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#include "pool.h"

#ifndef GIT_WIN32

#include <unistd.h>

#endif

struct git_pool_page {

git_pool_page *next;

uint32_t size;

uint32_t avail;

char data[GIT_FLEX_ARRAY];

};

#define GIT_POOL_MIN_USABLE 4

#define GIT_POOL_MIN_PAGESZ 2 * sizeof(void*)

static void *pool_alloc_page(git_pool *pool, uint32_t size);

static void pool_insert_page(git_pool *pool, git_pool_page *page);

int git_pool_init(

git_pool *pool, uint32_t item_size, uint32_t items_per_page)

{

assert(pool);

if (!item_size)

item_size = 1;

/* round up item_size for decent object alignment */

if (item_size > 4)

item_size = (item_size + 7) & ~7;

else if (item_size == 3)

item_size = 4;

if (!items_per_page)

items_per_page = git_pool__suggest_items_per_page(item_size);

if (item_size * items_per_page < GIT_POOL_MIN_PAGESZ)

items_per_page = (GIT_POOL_MIN_PAGESZ + item_size - 1) / item_size;

memset(pool, 0, sizeof(git_pool));

pool->item_size = item_size;

pool->page_size = item_size * items_per_page;

return 0;

}

void git_pool_clear(git_pool *pool)

{

git_pool_page *scan, *next;

for (scan = pool->open; scan != NULL; scan = next) {

next = scan->next;

git__free(scan);

}

pool->open = NULL;

for (scan = pool->full; scan != NULL; scan = next) {

next = scan->next;

git__free(scan);

}

pool->full = NULL;

pool->free_list = NULL;

pool->items = 0;

pool->has_string_alloc = 0;

pool->has_multi_item_alloc = 0;

pool->has_large_page_alloc = 0;

}

void git_pool_swap(git_pool *a, git_pool *b)

{

git_pool temp;

if (a == b)

return;

memcpy(&temp, a, sizeof(temp));

memcpy(a, b, sizeof(temp));

memcpy(b, &temp, sizeof(temp));

}

static void pool_insert_page(git_pool *pool, git_pool_page *page)

{

git_pool_page *scan;

/* If there are no open pages or this page has the most open space,

* insert it at the beginning of the list. This is the common case.

*/

if (pool->open == NULL || pool->open->avail < page->avail) {

page->next = pool->open;

pool->open = page;

return;

}

/* Otherwise insert into sorted position. */

for (scan = pool->open;

scan->next && scan->next->avail > page->avail;

scan = scan->next);

page->next = scan->next;

scan->next = page;

}

static void *pool_alloc_page(git_pool *pool, uint32_t size)

{

git_pool_page *page;

uint32_t alloc_size;

if (size <= pool->page_size)

alloc_size = pool->page_size;

else {

alloc_size = size;

pool->has_large_page_alloc = 1;

}

page = git__calloc(1, alloc_size + sizeof(git_pool_page));

if (!page)

return NULL;

page->size = alloc_size;

page->avail = alloc_size - size;

if (page->avail > 0)

pool_insert_page(pool, page);

else {

page->next = pool->full;

pool->full = page;

}

pool->items++;

return page->data;

}

GIT_INLINE(void) pool_remove_page(

git_pool *pool, git_pool_page *page, git_pool_page *prev)

{

if (prev == NULL)

pool->open = page->next;

else

prev->next = page->next;

}

void *git_pool_malloc(git_pool *pool, uint32_t items)

{

git_pool_page *scan = pool->open, *prev;

uint32_t size = items * pool->item_size;

void *ptr = NULL;

pool->has_string_alloc = 0;

if (items > 1)

pool->has_multi_item_alloc = 1;

else if (pool->free_list != NULL) {

ptr = pool->free_list;

pool->free_list = *((void **)pool->free_list);

return ptr;

}

/* just add a block if there is no open one to accomodate this */

if (size >= pool->page_size || !scan || scan->avail < size)

return pool_alloc_page(pool, size);

pool->items++;

/* find smallest block in free list with space */

for (scan = pool->open, prev = NULL;

scan->next && scan->next->avail >= size;

prev = scan, scan = scan->next);

/* allocate space from the block */

ptr = &scan->data[scan->size - scan->avail];

scan->avail -= size;

/* move to full list if there is almost no space left */

if (scan->avail < pool->item_size || scan->avail < GIT_POOL_MIN_USABLE) {

pool_remove_page(pool, scan, prev);

scan->next = pool->full;

pool->full = scan;

}

/* reorder list if block is now smaller than the one after it */

else if (scan->next != NULL && scan->next->avail > scan->avail) {

pool_remove_page(pool, scan, prev);

pool_insert_page(pool, scan);

}

return ptr;

}

char *git_pool_strndup(git_pool *pool, const char *str, size_t n)

{

void *ptr = NULL;

assert(pool && str && pool->item_size == sizeof(char));

if ((ptr = git_pool_malloc(pool, (uint32_t)(n + 1))) != NULL) {

memcpy(ptr, str, n);

*(((char *)ptr) + n) = '\0';

}

pool->has_string_alloc = 1;

return ptr;

}

char *git_pool_strdup(git_pool *pool, const char *str)

{

assert(pool && str && pool->item_size == sizeof(char));

return git_pool_strndup(pool, str, strlen(str));

}

char *git_pool_strdup_safe(git_pool *pool, const char *str)

{

return str ? git_pool_strdup(pool, str) : NULL;

}

char *git_pool_strcat(git_pool *pool, const char *a, const char *b)

{

void *ptr;

size_t len_a, len_b;

assert(pool && a && b && pool->item_size == sizeof(char));

len_a = a ? strlen(a) : 0;

len_b = b ? strlen(b) : 0;

if ((ptr = git_pool_malloc(pool, (uint32_t)(len_a + len_b + 1))) != NULL) {

if (len_a)

memcpy(ptr, a, len_a);

if (len_b)

memcpy(((char *)ptr) + len_a, b, len_b);

*(((char *)ptr) + len_a + len_b) = '\0';

}

pool->has_string_alloc = 1;

return ptr;

}

void git_pool_free(git_pool *pool, void *ptr)

{

assert(pool && ptr && pool->item_size >= sizeof(void*));

*((void **)ptr) = pool->free_list;

pool->free_list = ptr;

}

uint32_t git_pool__open_pages(git_pool *pool)

{

uint32_t ct = 0;

git_pool_page *scan;

for (scan = pool->open; scan != NULL; scan = scan->next) ct++;

return ct;

}

uint32_t git_pool__full_pages(git_pool *pool)

{

uint32_t ct = 0;

git_pool_page *scan;

for (scan = pool->full; scan != NULL; scan = scan->next) ct++;

return ct;

}

bool git_pool__ptr_in_pool(git_pool *pool, void *ptr)

{

git_pool_page *scan;

for (scan = pool->open; scan != NULL; scan = scan->next)

if ((void *)scan->data <= ptr &&

(void *)(((char *)scan->data) + scan->size) > ptr)

return true;

for (scan = pool->full; scan != NULL; scan = scan->next)

if ((void *)scan->data <= ptr &&

(void *)(((char *)scan->data) + scan->size) > ptr)

return true;

return false;

}

uint32_t git_pool__system_page_size(void)

{

static uint32_t size = 0;

if (!size) {

#ifdef GIT_WIN32

SYSTEM_INFO info;

GetSystemInfo(&info);

size = (uint32_t)info.dwPageSize;

#elif defined(__amigaos4__)

size = (uint32_t)4096; /* 4K as there is no global value we can query */

#else

size = (uint32_t)sysconf(_SC_PAGE_SIZE);

#endif

size -= 2 * sizeof(void *); /* allow space for malloc overhead */

}

return size;

}

uint32_t git_pool__suggest_items_per_page(uint32_t item_size)

{

uint32_t page_bytes =

git_pool__system_page_size() - sizeof(git_pool_page);

return page_bytes / item_size;

}