mono/sgen/sgen-array-list.h

   1 /*
   2  * sgen-array-list.h: A pointer array that doesn't use reallocs.
   3  *
   4  * Copyright (C) 2016 Xamarin Inc
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Library General Public
   8  * License 2.0 as published by the Free Software Foundation;
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Library General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Library General Public
  16  * License 2.0 along with this library; if not, write to the Free
  17  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20 #ifndef __MONO_SGEN_ARRAY_LIST_H__
  21 #define __MONO_SGEN_ARRAY_LIST_H__
  22
  23 #include <glib.h>
  24
  25 #define SGEN_ARRAY_LIST_BUCKETS (32)
  26 #define SGEN_ARRAY_LIST_MIN_BUCKET_BITS (5)
  27 #define SGEN_ARRAY_LIST_MIN_BUCKET_SIZE (1 << SGEN_ARRAY_LIST_MIN_BUCKET_BITS)
  28
  29 typedef void (*SgenArrayListBucketAllocCallback) (gpointer *bucket, guint32 new_bucket_size, gboolean alloc);
  30 typedef gboolean (*SgenArrayListIsSlotSetFunc) (volatile gpointer *slot);
  31 typedef gboolean (*SgenArrayListSetSlotFunc) (volatile gpointer *slot, gpointer ptr, int data);
  32
  33 /*
  34  * 'entries' is an array of pointers to buckets of increasing size. The first
  35  * bucket has size 'MIN_BUCKET_SIZE', and each bucket is twice the size of the
  36  * previous, i.e.:
  37  *
  38  *           |-------|-- MIN_BUCKET_SIZE
  39  *    [0] -> xxxxxxxx
  40  *    [1] -> xxxxxxxxxxxxxxxx
  41  *    [2] -> xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  42  *    ...
  43  *
  44  * 'slot_hint' denotes the position of the last allocation, so that the
  45  * whole array needn't be searched on every allocation.
  46  *
  47  * The size of the spine, 'SGEN_ARRAY_LIST_BUCKETS', is chosen so
  48  * that the maximum number of entries is no less than G_MAXUINT32.
  49  */
  50
  51 typedef struct {
  52         volatile gpointer *volatile entries [SGEN_ARRAY_LIST_BUCKETS];
  53         volatile guint32 capacity;
  54         volatile guint32 slot_hint;
  55         volatile guint32 next_slot;
  56         SgenArrayListBucketAllocCallback bucket_alloc_callback;
  57         SgenArrayListIsSlotSetFunc is_slot_set_func;
  58         SgenArrayListSetSlotFunc set_slot_func;
  59         int mem_type; /* sgen internal mem type or -1 for malloc allocation */
  60 } SgenArrayList;
  61
  62 /*
  63  * Computes floor(log2(index + MIN_BUCKET_SIZE)) - 1, giving the index
  64  * of the bucket containing a slot.
  65  */
  66 static inline guint32
  67 sgen_array_list_index_bucket (guint32 index)
  68 {
  69 #ifdef __GNUC__
  70         return CHAR_BIT * sizeof (index) - __builtin_clz (index + SGEN_ARRAY_LIST_MIN_BUCKET_SIZE) - 1 - SGEN_ARRAY_LIST_MIN_BUCKET_BITS;
  71 #else
  72         guint count = 0;
  73         index += SGEN_ARRAY_LIST_MIN_BUCKET_SIZE;
  74         while (index) {
  75                 ++count;
  76                 index >>= 1;
  77         }
  78         return count - 1 - SGEN_ARRAY_LIST_MIN_BUCKET_BITS;
  79 #endif
  80 }
  81
  82 static inline guint32
  83 sgen_array_list_bucket_size (guint32 index)
  84 {
  85         return 1 << (index + SGEN_ARRAY_LIST_MIN_BUCKET_BITS);
  86 }
  87
  88 static inline void
  89 sgen_array_list_bucketize (guint32 index, guint32 *bucket, guint32 *offset)
  90 {
  91         *bucket = sgen_array_list_index_bucket (index);
  92         *offset = index - sgen_array_list_bucket_size (*bucket) + SGEN_ARRAY_LIST_MIN_BUCKET_SIZE;
  93 }
  94
  95 static inline volatile gpointer *
  96 sgen_array_list_get_slot (SgenArrayList *array, guint32 index)
  97 {
  98         guint32 bucket, offset;
  99
 100         SGEN_ASSERT (0, index < array->capacity, "Why are we accessing an entry that is not allocated");
 101
 102         sgen_array_list_bucketize (index, &bucket, &offset);
 103         return &(array->entries [bucket] [offset]);
 104 }
 105
 106 #define SGEN_ARRAY_LIST_INIT(bucket_alloc_callback, is_slot_set_func, set_slot_func, mem_type)  { { NULL }, 0, 0, 0, (bucket_alloc_callback), (is_slot_set_func), (set_slot_func), (mem_type) }
 107
 108 #define SGEN_ARRAY_LIST_FOREACH_SLOT(array, slot) {                     \
 109         guint32 __bucket, __offset;                                     \
 110         const guint32 __max_bucket = sgen_array_list_index_bucket ((array)->capacity); \
 111         guint32 __index = 0;                                            \
 112         const guint32 __next_slot = (array)->next_slot;                 \
 113         for (__bucket = 0; __bucket < __max_bucket; ++__bucket) {       \
 114                 volatile gpointer *__entries = (array)->entries [__bucket]; \
 115                 for (__offset = 0; __offset < sgen_array_list_bucket_size (__bucket); ++__offset, ++__index) { \
 116                         if (__index >= __next_slot)                     \
 117                                 break;                                  \
 118                         slot = &__entries [__offset];
 119
 120 #define SGEN_ARRAY_LIST_END_FOREACH_SLOT        } } }
 121
 122 #define SGEN_ARRAY_LIST_FOREACH_SLOT_RANGE(array, begin, end, slot, index) {    \
 123         for (index = (begin); index < (end); index++) {         \
 124                 guint32 __bucket, __offset;                             \
 125                 volatile gpointer *__entries;                           \
 126                 sgen_array_list_bucketize (index, &__bucket, &__offset); \
 127                 __entries = (array)->entries [__bucket];                \
 128                 slot = &__entries [__offset];
 129
 130 #define SGEN_ARRAY_LIST_END_FOREACH_SLOT_RANGE  } }
 131
 132 guint32 sgen_array_list_alloc_block (SgenArrayList *array, guint32 slots_to_add);
 133 guint32 sgen_array_list_add (SgenArrayList *array, gpointer ptr, int data, gboolean increase_size_before_set);
 134 guint32 sgen_array_list_find (SgenArrayList *array, gpointer ptr);
 135 void sgen_array_list_remove_nulls (SgenArrayList *array);
 136
 137 #endif