src/common/index-allocator.c

   1 /*
   2  * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #include <assert.h>
   9 #include <inttypes.h>
  10
  11 #include <urcu.h>
  12 #include <urcu/list.h>
  13
  14 #include "macros.h"
  15 #include "error.h"
  16
  17 #include "index-allocator.h"
  18
  19 struct lttng_index_allocator {
  20         struct cds_list_head unused_list;
  21         uint64_t size;
  22         uint64_t position;
  23 };
  24
  25 struct lttng_index {
  26         uint64_t index;
  27         struct cds_list_head head;
  28 };
  29
  30 struct lttng_index_allocator *lttng_index_allocator_create(
  31                 uint64_t index_count)
  32 {
  33         struct lttng_index_allocator *allocator = NULL;
  34
  35         allocator = zmalloc(sizeof(*allocator));
  36         if (!allocator) {
  37                 PERROR("Failed to allocate index allocator");
  38                 goto end;
  39         }
  40
  41         allocator->size = index_count;
  42         allocator->position = 0;
  43
  44         CDS_INIT_LIST_HEAD(&allocator->unused_list);
  45
  46 end:
  47         return allocator;
  48 }
  49
  50 uint64_t lttng_index_allocator_get_index_count(struct lttng_index_allocator *allocator)
  51 {
  52         return allocator->size;
  53 }
  54
  55 enum lttng_index_allocator_status lttng_index_allocator_alloc(
  56                 struct lttng_index_allocator *allocator,
  57                 uint64_t *allocated_index)
  58 {
  59         enum lttng_index_allocator_status status =
  60                         LTTNG_INDEX_ALLOCATOR_STATUS_OK;
  61
  62         if (cds_list_empty(&allocator->unused_list)) {
  63                 if (allocator->position >= allocator->size) {
  64                         /* No indices left. */
  65                         status = LTTNG_INDEX_ALLOCATOR_STATUS_EMPTY;
  66                         goto end;
  67                 }
  68
  69                 *allocated_index = allocator->position++;
  70         } else {
  71                 struct lttng_index *index;
  72
  73                 index = cds_list_first_entry(&allocator->unused_list,
  74                                 typeof(*index), head);
  75                 cds_list_del(&index->head);
  76                 *allocated_index = index->index;
  77                 free(index);
  78         }
  79
  80 end:
  81         return status;
  82 }
  83
  84 enum lttng_index_allocator_status lttng_index_allocator_release(
  85                 struct lttng_index_allocator *allocator, uint64_t idx)
  86 {
  87         struct lttng_index *index = NULL;
  88         enum lttng_index_allocator_status status =
  89                         LTTNG_INDEX_ALLOCATOR_STATUS_OK;
  90
  91         assert(idx < allocator->size);
  92
  93         index = zmalloc(sizeof(*index));
  94         if (!index) {
  95                 PERROR("Failed to allocate free index queue");
  96                 status = LTTNG_INDEX_ALLOCATOR_STATUS_ERROR;
  97                 goto end;
  98         }
  99
 100         index->index = idx;
 101         cds_list_add_tail(&index->head, &allocator->unused_list);
 102
 103 end:
 104         return status;
 105 }
 106
 107 void lttng_index_allocator_destroy(struct lttng_index_allocator *allocator)
 108 {
 109         struct lttng_index *index = NULL, *tmp_index = NULL;
 110
 111         if (!allocator) {
 112                 return;
 113         }
 114
 115         if (lttng_index_allocator_get_index_count(allocator) > 0) {
 116                 WARN("Destroying index allocator with %" PRIu64
 117                                 " slot indexes still in use",
 118                                 lttng_index_allocator_get_index_count(allocator));
 119         }
 120
 121         cds_list_for_each_entry_safe(index, tmp_index,
 122                         &allocator->unused_list, head) {
 123                 cds_list_del(&index->head);
 124                 free(index);
 125         }
 126
 127         free(allocator);
 128 }