mono/metadata/sgen-toggleref.c

   1 /*
   2  * sgen-toggleref.c: toggleref support for sgen
   3  *
   4  * Author:
   5  *  Rodrigo Kumpera (kumpera@gmail.com)
   6  *
   7  * Copyright 2011 Xamarin, Inc.
   8  * Copyright (C) 2012 Xamarin Inc
   9  *
  10  * This library is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Library General Public
  12  * License 2.0 as published by the Free Software Foundation;
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Library General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Library General Public
  20  * License 2.0 along with this library; if not, write to the Free
  21  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  */
  23
  24 #include "config.h"
  25
  26 #ifdef HAVE_SGEN_GC
  27
  28 #include "sgen/sgen-gc.h"
  29 #include "sgen-toggleref.h"
  30 #include "sgen/sgen-client.h"
  31
  32
  33 /*only one of the two can be non null at a given time*/
  34 typedef struct {
  35         GCObject *strong_ref;
  36         GCObject *weak_ref;
  37 } MonoGCToggleRef;
  38
  39 static MonoToggleRefStatus (*toggleref_callback) (MonoObject *obj);
  40 static MonoGCToggleRef *toggleref_array;
  41 static int toggleref_array_size;
  42 static int toggleref_array_capacity;
  43
  44 void
  45 sgen_process_togglerefs (void)
  46 {
  47         int i, w;
  48         int toggle_ref_counts [3] = { 0, 0, 0 };
  49
  50         SGEN_LOG (4, "Proccessing ToggleRefs %d", toggleref_array_size);
  51
  52         for (i = w = 0; i < toggleref_array_size; ++i) {
  53                 int res;
  54                 MonoGCToggleRef r = toggleref_array [i];
  55
  56                 MonoObject *obj;
  57
  58                 if (r.strong_ref)
  59                         obj = r.strong_ref;
  60                 else if (r.weak_ref)
  61                         obj = r.weak_ref;
  62                 else
  63                         continue;
  64
  65                 res = toggleref_callback (obj);
  66                 ++toggle_ref_counts [res];
  67                 switch (res) {
  68                 case MONO_TOGGLE_REF_DROP:
  69                         break;
  70                 case MONO_TOGGLE_REF_STRONG:
  71                         toggleref_array [w].strong_ref = obj;
  72                         toggleref_array [w].weak_ref = NULL;
  73                         ++w;
  74                         break;
  75                 case MONO_TOGGLE_REF_WEAK:
  76                         toggleref_array [w].strong_ref = NULL;
  77                         toggleref_array [w].weak_ref = obj;
  78                         ++w;
  79                         break;
  80                 default:
  81                         g_assert_not_reached ();
  82                 }
  83         }
  84
  85         toggleref_array_size = w;
  86
  87         SGEN_LOG (4, "Done Proccessing ToggleRefs dropped %d strong %d weak %d final size %d",
  88                 toggle_ref_counts [MONO_TOGGLE_REF_DROP],
  89                 toggle_ref_counts [MONO_TOGGLE_REF_STRONG],
  90                 toggle_ref_counts [MONO_TOGGLE_REF_WEAK],
  91                 w);
  92 }
  93
  94 void sgen_client_mark_togglerefs (char *start, char *end, ScanCopyContext ctx)
  95 {
  96         CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
  97         SgenGrayQueue *queue = ctx.queue;
  98         int i;
  99
 100         SGEN_LOG (4, "Marking ToggleRefs %d", toggleref_array_size);
 101
 102         for (i = 0; i < toggleref_array_size; ++i) {
 103                 if (toggleref_array [i].strong_ref) {
 104                         GCObject *object = toggleref_array [i].strong_ref;
 105                         if ((char*)object >= start && (char*)object < end) {
 106                                 SGEN_LOG (6, "\tcopying strong slot %d", i);
 107                                 copy_func (&toggleref_array [i].strong_ref, queue);
 108                         }
 109                 }
 110         }
 111         sgen_drain_gray_stack (-1, ctx);
 112 }
 113
 114 void sgen_client_clear_togglerefs (char *start, char *end, ScanCopyContext ctx)
 115 {
 116         CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
 117         SgenGrayQueue *queue = ctx.queue;
 118         int i;
 119
 120         SGEN_LOG (4, "Clearing ToggleRefs %d", toggleref_array_size);
 121
 122         for (i = 0; i < toggleref_array_size; ++i) {
 123                 if (toggleref_array [i].weak_ref) {
 124                         GCObject *object = toggleref_array [i].weak_ref;
 125
 126                         if ((char*)object >= start && (char*)object < end) {
 127                                 if (sgen_gc_is_object_ready_for_finalization (object)) {
 128                                         SGEN_LOG (6, "\tcleaning weak slot %d", i);
 129                                         toggleref_array [i].weak_ref = NULL; /* We defer compaction to only happen on the callback step. */
 130                                 } else {
 131                                         SGEN_LOG (6, "\tkeeping weak slot %d", i);
 132                                         copy_func (&toggleref_array [i].weak_ref, queue);
 133                                 }
 134                         }
 135                 }
 136         }
 137         sgen_drain_gray_stack (-1, ctx);
 138 }
 139
 140 static void
 141 ensure_toggleref_capacity (int capacity)
 142 {
 143         if (!toggleref_array) {
 144                 toggleref_array_capacity = 32;
 145                 toggleref_array = sgen_alloc_internal_dynamic (
 146                         toggleref_array_capacity * sizeof (MonoGCToggleRef),
 147                         INTERNAL_MEM_TOGGLEREF_DATA,
 148                         TRUE);
 149         }
 150         if (toggleref_array_size + capacity >= toggleref_array_capacity) {
 151                 MonoGCToggleRef *tmp;
 152                 int old_capacity = toggleref_array_capacity;
 153                 while (toggleref_array_capacity < toggleref_array_size + capacity)
 154                         toggleref_array_capacity *= 2;
 155
 156                 tmp = sgen_alloc_internal_dynamic (
 157                         toggleref_array_capacity * sizeof (MonoGCToggleRef),
 158                         INTERNAL_MEM_TOGGLEREF_DATA,
 159                         TRUE);
 160
 161                 memcpy (tmp, toggleref_array, toggleref_array_size * sizeof (MonoGCToggleRef));
 162
 163                 sgen_free_internal_dynamic (toggleref_array, old_capacity * sizeof (MonoGCToggleRef), INTERNAL_MEM_TOGGLEREF_DATA);
 164                 toggleref_array = tmp;
 165         }
 166 }
 167
 168 /**
 169  * mono_gc_toggleref_add:
 170  * @object object to register for toggleref processing
 171  * @strong_ref if true the object is registered with a strong ref, a weak one otherwise
 172  *
 173  * Register a given object for toggleref processing. It will be stored internally and the toggleref callback will be called
 174  * on it until it returns MONO_TOGGLE_REF_DROP or is collected.
 175 */
 176 void
 177 mono_gc_toggleref_add (MonoObject *object, mono_bool strong_ref)
 178 {
 179         if (!toggleref_callback)
 180                 return;
 181
 182         SGEN_LOG (4, "Adding toggleref %p %d", object, strong_ref);
 183
 184         sgen_gc_lock ();
 185
 186         ensure_toggleref_capacity (1);
 187         toggleref_array [toggleref_array_size].strong_ref = strong_ref ? object : NULL;
 188         toggleref_array [toggleref_array_size].weak_ref = strong_ref ? NULL : object;
 189         ++toggleref_array_size;
 190
 191         sgen_gc_unlock ();
 192 }
 193
 194 /**
 195  * mono_gc_toggleref_register_callback:
 196  * @callback callback used to determine the new state of the given object.
 197  *
 198  * The callback must decide the status of a given object. It must return one of the values in the MONO_TOGGLE_REF_ enum.
 199  * This function is called with the world running but with the GC locked. This means that you can do everything that doesn't
 200  * require GC interaction. This includes, but not limited to, allocating objects, (de)registering for finalization, manipulating
 201  *gchandles, storing to reference fields or interacting with other threads that might perform such operations.
 202  */
 203 void
 204 mono_gc_toggleref_register_callback (MonoToggleRefStatus (*proccess_toggleref) (MonoObject *obj))
 205 {
 206         toggleref_callback = proccess_toggleref;
 207 }
 208
 209 static MonoToggleRefStatus
 210 test_toggleref_callback (MonoObject *obj)
 211 {
 212         static MonoClassField *mono_toggleref_test_field;
 213         int status = MONO_TOGGLE_REF_DROP;
 214
 215         if (!mono_toggleref_test_field) {
 216                 mono_toggleref_test_field = mono_class_get_field_from_name (mono_object_get_class (obj), "__test");
 217                 g_assert (mono_toggleref_test_field);
 218         }
 219
 220         mono_field_get_value (obj, mono_toggleref_test_field, &status);
 221         printf ("toggleref-cb obj %d\n", status);
 222         return status;
 223 }
 224
 225 void
 226 sgen_register_test_toggleref_callback (void)
 227 {
 228         toggleref_callback = test_toggleref_callback;
 229 }
 230
 231 #endif