cds
2.3.2
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Lock-free skip-list map. More...
#include <cds/container/impl/skip_list_map.h>
Public Types | |
typedef GC | gc |
Garbage collector. | |
typedef Key | key_type |
Key type. | |
typedef T | mapped_type |
Mapped type. | |
typedef Traits | traits |
Map traits. | |
typedef std::pair< Key const, T > | value_type |
Key-value pair to be stored in the map. | |
typedef base_class::back_off | back_off |
Back-off strategy. | |
typedef traits::allocator | allocator_type |
Allocator type used for allocate/deallocate the skip-list nodes. | |
typedef base_class::item_counter | item_counter |
Item counting policy used. | |
typedef maker::key_comparator | key_comparator |
key comparison functor | |
typedef base_class::memory_model | memory_model |
Memory ordering, see cds::opt::memory_model . | |
typedef traits::random_level_generator | random_level_generator |
random level generator | |
typedef traits::stat | stat |
internal statistics type | |
typedef gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_set< node_type, value_type > > | guarded_ptr |
Guarded pointer. | |
Public Member Functions | |
SkipListMap () | |
Default ctor. | |
~SkipListMap () | |
Destructor destroys the set object. | |
template<typename K > | |
bool | insert (K const &key) |
Inserts new node with key and default value. More... | |
template<typename K , typename V > | |
bool | insert (K const &key, V const &val) |
Inserts new node. More... | |
template<typename K , typename Func > | |
bool | insert_with (K const &key, Func func) |
Inserts new node and initialize it by a functor. More... | |
template<typename K , typename... Args> | |
bool | emplace (K &&key, Args &&... args) |
For key key inserts data of type value_type created in-place from std::forward<Args>(args)... More... | |
template<typename K , typename Func > | |
std::pair< bool, bool > | update (K const &key, Func func, bool bInsert=true) |
Updates data by key . More... | |
template<typename K > | |
bool | erase (K const &key) |
Delete key from the map. More... | |
template<typename K , typename Less > | |
bool | erase_with (K const &key, Less pred) |
Deletes the item from the map using pred predicate for searching. More... | |
template<typename K , typename Func > | |
bool | erase (K const &key, Func f) |
Delete key from the map. More... | |
template<typename K , typename Less , typename Func > | |
bool | erase_with (K const &key, Less pred, Func f) |
Deletes the item from the map using pred predicate for searching. More... | |
template<typename K > | |
guarded_ptr | extract (K const &key) |
Extracts the item from the map with specified key . More... | |
template<typename K , typename Less > | |
guarded_ptr | extract_with (K const &key, Less pred) |
Extracts the item from the map with comparing functor pred . More... | |
guarded_ptr | extract_min () |
Extracts an item with minimal key from the map. More... | |
guarded_ptr | extract_max () |
Extracts an item with maximal key from the map. More... | |
template<typename K , typename Func > | |
bool | find (K const &key, Func f) |
Find the key key . More... | |
template<typename K , typename Less , typename Func > | |
bool | find_with (K const &key, Less pred, Func f) |
Finds the key val using pred predicate for searching. More... | |
template<typename K > | |
bool | contains (K const &key) |
Checks whether the map contains key . More... | |
template<typename K , typename Less > | |
bool | contains (K const &key, Less pred) |
Checks whether the set contains key using pred predicate for searching. More... | |
template<typename K > | |
guarded_ptr | get (K const &key) |
Finds the key key and return the item found. More... | |
template<typename K , typename Less > | |
guarded_ptr | get_with (K const &key, Less pred) |
Finds the key key and return the item found. More... | |
void | clear () |
Clears the map. | |
bool | empty () const |
Checks if the map is empty. | |
size_t | size () const |
Returns item count in the map. | |
stat const & | statistics () const |
Returns const reference to internal statistics. | |
Static Public Attributes | |
static size_t const | c_nHazardPtrCount = base_class::c_nHazardPtrCount |
Count of hazard pointer required for the skip-list. | |
Forward iterators (only for debugging purpose) | |
typedef skip_list::details::iterator< typename base_class::iterator > | iterator |
Iterator type. More... | |
typedef skip_list::details::iterator< typename base_class::const_iterator > | const_iterator |
Const forward iterator type. | |
iterator | begin () |
Returns a forward iterator addressing the first element in a map. | |
const_iterator | begin () const |
Returns a forward const iterator addressing the first element in a map. | |
const_iterator | cbegin () const |
Returns a forward const iterator addressing the first element in a map. | |
iterator | end () |
Returns a forward iterator that addresses the location succeeding the last element in a map. | |
const_iterator | end () const |
Returns a forward const iterator that addresses the location succeeding the last element in a map. | |
const_iterator | cend () const |
Returns a forward const iterator that addresses the location succeeding the last element in a map. | |
Additional Inherited Members | |
Protected Types inherited from cds::intrusive::SkipListSet< GC, std::pair< Key const, T >, Traits > | |
typedef node_type::atomic_marked_ptr | atomic_node_ptr |
Atomic marked node pointer. | |
typedef node_type::marked_ptr | marked_node_ptr |
Node marked pointer. | |
typedef GC | gc |
Garbage collector. | |
typedef std::pair< Key const, T > | value_type |
type of value stored in the skip-list | |
typedef Traits | traits |
Traits template parameter. | |
typedef traits::hook | hook |
hook type | |
typedef hook::node_type | node_type |
node type | |
typedef implementation_defined | key_comparator |
key comparison functor based on opt::compare and opt::less option setter. | |
typedef traits::disposer | disposer |
item disposer | |
typedef get_node_traits< value_type, node_type, hook >::type | node_traits |
node traits | |
typedef traits::item_counter | item_counter |
Item counting policy. | |
typedef traits::memory_model | memory_model |
Memory ordering, see cds::opt::memory_model option. | |
typedef traits::random_level_generator | random_level_generator |
random level generator | |
typedef traits::allocator | allocator_type |
allocator for maintaining array of next pointers of the node | |
typedef traits::back_off | back_off |
Back-off strategy. | |
typedef traits::stat | stat |
internal statistics type | |
typedef gc::template guarded_ptr< value_type > | guarded_ptr |
Guarded pointer. | |
typedef skip_list::details::iterator< gc, node_traits, back_off, false > | iterator |
Iterator type. More... | |
typedef skip_list::details::iterator< gc, node_traits, back_off, true > | const_iterator |
Const iterator type. | |
Protected Member Functions inherited from cds::intrusive::SkipListSet< GC, std::pair< Key const, T >, Traits > | |
SkipListSet () | |
Default constructor. More... | |
~SkipListSet () | |
Clears and destructs the skip-list. | |
bool | insert (value_type &val) |
Inserts new node. More... | |
bool | insert (value_type &val, Func f) |
Inserts new node. More... | |
std::pair< bool, bool > | update (value_type &val, Func func, bool bInsert=true) |
Updates the node. More... | |
bool | unlink (value_type &val) |
Unlinks the item val from the set. More... | |
guarded_ptr | extract (Q const &key) |
Extracts the item from the set with specified key . More... | |
guarded_ptr | extract_with (Q const &key, Less pred) |
Extracts the item from the set with comparing functor pred . More... | |
guarded_ptr | extract_min () |
Extracts an item with minimal key from the list. More... | |
guarded_ptr | extract_max () |
Extracts an item with maximal key from the list. More... | |
bool | erase (Q const &key) |
Deletes the item from the set. More... | |
bool | erase (Q const &key, Func f) |
Deletes the item from the set. More... | |
bool | erase_with (Q const &key, Less pred) |
Deletes the item from the set with comparing functor pred . More... | |
bool | erase_with (Q const &key, Less pred, Func f) |
Deletes the item from the set with comparing functor pred . More... | |
bool | find (Q &key, Func f) |
Finds key . More... | |
bool | find_with (Q &key, Less pred, Func f) |
Finds the key key with pred predicate for comparing. More... | |
bool | contains (Q const &key) |
Checks whether the set contains key . More... | |
bool | contains (Q const &key, Less pred) |
Checks whether the set contains key using pred predicate for searching. More... | |
guarded_ptr | get (Q const &key) |
Finds key and return the item found. More... | |
guarded_ptr | get_with (Q const &key, Less pred) |
Finds key and return the item found. More... | |
size_t | size () const |
Returns item count in the set. More... | |
bool | empty () const |
Checks if the set is empty. | |
void | clear () |
Clears the set (not atomic) More... | |
stat const & | statistics () const |
Returns const reference to internal statistics. | |
iterator | begin () |
Returns a forward iterator addressing the first element in a set. | |
const_iterator | begin () const |
Returns a forward const iterator addressing the first element in a set. | |
const_iterator | cbegin () const |
Returns a forward const iterator addressing the first element in a set. | |
iterator | end () |
Returns a forward iterator that addresses the location succeeding the last element in a set. | |
const_iterator | end () const |
Returns a forward const iterator that addresses the location succeeding the last element in a set. | |
const_iterator | cend () const |
Returns a forward const iterator that addresses the location succeeding the last element in a set. | |
Static Protected Member Functions inherited from cds::intrusive::SkipListSet< GC, std::pair< Key const, T >, Traits > | |
static constexpr unsigned int | max_height () noexcept |
Returns maximum height of skip-list. The max height is a constant for each object and does not exceed 32. | |
Static Protected Attributes inherited from cds::intrusive::SkipListSet< GC, std::pair< Key const, T >, Traits > | |
static unsigned int const | c_nMaxHeight |
Max node height. The actual node height should be in range [0 .. c_nMaxHeight) More... | |
static size_t const | c_nHazardPtrCount |
Count of hazard pointer required for the skip-list. | |
Lock-free skip-list map.
The implementation of well-known probabilistic data structure called skip-list invented by W.Pugh in his papers:
A skip-list is a probabilistic data structure that provides expected logarithmic time search without the need of rebalance. The skip-list is a collection of sorted linked list. Nodes are ordered by key. Each node is linked into a subset of the lists. Each list has a level, ranging from 0 to 32. The bottom-level list contains all the nodes, and each higher-level list is a sublist of the lower-level lists. Each node is created with a random top level (with a random height), and belongs to all lists up to that level. The probability that a node has the height 1 is 1/2. The probability that a node has the height N is 1/2 ** N (more precisely, the distribution depends on an random generator provided, but our generators have this property).
The lock-free variant of skip-list is implemented according to book
Template arguments:
GC
- Garbage collector used.K
- type of a key to be stored in the list.T
- type of a value to be stored in the list.Traits
- map traits, default is skip_list::traits
It is possible to declare option-based list with cds::container::skip_list::make_traits
metafunction istead of Traits
template argument.Like STL map class, SkipListMap
stores the key-value pair as std:pair< K const, T>
.
gc::HP
). Those GCs should be explicitly initialized with hazard pointer enough:SkipListMap
for each GC
. You should include:<cds/container/skip_list_map_hp.h>
for gc::HP
garbage collector<cds/container/skip_list_map_dhp.h>
for gc::DHP
garbage collector<cds/container/skip_list_map_rcu.h>
for RCU type<cds/container/skip_list_map_nogc.h>
for non-deletable SkipListMap typedef skip_list::details::iterator< typename base_class::iterator > cds::container::SkipListMap< GC, Key, T, Traits >::iterator |
Iterator type.
The forward iterator has some features:
gc::HP
), a guard is a limited resource per thread, so an exception (or assertion) "no free guard" may be thrown if the limit of guard count per thread is exceeded.The iterator interface:
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Checks whether the map contains key
.
The function searches the item with key equal to key
and returns true
if it is found, and false
otherwise.
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Checks whether the set contains key
using pred
predicate for searching.
The function is similar to contains( key )
but pred
is used for key comparing. Less
functor has the interface like std::less
. Less
must imply the same element order as the comparator used for building the set.
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For key key
inserts data of type value_type
created in-place from std::forward<Args>(args)...
Returns true
if inserting successful, false
otherwise.
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Deletes the item from the map using pred
predicate for searching.
The function is an analog of erase(K const&) but pred
is used for key comparing. Less
functor has the interface like std::less
. Less
must imply the same element order as the comparator used for building the map.
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Deletes the item from the map using pred
predicate for searching.
The function is an analog of erase(K const&, Func) but pred
is used for key comparing. Less
functor has the interface like std::less
. Less
must imply the same element order as the comparator used for building the map.
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Extracts the item from the map with specified key
.
The function searches an item with key equal to key
in the map, unlinks it from the map, and returns a guarded pointer to the item found. If key
is not found the function returns an empty guarded pointer.
Note the compare functor should accept a parameter of type K
that can be not the same as key_type
.
The item extracted is freed automatically by garbage collector GC
when returned guarded_ptr
object will be destroyed or released.
guarded_ptr
object uses the GC's guard that can be limited resource.Usage:
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Extracts an item with maximal key from the map.
The function searches an item with maximal key, unlinks it, and returns a guarded pointer to item found. If the skip-list is empty the function returns an empty guarded_ptr
.
The item found is freed by garbage collector GC
automatically when returned guarded_ptr
object will be destroyed or released.
guarded_ptr
object uses the GC's guard that can be limited resource.Usage:
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Extracts an item with minimal key from the map.
The function searches an item with minimal key, unlinks it, and returns an guarded pointer to the item found. If the skip-list is empty the function returns an empty guarded pointer.
The item extracted is freed automatically by garbage collector GC
when returned guarded_ptr
object will be destroyed or released.
guarded_ptr
object uses the GC's guard that can be limited resource.Usage:
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Extracts the item from the map with comparing functor pred
.
The function is an analog of extract(K const&) but pred
predicate is used for key comparing.
Less
functor has the semantics like std::less
but should take arguments of type key_type and K
in any order. pred
must imply the same element order as the comparator used for building the map.
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Finds the key val
using pred
predicate for searching.
The function is an analog of find(K const&, Func) but pred
is used for key comparing. Less
functor has the interface like std::less
. Less
must imply the same element order as the comparator used for building the map.
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Finds the key key
and return the item found.
The function searches the item with key equal to key
and returns a guarded pointer to the item found. If key
is not found the function returns an empty guarded pointer.
It is safe when a concurrent thread erases the item returned as guarded_ptr
. In this case the item will be freed later by garbage collector GC
automatically when guarded_ptr
object will be destroyed or released.
guarded_ptr
object uses one GC's guard which can be limited resource.Usage:
Note the compare functor specified for class Traits
template parameter should accept a parameter of type K
that can be not the same as value_type
.
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Finds the key key
and return the item found.
The function is an analog of get( K const&) but pred
is used for comparing the keys.
Less
functor has the semantics like std::less
but should take arguments of type key_type and K
in any order. pred
must imply the same element order as the comparator used for building the map.
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Inserts new node with key and default value.
The function creates a node with key
and default value, and then inserts the node created into the map.
Preconditions:
key_type
should be constructible from a value of type K
. In trivial case, K
is equal to key_type
.mapped_type
should be default-constructible.Returns true
if inserting successful, false
otherwise.
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Inserts new node.
The function creates a node with copy of val
value and then inserts the node created into the map.
Preconditions:
key_type
should be constructible from key
of type K
.value_type
should be constructible from val
of type V
.Returns true
if val
is inserted into the set, false
otherwise.
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Inserts new node and initialize it by a functor.
This function inserts new node with key key
and if inserting is successful then it calls func
functor with signature
The argument item
of user-defined functor func
is the reference to the map's item inserted:
item.first
is a const reference to item's key that cannot be changed.item.second
is a reference to item's value that may be changed.key_type
should be constructible from value of type K
.
The function allows to split creating of new item into two part:
key
;func
functorThis can be useful if complete initialization of object of value_type
is heavyweight and it is preferable that the initialization should be completed only if inserting is successful.
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Updates data by key
.
The operation performs inserting or changing data with lock-free manner.
If the key
not found in the map, then the new item created from key
will be inserted into the map iff bInsert
is true
(note that in this case the key_type should be constructible from type K
). Otherwise, if key
is found, the functor func
is called with item found. The functor Func
signature:
where:
bNew
- true
if the item has been inserted, false
otherwiseitem
- item of the mapThe functor may change any fields of the item.second
that is value_type.
Returns std::pair<bool, bool>
where first
is true
if operation is successful, second
is true
if new item has been added or false
if key
already exists.