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d8cc8daef9
need...but most of it remains.
173 lines
4.3 KiB
C
173 lines
4.3 KiB
C
/*
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* Routines to provide a memory-efficient hashtable.
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*
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* Copyright (C) 2007-2014 Wayne Davison
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, visit the http://fsf.org website.
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*/
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#include "rsync.h"
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#define HASH_LOAD_LIMIT(size) ((size)*3/4)
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struct hashtable *hashtable_create(int size, int key64)
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{
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int req = size;
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struct hashtable *tbl;
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int node_size = key64 ? sizeof (struct ht_int64_node)
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: sizeof (struct ht_int32_node);
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/* Pick a power of 2 that can hold the requested size. */
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if (size & (size-1) || size < 16) {
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size = 16;
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while (size < req)
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size *= 2;
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}
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if (!(tbl = new(struct hashtable))
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|| !(tbl->nodes = new_array0(char, size * node_size)))
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out_of_memory("hashtable_create");
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tbl->size = size;
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tbl->entries = 0;
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tbl->node_size = node_size;
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tbl->key64 = key64 ? 1 : 0;
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if (DEBUG_GTE(HASH, 1)) {
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char buf[32];
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if (req != size)
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snprintf(buf, sizeof buf, "req: %d, ", req);
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else
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*buf = '\0';
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rprintf(FINFO, "[%s] created hashtable %lx (%ssize: %d, keys: %d-bit)\n",
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who_am_i(), (long)tbl, buf, size, key64 ? 64 : 32);
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}
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return tbl;
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}
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void hashtable_destroy(struct hashtable *tbl)
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{
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if (DEBUG_GTE(HASH, 1)) {
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rprintf(FINFO, "[%s] destroyed hashtable %lx (size: %d, keys: %d-bit)\n",
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who_am_i(), (long)tbl, tbl->size, tbl->key64 ? 64 : 32);
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}
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free(tbl->nodes);
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free(tbl);
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}
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/* This returns the node for the indicated key, either newly created or
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* already existing. Returns NULL if not allocating and not found. */
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void *hashtable_find(struct hashtable *tbl, int64 key, int allocate_if_missing)
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{
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int key64 = tbl->key64;
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struct ht_int32_node *node;
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uint32 ndx;
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if (key64 ? key == 0 : (int32)key == 0) {
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rprintf(FERROR, "Internal hashtable error: illegal key supplied!\n");
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exit_cleanup(RERR_MESSAGEIO);
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}
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if (allocate_if_missing && tbl->entries > HASH_LOAD_LIMIT(tbl->size)) {
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void *old_nodes = tbl->nodes;
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int size = tbl->size * 2;
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int i;
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if (!(tbl->nodes = new_array0(char, size * tbl->node_size)))
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out_of_memory("hashtable_node");
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tbl->size = size;
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tbl->entries = 0;
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if (DEBUG_GTE(HASH, 1)) {
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rprintf(FINFO, "[%s] growing hashtable %lx (size: %d, keys: %d-bit)\n",
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who_am_i(), (long)tbl, size, key64 ? 64 : 32);
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}
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for (i = size / 2; i-- > 0; ) {
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struct ht_int32_node *move_node = HT_NODE(tbl, old_nodes, i);
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int64 move_key = HT_KEY(move_node, key64);
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if (move_key == 0)
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continue;
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node = hashtable_find(tbl, move_key, 1);
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node->data = move_node->data;
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}
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free(old_nodes);
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}
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if (!key64) {
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/* Based on Jenkins One-at-a-time hash. */
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uchar buf[4], *keyp = buf;
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int i;
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SIVALu(buf, 0, key);
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for (ndx = 0, i = 0; i < 4; i++) {
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ndx += keyp[i];
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ndx += (ndx << 10);
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ndx ^= (ndx >> 6);
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}
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ndx += (ndx << 3);
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ndx ^= (ndx >> 11);
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ndx += (ndx << 15);
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} else {
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/* Based on Jenkins hashword() from lookup3.c. */
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uint32 a, b, c;
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/* Set up the internal state */
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a = b = c = 0xdeadbeef + (8 << 2);
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#define rot(x,k) (((x)<<(k)) ^ ((x)>>(32-(k))))
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#if SIZEOF_INT64 >= 8
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b += (uint32)(key >> 32);
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#endif
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a += (uint32)key;
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c ^= b; c -= rot(b, 14);
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a ^= c; a -= rot(c, 11);
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b ^= a; b -= rot(a, 25);
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c ^= b; c -= rot(b, 16);
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a ^= c; a -= rot(c, 4);
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b ^= a; b -= rot(a, 14);
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c ^= b; c -= rot(b, 24);
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#undef rot
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ndx = c;
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}
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/* If it already exists, return the node. If we're not
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* allocating, return NULL if the key is not found. */
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while (1) {
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int64 nkey;
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ndx &= tbl->size - 1;
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node = HT_NODE(tbl, tbl->nodes, ndx);
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nkey = HT_KEY(node, key64);
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if (nkey == key)
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return node;
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if (nkey == 0) {
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if (!allocate_if_missing)
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return NULL;
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break;
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}
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ndx++;
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}
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/* Take over this empty spot and then return the node. */
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if (key64)
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((struct ht_int64_node*)node)->key = key;
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else
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node->key = (int32)key;
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tbl->entries++;
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return node;
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}
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