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// Copyright 2008 Abby Levenberg, David Talbot
//
// This file is part of RandLM
//
// RandLM is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// RandLM is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with RandLM. If not, see <http://www.gnu.org/licenses/>.
#ifndef INC_RANDLM_CACHE_H
#define INC_RANDLM_CACHE_H
#include <iterator>
#include <map>
#include <ctime>
#include <iostream>
namespace randlm {
template<typename T>
class CacheNode {
public:
typedef std::map<wordID_t, CacheNode<T>* > childMap;
// initialise value to 'unknown' (i.e. not yet queried or cached).
CacheNode(T unknown_value) : value_(unknown_value) {}
childMap childs_; // child pointers
T value_; // value stored
const void* state_; // state pointer
};
template<typename T>
class Cache {
public:
typedef typename std::map<wordID_t, CacheNode<T>* >::iterator childPtr;
// unknown_value is used to indicate the ngram was not queried (yet)
// null_value_ indicates it was queried but not found in model
// space usage is handled by client.
Cache(T unknown_value, T null_value) :
cur_nodes_(0), unknown_value_(unknown_value), null_value_(null_value) {
root_ = newNode();
}
~Cache() {
if(clear()) {
delete root_;
root_ = NULL;
} else {
std::cerr << "Error freeing cache memory.\n";
}
}
bool setCacheNgram(const wordID_t* ngram, int len, T value, const void* state) {
// inserts full ngram into cache
CacheNode<T>* node = root_;
for (int i = len - 1; i > -1; --i) {
childPtr child = node->childs_.find(ngram[i]);
if( child != node->childs_.end() ) {
// current node is already prefix. Go to child node
node = node->childs_[ngram[i]];
} else {
// no child for prefix. set new child link in current node
CacheNode<T> * newChild = newNode(node);
node->childs_[ngram[i]] = newChild;
// go to new node
node = newChild;
}
}
node->value_ = value;
node->state_ = state;
return true;
}
bool checkCacheNgram(const wordID_t* ngram, int len, T* value, const void** state) {
// finds value for this full ngram only (returns false if full ngram not in cache)
CacheNode<T> * node = root_;
for(int i = len - 1; i > -1; --i) {
// go to deepest level node of ngram in cache
childPtr child = node->childs_.find(ngram[i]);
if( child != node->childs_.end() ) {
// switch to child node
node = node->childs_[ngram[i]];
} else {
// not cached
return false;
}
}
*value = node->value_;
if(state) *state = node->state_;
return *value != null_value_ && *value != unknown_value_;
}
int getCache2(const wordID_t* ngram, int len, T** values, int* found) {
// set values array to point to cache value nodes
CacheNode<T> * node = root_;
*found = 0;
//values[0] = &node->value_; // pointer to root node's value
bool all_found = true;
for(int i = len - 1; i > -1; --i) {
// go to deepest level node of ngram in cache
childPtr child = node->childs_.find(ngram[i]);
if( child != node->childs_.end() ) {
// switch to child node
node = node->childs_[ngram[i]];
// get pointer to value (index by length - 1)
values[i] = &node->value_;
// if null_value then assume all extensions impossible
if (node->value_ == null_value_) {
return len - 1 - i; // max length posible
}
all_found = all_found && (node->value_ != unknown_value_);
if (all_found)
++(*found);
} else {
// initialise uncached values
CacheNode<T> * newChild = newNode(node);
node->childs_[ngram[i]] = newChild;
// go to new node
node = newChild;
values[i] = &node->value_;
}
}
return len; // all possible
}
int getCache(const wordID_t* ngram, int len, T** values, int* found) {
// get pointers to values for ngram and constituents.
// returns upper bound on longest subngram in model.
// 'found' stores longest non-null and known value found.
CacheNode<T> * node = root_;
*found = 0;
values[0] = &node->value_; // pointer to root node's value
bool all_found = true;
for(int i = len - 1; i > -1; --i) {
// go to deepest level node of ngram in cache
childPtr child = node->childs_.find(ngram[i]);
if( child != node->childs_.end() ) {
// switch to child node
node = node->childs_[ngram[i]];
// get pointer to value (index by length - 1)
values[len - i] = &node->value_;
// if null_value then assume all extensions impossible
if (node->value_ == null_value_)
return len - 1 - i; // max length posible
all_found = all_found && (node->value_ != unknown_value_);
if (all_found)
++(*found);
} else {
// initialise uncached values
CacheNode<T> * newChild = newNode(node);
node->childs_[ngram[i]] = newChild;
// go to new node
node = newChild;
values[len - i] = &node->value_;
}
}
return len; // all possible
}
bool clear() {
std::cerr << "Clearing cache with " << static_cast<float>(cur_nodes_ * nodeSize())
/ static_cast<float>(1ull << 20) << "MB" << std::endl;
return clearNodes(root_);
}
int nodes() {
// returns number of nodes
return cur_nodes_;
}
int nodeSize() {
return sizeof(CacheNode<T>) + sizeof(root_->childs_);
}
private:
CacheNode<T> * root_;
count_t cur_nodes_;
T unknown_value_; // Used to initialise data at each node
T null_value_; // Indicates cached something not in model
CacheNode<T>* newNode(CacheNode<T> * node = 0) {
++cur_nodes_;
return new CacheNode<T>(unknown_value_);
}
bool clearNodes(CacheNode<T> * node) {
//delete children from this node
if(!node->childs_.empty()) {
iterate(node->childs_, itr) {
if(!clearNodes(itr->second))
std::cerr << "Error emptying cache\n";
delete itr->second;
--cur_nodes_;
}
node->childs_.clear();
}
return true;
}
};
} //end namespace
#endif //INC_RANDLM_CACHE_H
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