int
buflib_alloc_ex(struct buflib_context *ctx, size_t size, const char *name,
struct buflib_callbacks *ops)
{
union buflib_data *handle, *block;
size_t name_len = name ? B_ALIGN_UP(strlen(name)+1) : 0;
bool last;
/* This really is assigned a value before use */
int block_len;
size += name_len;
size = (size + sizeof(union buflib_data) - 1) /
sizeof(union buflib_data)
/* add 4 objects for alloc len, pointer to handle table entry and
* name length, and the ops pointer */
+ 4;
handle_alloc:
handle = handle_alloc(ctx);
if (!handle)
{
/* If allocation has failed, and compaction has succeded, it may be
* possible to get a handle by trying again.
*/
union buflib_data* last_block = find_block_before(ctx,
ctx->alloc_end, false);
struct buflib_callbacks* ops = last_block[2].ops;
unsigned hints = 0;
if (!ops || !ops->shrink_callback)
{ /* the last one isn't shrinkable
* make room in front of a shrinkable and move this alloc */
hints = BUFLIB_SHRINK_POS_FRONT;
hints |= last_block->val * sizeof(union buflib_data);
}
else if (ops && ops->shrink_callback)
{ /* the last is shrinkable, make room for handles directly */
hints = BUFLIB_SHRINK_POS_BACK;
hints |= 16*sizeof(union buflib_data);
}
/* buflib_compact_and_shrink() will compact and move last_block()
* if possible */
if (buflib_compact_and_shrink(ctx, hints))
goto handle_alloc;
return -1;
}
buffer_alloc:
/* need to re-evaluate last before the loop because the last allocation
* possibly made room in its front to fit this, so last would be wrong */
last = false;
for (block = find_first_free(ctx);;block += block_len)
{
/* If the last used block extends all the way to the handle table, the
* block "after" it doesn't have a header. Because of this, it's easier
* to always find the end of allocation by saving a pointer, and always
* calculate the free space at the end by comparing it to the
* last_handle pointer.
*/
if(block == ctx->alloc_end)
{
last = true;
block_len = ctx->last_handle - block;
if ((size_t)block_len < size)
block = NULL;
break;
}
block_len = block->val;
/* blocks with positive length are already allocated. */
if(block_len > 0)
continue;
block_len = -block_len;
/* The search is first-fit, any fragmentation this causes will be
* handled at compaction.
*/
if ((size_t)block_len >= size)
break;
}
if (!block)
{
/* Try compacting if allocation failed */
unsigned hint = BUFLIB_SHRINK_POS_FRONT |
((size*sizeof(union buflib_data))&BUFLIB_SHRINK_SIZE_MASK);
if (buflib_compact_and_shrink(ctx, hint))
{
goto buffer_alloc;
} else {
handle->val=1;
handle_free(ctx, handle);
return -2;
}
}
/* Set up the allocated block, by marking the size allocated, and storing
* a pointer to the handle.
*/
union buflib_data *name_len_slot;
block->val = size;
block[1].handle = handle;
block[2].ops = ops;
strcpy(block[3].name, name);
name_len_slot = (union buflib_data*)B_ALIGN_UP(block[3].name + name_len);
name_len_slot->val = 1 + name_len/sizeof(union buflib_data);
handle->alloc = (char*)(name_len_slot + 1);
block += size;
/* alloc_end must be kept current if we're taking the last block. */
if (last)
ctx->alloc_end = block;
/* Only free blocks *before* alloc_end have tagged length. */
else if ((size_t)block_len > size)
block->val = size - block_len;
/* Return the handle index as a positive integer. */
return ctx->handle_table - handle;
}
int
buflib_alloc_ex(struct buflib_context *ctx, size_t size, const char *name,
struct buflib_callbacks *ops)
{
/* busy wait if there's a thread owning the lock */
while (ctx->handle_lock != 0) YIELD();
union buflib_data *handle, *block;
size_t name_len = name ? B_ALIGN_UP(strlen(name)+1) : 0;
bool last;
/* This really is assigned a value before use */
int block_len;
size += name_len;
size = (size + sizeof(union buflib_data) - 1) /
sizeof(union buflib_data)
/* add 4 objects for alloc len, pointer to handle table entry and
* name length, and the ops pointer */
+ 4;
handle_alloc:
handle = handle_alloc(ctx);
if (!handle)
{
/* If allocation has failed, and compaction has succeded, it may be
* possible to get a handle by trying again.
*/
if (!ctx->compact && buflib_compact(ctx))
goto handle_alloc;
else
{ /* first try to shrink the alloc before the handle table
* to make room for new handles */
int handle = ctx->handle_table - ctx->last_handle;
union buflib_data* last_block = handle_to_block(ctx, handle);
struct buflib_callbacks* ops = last_block[2].ops;
if (ops && ops->shrink_callback)
{
char *data = buflib_get_data(ctx, handle);
unsigned hint = BUFLIB_SHRINK_POS_BACK | 10*sizeof(union buflib_data);
if (ops->shrink_callback(handle, hint, data,
(char*)(last_block+last_block->val)-data) == BUFLIB_CB_OK)
{ /* retry one more time */
goto handle_alloc;
}
}
return 0;
}
}
buffer_alloc:
/* need to re-evaluate last before the loop because the last allocation
* possibly made room in its front to fit this, so last would be wrong */
last = false;
for (block = ctx->first_free_block;;block += block_len)
{
/* If the last used block extends all the way to the handle table, the
* block "after" it doesn't have a header. Because of this, it's easier
* to always find the end of allocation by saving a pointer, and always
* calculate the free space at the end by comparing it to the
* last_handle pointer.
*/
if(block == ctx->alloc_end)
{
last = true;
block_len = ctx->last_handle - block;
if ((size_t)block_len < size)
block = NULL;
break;
}
block_len = block->val;
/* blocks with positive length are already allocated. */
if(block_len > 0)
continue;
block_len = -block_len;
/* The search is first-fit, any fragmentation this causes will be
* handled at compaction.
*/
if ((size_t)block_len >= size)
break;
}
if (!block)
{
/* Try compacting if allocation failed */
if (buflib_compact_and_shrink(ctx,
(size*sizeof(union buflib_data))&BUFLIB_SHRINK_SIZE_MASK))
{
goto buffer_alloc;
} else {
handle->val=1;
handle_free(ctx, handle);
return 0;
}
}
/* Set up the allocated block, by marking the size allocated, and storing
* a pointer to the handle.
*/
union buflib_data *name_len_slot;
block->val = size;
block[1].handle = handle;
block[2].ops = ops ?: &default_callbacks;
strcpy(block[3].name, name);
name_len_slot = (union buflib_data*)B_ALIGN_UP(block[3].name + name_len);
name_len_slot->val = 1 + name_len/sizeof(union buflib_data);
handle->alloc = (char*)(name_len_slot + 1);
/* If we have just taken the first free block, the next allocation search
* can save some time by starting after this block.
*/
if (block == ctx->first_free_block)
ctx->first_free_block += size;
block += size;
/* alloc_end must be kept current if we're taking the last block. */
if (last)
ctx->alloc_end = block;
/* Only free blocks *before* alloc_end have tagged length. */
else if ((size_t)block_len > size)
block->val = size - block_len;
/* Return the handle index as a positive integer. */
return ctx->handle_table - handle;
}
