src/util/magma/u_magma_map.c

/*
 * Copyright © 2022 Google, LLC
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "u_magma_map.h"
#include "util/u_atomic.h"
#include <stddef.h>

static const uint32_t kInvalidHandle = 0;

struct u_magma_map_entry {
   uint64_t object;
   uint32_t handle;
   uint32_t free_index;
   bool     valid;
};

void u_magma_map_init(struct u_magma_map* map)
{
   size_t node_size = 8;  /* grows as necessary */
   uint32_t sentinel = kInvalidHandle;

   util_sparse_array_init(&map->array, sizeof(struct u_magma_map_entry), node_size);
   util_sparse_array_free_list_init(&map->free_list, &map->array, sentinel,
                                    offsetof(struct u_magma_map_entry, free_index));

   map->current_handle = kInvalidHandle;
}

void u_magma_map_release(struct u_magma_map* map)
{
   struct u_magma_map_entry* entry;
   while ((entry = util_sparse_array_free_list_pop_elem(&map->free_list))) {
   }
   util_sparse_array_finish(&map->array);
}

uint32_t u_magma_map_get(struct u_magma_map* map, uint64_t object)
{
   struct u_magma_map_entry* entry;
   entry = util_sparse_array_free_list_pop_elem(&map->free_list);

   if (!entry) {
      uint32_t handle = p_atomic_inc_return(&map->current_handle);

      entry = util_sparse_array_get(&map->array, handle);

      entry->handle = handle;
   }

   entry->object = object;
   entry->valid = true;

   return entry->handle;
}

static struct u_magma_map_entry* query(struct u_magma_map* map, uint32_t handle) {
   if (handle == kInvalidHandle)
      return NULL;

   struct u_magma_map_entry* entry = util_sparse_array_get(&map->array, handle);
   if (entry->valid)
      return entry;

   // We may have just allocated a node;
   // it will be reused when current_handle reaches handle.
   return NULL;
}

bool u_magma_map_query(struct u_magma_map* map, uint32_t handle, uint64_t* object_out)
{
   struct u_magma_map_entry* entry = query(map, handle);
   if (!entry)
      return false;

   *object_out = entry->object;
   return true;
}

void u_magma_map_put(struct u_magma_map* map, uint32_t handle)
{
   struct u_magma_map_entry* entry = query(map, handle);
   assert(entry);
   assert(entry->valid);

   entry->valid = false;

   util_sparse_array_free_list_push(&map->free_list, &handle, 1);
}