git.m6w6.name Git - m6w6/libmemcached/blob - libmemcached/hash.c

   1 /*  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
   2  *
   3  *  Libmemcached library
   4  *
   5  *  Copyright (C) 2011 Data Differential, http://datadifferential.com/
   6  *  Copyright (C) 2006-2009 Brian Aker All rights reserved.
   7  *
   8  *  Redistribution and use in source and binary forms, with or without
   9  *  modification, are permitted provided that the following conditions are
  10  *  met:
  11  *
  12  *      * Redistributions of source code must retain the above copyright
  13  *  notice, this list of conditions and the following disclaimer.
  14  *
  15  *      * Redistributions in binary form must reproduce the above
  16  *  copyright notice, this list of conditions and the following disclaimer
  17  *  in the documentation and/or other materials provided with the
  18  *  distribution.
  19  *
  20  *      * The names of its contributors may not be used to endorse or
  21  *  promote products derived from this software without specific prior
  22  *  written permission.
  23  *
  24  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  25  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  26  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  27  *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  28  *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  30  *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  34  *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  *
  36  */
  37
  38
  39 #include <libmemcached/common.h>
  40 #include <libmemcached/virtual_bucket.h>
  41
  42
  43 uint32_t memcached_generate_hash_value(const char *key, size_t key_length, memcached_hash_t hash_algorithm)
  44 {
  45   return libhashkit_digest(key, key_length, (hashkit_hash_algorithm_t)hash_algorithm);
  46 }
  47
  48 static inline uint32_t generate_hash(const memcached_st *ptr, const char *key, size_t key_length)
  49 {
  50   return hashkit_digest(&ptr->hashkit, key, key_length);
  51 }
  52
  53 static uint32_t dispatch_host(const memcached_st *ptr, uint32_t hash)
  54 {
  55   switch (ptr->distribution)
  56   {
  57   case MEMCACHED_DISTRIBUTION_CONSISTENT:
  58   case MEMCACHED_DISTRIBUTION_CONSISTENT_WEIGHTED:
  59   case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA:
  60   case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY:
  61     {
  62       uint32_t num= ptr->ketama.continuum_points_counter;
  63       WATCHPOINT_ASSERT(ptr->continuum);
  64
  65       hash= hash;
  66       memcached_continuum_item_st *begin, *end, *left, *right, *middle;
  67       begin= left= ptr->ketama.continuum;
  68       end= right= ptr->ketama.continuum + num;
  69
  70       while (left < right)
  71       {
  72         middle= left + (right - left) / 2;
  73         if (middle->value < hash)
  74           left= middle + 1;
  75         else
  76           right= middle;
  77       }
  78       if (right == end)
  79         right= begin;
  80       return right->index;
  81     }
  82   case MEMCACHED_DISTRIBUTION_MODULA:
  83     return hash % memcached_server_count(ptr);
  84   case MEMCACHED_DISTRIBUTION_RANDOM:
  85     return (uint32_t) random() % memcached_server_count(ptr);
  86   case MEMCACHED_DISTRIBUTION_VIRTUAL_BUCKET:
  87     {
  88       return memcached_virtual_bucket_get(ptr, hash);
  89     }
  90   default:
  91   case MEMCACHED_DISTRIBUTION_CONSISTENT_MAX:
  92     WATCHPOINT_ASSERT(0); /* We have added a distribution without extending the logic */
  93     return hash % memcached_server_count(ptr);
  94   }
  95   /* NOTREACHED */
  96 }
  97
  98 /*
  99   One version is public and will not modify the distribution hash, the other will.
 100 */
 101 static inline uint32_t _generate_hash_wrapper(const memcached_st *ptr, const char *key, size_t key_length)
 102 {
 103   WATCHPOINT_ASSERT(memcached_server_count(ptr));
 104
 105   if (memcached_server_count(ptr) == 1)
 106     return 0;
 107
 108   if (ptr->flags.hash_with_prefix_key)
 109   {
 110     size_t temp_length= memcached_array_size(ptr->prefix_key) + key_length;
 111     char temp[temp_length];
 112
 113     if (temp_length > MEMCACHED_MAX_KEY -1)
 114       return 0;
 115
 116     strncpy(temp, memcached_array_string(ptr->prefix_key), memcached_array_size(ptr->prefix_key));
 117     strncpy(temp + memcached_array_size(ptr->prefix_key), key, key_length);
 118
 119     return generate_hash(ptr, temp, temp_length);
 120   }
 121   else
 122   {
 123     return generate_hash(ptr, key, key_length);
 124   }
 125 }
 126
 127 static inline void _regen_for_auto_eject(memcached_st *ptr)
 128 {
 129   if (_is_auto_eject_host(ptr) && ptr->ketama.next_distribution_rebuild)
 130   {
 131     struct timeval now;
 132
 133     if (gettimeofday(&now, NULL) == 0 &&
 134         now.tv_sec > ptr->ketama.next_distribution_rebuild)
 135     {
 136       run_distribution(ptr);
 137     }
 138   }
 139 }
 140
 141 void memcached_autoeject(memcached_st *ptr)
 142 {
 143   _regen_for_auto_eject(ptr);
 144 }
 145
 146 uint32_t memcached_generate_hash_with_redistribution(memcached_st *ptr, const char *key, size_t key_length)
 147 {
 148   uint32_t hash= _generate_hash_wrapper(ptr, key, key_length);
 149
 150   _regen_for_auto_eject(ptr);
 151
 152   return dispatch_host(ptr, hash);
 153 }
 154
 155 uint32_t memcached_generate_hash(const memcached_st *ptr, const char *key, size_t key_length)
 156 {
 157   return dispatch_host(ptr, _generate_hash_wrapper(ptr, key, key_length));
 158 }
 159
 160 const hashkit_st *memcached_get_hashkit(const memcached_st *ptr)
 161 {
 162   return &ptr->hashkit;
 163 }
 164
 165 memcached_return_t memcached_set_hashkit(memcached_st *self, hashkit_st *hashk)
 166 {
 167   hashkit_free(&self->hashkit);
 168   hashkit_clone(&self->hashkit, hashk);
 169
 170   return MEMCACHED_SUCCESS;
 171 }
 172
 173 const char * libmemcached_string_hash(memcached_hash_t type)
 174 {
 175   switch (type)
 176   {
 177   case MEMCACHED_HASH_DEFAULT: return "MEMCACHED_HASH_DEFAULT";
 178   case MEMCACHED_HASH_MD5: return "MEMCACHED_HASH_MD5";
 179   case MEMCACHED_HASH_CRC: return "MEMCACHED_HASH_CRC";
 180   case MEMCACHED_HASH_FNV1_64: return "MEMCACHED_HASH_FNV1_64";
 181   case MEMCACHED_HASH_FNV1A_64: return "MEMCACHED_HASH_FNV1A_64";
 182   case MEMCACHED_HASH_FNV1_32: return "MEMCACHED_HASH_FNV1_32";
 183   case MEMCACHED_HASH_FNV1A_32: return "MEMCACHED_HASH_FNV1A_32";
 184   case MEMCACHED_HASH_HSIEH: return "MEMCACHED_HASH_HSIEH";
 185   case MEMCACHED_HASH_MURMUR: return "MEMCACHED_HASH_MURMUR";
 186   case MEMCACHED_HASH_JENKINS: return "MEMCACHED_HASH_JENKINS";
 187   case MEMCACHED_HASH_CUSTOM: return "MEMCACHED_HASH_CUSTOM";
 188   default:
 189   case MEMCACHED_HASH_MAX: return "INVALID memcached_hash_t";
 190   }
 191 }