lib/object-collection.c

   1 /*
   2  * Copyright (c) 2016 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18
  19 #include "object-collection.h"
  20 #include "util.h"
  21
  22 void
  23 object_collection_init(struct object_collection *coll)
  24 {
  25     coll->objs = coll->stub;
  26     coll->n = 0;
  27     coll->capacity = ARRAY_SIZE(coll->stub);
  28 }
  29
  30 void
  31 object_collection_add(struct object_collection *coll, void *obj)
  32 {
  33     if (coll->n >= coll->capacity) {
  34         size_t old_size, new_size;
  35
  36         old_size = coll->capacity * sizeof *coll->objs;
  37         coll->capacity *= 2;
  38         new_size = coll->capacity * sizeof *coll->objs;
  39
  40         if (coll->objs == coll->stub) {
  41             coll->objs = xmalloc(new_size);
  42             memcpy(coll->objs, coll->stub, old_size);
  43         } else {
  44             coll->objs = xrealloc(coll->objs, new_size);
  45         }
  46     }
  47
  48     coll->objs[coll->n++] = obj;
  49 }
  50
  51 void
  52 object_collection_remove(struct object_collection *coll, void *obj)
  53 {
  54     size_t i;
  55
  56     for (i = 0; i < coll->n; i++) {
  57         if (coll->objs[i] == obj) {
  58             break;
  59         }
  60     }
  61     if (i == coll->n) {
  62         return;
  63     }
  64
  65     coll->n--;
  66     /* Swap the last item in if needed. */
  67     if (i != coll->n) {
  68         coll->objs[i] = coll->objs[coll->n];
  69     }
  70
  71     /* Shrink? Watermark at '/ 4' to get hysteresis and leave spare
  72      * capacity. */
  73     if (coll->objs != coll->stub && coll->n <= coll->capacity / 4) {
  74         size_t actual_size, new_size;
  75
  76         actual_size = coll->n * sizeof *coll->objs;
  77         coll->capacity /= 2;
  78         new_size = coll->capacity * sizeof *coll->objs;
  79
  80         if (new_size <= sizeof(coll->stub)) {
  81             memcpy(coll->stub, coll->objs, actual_size);
  82             free(coll->objs);
  83             coll->objs = coll->stub;
  84         } else {
  85             coll->objs = xrealloc(coll->objs, new_size);
  86         }
  87     }
  88 }
  89
  90 void
  91 object_collection_move(struct object_collection *to,
  92                        struct object_collection *from)
  93 {
  94     ovs_assert(to->n == 0);
  95
  96     *to = *from;
  97     if (from->objs == from->stub) {
  98         to->objs = to->stub;
  99     }
 100     object_collection_init(from);
 101 }
 102
 103 /* Returns a NULL-terminated array of object pointers,
 104  * destroys 'rules'. */
 105 void *
 106 object_collection_detach(struct object_collection *coll)
 107 {
 108     void **array;
 109
 110     object_collection_add(coll, NULL);
 111
 112     if (coll->objs == coll->stub) {
 113         coll->objs = xmemdup(coll->objs, coll->n * sizeof *coll->objs);
 114     }
 115
 116     array = coll->objs;
 117     object_collection_init(coll);
 118
 119     return array;
 120 }
 121
 122 void
 123 object_collection_destroy(struct object_collection *coll)
 124 {
 125     if (coll->objs != coll->stub) {
 126         free(coll->objs);
 127     }
 128
 129     /* Make repeated destruction harmless. */
 130     object_collection_init(coll);
 131 }