// Copyright (c) 2005, Google Inc.
|
// 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.
|
// * Neither the name of Google Inc. nor the names of its
|
// contributors may 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.
|
|
// ---
|
//
|
// A sparse hashtable is a particular implementation of
|
// a hashtable: one that is meant to minimize memory use.
|
// It does this by using a *sparse table* (cf sparsetable.h),
|
// which uses between 1 and 2 bits to store empty buckets
|
// (we may need another bit for hashtables that support deletion).
|
//
|
// When empty buckets are so cheap, an appealing hashtable
|
// implementation is internal probing, in which the hashtable
|
// is a single table, and collisions are resolved by trying
|
// to insert again in another bucket. The most cache-efficient
|
// internal probing schemes are linear probing (which suffers,
|
// alas, from clumping) and quadratic probing, which is what
|
// we implement by default.
|
//
|
// Deleted buckets are a bit of a pain. We have to somehow mark
|
// deleted buckets (the probing must distinguish them from empty
|
// buckets). The most principled way is to have another bitmap,
|
// but that's annoying and takes up space. Instead we let the
|
// user specify an "impossible" key. We set deleted buckets
|
// to have the impossible key.
|
//
|
// Note it is possible to change the value of the delete key
|
// on the fly; you can even remove it, though after that point
|
// the hashtable is insert_only until you set it again.
|
//
|
// You probably shouldn't use this code directly. Use
|
// sparse_hash_map<> or sparse_hash_set<> instead.
|
//
|
// You can modify the following, below:
|
// HT_OCCUPANCY_PCT -- how full before we double size
|
// HT_EMPTY_PCT -- how empty before we halve size
|
// HT_MIN_BUCKETS -- smallest bucket size
|
// HT_DEFAULT_STARTING_BUCKETS -- default bucket size at construct-time
|
//
|
// You can also change enlarge_factor (which defaults to
|
// HT_OCCUPANCY_PCT), and shrink_factor (which defaults to
|
// HT_EMPTY_PCT) with set_resizing_parameters().
|
//
|
// How to decide what values to use?
|
// shrink_factor's default of .4 * OCCUPANCY_PCT, is probably good.
|
// HT_MIN_BUCKETS is probably unnecessary since you can specify
|
// (indirectly) the starting number of buckets at construct-time.
|
// For enlarge_factor, you can use this chart to try to trade-off
|
// expected lookup time to the space taken up. By default, this
|
// code uses quadratic probing, though you can change it to linear
|
// via _JUMP below if you really want to.
|
//
|
// From http://www.augustana.ca/~mohrj/courses/1999.fall/csc210/lecture_notes/hashing.html
|
// NUMBER OF PROBES / LOOKUP Successful Unsuccessful
|
// Quadratic collision resolution 1 - ln(1-L) - L/2 1/(1-L) - L - ln(1-L)
|
// Linear collision resolution [1+1/(1-L)]/2 [1+1/(1-L)2]/2
|
//
|
// -- enlarge_factor -- 0.10 0.50 0.60 0.75 0.80 0.90 0.99
|
// QUADRATIC COLLISION RES.
|
// probes/successful lookup 1.05 1.44 1.62 2.01 2.21 2.85 5.11
|
// probes/unsuccessful lookup 1.11 2.19 2.82 4.64 5.81 11.4 103.6
|
// LINEAR COLLISION RES.
|
// probes/successful lookup 1.06 1.5 1.75 2.5 3.0 5.5 50.5
|
// probes/unsuccessful lookup 1.12 2.5 3.6 8.5 13.0 50.0 5000.0
|
//
|
// The value type is required to be copy constructible and default
|
// constructible, but it need not be (and commonly isn't) assignable.
|
|
#ifndef _SPARSEHASHTABLE_H_
|
#define _SPARSEHASHTABLE_H_
|
|
#include "sparseconfig.h"
|
#include <assert.h>
|
#include <algorithm> // For swap(), eg
|
#include <iterator> // for iterator tags
|
#include <limits> // for numeric_limits
|
#include <utility> // for pair
|
#include "../type_traits.h" // for remove_const
|
#include "hashtable-common.h"
|
#include "../sparsetable.h" // IWYU pragma: export
|
#include <stdexcept> // For length_error
|
|
_START_GOOGLE_NAMESPACE_
|
|
namespace base { // just to make google->opensource transition easier
|
using GOOGLE_NAMESPACE::remove_const;
|
}
|
|
#ifndef SPARSEHASH_STAT_UPDATE
|
#define SPARSEHASH_STAT_UPDATE(x) ((void) 0)
|
#endif
|
|
// The probing method
|
// Linear probing
|
// #define JUMP_(key, num_probes) ( 1 )
|
// Quadratic probing
|
#define JUMP_(key, num_probes) ( num_probes )
|
|
// The smaller this is, the faster lookup is (because the group bitmap is
|
// smaller) and the faster insert is, because there's less to move.
|
// On the other hand, there are more groups. Since group::size_type is
|
// a short, this number should be of the form 32*x + 16 to avoid waste.
|
static const u_int16_t DEFAULT_GROUP_SIZE = 48; // fits in 1.5 words
|
|
// Hashtable class, used to implement the hashed associative containers
|
// hash_set and hash_map.
|
//
|
// Value: what is stored in the table (each bucket is a Value).
|
// Key: something in a 1-to-1 correspondence to a Value, that can be used
|
// to search for a Value in the table (find() takes a Key).
|
// HashFcn: Takes a Key and returns an integer, the more unique the better.
|
// ExtractKey: given a Value, returns the unique Key associated with it.
|
// Must inherit from unary_function, or at least have a
|
// result_type enum indicating the return type of operator().
|
// SetKey: given a Value* and a Key, modifies the value such that
|
// ExtractKey(value) == key. We guarantee this is only called
|
// with key == deleted_key.
|
// EqualKey: Given two Keys, says whether they are the same (that is,
|
// if they are both associated with the same Value).
|
// Alloc: STL allocator to use to allocate memory.
|
|
template <class Value, class Key, class HashFcn,
|
class ExtractKey, class SetKey, class EqualKey, class Alloc>
|
class sparse_hashtable;
|
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
struct sparse_hashtable_iterator;
|
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
struct sparse_hashtable_const_iterator;
|
|
// As far as iterating, we're basically just a sparsetable
|
// that skips over deleted elements.
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
struct sparse_hashtable_iterator {
|
private:
|
typedef typename A::template rebind<V>::other value_alloc_type;
|
|
public:
|
typedef sparse_hashtable_iterator<V,K,HF,ExK,SetK,EqK,A> iterator;
|
typedef sparse_hashtable_const_iterator<V,K,HF,ExK,SetK,EqK,A> const_iterator;
|
typedef typename sparsetable<V,DEFAULT_GROUP_SIZE,value_alloc_type>::nonempty_iterator
|
st_iterator;
|
|
typedef std::forward_iterator_tag iterator_category; // very little defined!
|
typedef V value_type;
|
typedef typename value_alloc_type::difference_type difference_type;
|
typedef typename value_alloc_type::size_type size_type;
|
typedef typename value_alloc_type::reference reference;
|
typedef typename value_alloc_type::pointer pointer;
|
|
// "Real" constructor and default constructor
|
sparse_hashtable_iterator(const sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> *h,
|
st_iterator it, st_iterator it_end)
|
: ht(h), pos(it), end(it_end) { advance_past_deleted(); }
|
sparse_hashtable_iterator() { } // not ever used internally
|
// The default destructor is fine; we don't define one
|
// The default operator= is fine; we don't define one
|
|
// Happy dereferencer
|
reference operator*() const { return *pos; }
|
pointer operator->() const { return &(operator*()); }
|
|
// Arithmetic. The only hard part is making sure that
|
// we're not on a marked-deleted array element
|
void advance_past_deleted() {
|
while ( pos != end && ht->test_deleted(*this) )
|
++pos;
|
}
|
iterator& operator++() {
|
assert(pos != end); ++pos; advance_past_deleted(); return *this;
|
}
|
iterator operator++(int) { iterator tmp(*this); ++*this; return tmp; }
|
|
// Comparison.
|
bool operator==(const iterator& it) const { return pos == it.pos; }
|
bool operator!=(const iterator& it) const { return pos != it.pos; }
|
|
|
// The actual data
|
const sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> *ht;
|
st_iterator pos, end;
|
};
|
|
// Now do it all again, but with const-ness!
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
struct sparse_hashtable_const_iterator {
|
private:
|
typedef typename A::template rebind<V>::other value_alloc_type;
|
|
public:
|
typedef sparse_hashtable_iterator<V,K,HF,ExK,SetK,EqK,A> iterator;
|
typedef sparse_hashtable_const_iterator<V,K,HF,ExK,SetK,EqK,A> const_iterator;
|
typedef typename sparsetable<V,DEFAULT_GROUP_SIZE,value_alloc_type>::const_nonempty_iterator
|
st_iterator;
|
|
typedef std::forward_iterator_tag iterator_category; // very little defined!
|
typedef V value_type;
|
typedef typename value_alloc_type::difference_type difference_type;
|
typedef typename value_alloc_type::size_type size_type;
|
typedef typename value_alloc_type::const_reference reference;
|
typedef typename value_alloc_type::const_pointer pointer;
|
|
// "Real" constructor and default constructor
|
sparse_hashtable_const_iterator(const sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> *h,
|
st_iterator it, st_iterator it_end)
|
: ht(h), pos(it), end(it_end) { advance_past_deleted(); }
|
// This lets us convert regular iterators to const iterators
|
sparse_hashtable_const_iterator() { } // never used internally
|
sparse_hashtable_const_iterator(const iterator &it)
|
: ht(it.ht), pos(it.pos), end(it.end) { }
|
// The default destructor is fine; we don't define one
|
// The default operator= is fine; we don't define one
|
|
// Happy dereferencer
|
reference operator*() const { return *pos; }
|
pointer operator->() const { return &(operator*()); }
|
|
// Arithmetic. The only hard part is making sure that
|
// we're not on a marked-deleted array element
|
void advance_past_deleted() {
|
while ( pos != end && ht->test_deleted(*this) )
|
++pos;
|
}
|
const_iterator& operator++() {
|
assert(pos != end); ++pos; advance_past_deleted(); return *this;
|
}
|
const_iterator operator++(int) { const_iterator tmp(*this); ++*this; return tmp; }
|
|
// Comparison.
|
bool operator==(const const_iterator& it) const { return pos == it.pos; }
|
bool operator!=(const const_iterator& it) const { return pos != it.pos; }
|
|
|
// The actual data
|
const sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> *ht;
|
st_iterator pos, end;
|
};
|
|
// And once again, but this time freeing up memory as we iterate
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
struct sparse_hashtable_destructive_iterator {
|
private:
|
typedef typename A::template rebind<V>::other value_alloc_type;
|
|
public:
|
typedef sparse_hashtable_destructive_iterator<V,K,HF,ExK,SetK,EqK,A> iterator;
|
typedef typename sparsetable<V,DEFAULT_GROUP_SIZE,value_alloc_type>::destructive_iterator
|
st_iterator;
|
|
typedef std::forward_iterator_tag iterator_category; // very little defined!
|
typedef V value_type;
|
typedef typename value_alloc_type::difference_type difference_type;
|
typedef typename value_alloc_type::size_type size_type;
|
typedef typename value_alloc_type::reference reference;
|
typedef typename value_alloc_type::pointer pointer;
|
|
// "Real" constructor and default constructor
|
sparse_hashtable_destructive_iterator(const
|
sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> *h,
|
st_iterator it, st_iterator it_end)
|
: ht(h), pos(it), end(it_end) { advance_past_deleted(); }
|
sparse_hashtable_destructive_iterator() { } // never used internally
|
// The default destructor is fine; we don't define one
|
// The default operator= is fine; we don't define one
|
|
// Happy dereferencer
|
reference operator*() const { return *pos; }
|
pointer operator->() const { return &(operator*()); }
|
|
// Arithmetic. The only hard part is making sure that
|
// we're not on a marked-deleted array element
|
void advance_past_deleted() {
|
while ( pos != end && ht->test_deleted(*this) )
|
++pos;
|
}
|
iterator& operator++() {
|
assert(pos != end); ++pos; advance_past_deleted(); return *this;
|
}
|
iterator operator++(int) { iterator tmp(*this); ++*this; return tmp; }
|
|
// Comparison.
|
bool operator==(const iterator& it) const { return pos == it.pos; }
|
bool operator!=(const iterator& it) const { return pos != it.pos; }
|
|
|
// The actual data
|
const sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> *ht;
|
st_iterator pos, end;
|
};
|
|
|
template <class Value, class Key, class HashFcn,
|
class ExtractKey, class SetKey, class EqualKey, class Alloc>
|
class sparse_hashtable {
|
private:
|
typedef typename Alloc::template rebind<Value>::other value_alloc_type;
|
|
public:
|
typedef Key key_type;
|
typedef Value value_type;
|
typedef HashFcn hasher;
|
typedef EqualKey key_equal;
|
typedef Alloc allocator_type;
|
|
typedef typename value_alloc_type::size_type size_type;
|
typedef typename value_alloc_type::difference_type difference_type;
|
typedef typename value_alloc_type::reference reference;
|
typedef typename value_alloc_type::const_reference const_reference;
|
typedef typename value_alloc_type::pointer pointer;
|
typedef typename value_alloc_type::const_pointer const_pointer;
|
typedef sparse_hashtable_iterator<Value, Key, HashFcn, ExtractKey,
|
SetKey, EqualKey, Alloc>
|
iterator;
|
|
typedef sparse_hashtable_const_iterator<Value, Key, HashFcn, ExtractKey,
|
SetKey, EqualKey, Alloc>
|
const_iterator;
|
|
typedef sparse_hashtable_destructive_iterator<Value, Key, HashFcn, ExtractKey,
|
SetKey, EqualKey, Alloc>
|
destructive_iterator;
|
|
// These come from tr1. For us they're the same as regular iterators.
|
typedef iterator local_iterator;
|
typedef const_iterator const_local_iterator;
|
|
// How full we let the table get before we resize, by default.
|
// Knuth says .8 is good -- higher causes us to probe too much,
|
// though it saves memory.
|
static const int HT_OCCUPANCY_PCT; // = 80 (out of 100);
|
|
// How empty we let the table get before we resize lower, by default.
|
// (0.0 means never resize lower.)
|
// It should be less than OCCUPANCY_PCT / 2 or we thrash resizing
|
static const int HT_EMPTY_PCT; // = 0.4 * HT_OCCUPANCY_PCT;
|
|
// Minimum size we're willing to let hashtables be.
|
// Must be a power of two, and at least 4.
|
// Note, however, that for a given hashtable, the initial size is a
|
// function of the first constructor arg, and may be >HT_MIN_BUCKETS.
|
static const size_type HT_MIN_BUCKETS = 4;
|
|
// By default, if you don't specify a hashtable size at
|
// construction-time, we use this size. Must be a power of two, and
|
// at least HT_MIN_BUCKETS.
|
static const size_type HT_DEFAULT_STARTING_BUCKETS = 32;
|
|
// ITERATOR FUNCTIONS
|
iterator begin() { return iterator(this, table.nonempty_begin(),
|
table.nonempty_end()); }
|
iterator end() { return iterator(this, table.nonempty_end(),
|
table.nonempty_end()); }
|
const_iterator begin() const { return const_iterator(this,
|
table.nonempty_begin(),
|
table.nonempty_end()); }
|
const_iterator end() const { return const_iterator(this,
|
table.nonempty_end(),
|
table.nonempty_end()); }
|
|
// These come from tr1 unordered_map. They iterate over 'bucket' n.
|
// For sparsehashtable, we could consider each 'group' to be a bucket,
|
// I guess, but I don't really see the point. We'll just consider
|
// bucket n to be the n-th element of the sparsetable, if it's occupied,
|
// or some empty element, otherwise.
|
local_iterator begin(size_type i) {
|
if (table.test(i))
|
return local_iterator(this, table.get_iter(i), table.nonempty_end());
|
else
|
return local_iterator(this, table.nonempty_end(), table.nonempty_end());
|
}
|
local_iterator end(size_type i) {
|
local_iterator it = begin(i);
|
if (table.test(i) && !test_deleted(i))
|
++it;
|
return it;
|
}
|
const_local_iterator begin(size_type i) const {
|
if (table.test(i))
|
return const_local_iterator(this, table.get_iter(i),
|
table.nonempty_end());
|
else
|
return const_local_iterator(this, table.nonempty_end(),
|
table.nonempty_end());
|
}
|
const_local_iterator end(size_type i) const {
|
const_local_iterator it = begin(i);
|
if (table.test(i) && !test_deleted(i))
|
++it;
|
return it;
|
}
|
|
// This is used when resizing
|
destructive_iterator destructive_begin() {
|
return destructive_iterator(this, table.destructive_begin(),
|
table.destructive_end());
|
}
|
destructive_iterator destructive_end() {
|
return destructive_iterator(this, table.destructive_end(),
|
table.destructive_end());
|
}
|
|
|
// ACCESSOR FUNCTIONS for the things we templatize on, basically
|
hasher hash_funct() const { return settings; }
|
key_equal key_eq() const { return key_info; }
|
allocator_type get_allocator() const { return table.get_allocator(); }
|
|
// Accessor function for statistics gathering.
|
int num_table_copies() const { return settings.num_ht_copies(); }
|
|
private:
|
// We need to copy values when we set the special marker for deleted
|
// elements, but, annoyingly, we can't just use the copy assignment
|
// operator because value_type might not be assignable (it's often
|
// pair<const X, Y>). We use explicit destructor invocation and
|
// placement new to get around this. Arg.
|
void set_value(pointer dst, const_reference src) {
|
dst->~value_type(); // delete the old value, if any
|
new(dst) value_type(src);
|
}
|
|
// This is used as a tag for the copy constructor, saying to destroy its
|
// arg We have two ways of destructively copying: with potentially growing
|
// the hashtable as we copy, and without. To make sure the outside world
|
// can't do a destructive copy, we make the typename private.
|
enum MoveDontCopyT {MoveDontCopy, MoveDontGrow};
|
|
// DELETE HELPER FUNCTIONS
|
// This lets the user describe a key that will indicate deleted
|
// table entries. This key should be an "impossible" entry --
|
// if you try to insert it for real, you won't be able to retrieve it!
|
// (NB: while you pass in an entire value, only the key part is looked
|
// at. This is just because I don't know how to assign just a key.)
|
private:
|
void squash_deleted() { // gets rid of any deleted entries we have
|
if ( num_deleted ) { // get rid of deleted before writing
|
sparse_hashtable tmp(MoveDontGrow, *this);
|
swap(tmp); // now we are tmp
|
}
|
assert(num_deleted == 0);
|
}
|
|
// Test if the given key is the deleted indicator. Requires
|
// num_deleted > 0, for correctness of read(), and because that
|
// guarantees that key_info.delkey is valid.
|
bool test_deleted_key(const key_type& key) const {
|
assert(num_deleted > 0);
|
return equals(key_info.delkey, key);
|
}
|
|
public:
|
void set_deleted_key(const key_type &key) {
|
// It's only safe to change what "deleted" means if we purge deleted guys
|
squash_deleted();
|
settings.set_use_deleted(true);
|
key_info.delkey = key;
|
}
|
void clear_deleted_key() {
|
squash_deleted();
|
settings.set_use_deleted(false);
|
}
|
key_type deleted_key() const {
|
assert(settings.use_deleted()
|
&& "Must set deleted key before calling deleted_key");
|
return key_info.delkey;
|
}
|
|
// These are public so the iterators can use them
|
// True if the item at position bucknum is "deleted" marker
|
bool test_deleted(size_type bucknum) const {
|
// Invariant: !use_deleted() implies num_deleted is 0.
|
assert(settings.use_deleted() || num_deleted == 0);
|
return num_deleted > 0 && table.test(bucknum) &&
|
test_deleted_key(get_key(table.unsafe_get(bucknum)));
|
}
|
bool test_deleted(const iterator &it) const {
|
// Invariant: !use_deleted() implies num_deleted is 0.
|
assert(settings.use_deleted() || num_deleted == 0);
|
return num_deleted > 0 && test_deleted_key(get_key(*it));
|
}
|
bool test_deleted(const const_iterator &it) const {
|
// Invariant: !use_deleted() implies num_deleted is 0.
|
assert(settings.use_deleted() || num_deleted == 0);
|
return num_deleted > 0 && test_deleted_key(get_key(*it));
|
}
|
bool test_deleted(const destructive_iterator &it) const {
|
// Invariant: !use_deleted() implies num_deleted is 0.
|
assert(settings.use_deleted() || num_deleted == 0);
|
return num_deleted > 0 && test_deleted_key(get_key(*it));
|
}
|
|
private:
|
void check_use_deleted(const char* caller) {
|
(void)caller; // could log it if the assert failed
|
assert(settings.use_deleted());
|
}
|
|
// Set it so test_deleted is true. true if object didn't used to be deleted.
|
// TODO(csilvers): make these private (also in densehashtable.h)
|
bool set_deleted(iterator &it) {
|
check_use_deleted("set_deleted()");
|
bool retval = !test_deleted(it);
|
// &* converts from iterator to value-type.
|
set_key(&(*it), key_info.delkey);
|
return retval;
|
}
|
// Set it so test_deleted is false. true if object used to be deleted.
|
bool clear_deleted(iterator &it) {
|
check_use_deleted("clear_deleted()");
|
// Happens automatically when we assign something else in its place.
|
return test_deleted(it);
|
}
|
|
// We also allow to set/clear the deleted bit on a const iterator.
|
// We allow a const_iterator for the same reason you can delete a
|
// const pointer: it's convenient, and semantically you can't use
|
// 'it' after it's been deleted anyway, so its const-ness doesn't
|
// really matter.
|
bool set_deleted(const_iterator &it) {
|
check_use_deleted("set_deleted()");
|
bool retval = !test_deleted(it);
|
set_key(const_cast<pointer>(&(*it)), key_info.delkey);
|
return retval;
|
}
|
// Set it so test_deleted is false. true if object used to be deleted.
|
bool clear_deleted(const_iterator &it) {
|
check_use_deleted("clear_deleted()");
|
return test_deleted(it);
|
}
|
|
// FUNCTIONS CONCERNING SIZE
|
public:
|
size_type size() const { return table.num_nonempty() - num_deleted; }
|
size_type max_size() const { return table.max_size(); }
|
bool empty() const { return size() == 0; }
|
size_type bucket_count() const { return table.size(); }
|
size_type max_bucket_count() const { return max_size(); }
|
// These are tr1 methods. Their idea of 'bucket' doesn't map well to
|
// what we do. We just say every bucket has 0 or 1 items in it.
|
size_type bucket_size(size_type i) const {
|
return begin(i) == end(i) ? 0 : 1;
|
}
|
|
private:
|
// Because of the above, size_type(-1) is never legal; use it for errors
|
static const size_type ILLEGAL_BUCKET = size_type(-1);
|
|
// Used after a string of deletes. Returns true if we actually shrunk.
|
// TODO(csilvers): take a delta so we can take into account inserts
|
// done after shrinking. Maybe make part of the Settings class?
|
bool maybe_shrink() {
|
assert(table.num_nonempty() >= num_deleted);
|
assert((bucket_count() & (bucket_count()-1)) == 0); // is a power of two
|
assert(bucket_count() >= HT_MIN_BUCKETS);
|
bool retval = false;
|
|
// If you construct a hashtable with < HT_DEFAULT_STARTING_BUCKETS,
|
// we'll never shrink until you get relatively big, and we'll never
|
// shrink below HT_DEFAULT_STARTING_BUCKETS. Otherwise, something
|
// like "dense_hash_set<int> x; x.insert(4); x.erase(4);" will
|
// shrink us down to HT_MIN_BUCKETS buckets, which is too small.
|
const size_type num_remain = table.num_nonempty() - num_deleted;
|
const size_type shrink_threshold = settings.shrink_threshold();
|
if (shrink_threshold > 0 && num_remain < shrink_threshold &&
|
bucket_count() > HT_DEFAULT_STARTING_BUCKETS) {
|
const float shrink_factor = settings.shrink_factor();
|
size_type sz = bucket_count() / 2; // find how much we should shrink
|
while (sz > HT_DEFAULT_STARTING_BUCKETS &&
|
num_remain < static_cast<size_type>(sz * shrink_factor)) {
|
sz /= 2; // stay a power of 2
|
}
|
sparse_hashtable tmp(MoveDontCopy, *this, sz);
|
swap(tmp); // now we are tmp
|
retval = true;
|
}
|
settings.set_consider_shrink(false); // because we just considered it
|
return retval;
|
}
|
|
// We'll let you resize a hashtable -- though this makes us copy all!
|
// When you resize, you say, "make it big enough for this many more elements"
|
// Returns true if we actually resized, false if size was already ok.
|
bool resize_delta(size_type delta) {
|
bool did_resize = false;
|
if ( settings.consider_shrink() ) { // see if lots of deletes happened
|
if ( maybe_shrink() )
|
did_resize = true;
|
}
|
if (table.num_nonempty() >=
|
(std::numeric_limits<size_type>::max)() - delta) {
|
assert(false && "resize overflow");
|
exit(-1);
|
}
|
if ( bucket_count() >= HT_MIN_BUCKETS &&
|
(table.num_nonempty() + delta) <= settings.enlarge_threshold() )
|
return did_resize; // we're ok as we are
|
|
// Sometimes, we need to resize just to get rid of all the
|
// "deleted" buckets that are clogging up the hashtable. So when
|
// deciding whether to resize, count the deleted buckets (which
|
// are currently taking up room). But later, when we decide what
|
// size to resize to, *don't* count deleted buckets, since they
|
// get discarded during the resize.
|
const size_type needed_size =
|
settings.min_buckets(table.num_nonempty() + delta, 0);
|
if ( needed_size <= bucket_count() ) // we have enough buckets
|
return did_resize;
|
|
size_type resize_to =
|
settings.min_buckets(table.num_nonempty() - num_deleted + delta,
|
bucket_count());
|
if (resize_to < needed_size && // may double resize_to
|
resize_to < (std::numeric_limits<size_type>::max)() / 2) {
|
// This situation means that we have enough deleted elements,
|
// that once we purge them, we won't actually have needed to
|
// grow. But we may want to grow anyway: if we just purge one
|
// element, say, we'll have to grow anyway next time we
|
// insert. Might as well grow now, since we're already going
|
// through the trouble of copying (in order to purge the
|
// deleted elements).
|
const size_type target =
|
static_cast<size_type>(settings.shrink_size(resize_to*2));
|
if (table.num_nonempty() - num_deleted + delta >= target) {
|
// Good, we won't be below the shrink threshhold even if we double.
|
resize_to *= 2;
|
}
|
}
|
|
sparse_hashtable tmp(MoveDontCopy, *this, resize_to);
|
swap(tmp); // now we are tmp
|
return true;
|
}
|
|
// Used to actually do the rehashing when we grow/shrink a hashtable
|
void copy_from(const sparse_hashtable &ht, size_type min_buckets_wanted) {
|
clear(); // clear table, set num_deleted to 0
|
|
// If we need to change the size of our table, do it now
|
const size_type resize_to =
|
settings.min_buckets(ht.size(), min_buckets_wanted);
|
if ( resize_to > bucket_count() ) { // we don't have enough buckets
|
table.resize(resize_to); // sets the number of buckets
|
settings.reset_thresholds(bucket_count());
|
}
|
|
// We use a normal iterator to get non-deleted bcks from ht
|
// We could use insert() here, but since we know there are
|
// no duplicates and no deleted items, we can be more efficient
|
assert((bucket_count() & (bucket_count()-1)) == 0); // a power of two
|
for ( const_iterator it = ht.begin(); it != ht.end(); ++it ) {
|
size_type num_probes = 0; // how many times we've probed
|
size_type bucknum;
|
const size_type bucket_count_minus_one = bucket_count() - 1;
|
for (bucknum = hash(get_key(*it)) & bucket_count_minus_one;
|
table.test(bucknum); // not empty
|
bucknum = (bucknum + JUMP_(key, num_probes)) & bucket_count_minus_one) {
|
++num_probes;
|
assert(num_probes < bucket_count()
|
&& "Hashtable is full: an error in key_equal<> or hash<>");
|
}
|
table.set(bucknum, *it); // copies the value to here
|
}
|
settings.inc_num_ht_copies();
|
}
|
|
// Implementation is like copy_from, but it destroys the table of the
|
// "from" guy by freeing sparsetable memory as we iterate. This is
|
// useful in resizing, since we're throwing away the "from" guy anyway.
|
void move_from(MoveDontCopyT mover, sparse_hashtable &ht,
|
size_type min_buckets_wanted) {
|
clear(); // clear table, set num_deleted to 0
|
|
// If we need to change the size of our table, do it now
|
size_type resize_to;
|
if ( mover == MoveDontGrow )
|
resize_to = ht.bucket_count(); // keep same size as old ht
|
else // MoveDontCopy
|
resize_to = settings.min_buckets(ht.size(), min_buckets_wanted);
|
if ( resize_to > bucket_count() ) { // we don't have enough buckets
|
table.resize(resize_to); // sets the number of buckets
|
settings.reset_thresholds(bucket_count());
|
}
|
|
// We use a normal iterator to get non-deleted bcks from ht
|
// We could use insert() here, but since we know there are
|
// no duplicates and no deleted items, we can be more efficient
|
assert( (bucket_count() & (bucket_count()-1)) == 0); // a power of two
|
// THIS IS THE MAJOR LINE THAT DIFFERS FROM COPY_FROM():
|
for ( destructive_iterator it = ht.destructive_begin();
|
it != ht.destructive_end(); ++it ) {
|
size_type num_probes = 0; // how many times we've probed
|
size_type bucknum;
|
for ( bucknum = hash(get_key(*it)) & (bucket_count()-1); // h % buck_cnt
|
table.test(bucknum); // not empty
|
bucknum = (bucknum + JUMP_(key, num_probes)) & (bucket_count()-1) ) {
|
++num_probes;
|
assert(num_probes < bucket_count()
|
&& "Hashtable is full: an error in key_equal<> or hash<>");
|
}
|
table.set(bucknum, *it); // copies the value to here
|
}
|
settings.inc_num_ht_copies();
|
}
|
|
|
// Required by the spec for hashed associative container
|
public:
|
// Though the docs say this should be num_buckets, I think it's much
|
// more useful as num_elements. As a special feature, calling with
|
// req_elements==0 will cause us to shrink if we can, saving space.
|
void resize(size_type req_elements) { // resize to this or larger
|
if ( settings.consider_shrink() || req_elements == 0 )
|
maybe_shrink();
|
if ( req_elements > table.num_nonempty() ) // we only grow
|
resize_delta(req_elements - table.num_nonempty());
|
}
|
|
// Get and change the value of shrink_factor and enlarge_factor. The
|
// description at the beginning of this file explains how to choose
|
// the values. Setting the shrink parameter to 0.0 ensures that the
|
// table never shrinks.
|
void get_resizing_parameters(float* shrink, float* grow) const {
|
*shrink = settings.shrink_factor();
|
*grow = settings.enlarge_factor();
|
}
|
void set_resizing_parameters(float shrink, float grow) {
|
settings.set_resizing_parameters(shrink, grow);
|
settings.reset_thresholds(bucket_count());
|
}
|
|
// CONSTRUCTORS -- as required by the specs, we take a size,
|
// but also let you specify a hashfunction, key comparator,
|
// and key extractor. We also define a copy constructor and =.
|
// DESTRUCTOR -- the default is fine, surprisingly.
|
explicit sparse_hashtable(size_type expected_max_items_in_table = 0,
|
const HashFcn& hf = HashFcn(),
|
const EqualKey& eql = EqualKey(),
|
const ExtractKey& ext = ExtractKey(),
|
const SetKey& set = SetKey(),
|
const Alloc& alloc = Alloc())
|
: settings(hf),
|
key_info(ext, set, eql),
|
num_deleted(0),
|
table((expected_max_items_in_table == 0
|
? HT_DEFAULT_STARTING_BUCKETS
|
: settings.min_buckets(expected_max_items_in_table, 0)),
|
alloc) {
|
settings.reset_thresholds(bucket_count());
|
}
|
|
// As a convenience for resize(), we allow an optional second argument
|
// which lets you make this new hashtable a different size than ht.
|
// We also provide a mechanism of saying you want to "move" the ht argument
|
// into us instead of copying.
|
sparse_hashtable(const sparse_hashtable& ht,
|
size_type min_buckets_wanted = HT_DEFAULT_STARTING_BUCKETS)
|
: settings(ht.settings),
|
key_info(ht.key_info),
|
num_deleted(0),
|
table(0, ht.get_allocator()) {
|
settings.reset_thresholds(bucket_count());
|
copy_from(ht, min_buckets_wanted); // copy_from() ignores deleted entries
|
}
|
sparse_hashtable(MoveDontCopyT mover, sparse_hashtable& ht,
|
size_type min_buckets_wanted = HT_DEFAULT_STARTING_BUCKETS)
|
: settings(ht.settings),
|
key_info(ht.key_info),
|
num_deleted(0),
|
table(0, ht.get_allocator()) {
|
settings.reset_thresholds(bucket_count());
|
move_from(mover, ht, min_buckets_wanted); // ignores deleted entries
|
}
|
|
sparse_hashtable& operator= (const sparse_hashtable& ht) {
|
if (&ht == this) return *this; // don't copy onto ourselves
|
settings = ht.settings;
|
key_info = ht.key_info;
|
num_deleted = ht.num_deleted;
|
// copy_from() calls clear and sets num_deleted to 0 too
|
copy_from(ht, HT_MIN_BUCKETS);
|
// we purposefully don't copy the allocator, which may not be copyable
|
return *this;
|
}
|
|
// Many STL algorithms use swap instead of copy constructors
|
void swap(sparse_hashtable& ht) {
|
std::swap(settings, ht.settings);
|
std::swap(key_info, ht.key_info);
|
std::swap(num_deleted, ht.num_deleted);
|
table.swap(ht.table);
|
settings.reset_thresholds(bucket_count()); // also resets consider_shrink
|
ht.settings.reset_thresholds(ht.bucket_count());
|
// we purposefully don't swap the allocator, which may not be swap-able
|
}
|
|
// It's always nice to be able to clear a table without deallocating it
|
void clear() {
|
if (!empty() || (num_deleted != 0)) {
|
table.clear();
|
}
|
settings.reset_thresholds(bucket_count());
|
num_deleted = 0;
|
}
|
|
// LOOKUP ROUTINES
|
private:
|
// Returns a pair of positions: 1st where the object is, 2nd where
|
// it would go if you wanted to insert it. 1st is ILLEGAL_BUCKET
|
// if object is not found; 2nd is ILLEGAL_BUCKET if it is.
|
// Note: because of deletions where-to-insert is not trivial: it's the
|
// first deleted bucket we see, as long as we don't find the key later
|
std::pair<size_type, size_type> find_position(const key_type &key) const {
|
size_type num_probes = 0; // how many times we've probed
|
const size_type bucket_count_minus_one = bucket_count() - 1;
|
size_type bucknum = hash(key) & bucket_count_minus_one;
|
size_type insert_pos = ILLEGAL_BUCKET; // where we would insert
|
SPARSEHASH_STAT_UPDATE(total_lookups += 1);
|
while ( 1 ) { // probe until something happens
|
if ( !table.test(bucknum) ) { // bucket is empty
|
SPARSEHASH_STAT_UPDATE(total_probes += num_probes);
|
if ( insert_pos == ILLEGAL_BUCKET ) // found no prior place to insert
|
return std::pair<size_type,size_type>(ILLEGAL_BUCKET, bucknum);
|
else
|
return std::pair<size_type,size_type>(ILLEGAL_BUCKET, insert_pos);
|
|
} else if ( test_deleted(bucknum) ) {// keep searching, but mark to insert
|
if ( insert_pos == ILLEGAL_BUCKET )
|
insert_pos = bucknum;
|
|
} else if ( equals(key, get_key(table.unsafe_get(bucknum))) ) {
|
SPARSEHASH_STAT_UPDATE(total_probes += num_probes);
|
return std::pair<size_type,size_type>(bucknum, ILLEGAL_BUCKET);
|
}
|
++num_probes; // we're doing another probe
|
bucknum = (bucknum + JUMP_(key, num_probes)) & bucket_count_minus_one;
|
assert(num_probes < bucket_count()
|
&& "Hashtable is full: an error in key_equal<> or hash<>");
|
}
|
}
|
|
public:
|
|
iterator find(const key_type& key) {
|
if ( size() == 0 ) return end();
|
std::pair<size_type, size_type> pos = find_position(key);
|
if ( pos.first == ILLEGAL_BUCKET ) // alas, not there
|
return end();
|
else
|
return iterator(this, table.get_iter(pos.first), table.nonempty_end());
|
}
|
|
const_iterator find(const key_type& key) const {
|
if ( size() == 0 ) return end();
|
std::pair<size_type, size_type> pos = find_position(key);
|
if ( pos.first == ILLEGAL_BUCKET ) // alas, not there
|
return end();
|
else
|
return const_iterator(this,
|
table.get_iter(pos.first), table.nonempty_end());
|
}
|
|
// This is a tr1 method: the bucket a given key is in, or what bucket
|
// it would be put in, if it were to be inserted. Shrug.
|
size_type bucket(const key_type& key) const {
|
std::pair<size_type, size_type> pos = find_position(key);
|
return pos.first == ILLEGAL_BUCKET ? pos.second : pos.first;
|
}
|
|
// Counts how many elements have key key. For maps, it's either 0 or 1.
|
size_type count(const key_type &key) const {
|
std::pair<size_type, size_type> pos = find_position(key);
|
return pos.first == ILLEGAL_BUCKET ? 0 : 1;
|
}
|
|
// Likewise, equal_range doesn't really make sense for us. Oh well.
|
std::pair<iterator,iterator> equal_range(const key_type& key) {
|
iterator pos = find(key); // either an iterator or end
|
if (pos == end()) {
|
return std::pair<iterator,iterator>(pos, pos);
|
} else {
|
const iterator startpos = pos++;
|
return std::pair<iterator,iterator>(startpos, pos);
|
}
|
}
|
std::pair<const_iterator,const_iterator> equal_range(const key_type& key)
|
const {
|
const_iterator pos = find(key); // either an iterator or end
|
if (pos == end()) {
|
return std::pair<const_iterator,const_iterator>(pos, pos);
|
} else {
|
const const_iterator startpos = pos++;
|
return std::pair<const_iterator,const_iterator>(startpos, pos);
|
}
|
}
|
|
|
// INSERTION ROUTINES
|
private:
|
// Private method used by insert_noresize and find_or_insert.
|
iterator insert_at(const_reference obj, size_type pos) {
|
if (size() >= max_size()) {
|
assert(false && "insert overflow");
|
exit(-1);
|
}
|
if ( test_deleted(pos) ) { // just replace if it's been deleted
|
// The set() below will undelete this object. We just worry about stats
|
assert(num_deleted > 0);
|
--num_deleted; // used to be, now it isn't
|
}
|
table.set(pos, obj);
|
return iterator(this, table.get_iter(pos), table.nonempty_end());
|
}
|
|
// If you know *this is big enough to hold obj, use this routine
|
std::pair<iterator, bool> insert_noresize(const_reference obj) {
|
// First, double-check we're not inserting delkey
|
assert((!settings.use_deleted() || !equals(get_key(obj), key_info.delkey))
|
&& "Inserting the deleted key");
|
const std::pair<size_type,size_type> pos = find_position(get_key(obj));
|
if ( pos.first != ILLEGAL_BUCKET) { // object was already there
|
return std::pair<iterator,bool>(iterator(this, table.get_iter(pos.first),
|
table.nonempty_end()),
|
false); // false: we didn't insert
|
} else { // pos.second says where to put it
|
return std::pair<iterator,bool>(insert_at(obj, pos.second), true);
|
}
|
}
|
|
// Specializations of insert(it, it) depending on the power of the iterator:
|
// (1) Iterator supports operator-, resize before inserting
|
template <class ForwardIterator>
|
void insert(ForwardIterator f, ForwardIterator l, std::forward_iterator_tag) {
|
size_t dist = std::distance(f, l);
|
if (dist >= (std::numeric_limits<size_type>::max)()) {
|
assert(false && "insert-range overflow");
|
exit(-1);
|
}
|
resize_delta(static_cast<size_type>(dist));
|
for ( ; dist > 0; --dist, ++f) {
|
insert_noresize(*f);
|
}
|
}
|
|
// (2) Arbitrary iterator, can't tell how much to resize
|
template <class InputIterator>
|
void insert(InputIterator f, InputIterator l, std::input_iterator_tag) {
|
for ( ; f != l; ++f)
|
insert(*f);
|
}
|
|
public:
|
// This is the normal insert routine, used by the outside world
|
std::pair<iterator, bool> insert(const_reference obj) {
|
resize_delta(1); // adding an object, grow if need be
|
return insert_noresize(obj);
|
}
|
|
// When inserting a lot at a time, we specialize on the type of iterator
|
template <class InputIterator>
|
void insert(InputIterator f, InputIterator l) {
|
// specializes on iterator type
|
insert(f, l,
|
typename std::iterator_traits<InputIterator>::iterator_category());
|
}
|
|
// DefaultValue is a functor that takes a key and returns a value_type
|
// representing the default value to be inserted if none is found.
|
template <class DefaultValue>
|
value_type& find_or_insert(const key_type& key) {
|
// First, double-check we're not inserting delkey
|
assert((!settings.use_deleted() || !equals(key, key_info.delkey))
|
&& "Inserting the deleted key");
|
const std::pair<size_type,size_type> pos = find_position(key);
|
DefaultValue default_value;
|
if ( pos.first != ILLEGAL_BUCKET) { // object was already there
|
return *table.get_iter(pos.first);
|
} else if (resize_delta(1)) { // needed to rehash to make room
|
// Since we resized, we can't use pos, so recalculate where to insert.
|
return *insert_noresize(default_value(key)).first;
|
} else { // no need to rehash, insert right here
|
return *insert_at(default_value(key), pos.second);
|
}
|
}
|
|
// DELETION ROUTINES
|
size_type erase(const key_type& key) {
|
// First, double-check we're not erasing delkey.
|
assert((!settings.use_deleted() || !equals(key, key_info.delkey))
|
&& "Erasing the deleted key");
|
assert(!settings.use_deleted() || !equals(key, key_info.delkey));
|
const_iterator pos = find(key); // shrug: shouldn't need to be const
|
if ( pos != end() ) {
|
assert(!test_deleted(pos)); // or find() shouldn't have returned it
|
set_deleted(pos);
|
++num_deleted;
|
// will think about shrink after next insert
|
settings.set_consider_shrink(true);
|
return 1; // because we deleted one thing
|
} else {
|
return 0; // because we deleted nothing
|
}
|
}
|
|
// We return the iterator past the deleted item.
|
void erase(iterator pos) {
|
if ( pos == end() ) return; // sanity check
|
if ( set_deleted(pos) ) { // true if object has been newly deleted
|
++num_deleted;
|
// will think about shrink after next insert
|
settings.set_consider_shrink(true);
|
}
|
}
|
|
void erase(iterator f, iterator l) {
|
for ( ; f != l; ++f) {
|
if ( set_deleted(f) ) // should always be true
|
++num_deleted;
|
}
|
// will think about shrink after next insert
|
settings.set_consider_shrink(true);
|
}
|
|
// We allow you to erase a const_iterator just like we allow you to
|
// erase an iterator. This is in parallel to 'delete': you can delete
|
// a const pointer just like a non-const pointer. The logic is that
|
// you can't use the object after it's erased anyway, so it doesn't matter
|
// if it's const or not.
|
void erase(const_iterator pos) {
|
if ( pos == end() ) return; // sanity check
|
if ( set_deleted(pos) ) { // true if object has been newly deleted
|
++num_deleted;
|
// will think about shrink after next insert
|
settings.set_consider_shrink(true);
|
}
|
}
|
void erase(const_iterator f, const_iterator l) {
|
for ( ; f != l; ++f) {
|
if ( set_deleted(f) ) // should always be true
|
++num_deleted;
|
}
|
// will think about shrink after next insert
|
settings.set_consider_shrink(true);
|
}
|
|
|
// COMPARISON
|
bool operator==(const sparse_hashtable& ht) const {
|
if (size() != ht.size()) {
|
return false;
|
} else if (this == &ht) {
|
return true;
|
} else {
|
// Iterate through the elements in "this" and see if the
|
// corresponding element is in ht
|
for ( const_iterator it = begin(); it != end(); ++it ) {
|
const_iterator it2 = ht.find(get_key(*it));
|
if ((it2 == ht.end()) || (*it != *it2)) {
|
return false;
|
}
|
}
|
return true;
|
}
|
}
|
bool operator!=(const sparse_hashtable& ht) const {
|
return !(*this == ht);
|
}
|
|
|
// I/O
|
// We support reading and writing hashtables to disk. NOTE that
|
// this only stores the hashtable metadata, not the stuff you've
|
// actually put in the hashtable! Alas, since I don't know how to
|
// write a hasher or key_equal, you have to make sure everything
|
// but the table is the same. We compact before writing.
|
//
|
// The OUTPUT type needs to support a Write() operation. File and
|
// OutputBuffer are appropriate types to pass in.
|
//
|
// The INPUT type needs to support a Read() operation. File and
|
// InputBuffer are appropriate types to pass in.
|
template <typename OUTPUT>
|
bool write_metadata(OUTPUT *fp) {
|
squash_deleted(); // so we don't have to worry about delkey
|
return table.write_metadata(fp);
|
}
|
|
template <typename INPUT>
|
bool read_metadata(INPUT *fp) {
|
num_deleted = 0; // since we got rid before writing
|
const bool result = table.read_metadata(fp);
|
settings.reset_thresholds(bucket_count());
|
return result;
|
}
|
|
// Only meaningful if value_type is a POD.
|
template <typename OUTPUT>
|
bool write_nopointer_data(OUTPUT *fp) {
|
return table.write_nopointer_data(fp);
|
}
|
|
// Only meaningful if value_type is a POD.
|
template <typename INPUT>
|
bool read_nopointer_data(INPUT *fp) {
|
return table.read_nopointer_data(fp);
|
}
|
|
// INPUT and OUTPUT must be either a FILE, *or* a C++ stream
|
// (istream, ostream, etc) *or* a class providing
|
// Read(void*, size_t) and Write(const void*, size_t)
|
// (respectively), which writes a buffer into a stream
|
// (which the INPUT/OUTPUT instance presumably owns).
|
|
typedef sparsehash_internal::pod_serializer<value_type> NopointerSerializer;
|
|
// ValueSerializer: a functor. operator()(OUTPUT*, const value_type&)
|
template <typename ValueSerializer, typename OUTPUT>
|
bool serialize(ValueSerializer serializer, OUTPUT *fp) {
|
squash_deleted(); // so we don't have to worry about delkey
|
return table.serialize(serializer, fp);
|
}
|
|
// ValueSerializer: a functor. operator()(INPUT*, value_type*)
|
template <typename ValueSerializer, typename INPUT>
|
bool unserialize(ValueSerializer serializer, INPUT *fp) {
|
num_deleted = 0; // since we got rid before writing
|
const bool result = table.unserialize(serializer, fp);
|
settings.reset_thresholds(bucket_count());
|
return result;
|
}
|
|
private:
|
// Table is the main storage class.
|
typedef sparsetable<value_type, DEFAULT_GROUP_SIZE, value_alloc_type> Table;
|
|
// Package templated functors with the other types to eliminate memory
|
// needed for storing these zero-size operators. Since ExtractKey and
|
// hasher's operator() might have the same function signature, they
|
// must be packaged in different classes.
|
struct Settings :
|
sparsehash_internal::sh_hashtable_settings<key_type, hasher,
|
size_type, HT_MIN_BUCKETS> {
|
explicit Settings(const hasher& hf)
|
: sparsehash_internal::sh_hashtable_settings<key_type, hasher,
|
size_type, HT_MIN_BUCKETS>(
|
hf, HT_OCCUPANCY_PCT / 100.0f, HT_EMPTY_PCT / 100.0f) {}
|
};
|
|
// KeyInfo stores delete key and packages zero-size functors:
|
// ExtractKey and SetKey.
|
class KeyInfo : public ExtractKey, public SetKey, public EqualKey {
|
public:
|
KeyInfo(const ExtractKey& ek, const SetKey& sk, const EqualKey& eq)
|
: ExtractKey(ek),
|
SetKey(sk),
|
EqualKey(eq) {
|
}
|
// We want to return the exact same type as ExtractKey: Key or const Key&
|
typename ExtractKey::result_type get_key(const_reference v) const {
|
return ExtractKey::operator()(v);
|
}
|
void set_key(pointer v, const key_type& k) const {
|
SetKey::operator()(v, k);
|
}
|
bool equals(const key_type& a, const key_type& b) const {
|
return EqualKey::operator()(a, b);
|
}
|
|
// Which key marks deleted entries.
|
// TODO(csilvers): make a pointer, and get rid of use_deleted (benchmark!)
|
typename base::remove_const<key_type>::type delkey;
|
};
|
|
// Utility functions to access the templated operators
|
size_type hash(const key_type& v) const {
|
return settings.hash(v);
|
}
|
bool equals(const key_type& a, const key_type& b) const {
|
return key_info.equals(a, b);
|
}
|
typename ExtractKey::result_type get_key(const_reference v) const {
|
return key_info.get_key(v);
|
}
|
void set_key(pointer v, const key_type& k) const {
|
key_info.set_key(v, k);
|
}
|
|
private:
|
// Actual data
|
Settings settings;
|
KeyInfo key_info;
|
size_type num_deleted; // how many occupied buckets are marked deleted
|
Table table; // holds num_buckets and num_elements too
|
};
|
|
|
// We need a global swap as well
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
inline void swap(sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> &x,
|
sparse_hashtable<V,K,HF,ExK,SetK,EqK,A> &y) {
|
x.swap(y);
|
}
|
|
#undef JUMP_
|
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
const typename sparse_hashtable<V,K,HF,ExK,SetK,EqK,A>::size_type
|
sparse_hashtable<V,K,HF,ExK,SetK,EqK,A>::ILLEGAL_BUCKET;
|
|
// How full we let the table get before we resize. Knuth says .8 is
|
// good -- higher causes us to probe too much, though saves memory
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
const int sparse_hashtable<V,K,HF,ExK,SetK,EqK,A>::HT_OCCUPANCY_PCT = 80;
|
|
// How empty we let the table get before we resize lower.
|
// It should be less than OCCUPANCY_PCT / 2 or we thrash resizing
|
template <class V, class K, class HF, class ExK, class SetK, class EqK, class A>
|
const int sparse_hashtable<V,K,HF,ExK,SetK,EqK,A>::HT_EMPTY_PCT
|
= static_cast<int>(0.4 *
|
sparse_hashtable<V,K,HF,ExK,SetK,EqK,A>::HT_OCCUPANCY_PCT);
|
|
_END_GOOGLE_NAMESPACE_
|
|
#endif /* _SPARSEHASHTABLE_H_ */
|
