APR_DECLARE_NONSTD(void *) apr_bucket_alloc(apr_size_t in_size,
apr_bucket_alloc_t *list)
{
node_header_t *node;
apr_memnode_t *active = list->blocks;
char *endp;
apr_size_t size;
size = in_size + SIZEOF_NODE_HEADER_T;
if (size <= SMALL_NODE_SIZE) {
if (list->freelist) {
node = list->freelist;
list->freelist = node->next;
APR_VALGRIND_UNDEFINED((char *)node + SIZEOF_NODE_HEADER_T,
SMALL_NODE_SIZE - SIZEOF_NODE_HEADER_T);
}
else {
endp = active->first_avail + SMALL_NODE_SIZE;
if (endp >= active->endp) {
list->blocks = apr_allocator_alloc(list->allocator, ALLOC_AMT);
if (!list->blocks) {
list->blocks = active;
return NULL;
}
list->blocks->next = active;
active = list->blocks;
endp = active->first_avail + SMALL_NODE_SIZE;
APR_VALGRIND_NOACCESS(active->first_avail,
active->endp - active->first_avail);
}
node = (node_header_t *)active->first_avail;
APR_VALGRIND_UNDEFINED(node, SMALL_NODE_SIZE);
node->alloc = list;
node->memnode = active;
node->size = SMALL_NODE_SIZE;
active->first_avail = endp;
}
}
else {
apr_memnode_t *memnode = apr_allocator_alloc(list->allocator, size);
if (!memnode) {
return NULL;
}
node = (node_header_t *)memnode->first_avail;
node->alloc = list;
node->memnode = memnode;
node->size = size;
}
return ((char *)node) + SIZEOF_NODE_HEADER_T;
}
heap_t *heap_make(apr_pool_t *pool)
{
apr_memnode_t *node;
heap_t *hp = apr_palloc(pool, sizeof(*hp));
hp->allocator = apr_pool_allocator_get(pool);
node = apr_allocator_alloc(hp->allocator, HEAP_INIT_SIZE);
if (node == NULL)
return NULL;
node->next = node;
node->ref = &node->next;
hp->active = node;
//hp->htop = node->first_avail;
hp->hend = node->first_avail;
hp->alloc_size = 0;
// gc never run, on the first run active node will be cleansed
hp->gc_last = NULL;
hp->gc_spot = NULL;
// make sure the memory is freed when the pool
// is cleared/destroyed
apr_pool_cleanup_register(pool, hp, heap_destroy, 0);
return hp;
}
buffer_t *buffer_make(apr_pool_t *pool, int max)
{
buffer_t *buf = apr_palloc(pool, sizeof(*buf));
buf->allocator = apr_pool_allocator_get(pool);
buf->node = apr_allocator_alloc(buf->allocator, max);
buf->offset = 0;
return buf;
}
/* =================================================================================
本函数的逻辑就是:
if (size <= SMALL_NODE_SIZE){
if(list中还有节点){
从list中取走一个node返回
}
else{
取当前node的剩余空间，或新分配一个node返回
}
}
else {
从allocator分配一个node返回
}
算法不好的地方就是，只要list中还有空node，就不会利用好当前节点剩余空间，
直接使用新的node
====================================================================================*/
APU_DECLARE_NONSTD(void *) apr_bucket_alloc(apr_size_t size,
apr_bucket_alloc_t *list)
{
node_header_t *node;
apr_memnode_t *active = list->blocks;
char *endp;
size += SIZEOF_NODE_HEADER_T;
if (size <= SMALL_NODE_SIZE) {
//如果list还有剩余节点，则分配第一个节点出去，list去除已分配出去的那个节点
if (list->freelist) {
node = list->freelist;
list->freelist = node->next;
}
else {
endp = active->first_avail + SMALL_NODE_SIZE;
if (endp >= active->endp) {
list->blocks = apr_allocator_alloc(list->allocator, ALLOC_AMT);
if (!list->blocks) {
list->blocks = active;
return NULL;
}
list->blocks->next = active;
active = list->blocks;
endp = active->first_avail + SMALL_NODE_SIZE;
}
node = (node_header_t *)active->first_avail;
node->alloc = list;
node->memnode = active;
node->size = SMALL_NODE_SIZE;
active->first_avail = endp;
}
}
else {
apr_memnode_t *memnode = apr_allocator_alloc(list->allocator, size);
if (!memnode) {
return NULL;
}
node = (node_header_t *)memnode->first_avail;
node->alloc = list;
node->memnode = memnode;
node->size = size;
}
return ((char *)node) + SIZEOF_NODE_HEADER_T;
}
void buffer_resize(buffer_t *self, int avail)
{
int size, new_size;
apr_memnode_t *new_node;
if (buffer_available(self) >= avail)
return;
size = buffer_len(self);
new_size = size + avail;
new_node = apr_allocator_alloc(self->allocator, new_size);
memcpy((char *)new_node + APR_MEMNODE_T_SIZE, buffer_ptr(self), size);
apr_allocator_free(self->allocator, self->node);
self->node = new_node;
self->offset = 0;
}
void heap_secure_space(heap_t *hp, int size)
{
apr_memnode_t *active = hp->active;
if (hp->hend + size > active->endp)
{
int anticipated_size = hp->hend - heap_htop(hp);
active = apr_allocator_alloc(hp->allocator, anticipated_size + size);
list_insert(active, hp->active);
hp->active = active;
//hp->htop = active->first_avail;
hp->hend = heap_htop(hp) + anticipated_size;
}
hp->hend += size;
}
APU_DECLARE_NONSTD(apr_bucket_alloc_t *) apr_bucket_alloc_create_ex(
apr_allocator_t *allocator)
{
apr_bucket_alloc_t *list;
apr_memnode_t *block;
block = apr_allocator_alloc(allocator, ALLOC_AMT);
if (!block) {
return NULL;
}
list = (apr_bucket_alloc_t *)block->first_avail;
list->pool = NULL;
list->allocator = allocator;
list->freelist = NULL;
list->blocks = block;
block->first_avail += APR_ALIGN_DEFAULT(sizeof(*list));
return list;
}
apr_status_t heap_gc(heap_t *hp, term_t *roots[], int root_sizes[], int nroots)
{
apr_memnode_t *saved_active;
apr_memnode_t *gc_node, *copy_node;
int node_size;
int i, j;
if (hp->gc_last == NULL) // gc never run
gc_node = hp->active;
else
gc_node = hp->gc_last->next;
node_size = node_alloc_size(gc_node);
// if gc_last node has enough space then use it for
// live term copies, otherwise, create a new node
// NB: gc_last may point to gc_node
if (hp->gc_last != NULL && hp->gc_last != gc_node && node_free_space(hp->gc_last) >= node_size)
copy_node = hp->gc_last;
else
copy_node = apr_allocator_alloc(hp->allocator, node_size);
// temporarily make copy_node active; restore later
saved_active = hp->active;
hp->active = copy_node;
hp->hend = heap_htop(hp);
// save gc_node reference for seek_alive;
// non-NULL gc_spot means gc in progress
hp->gc_spot = gc_node;
for (i = 0; i < nroots; i++)
for (j = 0; j < root_sizes[i]; j++)
seek_live(&roots[i][j], saved_active, hp);
assert(hp->active == copy_node); // no overflow
hp->gc_spot = NULL;
// restore active node
if (saved_active != gc_node)
hp->active = saved_active;
// insert copy_node into the ring:
// if gc_node is the last node left
// if copy_node is non-empty and was just created;
// free copy_node if it was just created
// and not put on the list
if (gc_node->next == gc_node ||
(node_alloc_size(copy_node) > 0 && copy_node != hp->gc_last))
{
list_insert(copy_node, gc_node);
hp->gc_last = copy_node;
}
else if (copy_node != hp->gc_last)
{
if (hp->active == copy_node)
hp->active = gc_node->next;
apr_allocator_free(hp->allocator, copy_node);
}
hp->alloc_size -= node_alloc_size(gc_node);
// reclaim memory
list_remove(gc_node);
gc_node->next = NULL;
apr_allocator_free(hp->allocator, gc_node);
// after gc is run, anticipated need is zero
hp->hend = heap_htop(hp);
return APR_SUCCESS;
}