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#include <stddef.h>
#include <stdalign.h>
#include "allocator_internal.h"
#define IS_BLACK_NODE(n) (n == NULL || n->color == COLOR_BLACK)
#define IS_RED_NODE(n) (n != NULL && n->color == COLOR_RED)
#ifdef DEBUG
#include <stdio.h>
int debug_tree_black_height(TreeAlloc *node) {
if (node == NULL) {
return 1;
}
return (IS_BLACK_NODE(node) ? 1 : 0) + debug_tree_black_height(node->left);
}
void debug_print_node(int indent, TreeAlloc *node, int bad) {
for (int ii = 0; ii < indent; ii++)
printf(" ");
if (IS_RED_NODE(node))
printf("\e[31m");
else if (bad)
printf("\e[30m]");
if (bad)
printf("\e[43m");
if (node)
printf("%p %lu\n", node, node->size);
else
printf("(nil) 0\n");
printf("\e[37m");
if (bad)
printf("\e[40m");
}
void debug_print_tree(int indent, void *p, int safe) {
TreeAlloc *node = (TreeAlloc*) p;
if (node != NULL) {
int bad = debug_tree_black_height(node->left) != debug_tree_black_height(node->right);
bad |= IS_RED_NODE(node) && (
IS_RED_NODE(node->left) ||
IS_RED_NODE(node->right) ||
IS_RED_NODE(node->parent) );
bad &= !safe;
debug_print_tree(indent + 1, node->left, safe);
debug_print_node(indent, node, bad);
debug_print_tree(indent + 1, node->right, safe);
}
}
#endif
TreeAlloc *insert_node_at(void *address, uintptr_t padding, uintptr_t align, uintptr_t size) {
return NULL;
}
/*
* Search for the node whose allocated region contains an address.
*/
TreeAlloc *search_by_address(TreeAlloc *root, void *address) {
TreeAlloc *head = root;
while (1) {
void *region_start = head;
void *region_end = head + head->size;
if (address < region_start) {
// The requested address is before this region's start.
if (head->left) {
// There is another region that comes before this one
// in memory.
head = head->left;
} else {
// This address is before any of the allocated regions.
return NULL;
}
} else if (address <= region_end) {
// The requested address is within the range of this region.
return head;
} else {
// The requested address is after this region's end.
if (head->right) {
// There is another region that comes after this one
// in memory.
head = head->right;
} else {
// This address is after any of the allocated regions.
return NULL;
}
}
}
}
static uintptr_t effective_size(TreeAlloc *head, uintptr_t padding, uintptr_t align) {
return head->size - (align_after(head + padding, align) - (void*) head);
}
/*
* This is the most optimistic estimate of size that we can use which also preserves the ordering over
* the tree. I had planned to use effective_size before I realized that it would break the tree
* ordering.
*/
static uintptr_t pessimistic_size(TreeAlloc *head, uintptr_t padding, uintptr_t align) {
return head->size - padding - align + 1;
}
TreeAlloc *search_by_size(TreeAlloc *root, uintptr_t padding, uintptr_t align, uintptr_t size) {
TreeAlloc *head = root;
while (1) {
uintptr_t esize = pessimistic_size(head, padding, align);
if (esize <= size) {
if (head->right == NULL) {
return NULL;
} else {
head = head->right;
}
} else {
if (head->left == NULL || pessimistic_size(head->left, padding, align) < size) {
return head;
} else {
head = head->left;
}
}
}
}
TreeAlloc *succ(TreeAlloc *el) {
if (el->right != NULL) {
el = el->right;
while (el->left != NULL) {
el = el->left;
}
return el;
}
while (el->parent != NULL && el == el->parent->right) {
el = el->parent;
}
return el->parent;
}
TreeAlloc *pred(TreeAlloc *el) {
if (el->left != NULL) {
el = el->left;
while (el->right != NULL) {
el = el->right;
}
return el;
}
while (el->parent != NULL && el == el->parent->left) {
el = el->parent;
}
return el->parent;
}
TreeAlloc *get_sibling(TreeAlloc *p, TreeAlloc *ta) {
if (!p)
return NULL;
else if (p->left == ta)
return p->right;
else
return p->left;
}
void rotate_left(TreeAlloc **root_ptr, TreeAlloc *ta) {
TreeAlloc *parent, *tmp;
tmp = ta->right;
parent = ta->parent;
if (tmp) {
ta->right = tmp->left;
tmp->left = ta;
tmp->parent = parent;
}
if (ta->right) ta->right->parent = ta;
ta->parent = tmp;
if (!parent) {
*root_ptr = tmp;
} else if (ta == parent->left) {
parent->left = tmp;
} else {
parent->right = tmp;
}
}
void rotate_right(TreeAlloc **root_ptr, TreeAlloc *ta) {
TreeAlloc *parent, *tmp;
tmp = ta->left;
parent = ta->parent;
if (tmp) {
ta->left = tmp->right;
tmp->right = ta;
tmp->parent = parent;
}
if (ta->left) ta->left->parent = ta;
ta->parent = tmp;
if (!parent) {
*root_ptr = tmp;
} else if (ta == parent->left) {
parent->left = tmp;
} else {
parent->right = tmp;
}
}
void repair_tree_after_insert(TreeAlloc **root_ptr, TreeAlloc *ta) {
TreeAlloc *parent = ta->parent;
if (ta == *root_ptr) {
ta->color = COLOR_BLACK;
} else if (IS_BLACK_NODE(parent)) {
return;
} else {
TreeAlloc *uncle = get_sibling(parent->parent, parent);
TreeAlloc *grandparent = parent->parent;
if (IS_RED_NODE(uncle)) {
parent->color = COLOR_BLACK;
uncle->color = COLOR_BLACK;
grandparent->color = COLOR_RED;
repair_tree_after_insert(root_ptr, grandparent);
} else {
if (parent->left == ta) {
if (grandparent->left == parent) {
rotate_right(root_ptr, grandparent);
grandparent->color = COLOR_RED;
parent->color = COLOR_BLACK;
} else {
rotate_right(root_ptr, parent);
rotate_left(root_ptr, grandparent);
grandparent->color = COLOR_RED;
ta->color = COLOR_BLACK;
}
} else {
if (grandparent->left == parent) {
rotate_left(root_ptr, parent);
rotate_right(root_ptr, grandparent);
grandparent->color = COLOR_RED;
ta->color = COLOR_BLACK;
} else {
rotate_left(root_ptr, grandparent);
grandparent->color = COLOR_RED;
parent->color = COLOR_BLACK;
}
}
}
}
}
// Inserts a node into an empty tree.
void insert_singleton(TreeAlloc **root_ptr, TreeAlloc *to_insert) {
#ifdef DEBUG
printf("= PRE-INSERT-SINGLETON =\n");
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
*root_ptr = to_insert;
to_insert->parent = NULL;
to_insert->color = COLOR_BLACK;
#ifdef DEBUG
printf("= POST-INSERT-SINGLETON =\n");
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
}
void insert_by_size(TreeAlloc** root_ptr, TreeAlloc* to_insert) {
#ifdef DEBUG
printf("=== PRE-INSERT-BY-SIZE ===\n");
printf("===== INSERTING =====\n");
debug_print_node(0, to_insert, 0);
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
TreeAlloc *tree_ptr = *root_ptr;
while (1) {
if (to_insert->size < tree_ptr->size) {
if (tree_ptr->left) {
tree_ptr = tree_ptr->left;
} else {
tree_ptr->left = to_insert;
to_insert->parent = tree_ptr;
break;
}
} else {
if (tree_ptr->right) {
tree_ptr = tree_ptr->right;
} else {
tree_ptr->right = to_insert;
to_insert->parent = tree_ptr;
break;
}
}
}
to_insert->color = COLOR_RED;
repair_tree_after_insert(root_ptr, to_insert);
#ifdef DEBUG
printf("== POST-INSERT-FIXUP ===\n");
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
}
void insert_by_addr(TreeAlloc** root_ptr, TreeAlloc* to_insert) {
#ifdef DEBUG
printf("=== PRE-INSERT-BY-ADDR ===\n");
printf("===== INSERTING =====\n");
debug_print_tree(0, to_insert, 0);
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
TreeAlloc *tree_ptr = *root_ptr;
while (1) {
if (to_insert < tree_ptr) {
if (tree_ptr->left) {
tree_ptr = tree_ptr->left;
} else {
tree_ptr->left = to_insert;
to_insert->parent = tree_ptr;
break;
}
} else {
if (tree_ptr->right) {
tree_ptr = tree_ptr->right;
} else {
tree_ptr->right = to_insert;
to_insert->parent = tree_ptr;
break;
}
}
}
to_insert->color = COLOR_RED;
repair_tree_after_insert(root_ptr, to_insert);
#ifdef DEBUG
printf("== POST-INSERT-FIXUP ===\n");
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
}
void replace_node(TreeAlloc **root_ptr, TreeAlloc *node, TreeAlloc *replace) {
if (!node->parent) {
*root_ptr = replace;
} else {
if (node == node->parent->left)
node->parent->left = replace;
else
node->parent->right = replace;
}
if (replace) replace->parent = node->parent;
}
void repair_after_remove(TreeAlloc **root_ptr, TreeAlloc *parent, TreeAlloc *node) {
#ifdef DEBUG
printf("delete fixup at %p -> %p\n", parent, node);
#endif
// In theory, the last two conditions should be the same ...
if (IS_RED_NODE(node) || (node != NULL && node == *root_ptr)) {
node->color = COLOR_BLACK;
} else {
TreeAlloc *sibling = get_sibling(parent, node);
if (IS_RED_NODE(sibling)) {
if (parent->left == node) {
rotate_left(root_ptr, parent);
} else {
rotate_right(root_ptr, parent);
}
// The rotate shouldn't touch the parent relationship of `node`
parent->parent->color = COLOR_BLACK;
parent->color = COLOR_RED;
sibling = get_sibling(parent, node);
}
if (IS_BLACK_NODE(sibling->left) && IS_BLACK_NODE(sibling->right)) {
if (node != NULL)
node->color = COLOR_BLACK;
sibling->color = COLOR_RED;
repair_after_remove(root_ptr, parent->parent, parent);
} else {
if (parent->left == node && IS_BLACK_NODE(sibling->right)) {
rotate_right(root_ptr, sibling);
sibling->color = COLOR_RED;
sibling = parent->right;
sibling->color = COLOR_BLACK;
}
if (parent->right == node && IS_BLACK_NODE(sibling->left)) {
rotate_left(root_ptr, sibling);
sibling->color = COLOR_RED;
sibling = parent->left;
sibling->color = COLOR_BLACK;
}
if (parent->left == node) {
rotate_left(root_ptr, parent);
} else {
rotate_right(root_ptr, parent);
}
if (node != NULL)
node->color = COLOR_BLACK;
TreeAlloc *uncle = get_sibling(parent->parent, parent);
if (uncle != NULL)
uncle->color = COLOR_BLACK;
char swap = parent->color;
parent->color = parent->parent->color;
parent->parent->color = swap;
}
}
}
void remove_node(TreeAlloc **root_ptr, TreeAlloc *to_remove) {
char do_repair = 0;
char old_color;
#ifdef DEBUG
printf("====== PRE-REMOVE ======\n");
printf("======= REMOVING =======\n");
debug_print_node(0, to_remove, 0);
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
TreeAlloc *replace, *parent_of_replace;
TreeAlloc *parent = to_remove->parent;
if (!to_remove->left) {
#ifdef DEBUG
printf("code path 1l\n");
#endif
replace = to_remove->right;
parent_of_replace = to_remove->parent;
do_repair = to_remove->color == COLOR_BLACK;
replace_node(root_ptr, to_remove, replace);
} else if (!to_remove->right) {
#ifdef DEBUG
printf("code path 1r\n");
#endif
replace = to_remove->left;
parent_of_replace = to_remove->parent;
do_repair = to_remove->color == COLOR_BLACK;
replace_node(root_ptr, to_remove, replace);
} else {
#ifdef DEBUG
printf("code path 2\n");
#endif
TreeAlloc *tmp = succ(to_remove);
replace = tmp->right;
do_repair = tmp->color == COLOR_BLACK;
if (tmp != to_remove->right) {
replace_node(root_ptr, tmp, replace);
tmp->right = to_remove->right;
to_remove->right->parent = tmp;
parent_of_replace = tmp->parent;
} else {
parent_of_replace = tmp;
}
replace_node(root_ptr, to_remove, tmp);
tmp->color = to_remove->color;
tmp->left = to_remove->left;
to_remove->left->parent = tmp;
}
// Make sure that it doesn't have any tree pointers it shouldn't have.
to_remove->parent = to_remove->left = to_remove->right = NULL;
#ifdef DEBUG
printf("==== PRE-REMOVE-FIXUP ===\n");
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 1);
printf("===== END OF TREES =====\n");
printf("considering fixing up %p -> %p\n", parent_of_replace, replace);
#endif
if (replace && parent_of_replace == NULL) {
replace->color = COLOR_BLACK;
} else if (parent_of_replace != NULL && do_repair) {
repair_after_remove(root_ptr, parent_of_replace, replace);
}
#ifdef DEBUG
printf("=== POST-REMOVE ===\n");
printf("===== CURRENT TREE =====\n");
debug_print_tree(0, *root_ptr, 0);
printf("===== END OF TREES =====\n");
#endif
}
TreeAlloc *get_new_region(Arena *arena, uintptr_t size, uintptr_t padding, uintptr_t align) {
uintptr_t realsize = size + align + alignof(WatermarkAlloc) + padding - 1;
#ifdef DEBUG
printf("Attemping request of size %ld\n", realsize);
#endif
if (realsize < MIN_NEW_MEM_SIZE) {
realsize = MIN_NEW_MEM_SIZE;
}
TreeAlloc *reg = (TreeAlloc *) arena->get_new_region(realsize);
if (reg == NULL) {
arena->error("can't allocate a new memory region!");
} else {
reg->parent = NULL;
reg->left = NULL;
reg->right = NULL;
reg->before = NULL;
reg->after = NULL;
reg->size = realsize;
}
return reg;
}
void unalloc(Arena *arena, void *addr) {
#ifdef DEBUG
printf("==== UNALLOCATING ====\n");
printf("=== FREESPACE TREE ===\n");
debug_print_tree(0, arena->root_freespace, 0);
printf("=== TREEALLOC TREE ===\n");
debug_print_tree(0, arena->root_treealloc, 0);
printf("==== END OF TREES ====\n");
#endif
if (arena->root_treealloc == NULL) {
arena->error("attempt to unallocate when there are no allocations!");
return;
}
// Find the node this address belongs to
TreeAlloc *node = search_by_address(arena->root_treealloc, addr);
if (node == NULL) {
arena->error("attempt to free memory outside any allocations!");
return;
}
// Handle the watermark allocator in this region
if (node->type == RT_WATERMARK) {
// TODO: handle watermark deallocation
return;
}
// Get rid of it
remove_node(&arena->root_treealloc, node);
// If there's free space on either side of it, merge it with the free space into a bigger chunk of
// free space.
uintptr_t size = node->size;
FreeSpace *start = (FreeSpace*) node;
if (node->before != NULL && node->before->type == RT_FREESPACE) {
start = (FreeSpace*) node->before;
size += node->before->size;
remove_node((TreeAlloc**) &arena->root_freespace, node->before);
}
if (node->after != NULL && node->after->type == RT_FREESPACE) {
size += node->after->size;
remove_node((TreeAlloc**) &arena->root_freespace, node->after);
}
start->type = RT_FREESPACE;
start->size = size;
// And finally, insert the resulting free space.
if (arena->root_freespace == NULL) {
insert_singleton((TreeAlloc**) &arena->root_freespace, (TreeAlloc*) start);
} else {
TreeAlloc *insert_point = search_by_size((TreeAlloc*) arena->root_freespace, 0, 1, size);
if (insert_point == NULL) {
insert_by_size((TreeAlloc**) &arena->root_freespace, (TreeAlloc*) start);
} else {
insert_by_size((TreeAlloc**) &arena->root_freespace, (TreeAlloc*) start);
}
}
}
void *alloc(Arena *arena, uintptr_t size, uintptr_t align) {
uintptr_t actual_align = lcm(alignof(struct WatermarkAlloc), align);
#ifdef DEBUG
printf("==== ALLOCATING =====\n");
printf("=== FREESPACE TREE ===\n");
debug_print_tree(0, arena->root_freespace, 0);
printf("=== TREEALLOC TREE ===\n");
debug_print_tree(0, arena->root_treealloc, 0);
printf("==== END OF TREES ====\n");
#endif
TreeAlloc *region;
if (arena->root_freespace == NULL) {
// Handle being out of freespace.
#ifdef DEBUG
printf("Out of freespace nodes; getting more\n");
#endif
region = get_new_region(arena, size, sizeof(TreeAlloc), actual_align);
} else {
region = search_by_size((TreeAlloc*) arena->root_freespace, sizeof(TreeAlloc), actual_align, size);
if (region == NULL) {
// Handle insufficient freespace or fragmentation.
#ifdef DEBUG
printf("Out of sufficiently large freespace nodes; getting more\n");
#endif
region = get_new_region(arena, size, sizeof(TreeAlloc), actual_align);
} else {
remove_node((TreeAlloc**) &arena->root_freespace, region);
}
}
void *true_end = align_after(align_after(((void*) region) + sizeof(TreeAlloc), actual_align) + size, alignof(WatermarkAlloc));
// The size of the new allocation (adjusted for region header and alignment
uintptr_t new_size = true_end - (void*) region;
// The size of the free space region following the new allocation
uintptr_t new_free_size = region->size - new_size;
region->right = NULL;
region->left = NULL;
region->type = RT_TREE_NODE;
region->size = size;
#ifdef DEBUG
printf("start: %p, end: %p, adjusted end: %p\n", region, ((void*) region) + size, true_end);
printf("size: %lu -> %lu\n", size, new_size);
printf("new_free_size: %lu\n", new_free_size);
#endif
if (arena->root_treealloc == NULL) {
insert_singleton((TreeAlloc**) &arena->root_treealloc, region);
} else {
insert_by_addr(&arena->root_treealloc, region);
}
if (region->size >= new_size + sizeof(FreeSpace)) {
// If there's enough free space after the allocation, use it!
region->size = new_size; // Safe because the allocated region tree is not sorted by size.
FreeSpace *new_free = (FreeSpace*) ((void*) region + new_size);
new_free->left = NULL;
new_free->right = NULL;
new_free->parent = NULL;
new_free->type = RT_FREESPACE;
new_free->size = new_free_size;
if (arena->root_freespace == NULL) {
insert_singleton((TreeAlloc**) &arena->root_freespace, (TreeAlloc*) new_free);
} else {
insert_by_size((TreeAlloc**) &arena->root_freespace, (TreeAlloc*) new_free);
}
// Set the region following this one to be the new free space
region->after = (TreeAlloc*) new_free;
} else {
// There isn't a free space after this one, so put the `next` pointer at the next allocated
// region if there is one.
region->after = search_by_address((TreeAlloc *) &arena->root_treealloc, region + region->size + 1);
}
// Are there any allocations before this one?
region->before = search_by_address((TreeAlloc *) &arena->root_treealloc, region - 1);
#ifdef DEBUG
printf("region is still at %p\n", region);
printf("=== POST-ALLOCATION ===\n");
printf("=== FREESPACE TREE ===\n");
debug_print_tree(0, arena->root_freespace, 0);
printf("=== TREEALLOC TREE ===\n");
debug_print_tree(0, arena->root_treealloc, 0);
printf("==== END OF TREES ====\n");
#endif
return align_after((void*) region + sizeof(TreeAlloc), actual_align);
}
void *alloc_growable(Arena *arena, uintptr_t size, uintptr_t align) {
// TODO: Basically the same as above, but put the allocated region in the center of the largest free
// space. Due to alignment and whatnot, the code will be gory.
return NULL;
}