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/*
* Copyright (c) 2022 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <hicn/util/pool.h>
#include <hicn/util/slab.h>
#include <stdlib.h>
/* BLOCK LINKED LISTS */
static void
block_add_to_head (block_t **head_ptr, block_t *block)
{
if (head_ptr == NULL || block == NULL)
return;
block->prev = NULL;
if (*head_ptr != NULL)
{
block->next = *head_ptr;
block->next->prev = block;
}
*head_ptr = block;
}
static block_t *
block_remove_from_head (block_t **head_ptr)
{
if (head_ptr == NULL || *head_ptr == NULL)
return NULL;
block_t *old_head = *head_ptr;
*head_ptr = old_head->next;
if (*head_ptr != NULL)
(*head_ptr)->prev = NULL;
return old_head;
}
static void
block_remove (block_t **head_ptr, block_t *block)
{
if (*head_ptr == NULL || block == NULL)
return;
if (block == *head_ptr)
*head_ptr = block->next;
if (block->next != NULL)
block->next->prev = block->prev;
if (block->prev != NULL)
block->prev->next = block->next;
}
static bool
is_block_list_empty (block_t *block)
{
return block == NULL;
}
static void
block_list_free (block_t **head)
{
if (head == NULL || *head == NULL)
return;
block_t *curr_block = *head;
while (curr_block != NULL)
{
block_t *next = curr_block->next;
pool_free (curr_block->pool);
free (curr_block);
curr_block = next;
}
*head = NULL;
}
/* BLOCK */
static bool
is_block_full (block_t *block)
{
return pool_get_free_indices_size (block->pool) == 0;
}
static void
block_set_ptr_in_chunks (block_t *block, size_t chunk_size)
{
void *chunk = block->pool;
// Cannot use `pool_foreach()` since it requires to know the type
// while here we use a generic (void *)
for (int i = 0; i < pool_get_alloc_size (block->pool); i++)
{
chunk_hdr_t *hdr = (chunk_hdr_t *) chunk;
hdr->block = block;
chunk = (uint8_t *) (chunk) + chunk_size; // Move to next chunk
}
}
static block_t *
block_create (size_t chunk_size, size_t num_chunks)
{
block_t *block = malloc (sizeof (block_t));
if (block == NULL)
return NULL;
block->prev = block->next = NULL;
_pool_init (&block->pool, chunk_size, num_chunks, 0);
block_set_ptr_in_chunks (block, chunk_size);
return block;
}
/* SLAB */
slab_t *
_slab_create (size_t elt_size, size_t num_elts)
{
// Initialize slab
slab_t *slab = malloc (sizeof (slab_t));
if (slab == NULL)
return NULL;
*slab = (slab_t){ .num_chunks = next_pow2 (num_elts),
.chunk_size = CHUNK_HDRLEN + elt_size,
.full = NULL,
.partial_or_empty = NULL };
// Add initial empty block to partial or empty list
block_t *block = block_create (slab->chunk_size, slab->num_chunks);
block_add_to_head (&slab->partial_or_empty, block);
return slab;
}
void
slab_free (slab_t *slab)
{
block_list_free (&slab->full);
block_list_free (&slab->partial_or_empty);
free (slab);
}
void *
_slab_get (slab_t *slab)
{
// Create new empty block if none with available chunks
if (is_block_list_empty (slab->partial_or_empty))
{
block_t *block = block_create (slab->chunk_size, slab->num_chunks);
block_add_to_head (&slab->partial_or_empty, block);
slab->num_chunks *= 2; // Grow size exponentially
}
// Get chunck from first block in 'partial_or_empty' list
void *chunk;
_pool_get (&slab->partial_or_empty->pool, &chunk, slab->chunk_size);
// If the current block (i.e. head of 'partial_or_empty' list) if full,
// move it to the 'full' list
if (is_block_full (slab->partial_or_empty))
{
block_t *block = block_remove_from_head (&slab->partial_or_empty);
block_add_to_head (&slab->full, block);
}
return (uint8_t *) chunk + CHUNK_HDRLEN;
}
void
_slab_put (slab_t *slab, void *chunk)
{
// Get which block the chunk (that we want to release) belong to
chunk_hdr_t *hdr = chunk_hdr (chunk);
block_t *block = hdr->block;
// Put chunk back into block
bool is_full = is_block_full (block);
_pool_put (&block->pool, (void *) &hdr, slab->chunk_size);
// If the block was previously full, move it to 'partial_or_empty' list
if (is_full)
{
block_remove (&slab->full, block);
block_add_to_head (&slab->partial_or_empty, block);
}
}
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