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/*
 * region-allocator.c -- region based memory allocator.
 *
 * Copyright (c) 2001-2006, NLnet Labs. All rights reserved.
 *
 * See LICENSE for the license.
 *
 */

#include "config.h"

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

#include "region-allocator.h"
#include "util.h"

/** This value is enough so that x*y does not overflow if both < than this */
#define REGION_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))

#ifdef ALIGNMENT
#undef ALIGNMENT
#endif
#ifndef PACKED_STRUCTS
#define REGION_ALIGN_UP(x, s)     (((x) + s - 1) & (~(s - 1)))
#if SIZEOF_OFF_T > SIZEOF_VOIDP
#define ALIGNMENT	(sizeof(off_t))
#else
#define ALIGNMENT	(sizeof(void *))
#endif
#else
#define REGION_ALIGN_UP(x, s) ((x)<SIZEOF_VOIDP?SIZEOF_VOIDP:(x))
#define ALIGNMENT 1
#endif /* PACKED_STRUCTS */
/* #define CHECK_DOUBLE_FREE 0 */ /* set to 1 to perform expensive check for double recycle() */

typedef struct cleanup cleanup_type;
struct cleanup
{
	void (*action)(void *);
	void *data;
};

struct recycle_elem {
	struct recycle_elem* next;
};

struct large_elem {
	struct large_elem* next;
	struct large_elem* prev;
};

struct region
{
	size_t        total_allocated;
	size_t        small_objects;
	size_t        large_objects;
	size_t        chunk_count;
	size_t        unused_space; /* Unused space due to alignment, etc. */

	size_t        allocated;
	char         *initial_data;
	char         *data;

	void         *(*allocator)(size_t);
	void          (*deallocator)(void *);

	size_t        maximum_cleanup_count;
	size_t        cleanup_count;
	cleanup_type *cleanups;
	struct large_elem* large_list;

	size_t        chunk_size;
	size_t        large_object_size;

	/* if not NULL recycling is enabled.
	 * It is an array of linked lists of parts held for recycle.
	 * The parts are all pointers to within the allocated chunks.
	 * Array [i] points to elements of size i. */
	struct recycle_elem** recycle_bin;
	/* amount of memory in recycle storage */
	size_t		recycle_size;
};


static region_type *
alloc_region_base(void *(*allocator)(size_t size),
		  void (*deallocator)(void *),
		  size_t initial_cleanup_count)
{
	region_type *result = (region_type *) allocator(sizeof(region_type));
	if (!result) return NULL;

	result->total_allocated = 0;
	result->small_objects = 0;
	result->large_objects = 0;
	result->chunk_count = 1;
	result->unused_space = 0;
	result->recycle_bin = NULL;
	result->recycle_size = 0;
	result->large_list = NULL;

	result->allocated = 0;
	result->data = NULL;
	result->initial_data = NULL;

	result->allocator = allocator;
	result->deallocator = deallocator;

	assert(initial_cleanup_count > 0);
	result->maximum_cleanup_count = initial_cleanup_count;
	result->cleanup_count = 0;
	result->cleanups = (cleanup_type *) allocator(
		result->maximum_cleanup_count * sizeof(cleanup_type));
	if (!result->cleanups) {
		deallocator(result);
		return NULL;
	}

	result->chunk_size = DEFAULT_CHUNK_SIZE;
	result->large_object_size = DEFAULT_LARGE_OBJECT_SIZE;
	return result;
}

region_type *
region_create(void *(*allocator)(size_t size),
	      void (*deallocator)(void *))
{
	region_type* result = alloc_region_base(allocator, deallocator,
		DEFAULT_INITIAL_CLEANUP_SIZE);
	if(!result)
		return NULL;
	result->data = (char *) allocator(result->chunk_size);
	if (!result->data) {
		deallocator(result->cleanups);
		deallocator(result);
		return NULL;
	}
	result->initial_data = result->data;

	return result;
}


region_type *region_create_custom(void *(*allocator)(size_t),
				  void (*deallocator)(void *),
				  size_t chunk_size,
				  size_t large_object_size,
				  size_t initial_cleanup_size,
				  int recycle)
{
	region_type* result = alloc_region_base(allocator, deallocator,
		initial_cleanup_size);
	if(!result)
		return NULL;
	assert(large_object_size <= chunk_size);
	result->chunk_size = chunk_size;
	result->large_object_size = large_object_size;
	if(result->chunk_size > 0) {
		result->data = (char *) allocator(result->chunk_size);
		if (!result->data) {
			deallocator(result->cleanups);
			deallocator(result);
			return NULL;
		}
		result->initial_data = result->data;
	}
	if(recycle) {
		result->recycle_bin = allocator(sizeof(struct recycle_elem*)
			* result->large_object_size);
		if(!result->recycle_bin) {
			region_destroy(result);
			return NULL;
		}
		memset(result->recycle_bin, 0, sizeof(struct recycle_elem*)
			* result->large_object_size);
	}
	return result;
}


void
region_destroy(region_type *region)
{
	void (*deallocator)(void *);
	if (!region)
		return;

	deallocator = region->deallocator;

	region_free_all(region);
	deallocator(region->cleanups);
	deallocator(region->initial_data);
	if(region->recycle_bin)
		deallocator(region->recycle_bin);
	if(region->large_list) {
		struct large_elem* p = region->large_list, *np;
		while(p) {
			np = p->next;
			deallocator(p);
			p = np;
		}
	}
	deallocator(region);
}


size_t
region_add_cleanup(region_type *region, void (*action)(void *), void *data)
{
	assert(action);

	if (region->cleanup_count >= region->maximum_cleanup_count) {
		cleanup_type *cleanups = (cleanup_type *) region->allocator(
			2 * region->maximum_cleanup_count * sizeof(cleanup_type));
		if (!cleanups)
			return 0;

		memcpy(cleanups, region->cleanups,
		       region->cleanup_count * sizeof(cleanup_type));
		region->deallocator(region->cleanups);

		region->cleanups = cleanups;
		region->maximum_cleanup_count *= 2;
	}

	region->cleanups[region->cleanup_count].action = action;
	region->cleanups[region->cleanup_count].data = data;

	++region->cleanup_count;
	return region->cleanup_count;
}

void
region_remove_cleanup(region_type *region, void (*action)(void *), void *data)
{
	size_t i;
	for(i=0; i<region->cleanup_count; i++) {
		if(region->cleanups[i].action == action &&
		   region->cleanups[i].data == data) {
			region->cleanup_count--;
			region->cleanups[i] =
				region->cleanups[region->cleanup_count];
			return;
		}
	}
}

void *
region_alloc(region_type *region, size_t size)
{
	size_t aligned_size;
	void *result;

	if (size == 0) {
		size = 1;
	}
	aligned_size = REGION_ALIGN_UP(size, ALIGNMENT);

	if (aligned_size >= region->large_object_size) {
		result = region->allocator(size + sizeof(struct large_elem));
		if (!result)
			return NULL;
		((struct large_elem*)result)->prev = NULL;
		((struct large_elem*)result)->next = region->large_list;
		if(region->large_list)
			region->large_list->prev = (struct large_elem*)result;
		region->large_list = (struct large_elem*)result;

		region->total_allocated += size;
		++region->large_objects;

		return (char *)result + sizeof(struct large_elem);
	}

	if (region->recycle_bin && region->recycle_bin[aligned_size]) {
		result = (void*)region->recycle_bin[aligned_size];
		region->recycle_bin[aligned_size] = region->recycle_bin[aligned_size]->next;
		region->recycle_size -= aligned_size;
		region->unused_space += aligned_size - size;
		return result;
	}

	if (region->allocated + aligned_size > region->chunk_size) {
		void *chunk = region->allocator(region->chunk_size);
		size_t wasted;
		if (!chunk)
			return NULL;

		wasted = (region->chunk_size - region->allocated) & (~(ALIGNMENT-1));
		if(
#ifndef PACKED_STRUCTS
			wasted >= ALIGNMENT
#else
			wasted >= SIZEOF_VOIDP
#endif
			) {
			/* put wasted part in recycle bin for later use */
			region->total_allocated += wasted;
			++region->small_objects;
			region_recycle(region, region->data+region->allocated, wasted);
			region->allocated += wasted;
		}
		++region->chunk_count;
		region->unused_space += region->chunk_size - region->allocated;

		if(!region_add_cleanup(region, region->deallocator, chunk)) {
			region->deallocator(chunk);
			region->chunk_count--;
			region->unused_space -=
                                region->chunk_size - region->allocated;
			return NULL;
		}
		region->allocated = 0;
		region->data = (char *) chunk;
	}

	result = region->data + region->allocated;
	region->allocated += aligned_size;

	region->total_allocated += aligned_size;
	region->unused_space += aligned_size - size;
	++region->small_objects;

	return result;
}

void *
region_alloc_init(region_type *region, const void *init, size_t size)
{
	void *result = region_alloc(region, size);
	if (!result) return NULL;
	memcpy(result, init, size);
	return result;
}

void *
region_alloc_zero(region_type *region, size_t size)
{
	void *result = region_alloc(region, size);
	if (!result) return NULL;
	memset(result, 0, size);
	return result;
}

void *
region_alloc_array_init(region_type *region, const void *init, size_t num,
	size_t size)
{
	if((num >= REGION_NO_OVERFLOW || size >= REGION_NO_OVERFLOW) &&
		num > 0 && SIZE_MAX / num < size) {
		log_msg(LOG_ERR, "region_alloc_array_init failed because of integer overflow");
		exit(1);
	}
	return region_alloc_init(region, init, num*size);
}

void *
region_alloc_array_zero(region_type *region, size_t num, size_t size)
{
	if((num >= REGION_NO_OVERFLOW || size >= REGION_NO_OVERFLOW) &&
		num > 0 && SIZE_MAX / num < size) {
		log_msg(LOG_ERR, "region_alloc_array_zero failed because of integer overflow");
		exit(1);
	}
	return region_alloc_zero(region, num*size);
}

void *
region_alloc_array(region_type *region, size_t num, size_t size)
{
	if((num >= REGION_NO_OVERFLOW || size >= REGION_NO_OVERFLOW) &&
		num > 0 && SIZE_MAX / num < size) {
		log_msg(LOG_ERR, "region_alloc_array failed because of integer overflow");
		exit(1);
	}
	return region_alloc(region, num*size);
}

void
region_free_all(region_type *region)
{
	size_t i;
	assert(region);
	assert(region->cleanups);

	i = region->cleanup_count;
	while (i > 0) {
		--i;
		assert(region->cleanups[i].action);
		region->cleanups[i].action(region->cleanups[i].data);
	}

	if(region->recycle_bin) {
		memset(region->recycle_bin, 0, sizeof(struct recycle_elem*)
			* region->large_object_size);
		region->recycle_size = 0;
	}

	if(region->large_list) {
		struct large_elem* p = region->large_list, *np;
		void (*deallocator)(void *) = region->deallocator;
		while(p) {
			np = p->next;
			deallocator(p);
			p = np;
		}
		region->large_list = NULL;
	}

	region->data = region->initial_data;
	region->cleanup_count = 0;
	region->allocated = 0;

	region->total_allocated = 0;
	region->small_objects = 0;
	region->large_objects = 0;
	region->chunk_count = 1;
	region->unused_space = 0;
}


char *
region_strdup(region_type *region, const char *string)
{
	return (char *) region_alloc_init(region, string, strlen(string) + 1);
}

void
region_recycle(region_type *region, void *block, size_t size)
{
	size_t aligned_size;

	if(!block || !region->recycle_bin)
		return;

	if (size == 0) {
		size = 1;
	}
	aligned_size = REGION_ALIGN_UP(size, ALIGNMENT);

	if(aligned_size < region->large_object_size) {
		struct recycle_elem* elem = (struct recycle_elem*)block;
		/* we rely on the fact that ALIGNMENT is void* so the next will fit */
		assert(aligned_size >= sizeof(struct recycle_elem));

#ifdef CHECK_DOUBLE_FREE
		if(CHECK_DOUBLE_FREE) {
			/* make sure the same ptr is not freed twice. */
			struct recycle_elem *p = region->recycle_bin[aligned_size];
			while(p) {
				assert(p != elem);
				p = p->next;
			}
		}
#endif

		elem->next = region->recycle_bin[aligned_size];
		region->recycle_bin[aligned_size] = elem;
		region->recycle_size += aligned_size;
		region->unused_space -= aligned_size - size;
		return;
	} else {
		struct large_elem* l;

		/* a large allocation */
		region->total_allocated -= size;
		--region->large_objects;

		l = (struct large_elem*)((char*)block-sizeof(struct large_elem));
		if(l->prev)
			l->prev->next = l->next;
		else	region->large_list = l->next;
		if(l->next)
			l->next->prev = l->prev;
		region->deallocator(l);
	}
}

void
region_dump_stats(region_type *region, FILE *out)
{
	fprintf(out, "%lu objects (%lu small/%lu large), %lu bytes allocated (%lu wasted) in %lu chunks, %lu cleanups, %lu in recyclebin",
		(unsigned long) (region->small_objects + region->large_objects),
		(unsigned long) region->small_objects,
		(unsigned long) region->large_objects,
		(unsigned long) region->total_allocated,
		(unsigned long) region->unused_space,
		(unsigned long) region->chunk_count,
		(unsigned long) region->cleanup_count,
		(unsigned long) region->recycle_size);
	if(region->recycle_bin) {
		/* print details of the recycle bin */
		size_t i;
		for(i=0; i<region->large_object_size; i++) {
			size_t count = 0;
			struct recycle_elem* el = region->recycle_bin[i];
			while(el) {
				count++;
				el = el->next;
			}
			if(i%ALIGNMENT == 0 && i!=0)
				fprintf(out, " %lu", (unsigned long)count);
		}
	}
}

size_t region_get_recycle_size(region_type* region)
{
	return region->recycle_size;
}

size_t region_get_mem(region_type* region)
{
	return region->total_allocated;
}

size_t region_get_mem_unused(region_type* region)
{
	return region->unused_space;
}

/* debug routine */
void
region_log_stats(region_type *region)
{
	char buf[10240], *str=buf;
	int strl = sizeof(buf);
	int len;
	snprintf(str, strl, "%lu objects (%lu small/%lu large), %lu bytes allocated (%lu wasted) in %lu chunks, %lu cleanups, %lu in recyclebin",
		(unsigned long) (region->small_objects + region->large_objects),
		(unsigned long) region->small_objects,
		(unsigned long) region->large_objects,
		(unsigned long) region->total_allocated,
		(unsigned long) region->unused_space,
		(unsigned long) region->chunk_count,
		(unsigned long) region->cleanup_count,
		(unsigned long) region->recycle_size);
	len = strlen(str);
	str+=len;
	strl-=len;
	if(region->recycle_bin) {
		/* print details of the recycle bin */
		size_t i;
		for(i=0; i<region->large_object_size; i++) {
			size_t count = 0;
			struct recycle_elem* el = region->recycle_bin[i];
			while(el) {
				count++;
				el = el->next;
			}
			if(i%ALIGNMENT == 0 && i!=0) {
				snprintf(str, strl, " %lu", (unsigned long)count);
				len = strlen(str);
				str+=len;
				strl-=len;
			}
		}
	}
	log_msg(LOG_INFO, "memory: %s", buf);
}