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/*
* sgen-toggleref.c: toggleref support for sgen
*
* Author:
* Rodrigo Kumpera (kumpera@gmail.com)
*
* Copyright 2011 Xamarin, Inc.
* Copyright (C) 2012 Xamarin Inc
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License 2.0 as published by the Free Software Foundation;
*
* 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License 2.0 along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "config.h"
#ifdef HAVE_SGEN_GC
#include "sgen-gc.h"
#include "sgen-toggleref.h"
/*only one of the two can be non null at a given time*/
typedef struct {
void *strong_ref;
void *weak_ref;
} MonoGCToggleRef;
static MonoToggleRefStatus (*toggleref_callback) (MonoObject *obj);
static MonoGCToggleRef *toggleref_array;
static int toggleref_array_size;
static int toggleref_array_capacity;
void
sgen_process_togglerefs (void)
{
int i, w;
int toggle_ref_counts [3] = { 0, 0, 0 };
SGEN_LOG (4, "Proccessing ToggleRefs %d", toggleref_array_size);
for (i = w = 0; i < toggleref_array_size; ++i) {
int res;
MonoGCToggleRef r = toggleref_array [i];
MonoObject *obj;
if (r.strong_ref)
obj = r.strong_ref;
else if (r.weak_ref)
obj = r.weak_ref;
else
continue;
res = toggleref_callback (obj);
++toggle_ref_counts [res];
switch (res) {
case MONO_TOGGLE_REF_DROP:
break;
case MONO_TOGGLE_REF_STRONG:
toggleref_array [w].strong_ref = obj;
toggleref_array [w].weak_ref = NULL;
++w;
break;
case MONO_TOGGLE_REF_WEAK:
toggleref_array [w].strong_ref = NULL;
toggleref_array [w].weak_ref = obj;
++w;
break;
default:
g_assert_not_reached ();
}
}
toggleref_array_size = w;
SGEN_LOG (4, "Done Proccessing ToggleRefs dropped %d strong %d weak %d final size %d",
toggle_ref_counts [MONO_TOGGLE_REF_DROP],
toggle_ref_counts [MONO_TOGGLE_REF_STRONG],
toggle_ref_counts [MONO_TOGGLE_REF_WEAK],
w);
}
void
sgen_scan_togglerefs (char *start, char *end, ScanCopyContext ctx)
{
CopyOrMarkObjectFunc copy_func = ctx.copy_func;
SgenGrayQueue *queue = ctx.queue;
int i;
SGEN_LOG (4, "Scanning ToggleRefs %d", toggleref_array_size);
for (i = 0; i < toggleref_array_size; ++i) {
if (toggleref_array [i].strong_ref) {
char *object = toggleref_array [i].strong_ref;
if (object >= start && object < end) {
SGEN_LOG (6, "\tcopying strong slot %d", i);
copy_func (&toggleref_array [i].strong_ref, queue);
}
} else if (toggleref_array [i].weak_ref) {
char *object = toggleref_array [i].weak_ref;
if (object >= start && object < end) {
if (sgen_gc_is_object_ready_for_finalization (object)) {
SGEN_LOG (6, "\tcleaning weak slot %d", i);
toggleref_array [i].weak_ref = NULL; /* We defer compaction to only happen on the callback step. */
} else {
SGEN_LOG (6, "\tkeeping weak slot %d", i);
copy_func (&toggleref_array [i].weak_ref, queue);
}
}
}
}
}
static void
ensure_toggleref_capacity (int capacity)
{
if (!toggleref_array) {
toggleref_array_capacity = 32;
toggleref_array = sgen_alloc_internal_dynamic (
toggleref_array_capacity * sizeof (MonoGCToggleRef),
INTERNAL_MEM_TOGGLEREF_DATA,
TRUE);
}
if (toggleref_array_size + capacity >= toggleref_array_capacity) {
MonoGCToggleRef *tmp;
int old_capacity = toggleref_array_capacity;
while (toggleref_array_capacity < toggleref_array_size + capacity)
toggleref_array_capacity *= 2;
tmp = sgen_alloc_internal_dynamic (
toggleref_array_capacity * sizeof (MonoGCToggleRef),
INTERNAL_MEM_TOGGLEREF_DATA,
TRUE);
memcpy (tmp, toggleref_array, toggleref_array_size * sizeof (MonoGCToggleRef));
sgen_free_internal_dynamic (toggleref_array, old_capacity * sizeof (MonoGCToggleRef), INTERNAL_MEM_TOGGLEREF_DATA);
toggleref_array = tmp;
}
}
/**
* mono_gc_toggleref_add:
* @object object to register for toggleref processing
* @strong_ref if true the object is registered with a strong ref, a weak one otherwise
*
* Register a given object for toggleref processing. It will be stored internally and the toggleref callback will be called
* on it until it returns MONO_TOGGLE_REF_DROP or is collected.
*/
void
mono_gc_toggleref_add (MonoObject *object, mono_bool strong_ref)
{
if (!toggleref_callback)
return;
SGEN_LOG (4, "Adding toggleref %p %d", object, strong_ref);
sgen_gc_lock ();
ensure_toggleref_capacity (1);
toggleref_array [toggleref_array_size].strong_ref = strong_ref ? object : NULL;
toggleref_array [toggleref_array_size].weak_ref = strong_ref ? NULL : object;
++toggleref_array_size;
sgen_gc_unlock ();
}
/**
* mono_gc_toggleref_register_callback:
* @callback callback used to determine the new state of the given object.
*
* The callback must decide the status of a given object. It must return one of the values in the MONO_TOGGLE_REF_ enum.
* This function is called with the world running but with the GC locked. This means that you can do everything that doesn't
* require GC interaction. This includes, but not limited to, allocating objects, (de)registering for finalization, manipulating
*gchandles, storing to reference fields or interacting with other threads that might perform such operations.
*/
void
mono_gc_toggleref_register_callback (MonoToggleRefStatus (*proccess_toggleref) (MonoObject *obj))
{
toggleref_callback = proccess_toggleref;
}
#endif
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