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rsync 3.1.2

    1: /*
    2:  * Routines to provide a memory-efficient hashtable.
    3:  *
    4:  * Copyright (C) 2007-2015 Wayne Davison
    5:  *
    6:  * This program is free software; you can redistribute it and/or modify
    7:  * it under the terms of the GNU General Public License as published by
    8:  * the Free Software Foundation; either version 3 of the License, or
    9:  * (at your option) any later version.
   10:  *
   11:  * This program is distributed in the hope that it will be useful,
   12:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   13:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   14:  * GNU General Public License for more details.
   15:  *
   16:  * You should have received a copy of the GNU General Public License along
   17:  * with this program; if not, visit the http://fsf.org website.
   18:  */
   19: 
   20: #include "rsync.h"
   21: 
   22: #define HASH_LOAD_LIMIT(size) ((size)*3/4)
   23: 
   24: struct hashtable *hashtable_create(int size, int key64)
   25: {
   26: 	int req = size;
   27: 	struct hashtable *tbl;
   28: 	int node_size = key64 ? sizeof (struct ht_int64_node)
   29: 			      : sizeof (struct ht_int32_node);
   30: 
   31: 	/* Pick a power of 2 that can hold the requested size. */
   32: 	if (size & (size-1) || size < 16) {
   33: 		size = 16;
   34: 		while (size < req)
   35: 			size *= 2;
   36: 	}
   37: 
   38: 	if (!(tbl = new(struct hashtable))
   39: 	 || !(tbl->nodes = new_array0(char, size * node_size)))
   40: 		out_of_memory("hashtable_create");
   41: 	tbl->size = size;
   42: 	tbl->entries = 0;
   43: 	tbl->node_size = node_size;
   44: 	tbl->key64 = key64 ? 1 : 0;
   45: 
   46: 	if (DEBUG_GTE(HASH, 1)) {
   47: 		char buf[32];
   48: 		if (req != size)
   49: 			snprintf(buf, sizeof buf, "req: %d, ", req);
   50: 		else
   51: 			*buf = '\0';
   52: 		rprintf(FINFO, "[%s] created hashtable %lx (%ssize: %d, keys: %d-bit)\n",
   53: 			who_am_i(), (long)tbl, buf, size, key64 ? 64 : 32);
   54: 	}
   55: 
   56: 	return tbl;
   57: }
   58: 
   59: void hashtable_destroy(struct hashtable *tbl)
   60: {
   61: 	if (DEBUG_GTE(HASH, 1)) {
   62: 		rprintf(FINFO, "[%s] destroyed hashtable %lx (size: %d, keys: %d-bit)\n",
   63: 			who_am_i(), (long)tbl, tbl->size, tbl->key64 ? 64 : 32);
   64: 	}
   65: 	free(tbl->nodes);
   66: 	free(tbl);
   67: }
   68: 
   69: /* This returns the node for the indicated key, either newly created or
   70:  * already existing.  Returns NULL if not allocating and not found. */
   71: void *hashtable_find(struct hashtable *tbl, int64 key, int allocate_if_missing)
   72: {
   73: 	int key64 = tbl->key64;
   74: 	struct ht_int32_node *node;
   75: 	uint32 ndx;
   76: 
   77: 	if (key64 ? key == 0 : (int32)key == 0) {
   78: 		rprintf(FERROR, "Internal hashtable error: illegal key supplied!\n");
   79: 		exit_cleanup(RERR_MESSAGEIO);
   80: 	}
   81: 
   82: 	if (allocate_if_missing && tbl->entries > HASH_LOAD_LIMIT(tbl->size)) {
   83: 		void *old_nodes = tbl->nodes;
   84: 		int size = tbl->size * 2;
   85: 		int i;
   86: 
   87: 		if (!(tbl->nodes = new_array0(char, size * tbl->node_size)))
   88: 			out_of_memory("hashtable_node");
   89: 		tbl->size = size;
   90: 		tbl->entries = 0;
   91: 
   92: 		if (DEBUG_GTE(HASH, 1)) {
   93: 			rprintf(FINFO, "[%s] growing hashtable %lx (size: %d, keys: %d-bit)\n",
   94: 				who_am_i(), (long)tbl, size, key64 ? 64 : 32);
   95: 		}
   96: 
   97: 		for (i = size / 2; i-- > 0; ) {
   98: 			struct ht_int32_node *move_node = HT_NODE(tbl, old_nodes, i);
   99: 			int64 move_key = HT_KEY(move_node, key64);
  100: 			if (move_key == 0)
  101: 				continue;
  102: 			node = hashtable_find(tbl, move_key, 1);
  103: 			node->data = move_node->data;
  104: 		}
  105: 
  106: 		free(old_nodes);
  107: 	}
  108: 
  109: 	if (!key64) {
  110: 		/* Based on Jenkins One-at-a-time hash. */
  111: 		uchar buf[4], *keyp = buf;
  112: 		int i;
  113: 
  114: 		SIVALu(buf, 0, key);
  115: 		for (ndx = 0, i = 0; i < 4; i++) {
  116: 			ndx += keyp[i];
  117: 			ndx += (ndx << 10);
  118: 			ndx ^= (ndx >> 6);
  119: 		}
  120: 		ndx += (ndx << 3);
  121: 		ndx ^= (ndx >> 11);
  122: 		ndx += (ndx << 15);
  123: 	} else {
  124: 		/* Based on Jenkins hashword() from lookup3.c. */
  125: 		uint32 a, b, c;
  126: 
  127: 		/* Set up the internal state */
  128: 		a = b = c = 0xdeadbeef + (8 << 2);
  129: 
  130: #define rot(x,k) (((x)<<(k)) ^ ((x)>>(32-(k))))
  131: #if SIZEOF_INT64 >= 8
  132: 		b += (uint32)(key >> 32);
  133: #endif
  134: 		a += (uint32)key;
  135: 		c ^= b; c -= rot(b, 14);
  136: 		a ^= c; a -= rot(c, 11);
  137: 		b ^= a; b -= rot(a, 25);
  138: 		c ^= b; c -= rot(b, 16);
  139: 		a ^= c; a -= rot(c, 4);
  140: 		b ^= a; b -= rot(a, 14);
  141: 		c ^= b; c -= rot(b, 24);
  142: #undef rot
  143: 		ndx = c;
  144: 	}
  145: 
  146: 	/* If it already exists, return the node.  If we're not
  147: 	 * allocating, return NULL if the key is not found. */
  148: 	while (1) {
  149: 		int64 nkey;
  150: 
  151: 		ndx &= tbl->size - 1;
  152: 		node = HT_NODE(tbl, tbl->nodes, ndx);
  153: 		nkey = HT_KEY(node, key64);
  154: 
  155: 		if (nkey == key)
  156: 			return node;
  157: 		if (nkey == 0) {
  158: 			if (!allocate_if_missing)
  159: 				return NULL;
  160: 			break;
  161: 		}
  162: 		ndx++;
  163: 	}
  164: 
  165: 	/* Take over this empty spot and then return the node. */
  166: 	if (key64)
  167: 		((struct ht_int64_node*)node)->key = key;
  168: 	else
  169: 		node->key = (int32)key;
  170: 	tbl->entries++;
  171: 	return node;
  172: }