lang/c/src/st.c

/*
 * This is a public domain general purpose hash table package written by
 * Peter Moore @ UCB. 
 */

/*
 * static char sccsid[] = "@(#) st.c 5.1 89/12/14 Crucible"; 
 */

#include "avro_private.h"
#include "avro/allocation.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "st.h"

typedef struct st_table_entry st_table_entry;

struct st_table_entry {
	unsigned int hash;
	st_data_t key;
	st_data_t record;
	st_table_entry *next;
};

#define ST_DEFAULT_MAX_DENSITY 5
#define ST_DEFAULT_INIT_TABLE_SIZE 11

	/*
	 * DEFAULT_MAX_DENSITY is the default for the largest we allow the
	 * average number of items per bin before increasing the number of
	 * bins
	 *
	 * DEFAULT_INIT_TABLE_SIZE is the default for the number of bins
	 * allocated initially
	 *
	 */
static int numcmp(long, long);
static int numhash(long);
static struct st_hash_type type_numhash = {
	HASH_FUNCTION_CAST numcmp,
	HASH_FUNCTION_CAST numhash
};

/*
 * extern int strcmp(const char *, const char *); 
 */
static int strhash(const char *);
static struct st_hash_type type_strhash = {
	HASH_FUNCTION_CAST strcmp,
	HASH_FUNCTION_CAST strhash
};

static void rehash(st_table *);

#ifdef RUBY
#define malloc xmalloc
#define calloc xcalloc
#endif

#define Calloc(n,s) (char*)avro_calloc((n),(s))

#define free_bins(tbl)  \
	avro_free(tbl->bins, tbl->num_bins * sizeof(st_table_entry *))

#define EQUAL(table,x,y) ((x)==(y) || (*table->type->compare)((x),(y)) == 0)

#define do_hash(key,table) (unsigned int)(*(table)->type->hash)((key))
#define do_hash_bin(key,table) (do_hash(key, table)%(table)->num_bins)

/*
 * MINSIZE is the minimum size of a dictionary.
 */

#define MINSIZE 8

/*
 * Table of prime numbers 2^n+a, 2<=n<=30. 
 */
static long primes[] = {
	8 + 3,
	16 + 3,
	32 + 5,
	64 + 3,
	128 + 3,
	256 + 27,
	512 + 9,
	1024 + 9,
	2048 + 5,
	4096 + 3,
	8192 + 27,
	16384 + 43,
	32768 + 3,
	65536 + 45,
	131072 + 29,
	262144 + 3,
	524288 + 21,
	1048576 + 7,
	2097152 + 17,
	4194304 + 15,
	8388608 + 9,
	16777216 + 43,
	33554432 + 35,
	67108864 + 15,
	134217728 + 29,
	268435456 + 3,
	536870912 + 11,
	1073741824 + 85,
	0
};

static int new_size(int size)
{
	unsigned int i;

#if 0
	for (i = 3; i < 31; i++) {
		if ((1 << i) > size)
			return 1 << i;
	}
	return -1;
#else
	int newsize;

	for (i = 0, newsize = MINSIZE;
	     i < sizeof(primes) / sizeof(primes[0]); i++, newsize <<= 1) {
		if (newsize > size)
			return primes[i];
	}
	/*
	 * Ran out of polynomials 
	 */
	return -1;		/* should raise exception */
#endif
}

#ifdef HASH_LOG
static int collision = 0;
static int init_st = 0;

static void stat_col()
{
	FILE *f = fopen("/tmp/col", "w");
	fprintf(f, "collision: %d\n", collision);
	fclose(f);
}
#endif

st_table *st_init_table_with_size(struct st_hash_type *type, int size)
{
	st_table *tbl;

#ifdef HASH_LOG
	if (init_st == 0) {
		init_st = 1;
		atexit(stat_col);
	}
#endif

	size = new_size(size);	/* round up to prime number */

	tbl = (st_table *) avro_new(st_table);
	tbl->type = type;
	tbl->num_entries = 0;
	tbl->num_bins = size;
	tbl->bins = (st_table_entry **) Calloc(size, sizeof(st_table_entry *));

	return tbl;
}

st_table *st_init_table(struct st_hash_type *type)
{
	return st_init_table_with_size(type, 0);
}

st_table *st_init_numtable(void)
{
	return st_init_table(&type_numhash);
}

st_table *st_init_numtable_with_size(int size)
{
	return st_init_table_with_size(&type_numhash, size);
}

st_table *st_init_strtable(void)
{
	return st_init_table(&type_strhash);
}

st_table *st_init_strtable_with_size(int size)
{
	return st_init_table_with_size(&type_strhash, size);
}

void st_free_table(st_table *table)
{
	register st_table_entry *ptr, *next;
	int i;

	for (i = 0; i < table->num_bins; i++) {
		ptr = table->bins[i];
		while (ptr != 0) {
			next = ptr->next;
			avro_freet(st_table_entry, ptr);
			ptr = next;
		}
	}
	free_bins(table);
	avro_freet(st_table, table);
}

#define PTR_NOT_EQUAL(table, ptr, hash_val, key) \
((ptr) != 0 && (ptr->hash != (hash_val) || !EQUAL((table), (key), (ptr)->key)))

#ifdef HASH_LOG
#define COLLISION collision++
#else
#define COLLISION
#endif

#define FIND_ENTRY(table, ptr, hash_val, bin_pos) do {\
    bin_pos = hash_val%(table)->num_bins;\
    ptr = (table)->bins[bin_pos];\
    if (PTR_NOT_EQUAL(table, ptr, hash_val, key)) {\
	COLLISION;\
	while (PTR_NOT_EQUAL(table, ptr->next, hash_val, key)) {\
	    ptr = ptr->next;\
	}\
	ptr = ptr->next;\
    }\
} while (0)

int st_lookup(st_table *table, register st_data_t key, st_data_t *value)
{
	unsigned int hash_val, bin_pos;
	register st_table_entry *ptr;

	hash_val = do_hash(key, table);
	FIND_ENTRY(table, ptr, hash_val, bin_pos);

	if (ptr == 0) {
		return 0;
	} else {
		if (value != 0)
			*value = ptr->record;
		return 1;
	}
}

#define ADD_DIRECT(table, key, value, hash_val, bin_pos)\
do {\
    st_table_entry *entry;\
    if (table->num_entries/(table->num_bins) > ST_DEFAULT_MAX_DENSITY) {\
	rehash(table);\
        bin_pos = hash_val % table->num_bins;\
    }\
    \
    entry = (st_table_entry *) avro_new(st_table_entry);\
    \
    entry->hash = hash_val;\
    entry->key = key;\
    entry->record = value;\
    entry->next = table->bins[bin_pos];\
    table->bins[bin_pos] = entry;\
    table->num_entries++;\
} while (0)

int st_insert(register st_table *table, register st_data_t key, st_data_t value)
{
	unsigned int hash_val, bin_pos;
	register st_table_entry *ptr;

	hash_val = do_hash(key, table);
	FIND_ENTRY(table, ptr, hash_val, bin_pos);

	if (ptr == 0) {
		ADD_DIRECT(table, key, value, hash_val, bin_pos);
		return 0;
	} else {
		ptr->record = value;
		return 1;
	}
}

void st_add_direct(st_table *table,st_data_t key,st_data_t value)
{
	unsigned int hash_val, bin_pos;

	hash_val = do_hash(key, table);
	bin_pos = hash_val % table->num_bins;
	ADD_DIRECT(table, key, value, hash_val, bin_pos);
}

static void rehash(register st_table *table)
{
	register st_table_entry *ptr, *next, **new_bins;
	int i, old_num_bins = table->num_bins, new_num_bins;
	unsigned int hash_val;

	new_num_bins = new_size(old_num_bins + 1);
	new_bins =
	    (st_table_entry **) Calloc(new_num_bins, sizeof(st_table_entry *));

	for (i = 0; i < old_num_bins; i++) {
		ptr = table->bins[i];
		while (ptr != 0) {
			next = ptr->next;
			hash_val = ptr->hash % new_num_bins;
			ptr->next = new_bins[hash_val];
			new_bins[hash_val] = ptr;
			ptr = next;
		}
	}
	free_bins(table);
	table->num_bins = new_num_bins;
	table->bins = new_bins;
}

st_table *st_copy(st_table *old_table)
{
	st_table *new_table;
	st_table_entry *ptr, *entry;
	int i, num_bins = old_table->num_bins;

	new_table = (st_table *) avro_new(st_table);
	if (new_table == 0) {
		return 0;
	}

	*new_table = *old_table;
	new_table->bins = (st_table_entry **)
	    Calloc((unsigned)num_bins, sizeof(st_table_entry *));

	if (new_table->bins == 0) {
		avro_freet(st_table, new_table);
		return 0;
	}

	for (i = 0; i < num_bins; i++) {
		new_table->bins[i] = 0;
		ptr = old_table->bins[i];
		while (ptr != 0) {
			entry = (st_table_entry *) avro_new(st_table_entry);
			if (entry == 0) {
				free_bins(new_table);
				avro_freet(st_table, new_table);
				return 0;
			}
			*entry = *ptr;
			entry->next = new_table->bins[i];
			new_table->bins[i] = entry;
			ptr = ptr->next;
		}
	}
	return new_table;
}

int st_delete(register st_table *table,register st_data_t *key,st_data_t *value)
{
	unsigned int hash_val;
	st_table_entry *tmp;
	register st_table_entry *ptr;

	hash_val = do_hash_bin(*key, table);
	ptr = table->bins[hash_val];

	if (ptr == 0) {
		if (value != 0)
			*value = 0;
		return 0;
	}

	if (EQUAL(table, *key, ptr->key)) {
		table->bins[hash_val] = ptr->next;
		table->num_entries--;
		if (value != 0)
			*value = ptr->record;
		*key = ptr->key;
		avro_freet(st_table_entry, ptr);
		return 1;
	}

	for (; ptr->next != 0; ptr = ptr->next) {
		if (EQUAL(table, ptr->next->key, *key)) {
			tmp = ptr->next;
			ptr->next = ptr->next->next;
			table->num_entries--;
			if (value != 0)
				*value = tmp->record;
			*key = tmp->key;
			avro_freet(st_table_entry, tmp);
			return 1;
		}
	}

	return 0;
}

int st_delete_safe(register st_table *table,register st_data_t *key,st_data_t *value,st_data_t never)
{
	unsigned int hash_val;
	register st_table_entry *ptr;

	hash_val = do_hash_bin(*key, table);
	ptr = table->bins[hash_val];

	if (ptr == 0) {
		if (value != 0)
			*value = 0;
		return 0;
	}

	for (; ptr != 0; ptr = ptr->next) {
		if ((ptr->key != never) && EQUAL(table, ptr->key, *key)) {
			table->num_entries--;
			*key = ptr->key;
			if (value != 0)
				*value = ptr->record;
			ptr->key = ptr->record = never;
			return 1;
		}
	}

	return 0;
}

static int delete_never(st_data_t key, st_data_t value, st_data_t never)
{
	AVRO_UNUSED(key);

	if (value == never)
		return ST_DELETE;
	return ST_CONTINUE;
}

void st_cleanup_safe(st_table *table,st_data_t never)
{
	int num_entries = table->num_entries;

	st_foreach(table, HASH_FUNCTION_CAST delete_never, never);
	table->num_entries = num_entries;
}

int st_foreach(st_table *table,int (*func) (ANYARGS),st_data_t arg)
{
	st_table_entry *ptr, *last, *tmp;
	enum st_retval retval;
	int i;

	for (i = 0; i < table->num_bins; i++) {
		last = 0;
		for (ptr = table->bins[i]; ptr != 0;) {
			retval = (enum st_retval) (*func) (ptr->key, ptr->record, arg);
			switch (retval) {
			case ST_CHECK:	/* check if hash is modified during
					 * iteration */
				tmp = 0;
				if (i < table->num_bins) {
					for (tmp = table->bins[i]; tmp;
					     tmp = tmp->next) {
						if (tmp == ptr)
							break;
					}
				}
				if (!tmp) {
					/*
					 * call func with error notice 
					 */
					return 1;
				}
				/*
				 * fall through 
				 */
			case ST_CONTINUE:
				last = ptr;
				ptr = ptr->next;
				break;
			case ST_STOP:
				return 0;
			case ST_DELETE:
				tmp = ptr;
				if (last == 0) {
					table->bins[i] = ptr->next;
				} else {
					last->next = ptr->next;
				}
				ptr = ptr->next;
				avro_freet(st_table_entry, tmp);
				table->num_entries--;
			}
		}
	}
	return 0;
}

static int strhash(register const char *string)
{
	register int c;

#ifdef HASH_ELFHASH
	register unsigned int h = 0, g;

	while ((c = *string++) != '\0') {
		h = (h << 4) + c;
		if (g = h & 0xF0000000)
			h ^= g >> 24;
		h &= ~g;
	}
	return h;
#elif defined(HASH_PERL)
	register int val = 0;

	while ((c = *string++) != '\0') {
		val += c;
		val += (val << 10);
		val ^= (val >> 6);
	}
	val += (val << 3);
	val ^= (val >> 11);

	return val + (val << 15);
#else
	register int val = 0;

	while ((c = *string++) != '\0') {
		val = val * 997 + c;
	}

	return val + (val >> 5);
#endif
}

static int numcmp(long x, long y)
{
	return x != y;
}

static int numhash(long n)
{
	return n;
}