From 1a070652ba97045c73b5e0f5237d35ea017bb04b Mon Sep 17 00:00:00 2001 From: Trond Norbye Date: Mon, 2 Mar 2009 10:15:34 +0100 Subject: [PATCH] Refactor: moved the hash function from assoc.c to hash.c --- Makefile.am | 8 +- assoc.c | 419 -------------------------------------------------- assoc.h | 1 - hash.c | 431 ++++++++++++++++++++++++++++++++++++++++++++++++++++ hash.h | 15 ++ memcached.h | 1 + 6 files changed, 454 insertions(+), 421 deletions(-) create mode 100644 hash.c create mode 100644 hash.h diff --git a/Makefile.am b/Makefile.am index 151f29b26c..9b7135fe4e 100644 --- a/Makefile.am +++ b/Makefile.am @@ -3,7 +3,13 @@ pkginclude_HEADERS = protocol_binary.h BUILT_SOURCES= @DTRACE_HEADER@ -memcached_SOURCES = memcached.c slabs.c slabs.h items.c items.h assoc.c assoc.h memcached.h thread.c stats.c stats.h daemon.c +memcached_SOURCES = memcached.c memcached.h \ + hash.c hash.h \ + slabs.c slabs.h \ + items.c items.h \ + assoc.c assoc.h \ + thread.c daemon.c \ + stats.c stats.h memcached_debug_SOURCES = $(memcached_SOURCES) memcached_CPPFLAGS = -DNDEBUG memcached_LDADD = @DTRACE_OBJ@ diff --git a/assoc.c b/assoc.c index 59711d4659..cbbfdeb7d7 100644 --- a/assoc.c +++ b/assoc.c @@ -30,425 +30,6 @@ static pthread_cond_t maintenance_cond = PTHREAD_COND_INITIALIZER; -/* - * Since the hash function does bit manipulation, it needs to know - * whether it's big or little-endian. ENDIAN_LITTLE and ENDIAN_BIG - * are set in the configure script. - */ -#if ENDIAN_BIG == 1 -# define HASH_LITTLE_ENDIAN 0 -# define HASH_BIG_ENDIAN 1 -#else -# if ENDIAN_LITTLE == 1 -# define HASH_LITTLE_ENDIAN 1 -# define HASH_BIG_ENDIAN 0 -# else -# define HASH_LITTLE_ENDIAN 0 -# define HASH_BIG_ENDIAN 0 -# endif -#endif - -#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); \ -} - -#if HASH_LITTLE_ENDIAN == 1 -uint32_t hash( - const void *key, /* the key to hash */ - size_t length, /* length of the key */ - const uint32_t initval) /* initval */ -{ - 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) + initval; - - u.ptr = key; - if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) { - const uint32_t *k = key; /* read 32-bit chunks */ -#ifdef VALGRIND - const uint8_t *k8; -#endif /* ifdef VALGRIND */ - - /*------ 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 */ - /* - * "k[2]&0xffffff" actually reads beyond the end of the string, but - * then masks off the part it's not allowed to read. Because the - * string is aligned, the masked-off tail is in the same word as the - * rest of the string. Every machine with memory protection I've seen - * does it on word boundaries, so is OK with this. But VALGRIND will - * still catch it and complain. The masking trick does make the hash - * noticably faster for short strings (like English words). - */ -#ifndef VALGRIND - - switch(length) - { - case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; - case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break; - case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break; - case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break; - case 8 : b+=k[1]; a+=k[0]; break; - case 7 : b+=k[1]&0xffffff; a+=k[0]; break; - case 6 : b+=k[1]&0xffff; a+=k[0]; break; - case 5 : b+=k[1]&0xff; a+=k[0]; break; - case 4 : a+=k[0]; break; - case 3 : a+=k[0]&0xffffff; break; - case 2 : a+=k[0]&0xffff; break; - case 1 : a+=k[0]&0xff; break; - case 0 : return c; /* zero length strings require no mixing */ - } - -#else /* make valgrind happy */ - - 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 c; /* zero length strings require no mixing */ - } - -#endif /* !valgrind */ - - } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) { - const uint16_t *k = 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; /* @fallthrough */ - case 10: c+=k[4]; /* @fallthrough@ */ - b+=k[2]+(((uint32_t)k[3])<<16); - a+=k[0]+(((uint32_t)k[1])<<16); - break; - case 9 : c+=k8[8]; /* @fallthrough */ - 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; /* @fallthrough */ - case 6 : b+=k[2]; - a+=k[0]+(((uint32_t)k[1])<<16); - break; - case 5 : b+=k8[4]; /* @fallthrough */ - case 4 : a+=k[0]+(((uint32_t)k[1])<<16); - break; - case 3 : a+=((uint32_t)k8[2])<<16; /* @fallthrough */ - case 2 : a+=k[0]; - break; - case 1 : a+=k8[0]; - break; - case 0 : return c; /* zero length strings require no mixing */ - } - - } else { /* need to read the key one byte at a time */ - const uint8_t *k = 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; - case 11: c+=((uint32_t)k[10])<<16; - case 10: c+=((uint32_t)k[9])<<8; - case 9 : c+=k[8]; - case 8 : b+=((uint32_t)k[7])<<24; - case 7 : b+=((uint32_t)k[6])<<16; - case 6 : b+=((uint32_t)k[5])<<8; - case 5 : b+=k[4]; - case 4 : a+=((uint32_t)k[3])<<24; - case 3 : a+=((uint32_t)k[2])<<16; - case 2 : a+=((uint32_t)k[1])<<8; - case 1 : a+=k[0]; - break; - case 0 : return c; /* zero length strings require no mixing */ - } - } - - final(a,b,c); - return c; /* zero length strings require no mixing */ -} - -#elif HASH_BIG_ENDIAN == 1 -/* - * hashbig(): - * This is the same as hashword() on big-endian machines. It is different - * from hashlittle() on all machines. hashbig() takes advantage of - * big-endian byte ordering. - */ -uint32_t hash( const void *key, size_t length, const uint32_t initval) -{ - uint32_t a,b,c; - union { const void *ptr; size_t i; } u; /* to cast key to (size_t) happily */ - - /* Set up the internal state */ - a = b = c = 0xdeadbeef + ((uint32_t)length) + initval; - - u.ptr = key; - if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) { - const uint32_t *k = key; /* read 32-bit chunks */ -#ifdef VALGRIND - const uint8_t *k8; -#endif /* ifdef VALGRIND */ - - /*------ 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 */ - /* - * "k[2]<<8" actually reads beyond the end of the string, but - * then shifts out the part it's not allowed to read. Because the - * string is aligned, the illegal read is in the same word as the - * rest of the string. Every machine with memory protection I've seen - * does it on word boundaries, so is OK with this. But VALGRIND will - * still catch it and complain. The masking trick does make the hash - * noticably faster for short strings (like English words). - */ -#ifndef VALGRIND - - switch(length) - { - case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; - case 11: c+=k[2]&0xffffff00; b+=k[1]; a+=k[0]; break; - case 10: c+=k[2]&0xffff0000; b+=k[1]; a+=k[0]; break; - case 9 : c+=k[2]&0xff000000; b+=k[1]; a+=k[0]; break; - case 8 : b+=k[1]; a+=k[0]; break; - case 7 : b+=k[1]&0xffffff00; a+=k[0]; break; - case 6 : b+=k[1]&0xffff0000; a+=k[0]; break; - case 5 : b+=k[1]&0xff000000; a+=k[0]; break; - case 4 : a+=k[0]; break; - case 3 : a+=k[0]&0xffffff00; break; - case 2 : a+=k[0]&0xffff0000; break; - case 1 : a+=k[0]&0xff000000; break; - case 0 : return c; /* zero length strings require no mixing */ - } - -#else /* make valgrind happy */ - - k8 = (const uint8_t *)k; - switch(length) /* all the case statements fall through */ - { - case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; - case 11: c+=((uint32_t)k8[10])<<8; /* fall through */ - case 10: c+=((uint32_t)k8[9])<<16; /* fall through */ - case 9 : c+=((uint32_t)k8[8])<<24; /* fall through */ - case 8 : b+=k[1]; a+=k[0]; break; - case 7 : b+=((uint32_t)k8[6])<<8; /* fall through */ - case 6 : b+=((uint32_t)k8[5])<<16; /* fall through */ - case 5 : b+=((uint32_t)k8[4])<<24; /* fall through */ - case 4 : a+=k[0]; break; - case 3 : a+=((uint32_t)k8[2])<<8; /* fall through */ - case 2 : a+=((uint32_t)k8[1])<<16; /* fall through */ - case 1 : a+=((uint32_t)k8[0])<<24; break; - case 0 : return c; - } - -#endif /* !VALGRIND */ - - } else { /* need to read the key one byte at a time */ - const uint8_t *k = key; - - /*--------------- all but the last block: affect some 32 bits of (a,b,c) */ - while (length > 12) - { - a += ((uint32_t)k[0])<<24; - a += ((uint32_t)k[1])<<16; - a += ((uint32_t)k[2])<<8; - a += ((uint32_t)k[3]); - b += ((uint32_t)k[4])<<24; - b += ((uint32_t)k[5])<<16; - b += ((uint32_t)k[6])<<8; - b += ((uint32_t)k[7]); - c += ((uint32_t)k[8])<<24; - c += ((uint32_t)k[9])<<16; - c += ((uint32_t)k[10])<<8; - c += ((uint32_t)k[11]); - 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+=k[11]; - case 11: c+=((uint32_t)k[10])<<8; - case 10: c+=((uint32_t)k[9])<<16; - case 9 : c+=((uint32_t)k[8])<<24; - case 8 : b+=k[7]; - case 7 : b+=((uint32_t)k[6])<<8; - case 6 : b+=((uint32_t)k[5])<<16; - case 5 : b+=((uint32_t)k[4])<<24; - case 4 : a+=k[3]; - case 3 : a+=((uint32_t)k[2])<<8; - case 2 : a+=((uint32_t)k[1])<<16; - case 1 : a+=((uint32_t)k[0])<<24; - break; - case 0 : return c; - } - } - - final(a,b,c); - return c; -} -#else /* HASH_XXX_ENDIAN == 1 */ -#error Must define HASH_BIG_ENDIAN or HASH_LITTLE_ENDIAN -#endif /* HASH_XXX_ENDIAN == 1 */ - typedef unsigned long int ub4; /* unsigned 4-byte quantities */ typedef unsigned char ub1; /* unsigned 1-byte quantities */ diff --git a/assoc.h b/assoc.h index b8ae9c30b5..dbb1caf16e 100644 --- a/assoc.h +++ b/assoc.h @@ -4,7 +4,6 @@ item *assoc_find(const char *key, const size_t nkey); int assoc_insert(item *item); void assoc_delete(const char *key, const size_t nkey); void do_assoc_move_next_bucket(void); -uint32_t hash( const void *key, size_t length, const uint32_t initval); int start_assoc_maintenance_thread(void); void stop_assoc_maintenance_thread(void); diff --git a/hash.c b/hash.c new file mode 100644 index 0000000000..fcfc1ffcd3 --- /dev/null +++ b/hash.c @@ -0,0 +1,431 @@ +/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */ +/* + * Hash table + * + * The hash function used here is by Bob Jenkins, 1996: + * + * "By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. + * You may use this code any way you wish, private, educational, + * or commercial. It's free." + * + */ +#include "memcached.h" + +/* + * Since the hash function does bit manipulation, it needs to know + * whether it's big or little-endian. ENDIAN_LITTLE and ENDIAN_BIG + * are set in the configure script. + */ +#if ENDIAN_BIG == 1 +# define HASH_LITTLE_ENDIAN 0 +# define HASH_BIG_ENDIAN 1 +#else +# if ENDIAN_LITTLE == 1 +# define HASH_LITTLE_ENDIAN 1 +# define HASH_BIG_ENDIAN 0 +# else +# define HASH_LITTLE_ENDIAN 0 +# define HASH_BIG_ENDIAN 0 +# endif +#endif + +#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); \ +} + +#if HASH_LITTLE_ENDIAN == 1 +uint32_t hash( + const void *key, /* the key to hash */ + size_t length, /* length of the key */ + const uint32_t initval) /* initval */ +{ + 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) + initval; + + u.ptr = key; + if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) { + const uint32_t *k = key; /* read 32-bit chunks */ +#ifdef VALGRIND + const uint8_t *k8; +#endif /* ifdef VALGRIND */ + + /*------ 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 */ + /* + * "k[2]&0xffffff" actually reads beyond the end of the string, but + * then masks off the part it's not allowed to read. Because the + * string is aligned, the masked-off tail is in the same word as the + * rest of the string. Every machine with memory protection I've seen + * does it on word boundaries, so is OK with this. But VALGRIND will + * still catch it and complain. The masking trick does make the hash + * noticably faster for short strings (like English words). + */ +#ifndef VALGRIND + + switch(length) + { + case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; + case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break; + case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break; + case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break; + case 8 : b+=k[1]; a+=k[0]; break; + case 7 : b+=k[1]&0xffffff; a+=k[0]; break; + case 6 : b+=k[1]&0xffff; a+=k[0]; break; + case 5 : b+=k[1]&0xff; a+=k[0]; break; + case 4 : a+=k[0]; break; + case 3 : a+=k[0]&0xffffff; break; + case 2 : a+=k[0]&0xffff; break; + case 1 : a+=k[0]&0xff; break; + case 0 : return c; /* zero length strings require no mixing */ + } + +#else /* make valgrind happy */ + + 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 c; /* zero length strings require no mixing */ + } + +#endif /* !valgrind */ + + } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) { + const uint16_t *k = 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; /* @fallthrough */ + case 10: c+=k[4]; /* @fallthrough@ */ + b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 9 : c+=k8[8]; /* @fallthrough */ + 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; /* @fallthrough */ + case 6 : b+=k[2]; + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 5 : b+=k8[4]; /* @fallthrough */ + case 4 : a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 3 : a+=((uint32_t)k8[2])<<16; /* @fallthrough */ + case 2 : a+=k[0]; + break; + case 1 : a+=k8[0]; + break; + case 0 : return c; /* zero length strings require no mixing */ + } + + } else { /* need to read the key one byte at a time */ + const uint8_t *k = 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; + case 11: c+=((uint32_t)k[10])<<16; + case 10: c+=((uint32_t)k[9])<<8; + case 9 : c+=k[8]; + case 8 : b+=((uint32_t)k[7])<<24; + case 7 : b+=((uint32_t)k[6])<<16; + case 6 : b+=((uint32_t)k[5])<<8; + case 5 : b+=k[4]; + case 4 : a+=((uint32_t)k[3])<<24; + case 3 : a+=((uint32_t)k[2])<<16; + case 2 : a+=((uint32_t)k[1])<<8; + case 1 : a+=k[0]; + break; + case 0 : return c; /* zero length strings require no mixing */ + } + } + + final(a,b,c); + return c; /* zero length strings require no mixing */ +} + +#elif HASH_BIG_ENDIAN == 1 +/* + * hashbig(): + * This is the same as hashword() on big-endian machines. It is different + * from hashlittle() on all machines. hashbig() takes advantage of + * big-endian byte ordering. + */ +uint32_t hash( const void *key, size_t length, const uint32_t initval) +{ + uint32_t a,b,c; + union { const void *ptr; size_t i; } u; /* to cast key to (size_t) happily */ + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + ((uint32_t)length) + initval; + + u.ptr = key; + if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) { + const uint32_t *k = key; /* read 32-bit chunks */ +#ifdef VALGRIND + const uint8_t *k8; +#endif /* ifdef VALGRIND */ + + /*------ 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 */ + /* + * "k[2]<<8" actually reads beyond the end of the string, but + * then shifts out the part it's not allowed to read. Because the + * string is aligned, the illegal read is in the same word as the + * rest of the string. Every machine with memory protection I've seen + * does it on word boundaries, so is OK with this. But VALGRIND will + * still catch it and complain. The masking trick does make the hash + * noticably faster for short strings (like English words). + */ +#ifndef VALGRIND + + switch(length) + { + case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; + case 11: c+=k[2]&0xffffff00; b+=k[1]; a+=k[0]; break; + case 10: c+=k[2]&0xffff0000; b+=k[1]; a+=k[0]; break; + case 9 : c+=k[2]&0xff000000; b+=k[1]; a+=k[0]; break; + case 8 : b+=k[1]; a+=k[0]; break; + case 7 : b+=k[1]&0xffffff00; a+=k[0]; break; + case 6 : b+=k[1]&0xffff0000; a+=k[0]; break; + case 5 : b+=k[1]&0xff000000; a+=k[0]; break; + case 4 : a+=k[0]; break; + case 3 : a+=k[0]&0xffffff00; break; + case 2 : a+=k[0]&0xffff0000; break; + case 1 : a+=k[0]&0xff000000; break; + case 0 : return c; /* zero length strings require no mixing */ + } + +#else /* make valgrind happy */ + + k8 = (const uint8_t *)k; + switch(length) /* all the case statements fall through */ + { + case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; + case 11: c+=((uint32_t)k8[10])<<8; /* fall through */ + case 10: c+=((uint32_t)k8[9])<<16; /* fall through */ + case 9 : c+=((uint32_t)k8[8])<<24; /* fall through */ + case 8 : b+=k[1]; a+=k[0]; break; + case 7 : b+=((uint32_t)k8[6])<<8; /* fall through */ + case 6 : b+=((uint32_t)k8[5])<<16; /* fall through */ + case 5 : b+=((uint32_t)k8[4])<<24; /* fall through */ + case 4 : a+=k[0]; break; + case 3 : a+=((uint32_t)k8[2])<<8; /* fall through */ + case 2 : a+=((uint32_t)k8[1])<<16; /* fall through */ + case 1 : a+=((uint32_t)k8[0])<<24; break; + case 0 : return c; + } + +#endif /* !VALGRIND */ + + } else { /* need to read the key one byte at a time */ + const uint8_t *k = key; + + /*--------------- all but the last block: affect some 32 bits of (a,b,c) */ + while (length > 12) + { + a += ((uint32_t)k[0])<<24; + a += ((uint32_t)k[1])<<16; + a += ((uint32_t)k[2])<<8; + a += ((uint32_t)k[3]); + b += ((uint32_t)k[4])<<24; + b += ((uint32_t)k[5])<<16; + b += ((uint32_t)k[6])<<8; + b += ((uint32_t)k[7]); + c += ((uint32_t)k[8])<<24; + c += ((uint32_t)k[9])<<16; + c += ((uint32_t)k[10])<<8; + c += ((uint32_t)k[11]); + 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+=k[11]; + case 11: c+=((uint32_t)k[10])<<8; + case 10: c+=((uint32_t)k[9])<<16; + case 9 : c+=((uint32_t)k[8])<<24; + case 8 : b+=k[7]; + case 7 : b+=((uint32_t)k[6])<<8; + case 6 : b+=((uint32_t)k[5])<<16; + case 5 : b+=((uint32_t)k[4])<<24; + case 4 : a+=k[3]; + case 3 : a+=((uint32_t)k[2])<<8; + case 2 : a+=((uint32_t)k[1])<<16; + case 1 : a+=((uint32_t)k[0])<<24; + break; + case 0 : return c; + } + } + + final(a,b,c); + return c; +} +#else /* HASH_XXX_ENDIAN == 1 */ +#error Must define HASH_BIG_ENDIAN or HASH_LITTLE_ENDIAN +#endif /* HASH_XXX_ENDIAN == 1 */ diff --git a/hash.h b/hash.h new file mode 100644 index 0000000000..aa02c58fbe --- /dev/null +++ b/hash.h @@ -0,0 +1,15 @@ +#ifndef HASH_H +#define HASH_H + +#ifdef __cplusplus +extern "C" { +#endif + +uint32_t hash(const void *key, size_t length, const uint32_t initval); + +#ifdef __cplusplus +} +#endif + +#endif /* HASH_H */ + diff --git a/memcached.h b/memcached.h index 1ee1e05eb1..f057da5aa6 100644 --- a/memcached.h +++ b/memcached.h @@ -304,6 +304,7 @@ extern int daemonize(int nochdir, int noclose); #include "assoc.h" #include "items.h" #include "trace.h" +#include "hash.h" /*