cds  2.3.2
cds::container::feldman_hashset::traits Struct Reference

FeldmanHashSet traits More...

#include <cds/container/details/feldman_hashset_base.h>

Public Types

typedef cds::opt::none hash_accessor
 Mandatory functor to get hash value from data node. More...
 
typedef cds::opt::none hash_splitter
 Hash splitter. More...
 
typedef cds::opt::none compare
 Hash comparing functor. More...
 
typedef cds::opt::none less
 Specifies binary predicate used for hash compare. More...
 
typedef cds::atomicity::item_counter item_counter
 Item counter. More...
 
typedef CDS_DEFAULT_ALLOCATOR allocator
 Item allocator. More...
 
typedef CDS_DEFAULT_ALLOCATOR node_allocator
 Array node allocator. More...
 
typedef cds::opt::v::relaxed_ordering memory_model
 C++ memory ordering model. More...
 
typedef cds::backoff::Default back_off
 Back-off strategy.
 
typedef empty_stat stat
 Internal statistics. More...
 
typedef cds::opt::v::rcu_throw_deadlock rcu_check_deadlock
 RCU deadlock checking policy (only for RCU-based FeldmanHashSet) More...
 

Static Public Attributes

static constexpr size_t const hash_size = 0
 The size of hash value in bytes. More...
 

Detailed Description

Member Typedef Documentation

◆ allocator

◆ compare

Hash comparing functor.

No default functor is provided. If the option is not specified, the less option is used.

◆ hash_accessor

Mandatory functor to get hash value from data node.

It is most-important feature of FeldmanHashSet. That functor must return a reference to fixed-sized hash value of data node. The return value of that functor specifies the type of hash value.

Example:

typedef uint8_t hash_type[32]; // 256-bit hash type
struct foo {
hash_type hash; // 256-bit hash value
// ... other fields
};
// Hash accessor
struct foo_hash_accessor {
hash_type const& operator()( foo const& d ) const
{
return d.hash;
}
};

◆ hash_splitter

Hash splitter.

This trait specifies hash bit-string splitter algorithm. By default, cds::algo::number_splitter is used if HashType is a number, cds::algo::split_bitstring otherwise.

◆ item_counter

Item counter.

The item counting is an important part of FeldmanHashSet algorithm: the empty() member function depends on correct item counting. Therefore, atomicity::empty_item_counter is not allowed as a type of the option.

Default is atomicity::item_counter. To avoid false sharing you can aldo use atomicity::cache_friendly_item_counter

◆ less

Specifies binary predicate used for hash compare.

If less and compare are not specified, memcmp() -like bit-wise hash comparator is used because the hash value is treated as fixed-sized bit-string.

◆ memory_model

C++ memory ordering model.

Can be opt::v::relaxed_ordering (relaxed memory model, the default) or opt::v::sequential_consistent (sequentially consisnent memory model).

◆ node_allocator

Array node allocator.

Allocator for array nodes. The allocator is used for creating headNode and arrayNode when the set grows. Default is CDS_DEFAULT_ALLOCATOR

◆ rcu_check_deadlock

◆ stat

Internal statistics.

By default, internal statistics is disabled (feldman_hashset::empty_stat). Use feldman_hashset::stat to enable it.

Field Documentation

◆ hash_size

constexpr size_t const cds::container::feldman_hashset::traits::hash_size = 0
static

The size of hash value in bytes.

By default, the size of hash value is sizeof( hash_type ). Sometimes it is not correct, for example, for that 6-byte struct static_assert will be thrown:

struct key_type {
uint32_t key1;
uint16_t subkey;
};
static_assert( sizeof( key_type ) == 6, "Key type size mismatch" );

For that case you can specify hash_size explicitly.

Value 0 means sizeof( hash_type ).


The documentation for this struct was generated from the following file:

cds 2.3.2 Developed by Maxim Khizhinsky aka khizmax and other contributors 2007 - 2017
Autogenerated Sun Dec 31 2017 12:10:33 by Doxygen 1.8.13