1 /* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
5 * Copyright (C) 2011 Data Differential, http://datadifferential.com/
6 * Copyright (C) 2006-2009 Brian Aker All rights reserved.
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16 * copyright notice, this list of conditions and the following disclaimer
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39 #include <libmemcached/common.h>
40 #include <libmemcached/virtual_bucket.h>
43 uint32_t memcached_generate_hash_value(const char *key
, size_t key_length
, memcached_hash_t hash_algorithm
)
45 return libhashkit_digest(key
, key_length
, (hashkit_hash_algorithm_t
)hash_algorithm
);
48 static inline uint32_t generate_hash(const memcached_st
*ptr
, const char *key
, size_t key_length
)
50 return hashkit_digest(&ptr
->hashkit
, key
, key_length
);
53 static uint32_t dispatch_host(const memcached_st
*ptr
, uint32_t hash
)
55 switch (ptr
->distribution
)
57 case MEMCACHED_DISTRIBUTION_CONSISTENT
:
58 case MEMCACHED_DISTRIBUTION_CONSISTENT_WEIGHTED
:
59 case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA
:
60 case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY
:
62 uint32_t num
= ptr
->ketama
.continuum_points_counter
;
63 WATCHPOINT_ASSERT(ptr
->continuum
);
66 memcached_continuum_item_st
*begin
, *end
, *left
, *right
, *middle
;
67 begin
= left
= ptr
->ketama
.continuum
;
68 end
= right
= ptr
->ketama
.continuum
+ num
;
72 middle
= left
+ (right
- left
) / 2;
73 if (middle
->value
< hash
)
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
:
88 return memcached_virtual_bucket_get(ptr
, hash
);
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
);
99 One version is public and will not modify the distribution hash, the other will.
101 static inline uint32_t _generate_hash_wrapper(const memcached_st
*ptr
, const char *key
, size_t key_length
)
103 WATCHPOINT_ASSERT(memcached_server_count(ptr
));
105 if (memcached_server_count(ptr
) == 1)
108 if (ptr
->flags
.hash_with_prefix_key
)
110 size_t temp_length
= memcached_array_size(ptr
->prefix_key
) + key_length
;
111 char temp
[temp_length
];
113 if (temp_length
> MEMCACHED_MAX_KEY
-1)
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
);
119 return generate_hash(ptr
, temp
, temp_length
);
123 return generate_hash(ptr
, key
, key_length
);
127 static inline void _regen_for_auto_eject(memcached_st
*ptr
)
129 if (_is_auto_eject_host(ptr
) && ptr
->ketama
.next_distribution_rebuild
)
133 if (gettimeofday(&now
, NULL
) == 0 &&
134 now
.tv_sec
> ptr
->ketama
.next_distribution_rebuild
)
136 run_distribution(ptr
);
141 void memcached_autoeject(memcached_st
*ptr
)
143 _regen_for_auto_eject(ptr
);
146 uint32_t memcached_generate_hash_with_redistribution(memcached_st
*ptr
, const char *key
, size_t key_length
)
148 uint32_t hash
= _generate_hash_wrapper(ptr
, key
, key_length
);
150 _regen_for_auto_eject(ptr
);
152 return dispatch_host(ptr
, hash
);
155 uint32_t memcached_generate_hash(const memcached_st
*ptr
, const char *key
, size_t key_length
)
157 return dispatch_host(ptr
, _generate_hash_wrapper(ptr
, key
, key_length
));
160 const hashkit_st
*memcached_get_hashkit(const memcached_st
*ptr
)
162 return &ptr
->hashkit
;
165 memcached_return_t
memcached_set_hashkit(memcached_st
*self
, hashkit_st
*hashk
)
167 hashkit_free(&self
->hashkit
);
168 hashkit_clone(&self
->hashkit
, hashk
);
170 return MEMCACHED_SUCCESS
;
173 const char * libmemcached_string_hash(memcached_hash_t type
)
175 return libhashkit_string_hash((hashkit_hash_algorithm_t
)type
);