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/* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Libmemcached library
*
* Copyright (C) 2011 Data Differential, http://datadifferential.com/
* Copyright (C) 2006-2009 Brian Aker All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* * The names of its contributors may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <libmemcached/common.h>
#include <sys/time.h>
#include <libmemcached/virtual_bucket.h>
uint32_t memcached_generate_hash_value(const char *key, size_t key_length, memcached_hash_t hash_algorithm)
{
return libhashkit_digest(key, key_length, (hashkit_hash_algorithm_t)hash_algorithm);
}
static inline uint32_t generate_hash(const Memcached *ptr, const char *key, size_t key_length)
{
return hashkit_digest(&ptr->hashkit, key, key_length);
}
static uint32_t dispatch_host(const Memcached *ptr, uint32_t hash)
{
switch (ptr->distribution)
{
case MEMCACHED_DISTRIBUTION_CONSISTENT:
case MEMCACHED_DISTRIBUTION_CONSISTENT_WEIGHTED:
case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA:
case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY:
{
uint32_t num= ptr->ketama.continuum_points_counter;
WATCHPOINT_ASSERT(ptr->ketama.continuum);
memcached_continuum_item_st *begin, *end, *left, *right, *middle;
begin= left= ptr->ketama.continuum;
end= right= ptr->ketama.continuum + num;
while (left < right)
{
middle= left + (right - left) / 2;
if (middle->value < hash)
left= middle + 1;
else
right= middle;
}
if (right == end)
right= begin;
return right->index;
}
case MEMCACHED_DISTRIBUTION_MODULA:
return hash % memcached_server_count(ptr);
case MEMCACHED_DISTRIBUTION_RANDOM:
return (uint32_t) random() % memcached_server_count(ptr);
case MEMCACHED_DISTRIBUTION_VIRTUAL_BUCKET:
{
return memcached_virtual_bucket_get(ptr, hash);
}
default:
case MEMCACHED_DISTRIBUTION_CONSISTENT_MAX:
WATCHPOINT_ASSERT(0); /* We have added a distribution without extending the logic */
return hash % memcached_server_count(ptr);
}
/* NOTREACHED */
}
/*
One version is public and will not modify the distribution hash, the other will.
*/
static inline uint32_t _generate_hash_wrapper(const Memcached *ptr, const char *key, size_t key_length)
{
WATCHPOINT_ASSERT(memcached_server_count(ptr));
if (memcached_server_count(ptr) == 1)
return 0;
if (ptr->flags.hash_with_namespace)
{
size_t temp_length= memcached_array_size(ptr->_namespace) + key_length;
char temp[MEMCACHED_MAX_KEY];
if (temp_length > MEMCACHED_MAX_KEY -1)
return 0;
strncpy(temp, memcached_array_string(ptr->_namespace), memcached_array_size(ptr->_namespace));
strncpy(temp + memcached_array_size(ptr->_namespace), key, key_length);
return generate_hash(ptr, temp, temp_length);
}
else
{
return generate_hash(ptr, key, key_length);
}
}
static inline void _regen_for_auto_eject(Memcached *ptr)
{
if (_is_auto_eject_host(ptr) && ptr->ketama.next_distribution_rebuild)
{
struct timeval now;
if (gettimeofday(&now, NULL) == 0 and
now.tv_sec > ptr->ketama.next_distribution_rebuild)
{
run_distribution(ptr);
}
}
}
void memcached_autoeject(memcached_st *ptr)
{
_regen_for_auto_eject(ptr);
}
uint32_t memcached_generate_hash_with_redistribution(memcached_st *ptr, const char *key, size_t key_length)
{
uint32_t hash= _generate_hash_wrapper(ptr, key, key_length);
_regen_for_auto_eject(ptr);
return dispatch_host(ptr, hash);
}
uint32_t memcached_generate_hash(const memcached_st *shell, const char *key, size_t key_length)
{
const Memcached* ptr= memcached2Memcached(shell);
if (ptr)
{
return dispatch_host(ptr, _generate_hash_wrapper(ptr, key, key_length));
}
return UINT32_MAX;
}
const hashkit_st *memcached_get_hashkit(const memcached_st *shell)
{
const Memcached* ptr= memcached2Memcached(shell);
if (ptr)
{
return &ptr->hashkit;
}
return NULL;
}
memcached_return_t memcached_set_hashkit(memcached_st *shell, hashkit_st *hashk)
{
Memcached* self= memcached2Memcached(shell);
if (self)
{
hashkit_free(&self->hashkit);
hashkit_clone(&self->hashkit, hashk);
return MEMCACHED_SUCCESS;
}
return MEMCACHED_INVALID_ARGUMENTS;
}
const char * libmemcached_string_hash(memcached_hash_t type)
{
return libhashkit_string_hash((hashkit_hash_algorithm_t)type);
}
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