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

   1 /*  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
   2  *
   3  *  Libmemcached library
   4  *
   5  *  Copyright (C) 2011 Data Differential, http://datadifferential.com/
   6  *  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 #include <libmemcached/common.h>
  39
  40 struct bucket_t {
  41   uint32_t master;
  42   uint32_t forward;
  43 };
  44
  45 struct memcached_virtual_bucket_t {
  46   bool has_forward;
  47   uint32_t size;
  48   uint32_t replicas;
  49   struct bucket_t buckets[];
  50 };
  51
  52 memcached_return_t memcached_virtual_bucket_create(memcached_st *self,
  53                                                    const uint32_t *host_map,
  54                                                    const uint32_t *forward_map,
  55                                                    const uint32_t buckets,
  56                                                    const uint32_t replicas)
  57 {
  58   if (! self || ! host_map || ! buckets)
  59   {
  60     return MEMCACHED_INVALID_ARGUMENTS;
  61   }
  62
  63   memcached_virtual_bucket_free(self);
  64
  65   struct memcached_virtual_bucket_t *virtual_bucket= (struct memcached_virtual_bucket_t *)malloc(sizeof(struct memcached_virtual_bucket_t) + sizeof(struct bucket_t) *buckets);
  66
  67   if (virtual_bucket == NULL)
  68   {
  69     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
  70   }
  71
  72
  73   virtual_bucket->size= buckets;
  74   virtual_bucket->replicas= replicas;
  75   self->virtual_bucket= virtual_bucket;
  76
  77   uint32_t x= 0;
  78   for (; x < buckets; x++)
  79   {
  80     virtual_bucket->buckets[x].master= host_map[x];
  81     if (forward_map)
  82     {
  83       virtual_bucket->buckets[x].forward= forward_map[x];
  84     }
  85     else
  86     {
  87       virtual_bucket->buckets[x].forward= 0;
  88     }
  89   }
  90
  91   return MEMCACHED_SUCCESS;
  92 }
  93
  94 void memcached_virtual_bucket_free(memcached_st *self)
  95 {
  96   if (self == NULL)
  97   {
  98     return;
  99   }
 100
 101   if (self->virtual_bucket == NULL)
 102   {
 103     return;
 104   }
 105
 106   free(self->virtual_bucket);
 107   self->virtual_bucket= NULL;
 108 }
 109
 110 uint32_t memcached_virtual_bucket_get(const memcached_st *self, uint32_t digest)
 111 {
 112   if (self == NULL)
 113   {
 114     return 0;
 115   }
 116
 117   if (self->virtual_bucket == NULL)
 118   {
 119     return 0;
 120   }
 121
 122   if (self->virtual_bucket)
 123   {
 124     uint32_t result= (uint32_t) (digest & (self->virtual_bucket->size -1));
 125     return self->virtual_bucket->buckets[result].master;
 126   }
 127
 128   return (uint32_t) (digest & (self->number_of_hosts -1));
 129 }