hash.c

文件系统源代码!!!!! 文件系统源代码

/**
* Copyright (C) 2008 Happy Fish / YuQing
*
* FastDFS may be copied only under the terms of the GNU General
* Public License V3, which may be found in the FastDFS source kit.
* Please visit the FastDFS Home Page http://www.csource.org/ for more detail.
**/

#include "hash.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

static unsigned int prime_array[] = {
    1,              /* 0 */
    3,              /* 1 */
    17,             /* 2 */
    37,             /* 3 */
    79,             /* 4 */
    163,            /* 5 */
    331,            /* 6 */
    673,            /* 7 */
    1361,           /* 8 */
    2729,           /* 9 */
    5471,           /* 10 */
    10949,          /* 11 */
    21911,          /* 12 */
    43853,          /* 13 */
    87719,          /* 14 */
    175447,         /* 15 */
    350899,         /* 16 */
    701819,         /* 17 */
    1403641,        /* 18 */
    2807303,        /* 19 */
    5614657,        /* 20 */
    11229331,       /* 21 */
    22458671,       /* 22 */
    44917381,       /* 23 */
    89834777,       /* 24 */
    179669557,      /* 25 */
    359339171,      /* 26 */
    718678369,      /* 27 */
    1437356741,     /* 28 */
    2147483647      /* 29 (largest signed int prime) */
};

#define PRIME_ARRAY_SIZE  30

int _hash_alloc_buckets(HashArray *pHash)
{
	ChainList *plist;
	ChainList *list_end;

	pHash->items=(ChainList *)malloc(sizeof(ChainList)*(*pHash->capacity));
	if (pHash->items == NULL)
	{
		return ENOMEM;
	}

	list_end = pHash->items + (*pHash->capacity);
	for (plist=pHash->items; plist!=list_end; plist++)
	{
		chain_init(plist, CHAIN_TYPE_APPEND, free, NULL);
	}

	return 0;
}

int hash_init(HashArray *pHash, HashFunc hash_func, \
		const unsigned int capacity, const double load_factor)
{
	unsigned int *pprime;
	unsigned int *prime_end;
	int result;

	if (pHash == NULL || hash_func == NULL)
	{
		return EINVAL;
	}

	memset(pHash, 0, sizeof(HashArray));
	prime_end = prime_array + PRIME_ARRAY_SIZE;
	for (pprime = prime_array; pprime!=prime_end; pprime++)
	{
		if (*pprime > capacity)
		{
			pHash->capacity = pprime;
			break;
		}
	}

	if (pHash->capacity == NULL)
	{
		return EINVAL;
	}

	if ((result=_hash_alloc_buckets(pHash)) != 0)
	{
		return result;
	}

	pHash->hash_func = hash_func;

	if (load_factor >= 0.10 && load_factor <= 1.00)
	{
		pHash->load_factor = load_factor;
	}
	else
	{
		pHash->load_factor = 0.50;
	}

	return 0;
}

void hash_destroy(HashArray *pHash)
{
	ChainList *plist;
	ChainList *list_end;

	if (pHash == NULL || pHash->items == NULL)
	{
		return;
	}

	list_end = pHash->items + (*pHash->capacity);
	for (plist=pHash->items; plist!=list_end; plist++)
	{
		chain_destroy(plist);
	}

	free(pHash->items);
	pHash->items = NULL;
	if (pHash->is_malloc_capacity)
	{
		free(pHash->capacity);
		pHash->capacity = NULL;
		pHash->is_malloc_capacity = false;
	}
}

void hash_stat_print(HashArray *pHash)
{
#define STAT_MAX_NUM  17
	ChainList *plist;
	ChainList *list_end;
	int totalLength;
	//ChainNode *pnode;
	//HashData *hash_data;
	int stats[STAT_MAX_NUM];
	int last;
	int index;
	int i;
	int max_length;
	int list_count;
	int bucket_used;

	if (pHash == NULL || pHash->items == NULL)
	{
		return;
	}

	memset(stats, 0, sizeof(stats));
	last = STAT_MAX_NUM - 1;
	list_end = pHash->items + (*pHash->capacity);
	max_length = 0;
	bucket_used = 0;
	for (plist=pHash->items; plist!=list_end; plist++)
	{
		list_count = chain_count(plist);
		if (list_count == 0)
		{
			continue;
		}

		bucket_used++;
		index = list_count - 1;
		if (index > last)
		{
			index = last;
		}
		stats[index]++;

		if (list_count > max_length)
		{
			max_length = list_count;
		}

		/*
		pnode = plist->head;
		while (pnode != NULL)
		{
			pnode = pnode->next;
		}
		*/
	}

	/*
	printf("collision stat:\n");
	for (i=0; i<last; i++)
	{
		if (stats[i] > 0) printf("%d: %d\n", i+1, stats[i]);
	}
	if (stats[i] > 0) printf(">=%d: %d\n", i+1, stats[i]);
	*/

	totalLength = 0;
	for (i=0; i<STAT_MAX_NUM; i++)
	{
		if (stats[i] > 0) totalLength += (i+1) * stats[i];
	}
	printf("capacity: %d, item_count=%d, bucket_used: %d, " \
		"avg length: %.4f, max length: %d, bucket / item = %.2f%%\n", 
               *pHash->capacity, pHash->item_count, bucket_used,
               bucket_used > 0 ? (double)totalLength / (double)bucket_used:0.00,
               max_length, (double)bucket_used*100.00/(double)*pHash->capacity);
}

static int _rehash1(HashArray *pHash, const int old_capacity, \
		unsigned int *new_capacity)
{
	ChainList *old_items;
	ChainList *plist;
	ChainList *list_end;
	ChainNode *pnode;
	HashData *hash_data;
	ChainList *pNewList;
	int result;

	old_items = pHash->items;
	pHash->capacity = new_capacity;
	if ((result=_hash_alloc_buckets(pHash)) != 0)
	{
		pHash->items = old_items;
		return result;
	}

	//printf("old: %d, new: %d\n", old_capacity, *pHash->capacity);
	list_end = old_items + old_capacity;
	for (plist=old_items; plist!=list_end; plist++)
	{
		pnode = plist->head;
		while (pnode != NULL)
		{
			hash_data = (HashData *) pnode->data;
			pNewList = pHash->items + (hash_data->hash_code % \
				(*pHash->capacity));

			//success to add node
			if (addNode(pNewList, hash_data) == 0)
			{
			}

			pnode = pnode->next;
		}

		plist->freeDataFunc = NULL;
		chain_destroy(plist);
	}

	free(old_items);
	return 0;
}

static int _rehash(HashArray *pHash)
{
	int result;
	unsigned int *pOldCapacity;

	pOldCapacity = pHash->capacity;
	if (pHash->is_malloc_capacity)
	{
		unsigned int *pprime;
		unsigned int *prime_end;

		pHash->capacity = NULL;

		prime_end = prime_array + PRIME_ARRAY_SIZE;
		for (pprime = prime_array; pprime!=prime_end; pprime++)
		{
			if (*pprime > *pOldCapacity)
			{
				pHash->capacity = pprime;
				break;
			}
		}
	}
	else
	{
		pHash->capacity++;
	}

	if ((result=_rehash1(pHash, *pOldCapacity, pHash->capacity)) != 0)
	{
		pHash->capacity = pOldCapacity;  //rollback
	}
	else
	{
		if (pHash->is_malloc_capacity)
		{
			free(pOldCapacity);
			pHash->is_malloc_capacity = false;
		}
	}

	/*printf("rehash, old_capacity=%d, new_capacity=%d\n", \
		old_capacity, *pHash->capacity);
	*/
	return result;
}

int _hash_conflict_count(HashArray *pHash)
{
	ChainList *plist;
	ChainList *list_end;
	ChainNode *pnode;
	ChainNode *pSubNode;
	int conflicted;
	int conflict_count;

	if (pHash == NULL || pHash->items == NULL)
	{
		return 0;
	}

	list_end = pHash->items + (*pHash->capacity);
	conflict_count = 0;
	for (plist=pHash->items; plist!=list_end; plist++)
	{
		if (plist->head == NULL || plist->head->next == NULL)
		{
			continue;
		}

		conflicted = 0;
		pnode = plist->head;
		while (pnode != NULL)
		{
			pSubNode = pnode->next;
			while (pSubNode != NULL)
			{
				if (((HashData *)pnode->data)->hash_code != \
					((HashData *)pSubNode->data)->hash_code)
				{
					conflicted = 1;
					break;
				}

				pSubNode = pSubNode->next;
			}

			if (conflicted)
			{
				break;
			}

			pnode = pnode->next;
		}

		conflict_count += conflicted;
	}

	return conflict_count;
}

int hash_best_op(HashArray *pHash, const int suggest_capacity)
{
	int old_capacity;
	int conflict_count;
	unsigned int *new_capacity;
	int result;

	if ((conflict_count=_hash_conflict_count(pHash)) == 0)
	{
		return 0;
	}

	old_capacity = *pHash->capacity;
	new_capacity = (unsigned int *)malloc(sizeof(unsigned int));
	if (new_capacity == NULL)
	{
		return -ENOMEM;
	}

	if ((suggest_capacity > 2) && (suggest_capacity >= pHash->item_count))
	{
		*new_capacity = suggest_capacity - 2;
		if (*new_capacity % 2 == 0)
		{
			++(*new_capacity);
		}
	}
	else
	{
		*new_capacity = 2 * (pHash->item_count - 1) + 1;
	}

	do
	{
		do
		{
			*new_capacity += 2;
		} while ((*new_capacity % 3 == 0) || (*new_capacity % 5 == 0) \
			 || (*new_capacity % 7 == 0));

		if ((result=_rehash1(pHash, old_capacity, new_capacity)) != 0)