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