mirror of https://github.com/PCSX2/pcsx2.git
942 lines
39 KiB
C++
942 lines
39 KiB
C++
// 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.
|
|
|
|
// ---
|
|
// Author: Craig Silverstein
|
|
//
|
|
// 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
|
|
// <google/sparse_hash_table> or <google/sparse_hash_set> instead.
|
|
//
|
|
// You can modify the following, below:
|
|
// HT_OCCUPANCY_FLT -- how full before we double size
|
|
// HT_EMPTY_FLT -- 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_resize_percent (which defaults to
|
|
// HT_OCCUPANCY_FLT), and shrink_resize_percent (which defaults to
|
|
// HT_EMPTY_FLT) with set_resizing_parameters().
|
|
//
|
|
// How to decide what values to use?
|
|
// shrink_resize_percent's default of .4 * OCCUPANCY_FLT, is probably good.
|
|
// HT_MIN_BUCKETS is probably unnecessary since you can specify
|
|
// (indirectly) the starting number of buckets at construct-time.
|
|
// For enlarge_resize_percent, 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_resize_percent -- 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_
|
|
|
|
#ifndef SPARSEHASH_STAT_UPDATE
|
|
#define SPARSEHASH_STAT_UPDATE(x) ((void) 0)
|
|
#endif
|
|
|
|
// The probing method
|
|
// Linear probing
|
|
// #define JUMP_(key, num_probes) ( 1 )
|
|
// Quadratic-ish probing
|
|
#define JUMP_(key, num_probes) ( num_probes )
|
|
|
|
|
|
// Hashtable class, used to implement the hashed associative containers
|
|
// hash_set and hash_map.
|
|
|
|
#include <google/sparsehash/sparseconfig.h>
|
|
#include <assert.h>
|
|
#include <algorithm> // For swap(), eg
|
|
#include <iterator> // for facts about iterator tags
|
|
#include <utility> // for pair<>
|
|
#include <google/sparsetable> // Since that's basically what we are
|
|
|
|
_START_GOOGLE_NAMESPACE_
|
|
|
|
using STL_NAMESPACE::pair;
|
|
|
|
// Alloc is completely ignored. It is present as a template parameter only
|
|
// for the sake of being compatible with the old SGI hashtable interface.
|
|
// TODO(csilvers): is that the right thing to do?
|
|
|
|
template <class Value, class Key, class HashFcn,
|
|
class ExtractKey, class EqualKey, class Alloc>
|
|
class sparse_hashtable;
|
|
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
struct sparse_hashtable_iterator;
|
|
|
|
template <class V, class K, class HF, class ExK, 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 EqK, class A>
|
|
struct sparse_hashtable_iterator {
|
|
public:
|
|
typedef sparse_hashtable_iterator<V,K,HF,ExK,EqK,A> iterator;
|
|
typedef sparse_hashtable_const_iterator<V,K,HF,ExK,EqK,A> const_iterator;
|
|
typedef typename sparsetable<V>::nonempty_iterator st_iterator;
|
|
|
|
typedef STL_NAMESPACE::forward_iterator_tag iterator_category;
|
|
typedef V value_type;
|
|
typedef ptrdiff_t difference_type;
|
|
typedef size_t size_type;
|
|
typedef V& reference; // Value
|
|
typedef V* pointer;
|
|
|
|
// "Real" constructor and default constructor
|
|
sparse_hashtable_iterator(const sparse_hashtable<V,K,HF,ExK,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,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 EqK, class A>
|
|
struct sparse_hashtable_const_iterator {
|
|
public:
|
|
typedef sparse_hashtable_iterator<V,K,HF,ExK,EqK,A> iterator;
|
|
typedef sparse_hashtable_const_iterator<V,K,HF,ExK,EqK,A> const_iterator;
|
|
typedef typename sparsetable<V>::const_nonempty_iterator st_iterator;
|
|
|
|
typedef STL_NAMESPACE::forward_iterator_tag iterator_category;
|
|
typedef V value_type;
|
|
typedef ptrdiff_t difference_type;
|
|
typedef size_t size_type;
|
|
typedef const V& reference; // Value
|
|
typedef const V* pointer;
|
|
|
|
// "Real" constructor and default constructor
|
|
sparse_hashtable_const_iterator(const sparse_hashtable<V,K,HF,ExK,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,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 EqK, class A>
|
|
struct sparse_hashtable_destructive_iterator {
|
|
public:
|
|
typedef sparse_hashtable_destructive_iterator<V,K,HF,ExK,EqK,A> iterator;
|
|
typedef typename sparsetable<V>::destructive_iterator st_iterator;
|
|
|
|
typedef STL_NAMESPACE::forward_iterator_tag iterator_category;
|
|
typedef V value_type;
|
|
typedef ptrdiff_t difference_type;
|
|
typedef size_t size_type;
|
|
typedef V& reference; // Value
|
|
typedef V* pointer;
|
|
|
|
// "Real" constructor and default constructor
|
|
sparse_hashtable_destructive_iterator(const
|
|
sparse_hashtable<V,K,HF,ExK,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,EqK,A> *ht;
|
|
st_iterator pos, end;
|
|
};
|
|
|
|
|
|
template <class Value, class Key, class HashFcn,
|
|
class ExtractKey, class EqualKey, class Alloc>
|
|
class sparse_hashtable {
|
|
public:
|
|
typedef Key key_type;
|
|
typedef Value value_type;
|
|
typedef HashFcn hasher;
|
|
typedef EqualKey key_equal;
|
|
|
|
typedef size_t size_type;
|
|
typedef ptrdiff_t difference_type;
|
|
typedef value_type* pointer;
|
|
typedef const value_type* const_pointer;
|
|
typedef value_type& reference;
|
|
typedef const value_type& const_reference;
|
|
typedef sparse_hashtable_iterator<Value, Key, HashFcn,
|
|
ExtractKey, EqualKey, Alloc>
|
|
iterator;
|
|
|
|
typedef sparse_hashtable_const_iterator<Value, Key, HashFcn,
|
|
ExtractKey, EqualKey, Alloc>
|
|
const_iterator;
|
|
|
|
typedef sparse_hashtable_destructive_iterator<Value, Key, HashFcn,
|
|
ExtractKey, EqualKey, Alloc>
|
|
destructive_iterator;
|
|
|
|
|
|
// 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
|
|
static const float HT_OCCUPANCY_FLT; // = 0.8f;
|
|
|
|
// How empty we let the table get before we resize lower.
|
|
// It should be less than OCCUPANCY_FLT / 2 or we thrash resizing
|
|
static const float HT_EMPTY_FLT; // = 0.4 * HT_OCCUPANCY_FLT;
|
|
|
|
// 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 minimum size is
|
|
// determined by the first constructor arg, and may be >HT_MIN_BUCKETS.
|
|
static const size_t 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_t 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()); }
|
|
|
|
// 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 hash; }
|
|
key_equal key_eq() const { return equals; }
|
|
|
|
// 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.
|
|
private:
|
|
void set_value(value_type* dst, const value_type 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);
|
|
}
|
|
|
|
public:
|
|
void set_deleted_key(const value_type &val) {
|
|
// It's only safe to change what "deleted" means if we purge deleted guys
|
|
squash_deleted();
|
|
use_deleted = true;
|
|
set_value(&delval, val); // save the key (and rest of val too)
|
|
}
|
|
void clear_deleted_key() {
|
|
squash_deleted();
|
|
use_deleted = false;
|
|
}
|
|
|
|
// 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 {
|
|
// The num_deleted test is crucial for read(): after read(), the ht values
|
|
// are garbage, and we don't want to think some of them are deleted.
|
|
return (use_deleted && num_deleted > 0 && table.test(bucknum) &&
|
|
equals(get_key(delval), get_key(table.get(bucknum))));
|
|
}
|
|
bool test_deleted(const iterator &it) const {
|
|
return (use_deleted && num_deleted > 0 &&
|
|
equals(get_key(delval), get_key(*it)));
|
|
}
|
|
bool test_deleted(const const_iterator &it) const {
|
|
return (use_deleted && num_deleted > 0 &&
|
|
equals(get_key(delval), get_key(*it)));
|
|
}
|
|
bool test_deleted(const destructive_iterator &it) const {
|
|
return (use_deleted && num_deleted > 0 &&
|
|
equals(get_key(delval), get_key(*it)));
|
|
}
|
|
// Set it so test_deleted is true. true if object didn't used to be deleted
|
|
// See below (at erase()) to explain why we allow const_iterators
|
|
bool set_deleted(const_iterator &it) {
|
|
assert(use_deleted); // bad if set_deleted_key() wasn't called
|
|
bool retval = !test_deleted(it);
|
|
// &* converts from iterator to value-type
|
|
set_value(const_cast<value_type*>(&(*it)), delval);
|
|
return retval;
|
|
}
|
|
// Set it so test_deleted is false. true if object used to be deleted
|
|
bool clear_deleted(const_iterator &it) {
|
|
assert(use_deleted); // bad if set_deleted_key() wasn't called
|
|
// happens automatically when we assign something else in its place
|
|
return test_deleted(it);
|
|
}
|
|
|
|
|
|
// FUNCTIONS CONCERNING SIZE
|
|
size_type size() const { return table.num_nonempty() - num_deleted; }
|
|
// Buckets are always a power of 2
|
|
size_type max_size() const { return (size_type(-1) >> 1U) + 1; }
|
|
bool empty() const { return size() == 0; }
|
|
size_type bucket_count() const { return table.size(); }
|
|
size_type max_bucket_count() const { return max_size(); }
|
|
|
|
private:
|
|
// Because of the above, size_type(-1) is never legal; use it for errors
|
|
static const size_type ILLEGAL_BUCKET = size_type(-1);
|
|
|
|
private:
|
|
// This is the smallest size a hashtable can be without being too crowded
|
|
// If you like, you can give a min #buckets as well as a min #elts
|
|
size_type min_size(size_type num_elts, size_type min_buckets_wanted) {
|
|
size_type sz = HT_MIN_BUCKETS;
|
|
while ( sz < min_buckets_wanted || num_elts >= sz * enlarge_resize_percent )
|
|
sz *= 2;
|
|
return sz;
|
|
}
|
|
|
|
// Used after a string of deletes
|
|
void 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);
|
|
|
|
// 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.
|
|
if (shrink_threshold > 0
|
|
&& (table.num_nonempty()-num_deleted) < shrink_threshold &&
|
|
bucket_count() > HT_DEFAULT_STARTING_BUCKETS ) {
|
|
size_type sz = bucket_count() / 2; // find how much we should shrink
|
|
while ( sz > HT_DEFAULT_STARTING_BUCKETS &&
|
|
(table.num_nonempty() - num_deleted) <= sz *
|
|
shrink_resize_percent )
|
|
sz /= 2; // stay a power of 2
|
|
sparse_hashtable tmp(MoveDontCopy, *this, sz);
|
|
swap(tmp); // now we are tmp
|
|
}
|
|
consider_shrink = false; // because we just considered it
|
|
}
|
|
|
|
// 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"
|
|
void resize_delta(size_type delta) {
|
|
if ( consider_shrink ) // see if lots of deletes happened
|
|
maybe_shrink();
|
|
if ( bucket_count() >= HT_MIN_BUCKETS &&
|
|
(table.num_nonempty() + delta) <= enlarge_threshold )
|
|
return; // 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 = min_size(table.num_nonempty() + delta, 0);
|
|
if ( needed_size > bucket_count() ) { // we don't have enough buckets
|
|
const size_type resize_to = min_size(table.num_nonempty() - num_deleted
|
|
+ delta, 0);
|
|
sparse_hashtable tmp(MoveDontCopy, *this, resize_to);
|
|
swap(tmp); // now we are tmp
|
|
}
|
|
}
|
|
|
|
// 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 = min_size(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
|
|
reset_thresholds();
|
|
}
|
|
|
|
// 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()); // or else the hashtable is full
|
|
}
|
|
table.set(bucknum, *it); // copies the value to here
|
|
}
|
|
}
|
|
|
|
// 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_t resize_to;
|
|
if ( mover == MoveDontGrow )
|
|
resize_to = ht.bucket_count(); // keep same size as old ht
|
|
else // MoveDontCopy
|
|
resize_to = min_size(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
|
|
reset_thresholds();
|
|
}
|
|
|
|
// 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()); // or else the hashtable is full
|
|
}
|
|
table.set(bucknum, *it); // copies the value to here
|
|
}
|
|
}
|
|
|
|
|
|
// 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 ( consider_shrink || req_elements == 0 )
|
|
maybe_shrink();
|
|
if ( req_elements > table.num_nonempty() ) // we only grow
|
|
resize_delta(req_elements - table.num_nonempty());
|
|
}
|
|
|
|
// Change the value of shrink_resize_percent and
|
|
// enlarge_resize_percent. 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 set_resizing_parameters(float shrink, float grow) {
|
|
assert(shrink >= 0.0);
|
|
assert(grow <= 1.0);
|
|
assert(shrink <= grow/2.0);
|
|
shrink_resize_percent = shrink;
|
|
enlarge_resize_percent = grow;
|
|
reset_thresholds();
|
|
}
|
|
|
|
// 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())
|
|
: hash(hf), equals(eql), get_key(ext), num_deleted(0), use_deleted(false),
|
|
delval(), enlarge_resize_percent(HT_OCCUPANCY_FLT),
|
|
shrink_resize_percent(HT_EMPTY_FLT),
|
|
table(expected_max_items_in_table == 0
|
|
? HT_DEFAULT_STARTING_BUCKETS
|
|
: min_size(expected_max_items_in_table, 0)) {
|
|
reset_thresholds();
|
|
}
|
|
|
|
// 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)
|
|
: hash(ht.hash), equals(ht.equals), get_key(ht.get_key),
|
|
num_deleted(0), use_deleted(ht.use_deleted), delval(ht.delval),
|
|
enlarge_resize_percent(ht.enlarge_resize_percent),
|
|
shrink_resize_percent(ht.shrink_resize_percent),
|
|
table() {
|
|
reset_thresholds();
|
|
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)
|
|
: hash(ht.hash), equals(ht.equals), get_key(ht.get_key),
|
|
num_deleted(0), use_deleted(ht.use_deleted), delval(ht.delval),
|
|
enlarge_resize_percent(ht.enlarge_resize_percent),
|
|
shrink_resize_percent(ht.shrink_resize_percent),
|
|
table() {
|
|
reset_thresholds();
|
|
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
|
|
clear();
|
|
hash = ht.hash;
|
|
equals = ht.equals;
|
|
get_key = ht.get_key;
|
|
use_deleted = ht.use_deleted;
|
|
set_value(&delval, ht.delval);
|
|
copy_from(ht, HT_MIN_BUCKETS); // sets num_deleted to 0 too
|
|
return *this;
|
|
}
|
|
|
|
// Many STL algorithms use swap instead of copy constructors
|
|
void swap(sparse_hashtable& ht) {
|
|
STL_NAMESPACE::swap(hash, ht.hash);
|
|
STL_NAMESPACE::swap(equals, ht.equals);
|
|
STL_NAMESPACE::swap(get_key, ht.get_key);
|
|
STL_NAMESPACE::swap(num_deleted, ht.num_deleted);
|
|
STL_NAMESPACE::swap(use_deleted, ht.use_deleted);
|
|
STL_NAMESPACE::swap(enlarge_resize_percent, ht.enlarge_resize_percent);
|
|
STL_NAMESPACE::swap(shrink_resize_percent, ht.shrink_resize_percent);
|
|
{ value_type tmp; // for annoying reasons, swap() doesn't work
|
|
set_value(&tmp, delval);
|
|
set_value(&delval, ht.delval);
|
|
set_value(&ht.delval, tmp);
|
|
}
|
|
table.swap(ht.table);
|
|
reset_thresholds();
|
|
ht.reset_thresholds();
|
|
}
|
|
|
|
// It's always nice to be able to clear a table without deallocating it
|
|
void clear() {
|
|
table.clear();
|
|
reset_thresholds();
|
|
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
|
|
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 pair<size_type,size_type>(ILLEGAL_BUCKET, bucknum);
|
|
else
|
|
return 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.get(bucknum))) ) {
|
|
SPARSEHASH_STAT_UPDATE(total_probes += num_probes);
|
|
return 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()); // don't probe too many times!
|
|
}
|
|
}
|
|
|
|
public:
|
|
iterator find(const key_type& key) {
|
|
if ( size() == 0 ) return end();
|
|
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();
|
|
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());
|
|
}
|
|
|
|
// Counts how many elements have key key. For maps, it's either 0 or 1.
|
|
size_type count(const key_type &key) const {
|
|
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.
|
|
pair<iterator,iterator> equal_range(const key_type& key) {
|
|
const iterator pos = find(key); // either an iterator or end
|
|
return pair<iterator,iterator>(pos, pos);
|
|
}
|
|
pair<const_iterator,const_iterator> equal_range(const key_type& key) const {
|
|
const const_iterator pos = find(key); // either an iterator or end
|
|
return pair<iterator,iterator>(pos, pos);
|
|
}
|
|
|
|
|
|
// INSERTION ROUTINES
|
|
private:
|
|
// If you know *this is big enough to hold obj, use this routine
|
|
pair<iterator, bool> insert_noresize(const value_type& obj) {
|
|
// First, double-check we're not inserting delval
|
|
assert(!use_deleted || !equals(get_key(obj), get_key(delval)));
|
|
const pair<size_type,size_type> pos = find_position(get_key(obj));
|
|
if ( pos.first != ILLEGAL_BUCKET) { // object was already there
|
|
return 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
|
|
if ( test_deleted(pos.second) ) { // just replace if it's been del.
|
|
// 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.second, obj);
|
|
return pair<iterator,bool>(iterator(this, table.get_iter(pos.second),
|
|
table.nonempty_end()),
|
|
true); // true: we did insert
|
|
}
|
|
}
|
|
|
|
public:
|
|
// This is the normal insert routine, used by the outside world
|
|
pair<iterator, bool> insert(const value_type& 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 STL_NAMESPACE::iterator_traits<InputIterator>::iterator_category());
|
|
}
|
|
|
|
// Iterator supports operator-, resize before inserting
|
|
template <class ForwardIterator>
|
|
void insert(ForwardIterator f, ForwardIterator l,
|
|
STL_NAMESPACE::forward_iterator_tag) {
|
|
size_type n = STL_NAMESPACE::distance(f, l); // TODO(csilvers): standard?
|
|
resize_delta(n);
|
|
for ( ; n > 0; --n, ++f)
|
|
insert_noresize(*f);
|
|
}
|
|
|
|
// Arbitrary iterator, can't tell how much to resize
|
|
template <class InputIterator>
|
|
void insert(InputIterator f, InputIterator l,
|
|
STL_NAMESPACE::input_iterator_tag) {
|
|
for ( ; f != l; ++f)
|
|
insert(*f);
|
|
}
|
|
|
|
|
|
// DELETION ROUTINES
|
|
size_type erase(const key_type& key) {
|
|
// First, double-check we're not erasing delval
|
|
assert(!use_deleted || !equals(key, get_key(delval)));
|
|
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;
|
|
consider_shrink = true; // will think about shrink after next insert
|
|
return 1; // because we deleted one thing
|
|
} else {
|
|
return 0; // because we deleted nothing
|
|
}
|
|
}
|
|
|
|
// This is really evil: really it should be iterator, not const_iterator.
|
|
// But...the only reason keys are const is to allow lookup.
|
|
// Since that's a moot issue for deleted keys, we allow const_iterators
|
|
void erase(const_iterator pos) {
|
|
if ( pos == end() ) return; // sanity check
|
|
if ( set_deleted(pos) ) { // true if object has been newly deleted
|
|
++num_deleted;
|
|
consider_shrink = true; // will think about shrink after next insert
|
|
}
|
|
}
|
|
|
|
void erase(const_iterator f, const_iterator l) {
|
|
for ( ; f != l; ++f) {
|
|
if ( set_deleted(f) ) // should always be true
|
|
++num_deleted;
|
|
}
|
|
consider_shrink = true; // will think about shrink after next insert
|
|
}
|
|
|
|
|
|
// COMPARISON
|
|
bool operator==(const sparse_hashtable& ht) const {
|
|
// We really want to check that the hash functions are the same
|
|
// but alas there's no way to do this. We just hope.
|
|
return ( num_deleted == ht.num_deleted && table == ht.table );
|
|
}
|
|
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.
|
|
bool write_metadata(FILE *fp) {
|
|
squash_deleted(); // so we don't have to worry about delkey
|
|
return table.write_metadata(fp);
|
|
}
|
|
|
|
bool read_metadata(FILE *fp) {
|
|
num_deleted = 0; // since we got rid before writing
|
|
bool result = table.read_metadata(fp);
|
|
reset_thresholds();
|
|
return result;
|
|
}
|
|
|
|
// Only meaningful if value_type is a POD.
|
|
bool write_nopointer_data(FILE *fp) {
|
|
return table.write_nopointer_data(fp);
|
|
}
|
|
|
|
// Only meaningful if value_type is a POD.
|
|
bool read_nopointer_data(FILE *fp) {
|
|
return table.read_nopointer_data(fp);
|
|
}
|
|
|
|
private:
|
|
// The actual data
|
|
hasher hash; // required by hashed_associative_container
|
|
key_equal equals;
|
|
ExtractKey get_key;
|
|
size_type num_deleted; // how many occupied buckets are marked deleted
|
|
bool use_deleted; // false until delval has been set
|
|
value_type delval; // which key marks deleted entries
|
|
float enlarge_resize_percent; // how full before resize
|
|
float shrink_resize_percent; // how empty before resize
|
|
size_type shrink_threshold; // table.size() * shrink_resize_percent
|
|
size_type enlarge_threshold; // table.size() * enlarge_resize_percent
|
|
sparsetable<value_type> table; // holds num_buckets and num_elements too
|
|
bool consider_shrink; // true if we should try to shrink before next insert
|
|
|
|
void reset_thresholds() {
|
|
enlarge_threshold = static_cast<size_type>(table.size()
|
|
* enlarge_resize_percent);
|
|
shrink_threshold = static_cast<size_type>(table.size()
|
|
* shrink_resize_percent);
|
|
consider_shrink = false; // whatever caused us to reset already considered
|
|
}
|
|
};
|
|
|
|
// We need a global swap as well
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
inline void swap(sparse_hashtable<V,K,HF,ExK,EqK,A> &x,
|
|
sparse_hashtable<V,K,HF,ExK,EqK,A> &y) {
|
|
x.swap(y);
|
|
}
|
|
|
|
#undef JUMP_
|
|
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
const typename sparse_hashtable<V,K,HF,ExK,EqK,A>::size_type
|
|
sparse_hashtable<V,K,HF,ExK,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 EqK, class A>
|
|
const float sparse_hashtable<V,K,HF,ExK,EqK,A>::HT_OCCUPANCY_FLT = 0.8f;
|
|
|
|
// How empty we let the table get before we resize lower.
|
|
// It should be less than OCCUPANCY_FLT / 2 or we thrash resizing
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
const float sparse_hashtable<V,K,HF,ExK,EqK,A>::HT_EMPTY_FLT = 0.4f *
|
|
sparse_hashtable<V,K,HF,ExK,EqK,A>::HT_OCCUPANCY_FLT;
|
|
|
|
_END_GOOGLE_NAMESPACE_
|
|
|
|
#endif /* _SPARSEHASHTABLE_H_ */
|