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

   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
  18 struct bucket_t {
  19   uint32_t master;
  20   uint32_t forward;
  21 };
  22
  23 struct memcached_virtual_bucket_t {
  24   bool has_forward;
  25   uint32_t size;
  26   uint32_t replicas;
  27   struct bucket_t buckets[];
  28 };
  29
  30 memcached_return_t memcached_virtual_bucket_create(memcached_st *self, const uint32_t *host_map,
  31                                                    const uint32_t *forward_map,
  32                                                    const uint32_t buckets,
  33                                                    const uint32_t replicas) {
  34   if (self == NULL || host_map == NULL || buckets == 0U) {
  35     return MEMCACHED_INVALID_ARGUMENTS;
  36   }
  37
  38   memcached_virtual_bucket_free(self);
  39
  40   struct memcached_virtual_bucket_t *virtual_bucket = (struct memcached_virtual_bucket_t *) malloc(
  41       sizeof(struct memcached_virtual_bucket_t) + sizeof(struct bucket_t) * buckets);
  42
  43   if (virtual_bucket == NULL) {
  44     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
  45   }
  46
  47   virtual_bucket->size = buckets;
  48   virtual_bucket->replicas = replicas;
  49   self->virtual_bucket = virtual_bucket;
  50
  51   uint32_t x = 0;
  52   for (; x < buckets; x++) {
  53     virtual_bucket->buckets[x].master = host_map[x];
  54     if (forward_map) {
  55       virtual_bucket->buckets[x].forward = forward_map[x];
  56     } else {
  57       virtual_bucket->buckets[x].forward = 0;
  58     }
  59   }
  60
  61   return MEMCACHED_SUCCESS;
  62 }
  63
  64 void memcached_virtual_bucket_free(memcached_st *self) {
  65   if (self) {
  66     if (self->virtual_bucket) {
  67       free(self->virtual_bucket);
  68       self->virtual_bucket = NULL;
  69     }
  70   }
  71 }
  72
  73 uint32_t memcached_virtual_bucket_get(const memcached_st *self, uint32_t digest) {
  74   if (self) {
  75     if (self->virtual_bucket) {
  76       uint32_t result = (uint32_t)(digest & (self->virtual_bucket->size - 1));
  77       return self->virtual_bucket->buckets[result].master;
  78     }
  79
  80     return (uint32_t)(digest & (self->number_of_hosts - 1));
  81   }
  82
  83   return 0;
  84 }