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Diffstat (limited to 'hashtable.c')
| -rw-r--r-- | hashtable.c | 662 |
1 files changed, 662 insertions, 0 deletions
diff --git a/hashtable.c b/hashtable.c new file mode 100644 index 0000000..2cc4e55 --- /dev/null +++ b/hashtable.c @@ -0,0 +1,662 @@ +/* + * Routines to provide a memory-efficient hashtable. + * + * Copyright (C) 2007-2022 Wayne Davison + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, visit the http://fsf.org website. + */ + +#include "rsync.h" + +#define HASH_LOAD_LIMIT(size) ((size)*3/4) + +struct hashtable *hashtable_create(int size, int key64) +{ + int req = size; + struct hashtable *tbl; + int node_size = key64 ? sizeof (struct ht_int64_node) + : sizeof (struct ht_int32_node); + + /* Pick a power of 2 that can hold the requested size. */ + if (size & (size-1) || size < 16) { + size = 16; + while (size < req) + size *= 2; + } + + tbl = new(struct hashtable); + tbl->nodes = new_array0(char, size * node_size); + tbl->size = size; + tbl->entries = 0; + tbl->node_size = node_size; + tbl->key64 = key64 ? 1 : 0; + + if (DEBUG_GTE(HASH, 1)) { + char buf[32]; + if (req != size) + snprintf(buf, sizeof buf, "req: %d, ", req); + else + *buf = '\0'; + rprintf(FINFO, "[%s] created hashtable %lx (%ssize: %d, keys: %d-bit)\n", + who_am_i(), (long)tbl, buf, size, key64 ? 64 : 32); + } + + return tbl; +} + +void hashtable_destroy(struct hashtable *tbl) +{ + if (DEBUG_GTE(HASH, 1)) { + rprintf(FINFO, "[%s] destroyed hashtable %lx (size: %d, keys: %d-bit)\n", + who_am_i(), (long)tbl, tbl->size, tbl->key64 ? 64 : 32); + } + free(tbl->nodes); + free(tbl); +} + +/* Returns the node that holds the indicated key if it exists. When it does not + * exist, it returns either NULL (when data_when_new is NULL), or it returns a + * new node with its node->data set to the indicated value. + * + * If your code doesn't know the data value for a new node in advance (usually + * because it doesn't know if a node is new or not) you should pass in a unique + * (non-0) value that you can use to check if the returned node is new. You can + * then overwrite the data with any value you want (even 0) since it only needs + * to be different than whatever data_when_new value you use later on. + * + * This return is a void* just because it might be pointing at a ht_int32_node + * or a ht_int64_node, and that makes the caller's assignment a little easier. */ +void *hashtable_find(struct hashtable *tbl, int64 key, void *data_when_new) +{ + int key64 = tbl->key64; + struct ht_int32_node *node; + uint32 ndx; + + if (key64 ? key == 0 : (int32)key == 0) { + rprintf(FERROR, "Internal hashtable error: illegal key supplied!\n"); + exit_cleanup(RERR_MESSAGEIO); + } + + if (data_when_new && tbl->entries > HASH_LOAD_LIMIT(tbl->size)) { + void *old_nodes = tbl->nodes; + int size = tbl->size * 2; + int i; + + tbl->nodes = new_array0(char, size * tbl->node_size); + tbl->size = size; + tbl->entries = 0; + + if (DEBUG_GTE(HASH, 1)) { + rprintf(FINFO, "[%s] growing hashtable %lx (size: %d, keys: %d-bit)\n", + who_am_i(), (long)tbl, size, key64 ? 64 : 32); + } + + for (i = size / 2; i-- > 0; ) { + struct ht_int32_node *move_node = HT_NODE(tbl, old_nodes, i); + int64 move_key = HT_KEY(move_node, key64); + if (move_key == 0) + continue; + if (move_node->data) + hashtable_find(tbl, move_key, move_node->data); + else { + node = hashtable_find(tbl, move_key, ""); + node->data = 0; + } + } + + free(old_nodes); + } + + if (!key64) { + /* Based on Jenkins One-at-a-time hash. */ + uchar buf[4], *keyp = buf; + int i; + + SIVALu(buf, 0, key); + for (ndx = 0, i = 0; i < 4; i++) { + ndx += keyp[i]; + ndx += (ndx << 10); + ndx ^= (ndx >> 6); + } + ndx += (ndx << 3); + ndx ^= (ndx >> 11); + ndx += (ndx << 15); + } else { + /* Based on Jenkins hashword() from lookup3.c. */ + uint32 a, b, c; + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + (8 << 2); + +#define rot(x,k) (((x)<<(k)) ^ ((x)>>(32-(k)))) +#if SIZEOF_INT64 >= 8 + b += (uint32)(key >> 32); +#endif + a += (uint32)key; + c ^= b; c -= rot(b, 14); + a ^= c; a -= rot(c, 11); + b ^= a; b -= rot(a, 25); + c ^= b; c -= rot(b, 16); + a ^= c; a -= rot(c, 4); + b ^= a; b -= rot(a, 14); + c ^= b; c -= rot(b, 24); +#undef rot + ndx = c; + } + + /* If it already exists, return the node. If we're not + * allocating, return NULL if the key is not found. */ + while (1) { + int64 nkey; + + ndx &= tbl->size - 1; + node = HT_NODE(tbl, tbl->nodes, ndx); + nkey = HT_KEY(node, key64); + + if (nkey == key) + return node; + if (nkey == 0) { + if (!data_when_new) + return NULL; + break; + } + ndx++; + } + + /* Take over this empty spot and then return the node. */ + if (key64) + ((struct ht_int64_node*)node)->key = key; + else + node->key = (int32)key; + node->data = data_when_new; + tbl->entries++; + return node; +} + +#ifndef WORDS_BIGENDIAN +# define HASH_LITTLE_ENDIAN 1 +# define HASH_BIG_ENDIAN 0 +#else +# define HASH_LITTLE_ENDIAN 0 +# define HASH_BIG_ENDIAN 1 +#endif + +/* + ------------------------------------------------------------------------------- + lookup3.c, by Bob Jenkins, May 2006, Public Domain. + + These are functions for producing 32-bit hashes for hash table lookup. + hash_word(), hashlittle(), hashlittle2(), hashbig(), mix(), and final() + are externally useful functions. Routines to test the hash are included + if SELF_TEST is defined. You can use this free for any purpose. It's in + the public domain. It has no warranty. + + You probably want to use hashlittle(). hashlittle() and hashbig() + hash byte arrays. hashlittle() is is faster than hashbig() on + little-endian machines. Intel and AMD are little-endian machines. + On second thought, you probably want hashlittle2(), which is identical to + hashlittle() except it returns two 32-bit hashes for the price of one. + You could implement hashbig2() if you wanted but I haven't bothered here. + + If you want to find a hash of, say, exactly 7 integers, do + a = i1; b = i2; c = i3; + mix(a,b,c); + a += i4; b += i5; c += i6; + mix(a,b,c); + a += i7; + final(a,b,c); + then use c as the hash value. If you have a variable length array of + 4-byte integers to hash, use hash_word(). If you have a byte array (like + a character string), use hashlittle(). If you have several byte arrays, or + a mix of things, see the comments above hashlittle(). + + Why is this so big? I read 12 bytes at a time into 3 4-byte integers, + then mix those integers. This is fast (you can do a lot more thorough + mixing with 12*3 instructions on 3 integers than you can with 3 instructions + on 1 byte), but shoehorning those bytes into integers efficiently is messy. +*/ + +#define hashsize(n) ((uint32_t)1<<(n)) +#define hashmask(n) (hashsize(n)-1) +#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k)))) + +/* + ------------------------------------------------------------------------------- + mix -- mix 3 32-bit values reversibly. + + This is reversible, so any information in (a,b,c) before mix() is + still in (a,b,c) after mix(). + + If four pairs of (a,b,c) inputs are run through mix(), or through + mix() in reverse, there are at least 32 bits of the output that + are sometimes the same for one pair and different for another pair. + This was tested for: + * pairs that differed by one bit, by two bits, in any combination + of top bits of (a,b,c), or in any combination of bottom bits of + (a,b,c). + * "differ" is defined as +, -, ^, or ~^. For + and -, I transformed + the output delta to a Gray code (a^(a>>1)) so a string of 1's (as + is commonly produced by subtraction) look like a single 1-bit + difference. + * the base values were pseudorandom, all zero but one bit set, or + all zero plus a counter that starts at zero. + + Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that + satisfy this are + 4 6 8 16 19 4 + 9 15 3 18 27 15 + 14 9 3 7 17 3 + Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing + for "differ" defined as + with a one-bit base and a two-bit delta. I + used http://burtleburtle.net/bob/hash/avalanche.html to choose + the operations, constants, and arrangements of the variables. + + This does not achieve avalanche. There are input bits of (a,b,c) + that fail to affect some output bits of (a,b,c), especially of a. The + most thoroughly mixed value is c, but it doesn't really even achieve + avalanche in c. + + This allows some parallelism. Read-after-writes are good at doubling + the number of bits affected, so the goal of mixing pulls in the opposite + direction as the goal of parallelism. I did what I could. Rotates + seem to cost as much as shifts on every machine I could lay my hands + on, and rotates are much kinder to the top and bottom bits, so I used + rotates. + ------------------------------------------------------------------------------- +*/ +#define mix(a,b,c) \ +{ \ + a -= c; a ^= rot(c, 4); c += b; \ + b -= a; b ^= rot(a, 6); a += c; \ + c -= b; c ^= rot(b, 8); b += a; \ + a -= c; a ^= rot(c,16); c += b; \ + b -= a; b ^= rot(a,19); a += c; \ + c -= b; c ^= rot(b, 4); b += a; \ +} + +/* + ------------------------------------------------------------------------------- + final -- final mixing of 3 32-bit values (a,b,c) into c + + Pairs of (a,b,c) values differing in only a few bits will usually + produce values of c that look totally different. This was tested for + * pairs that differed by one bit, by two bits, in any combination + of top bits of (a,b,c), or in any combination of bottom bits of + (a,b,c). + * "differ" is defined as +, -, ^, or ~^. For + and -, I transformed + the output delta to a Gray code (a^(a>>1)) so a string of 1's (as + is commonly produced by subtraction) look like a single 1-bit + difference. + * the base values were pseudorandom, all zero but one bit set, or + all zero plus a counter that starts at zero. + + These constants passed: + 14 11 25 16 4 14 24 + 12 14 25 16 4 14 24 + and these came close: + 4 8 15 26 3 22 24 + 10 8 15 26 3 22 24 + 11 8 15 26 3 22 24 + ------------------------------------------------------------------------------- +*/ +#define final(a,b,c) \ +{ \ + c ^= b; c -= rot(b,14); \ + a ^= c; a -= rot(c,11); \ + b ^= a; b -= rot(a,25); \ + c ^= b; c -= rot(b,16); \ + a ^= c; a -= rot(c,4); \ + b ^= a; b -= rot(a,14); \ + c ^= b; c -= rot(b,24); \ +} + + +/* + ------------------------------------------------------------------------------- + hashlittle() -- hash a variable-length key into a 32-bit value + k : the key (the unaligned variable-length array of bytes) + length : the length of the key, counting by bytes + val2 : IN: can be any 4-byte value OUT: second 32 bit hash. + Returns a 32-bit value. Every bit of the key affects every bit of + the return value. Two keys differing by one or two bits will have + totally different hash values. Note that the return value is better + mixed than val2, so use that first. + + The best hash table sizes are powers of 2. There is no need to do + mod a prime (mod is sooo slow!). If you need less than 32 bits, + use a bitmask. For example, if you need only 10 bits, do + h = (h & hashmask(10)); + In which case, the hash table should have hashsize(10) elements. + + If you are hashing n strings (uint8_t **)k, do it like this: + for (i=0, h=0; i<n; ++i) h = hashlittle( k[i], len[i], h); + + By Bob Jenkins, 2006. bob_jenkins@burtleburtle.net. You may use this + code any way you wish, private, educational, or commercial. It's free. + + Use for hash table lookup, or anything where one collision in 2^^32 is + acceptable. Do NOT use for cryptographic purposes. + ------------------------------------------------------------------------------- +*/ + +#define NON_ZERO_32(x) ((x) ? (x) : (uint32_t)1) +#define NON_ZERO_64(x, y) ((x) || (y) ? (y) | (int64)(x) << 32 | (y) : (int64)1) + +uint32_t hashlittle(const void *key, size_t length) +{ + uint32_t a,b,c; /* internal state */ + union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */ + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + ((uint32_t)length); + + u.ptr = key; + if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) { + const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */ + const uint8_t *k8; + + /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */ + while (length > 12) + { + a += k[0]; + b += k[1]; + c += k[2]; + mix(a,b,c); + length -= 12; + k += 3; + } + + /*----------------------------- handle the last (probably partial) block */ + k8 = (const uint8_t *)k; + switch(length) + { + case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; + case 11: c+=((uint32_t)k8[10])<<16; /* fall through */ + case 10: c+=((uint32_t)k8[9])<<8; /* fall through */ + case 9 : c+=k8[8]; /* fall through */ + case 8 : b+=k[1]; a+=k[0]; break; + case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */ + case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */ + case 5 : b+=k8[4]; /* fall through */ + case 4 : a+=k[0]; break; + case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */ + case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */ + case 1 : a+=k8[0]; break; + case 0 : return NON_ZERO_32(c); + } + } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) { + const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */ + const uint8_t *k8; + + /*--------------- all but last block: aligned reads and different mixing */ + while (length > 12) + { + a += k[0] + (((uint32_t)k[1])<<16); + b += k[2] + (((uint32_t)k[3])<<16); + c += k[4] + (((uint32_t)k[5])<<16); + mix(a,b,c); + length -= 12; + k += 6; + } + + /*----------------------------- handle the last (probably partial) block */ + k8 = (const uint8_t *)k; + switch(length) + { + case 12: c+=k[4]+(((uint32_t)k[5])<<16); + b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 11: c+=((uint32_t)k8[10])<<16; /* fall through */ + case 10: c+=k[4]; + b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 9 : c+=k8[8]; /* fall through */ + case 8 : b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */ + case 6 : b+=k[2]; + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 5 : b+=k8[4]; /* fall through */ + case 4 : a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */ + case 2 : a+=k[0]; + break; + case 1 : a+=k8[0]; + break; + case 0 : return NON_ZERO_32(c); /* zero length requires no mixing */ + } + + } else { /* need to read the key one byte at a time */ + const uint8_t *k = (const uint8_t *)key; + + /*--------------- all but the last block: affect some 32 bits of (a,b,c) */ + while (length > 12) + { + a += k[0]; + a += ((uint32_t)k[1])<<8; + a += ((uint32_t)k[2])<<16; + a += ((uint32_t)k[3])<<24; + b += k[4]; + b += ((uint32_t)k[5])<<8; + b += ((uint32_t)k[6])<<16; + b += ((uint32_t)k[7])<<24; + c += k[8]; + c += ((uint32_t)k[9])<<8; + c += ((uint32_t)k[10])<<16; + c += ((uint32_t)k[11])<<24; + mix(a,b,c); + length -= 12; + k += 12; + } + + /*-------------------------------- last block: affect all 32 bits of (c) */ + switch(length) /* all the case statements fall through */ + { + case 12: c+=((uint32_t)k[11])<<24; + /* FALLTHROUGH */ + case 11: c+=((uint32_t)k[10])<<16; + /* FALLTHROUGH */ + case 10: c+=((uint32_t)k[9])<<8; + /* FALLTHROUGH */ + case 9 : c+=k[8]; + /* FALLTHROUGH */ + case 8 : b+=((uint32_t)k[7])<<24; + /* FALLTHROUGH */ + case 7 : b+=((uint32_t)k[6])<<16; + /* FALLTHROUGH */ + case 6 : b+=((uint32_t)k[5])<<8; + /* FALLTHROUGH */ + case 5 : b+=k[4]; + /* FALLTHROUGH */ + case 4 : a+=((uint32_t)k[3])<<24; + /* FALLTHROUGH */ + case 3 : a+=((uint32_t)k[2])<<16; + /* FALLTHROUGH */ + case 2 : a+=((uint32_t)k[1])<<8; + /* FALLTHROUGH */ + case 1 : a+=k[0]; + break; + case 0 : return NON_ZERO_32(c); + } + } + + final(a,b,c); + return NON_ZERO_32(c); +} + +#if SIZEOF_INT64 >= 8 +/* + * hashlittle2: return 2 32-bit hash values joined into an int64. + * + * This is identical to hashlittle(), except it returns two 32-bit hash + * values instead of just one. This is good enough for hash table + * lookup with 2^^64 buckets, or if you want a second hash if you're not + * happy with the first, or if you want a probably-unique 64-bit ID for + * the key. *pc is better mixed than *pb, so use *pc first. If you want + * a 64-bit value do something like "*pc + (((uint64_t)*pb)<<32)". + */ +int64 hashlittle2(const void *key, size_t length) +{ + uint32_t a,b,c; /* internal state */ + union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */ + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + ((uint32_t)length); + + u.ptr = key; + if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) { + const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */ + const uint8_t *k8; + + /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */ + while (length > 12) + { + a += k[0]; + b += k[1]; + c += k[2]; + mix(a,b,c); + length -= 12; + k += 3; + } + + /*----------------------------- handle the last (probably partial) block */ + k8 = (const uint8_t *)k; + switch(length) + { + case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; + case 11: c+=((uint32_t)k8[10])<<16; /* fall through */ + case 10: c+=((uint32_t)k8[9])<<8; /* fall through */ + case 9 : c+=k8[8]; /* fall through */ + case 8 : b+=k[1]; a+=k[0]; break; + case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */ + case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */ + case 5 : b+=k8[4]; /* fall through */ + case 4 : a+=k[0]; break; + case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */ + case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */ + case 1 : a+=k8[0]; break; + case 0 : return NON_ZERO_64(b, c); + } + } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) { + const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */ + const uint8_t *k8; + + /*--------------- all but last block: aligned reads and different mixing */ + while (length > 12) + { + a += k[0] + (((uint32_t)k[1])<<16); + b += k[2] + (((uint32_t)k[3])<<16); + c += k[4] + (((uint32_t)k[5])<<16); + mix(a,b,c); + length -= 12; + k += 6; + } + + /*----------------------------- handle the last (probably partial) block */ + k8 = (const uint8_t *)k; + switch(length) + { + case 12: c+=k[4]+(((uint32_t)k[5])<<16); + b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 11: c+=((uint32_t)k8[10])<<16; /* fall through */ + case 10: c+=k[4]; + b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 9 : c+=k8[8]; /* fall through */ + case 8 : b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */ + case 6 : b+=k[2]; + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 5 : b+=k8[4]; /* fall through */ + case 4 : a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */ + case 2 : a+=k[0]; + break; + case 1 : a+=k8[0]; + break; + case 0 : return NON_ZERO_64(b, c); /* zero length strings require no mixing */ + } + + } else { /* need to read the key one byte at a time */ + const uint8_t *k = (const uint8_t *)key; + + /*--------------- all but the last block: affect some 32 bits of (a,b,c) */ + while (length > 12) + { + a += k[0]; + a += ((uint32_t)k[1])<<8; + a += ((uint32_t)k[2])<<16; + a += ((uint32_t)k[3])<<24; + b += k[4]; + b += ((uint32_t)k[5])<<8; + b += ((uint32_t)k[6])<<16; + b += ((uint32_t)k[7])<<24; + c += k[8]; + c += ((uint32_t)k[9])<<8; + c += ((uint32_t)k[10])<<16; + c += ((uint32_t)k[11])<<24; + mix(a,b,c); + length -= 12; + k += 12; + } + + /*-------------------------------- last block: affect all 32 bits of (c) */ + switch(length) /* all the case statements fall through */ + { + case 12: c+=((uint32_t)k[11])<<24; + /* FALLTHROUGH */ + case 11: c+=((uint32_t)k[10])<<16; + /* FALLTHROUGH */ + case 10: c+=((uint32_t)k[9])<<8; + /* FALLTHROUGH */ + case 9 : c+=k[8]; + /* FALLTHROUGH */ + case 8 : b+=((uint32_t)k[7])<<24; + /* FALLTHROUGH */ + case 7 : b+=((uint32_t)k[6])<<16; + /* FALLTHROUGH */ + case 6 : b+=((uint32_t)k[5])<<8; + /* FALLTHROUGH */ + case 5 : b+=k[4]; + /* FALLTHROUGH */ + case 4 : a+=((uint32_t)k[3])<<24; + /* FALLTHROUGH */ + case 3 : a+=((uint32_t)k[2])<<16; + /* FALLTHROUGH */ + case 2 : a+=((uint32_t)k[1])<<8; + /* FALLTHROUGH */ + case 1 : a+=k[0]; + break; + case 0 : return NON_ZERO_64(b, c); + } + } + + final(a,b,c); + return NON_ZERO_64(b, c); +} +#else +#define hashlittle2(key, len) hashlittle(key, len) +#endif |