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         uint64_t nb_allocated_indexes;
  24 };
  25
  26 struct lttng_index {
  27         uint64_t index;
  28         struct cds_list_head head;
  29 };
  30
  31 struct lttng_index_allocator *lttng_index_allocator_create(
  32                 uint64_t index_count)
  33 {
  34         struct lttng_index_allocator *allocator = NULL;
  35
  36         allocator = zmalloc(sizeof(*allocator));
  37         if (!allocator) {
  38                 PERROR("Failed to allocate index allocator");
  39                 goto end;
  40         }
  41
  42         allocator->size = index_count;
  43         allocator->position = 0;
  44         allocator->nb_allocated_indexes = 0;
  45
  46         CDS_INIT_LIST_HEAD(&allocator->unused_list);
  47
  48 end:
  49         return allocator;
  50 }
  51
  52 uint64_t lttng_index_allocator_get_index_count(struct lttng_index_allocator *allocator)
  53 {
  54         return allocator->nb_allocated_indexes;
  55 }
  56
  57 enum lttng_index_allocator_status lttng_index_allocator_alloc(
  58                 struct lttng_index_allocator *allocator,
  59                 uint64_t *allocated_index)
  60 {
  61         enum lttng_index_allocator_status status =
  62                         LTTNG_INDEX_ALLOCATOR_STATUS_OK;
  63
  64         if (cds_list_empty(&allocator->unused_list)) {
  65                 if (allocator->position >= allocator->size) {
  66                         /* No indices left. */
  67                         status = LTTNG_INDEX_ALLOCATOR_STATUS_EMPTY;
  68                         goto end;
  69                 }
  70
  71                 *allocated_index = allocator->position++;
  72         } else {
  73                 struct lttng_index *index;
  74
  75                 index = cds_list_first_entry(&allocator->unused_list,
  76                                 typeof(*index), head);
  77                 cds_list_del(&index->head);
  78                 *allocated_index = index->index;
  79                 free(index);
  80         }
  81
  82         allocator->nb_allocated_indexes++;
  83 end:
  84         return status;
  85 }
  86
  87 enum lttng_index_allocator_status lttng_index_allocator_release(
  88                 struct lttng_index_allocator *allocator, uint64_t idx)
  89 {
  90         struct lttng_index *index = NULL;
  91         enum lttng_index_allocator_status status =
  92                         LTTNG_INDEX_ALLOCATOR_STATUS_OK;
  93
  94         assert(idx < allocator->size);
  95
  96         index = zmalloc(sizeof(*index));
  97         if (!index) {
  98                 PERROR("Failed to allocate free index queue");
  99                 status = LTTNG_INDEX_ALLOCATOR_STATUS_ERROR;
 100                 goto end;
 101         }
 102
 103         index->index = idx;
 104         cds_list_add_tail(&index->head, &allocator->unused_list);
 105         allocator->nb_allocated_indexes--;
 106
 107 end:
 108         return status;
 109 }
 110
 111 void lttng_index_allocator_destroy(struct lttng_index_allocator *allocator)
 112 {
 113         struct lttng_index *index = NULL, *tmp_index = NULL;
 114
 115         if (!allocator) {
 116                 return;
 117         }
 118
 119         if (lttng_index_allocator_get_index_count(allocator) > 0) {
 120                 WARN("Destroying index allocator with %" PRIu64
 121                                 " slot indexes still in use",
 122                                 lttng_index_allocator_get_index_count(allocator));
 123         }
 124
 125         cds_list_for_each_entry_safe(index, tmp_index,
 126                         &allocator->unused_list, head) {
 127                 cds_list_del(&index->head);
 128                 free(index);
 129         }
 130
 131         free(allocator);
 132 }