 414856 kB
* VmData: 434620 kB
* VmStk: 84 kB
* VmExe: 1376 kB
* VmLib: 13036 kB
* VmPTE: 456 kB
* Threads: 3
* (gdb) print g_slice_debug_tree_statistics ()
* GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches
* GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization
* GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum
*/
}
#endif /* G_ENABLE_DEBUG */
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