git.m6w6.name Git - m6w6/libmemcached/blob - src/libmemcached/virtual_bucket.cc

   1 /*
   2     +--------------------------------------------------------------------+
   3     | libmemcached - C/C++ Client Library for memcached                  |
   4     +--------------------------------------------------------------------+
   5     | Redistribution and use in source and binary forms, with or without |
   6     | modification, are permitted under the terms of the BSD license.    |
   7     | You should have received a copy of the license in a bundled file   |
   8     | named LICENSE; in case you did not receive a copy you can review   |
   9     | the terms online at: https://opensource.org/licenses/BSD-3-Clause  |
  10     +--------------------------------------------------------------------+
  11     | Copyright (c) 2006-2014 Brian Aker   https://datadifferential.com/ |
  12     | Copyright (c) 2020 Michael Wallner   <mike@php.net>                |
  13     +--------------------------------------------------------------------+
  14 */
  15
  16 #include "libmemcached/common.h"
  17 #include "libmemcached/virtual_bucket.h"
  18
  19 struct bucket_t {
  20   uint32_t master;
  21   uint32_t forward;
  22 };
  23
  24 struct memcached_virtual_bucket_t {
  25   bool has_forward;
  26   uint32_t size;
  27   uint32_t replicas;
  28   struct bucket_t buckets[];
  29 };
  30
  31 memcached_return_t memcached_virtual_bucket_create(memcached_st *self, const uint32_t *host_map,
  32                                                    const uint32_t *forward_map,
  33                                                    const uint32_t buckets,
  34                                                    const uint32_t replicas) {
  35   if (self == NULL || host_map == NULL || buckets == 0U) {
  36     return MEMCACHED_INVALID_ARGUMENTS;
  37   }
  38
  39   memcached_virtual_bucket_free(self);
  40
  41   struct memcached_virtual_bucket_t *virtual_bucket = (struct memcached_virtual_bucket_t *) malloc(
  42       sizeof(struct memcached_virtual_bucket_t) + sizeof(struct bucket_t) * buckets);
  43
  44   if (virtual_bucket == NULL) {
  45     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
  46   }
  47
  48   virtual_bucket->size = buckets;
  49   virtual_bucket->replicas = replicas;
  50   self->virtual_bucket = virtual_bucket;
  51
  52   uint32_t x = 0;
  53   for (; x < buckets; x++) {
  54     virtual_bucket->buckets[x].master = host_map[x];
  55     if (forward_map) {
  56       virtual_bucket->buckets[x].forward = forward_map[x];
  57     } else {
  58       virtual_bucket->buckets[x].forward = 0;
  59     }
  60   }
  61
  62   return MEMCACHED_SUCCESS;
  63 }
  64
  65 void memcached_virtual_bucket_free(memcached_st *self) {
  66   if (self) {
  67     if (self->virtual_bucket) {
  68       free(self->virtual_bucket);
  69       self->virtual_bucket = NULL;
  70     }
  71   }
  72 }
  73
  74 uint32_t memcached_virtual_bucket_get(const memcached_st *self, uint32_t digest) {
  75   if (self) {
  76     if (self->virtual_bucket) {
  77       uint32_t result = (uint32_t)(digest & (self->virtual_bucket->size - 1));
  78       return self->virtual_bucket->buckets[result].master;
  79     }
  80
  81     return (uint32_t)(digest & (self->number_of_hosts - 1));
  82   }
  83
  84   return 0;
  85 }