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gslice: stop using ctors

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We can't initialise gslice from a ctor because g_slice_set_config() must
be called before gslice initialisation.

Instead, do the initialisation in a threadsafe way from the
initialisation function for the thread private data.  This will only be
called once per thread so the synchronisation doesn't pose a significant
overhead here.

Ensure that we try to grab the thread private data directly on entrance
to g_slice_alloc() so that we force the initialisation to occur.
Grabbing the private data is the common case anyway.

https://bugzilla.gnome.org/show_bug.cgi?id=660887
This commit is contained in:
Ryan Lortie 2011-10-04 16:38:28 -04:00
parent f1512917e6
commit 5bfb64d507
1 changed files with 21 additions and 6 deletions
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27
glib/gslice.c
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@ -51,7 +51,6 @@
#include "gtestutils.h"
#include "gthread.h"
#include "glib_trace.h"
#include "glib-ctor.h"
/* the GSlice allocator is split up into 4 layers, roughly modelled after the slab
* allocator and magazine extensions as outlined in:
@ -297,7 +296,8 @@ slice_config_init (SliceConfig *config)
config->debug_blocks = TRUE;
}
GLIB_CTOR (g_slice_init_nomessage)
static void
g_slice_init_nomessage (void)
{
/* we may not use g_error() or friends here */
mem_assert (sys_page_size == 0);
@ -361,8 +361,6 @@ GLIB_CTOR (g_slice_init_nomessage)
static inline guint
allocator_categorize (gsize aligned_chunk_size)
{
GLIB_ENSURE_CTOR (g_slice_init_nomessage);
/* 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 */
@ -414,7 +412,15 @@ thread_memory_from_self (void)
ThreadMemory *tmem = g_private_get (&private_thread_memory);
if (G_UNLIKELY (!tmem))
{
const guint n_magazines = MAX_SLAB_INDEX (allocator);
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];
@ -761,14 +767,23 @@ thread_memory_magazine2_free (ThreadMemory *tmem,
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 */
{
ThreadMemory *tmem = thread_memory_from_self();
guint ix = SLAB_INDEX (allocator, chunk_size);
if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
{