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
17 * in the documentation and/or other materials provided with the
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24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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39 #include <libmemcached/common.h>
43 #include <libmemcached/virtual_bucket.h>
45 uint32_t memcached_generate_hash_value(const char *key
, size_t key_length
, memcached_hash_t hash_algorithm
)
47 return libhashkit_digest(key
, key_length
, (hashkit_hash_algorithm_t
)hash_algorithm
);
50 static inline uint32_t generate_hash(const memcached_st
*ptr
, const char *key
, size_t key_length
)
52 return hashkit_digest(&ptr
->hashkit
, key
, key_length
);
55 static uint32_t dispatch_host(const memcached_st
*ptr
, uint32_t hash
)
57 switch (ptr
->distribution
)
59 case MEMCACHED_DISTRIBUTION_CONSISTENT
:
60 case MEMCACHED_DISTRIBUTION_CONSISTENT_WEIGHTED
:
61 case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA
:
62 case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY
:
64 uint32_t num
= ptr
->ketama
.continuum_points_counter
;
65 WATCHPOINT_ASSERT(ptr
->ketama
.continuum
);
68 memcached_continuum_item_st
*begin
, *end
, *left
, *right
, *middle
;
69 begin
= left
= ptr
->ketama
.continuum
;
70 end
= right
= ptr
->ketama
.continuum
+ num
;
74 middle
= left
+ (right
- left
) / 2;
75 if (middle
->value
< hash
)
84 case MEMCACHED_DISTRIBUTION_MODULA
:
85 return hash
% memcached_server_count(ptr
);
86 case MEMCACHED_DISTRIBUTION_RANDOM
:
87 return (uint32_t) random() % memcached_server_count(ptr
);
88 case MEMCACHED_DISTRIBUTION_VIRTUAL_BUCKET
:
90 return memcached_virtual_bucket_get(ptr
, hash
);
93 case MEMCACHED_DISTRIBUTION_CONSISTENT_MAX
:
94 WATCHPOINT_ASSERT(0); /* We have added a distribution without extending the logic */
95 return hash
% memcached_server_count(ptr
);
101 One version is public and will not modify the distribution hash, the other will.
103 static inline uint32_t _generate_hash_wrapper(const memcached_st
*ptr
, const char *key
, size_t key_length
)
105 WATCHPOINT_ASSERT(memcached_server_count(ptr
));
107 if (memcached_server_count(ptr
) == 1)
110 if (ptr
->flags
.hash_with_namespace
)
112 size_t temp_length
= memcached_array_size(ptr
->_namespace
) + key_length
;
113 char temp
[MEMCACHED_MAX_KEY
];
115 if (temp_length
> MEMCACHED_MAX_KEY
-1)
118 strncpy(temp
, memcached_array_string(ptr
->_namespace
), memcached_array_size(ptr
->_namespace
));
119 strncpy(temp
+ memcached_array_size(ptr
->_namespace
), key
, key_length
);
121 return generate_hash(ptr
, temp
, temp_length
);
125 return generate_hash(ptr
, key
, key_length
);
129 static inline void _regen_for_auto_eject(memcached_st
*ptr
)
131 if (_is_auto_eject_host(ptr
) && ptr
->ketama
.next_distribution_rebuild
)
135 if (gettimeofday(&now
, NULL
) == 0 &&
136 now
.tv_sec
> ptr
->ketama
.next_distribution_rebuild
)
138 run_distribution(ptr
);
143 void memcached_autoeject(memcached_st
*ptr
)
145 _regen_for_auto_eject(ptr
);
148 uint32_t memcached_generate_hash_with_redistribution(memcached_st
*ptr
, const char *key
, size_t key_length
)
150 uint32_t hash
= _generate_hash_wrapper(ptr
, key
, key_length
);
152 _regen_for_auto_eject(ptr
);
154 return dispatch_host(ptr
, hash
);
157 uint32_t memcached_generate_hash(const memcached_st
*ptr
, const char *key
, size_t key_length
)
159 return dispatch_host(ptr
, _generate_hash_wrapper(ptr
, key
, key_length
));
162 const hashkit_st
*memcached_get_hashkit(const memcached_st
*ptr
)
164 return &ptr
->hashkit
;
167 memcached_return_t
memcached_set_hashkit(memcached_st
*self
, hashkit_st
*hashk
)
169 hashkit_free(&self
->hashkit
);
170 hashkit_clone(&self
->hashkit
, hashk
);
172 return MEMCACHED_SUCCESS
;
175 const char * libmemcached_string_hash(memcached_hash_t type
)
177 return libhashkit_string_hash((hashkit_hash_algorithm_t
)type
);