minetest/src/util/container.h

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/*
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Minetest
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Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
This program 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#pragma once
#include "irrlichttypes.h"
#include "exceptions.h"
#include "threading/mutex_auto_lock.h"
#include "threading/semaphore.h"
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#include <list>
#include <vector>
#include <map>
#include <set>
#include <queue>
/*
Queue with unique values with fast checking of value existence
*/
template<typename Value>
class UniqueQueue
{
public:
/*
Does nothing if value is already queued.
Return value:
true: value added
false: value already exists
*/
bool push_back(const Value& value)
{
if (m_set.insert(value).second)
{
m_queue.push(value);
return true;
}
return false;
}
void pop_front()
{
m_set.erase(m_queue.front());
m_queue.pop();
}
const Value& front() const
{
return m_queue.front();
}
u32 size() const
{
return m_queue.size();
}
private:
std::set<Value> m_set;
std::queue<Value> m_queue;
};
template<typename Key, typename Value>
class MutexedMap
{
public:
MutexedMap() = default;
void set(const Key &name, const Value &value)
{
MutexAutoLock lock(m_mutex);
m_values[name] = value;
}
bool get(const Key &name, Value *result) const
{
MutexAutoLock lock(m_mutex);
auto n = m_values.find(name);
if (n == m_values.end())
return false;
if (result)
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*result = n->second;
return true;
}
std::vector<Value> getValues() const
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{
MutexAutoLock lock(m_mutex);
std::vector<Value> result;
result.reserve(m_values.size());
for (auto it = m_values.begin(); it != m_values.end(); ++it)
result.push_back(it->second);
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return result;
}
void clear() { m_values.clear(); }
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private:
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std::map<Key, Value> m_values;
mutable std::mutex m_mutex;
};
// Thread-safe Double-ended queue
template<typename T>
class MutexedQueue
{
public:
template<typename Key, typename U, typename Caller, typename CallerData>
friend class RequestQueue;
MutexedQueue() = default;
bool empty() const
{
MutexAutoLock lock(m_mutex);
return m_queue.empty();
}
void push_back(const T &t)
{
MutexAutoLock lock(m_mutex);
m_queue.push_back(t);
m_signal.post();
}
/* this version of pop_front returns a empty element of T on timeout.
* Make sure default constructor of T creates a recognizable "empty" element
*/
T pop_frontNoEx(u32 wait_time_max_ms)
{
if (m_signal.wait(wait_time_max_ms)) {
MutexAutoLock lock(m_mutex);
T t = std::move(m_queue.front());
m_queue.pop_front();
return t;
}
return T();
}
T pop_front(u32 wait_time_max_ms)
{
if (m_signal.wait(wait_time_max_ms)) {
MutexAutoLock lock(m_mutex);
T t = std::move(m_queue.front());
m_queue.pop_front();
return t;
}
throw ItemNotFoundException("MutexedQueue: queue is empty");
}
T pop_frontNoEx()
{
m_signal.wait();
MutexAutoLock lock(m_mutex);
T t = std::move(m_queue.front());
m_queue.pop_front();
return t;
}
T pop_back(u32 wait_time_max_ms=0)
{
if (m_signal.wait(wait_time_max_ms)) {
MutexAutoLock lock(m_mutex);
T t = std::move(m_queue.back());
m_queue.pop_back();
return t;
}
throw ItemNotFoundException("MutexedQueue: queue is empty");
}
/* this version of pop_back returns a empty element of T on timeout.
* Make sure default constructor of T creates a recognizable "empty" element
*/
T pop_backNoEx(u32 wait_time_max_ms)
{
if (m_signal.wait(wait_time_max_ms)) {
MutexAutoLock lock(m_mutex);
T t = std::move(m_queue.back());
m_queue.pop_back();
return t;
}
return T();
}
T pop_backNoEx()
{
m_signal.wait();
MutexAutoLock lock(m_mutex);
T t = std::move(m_queue.back());
m_queue.pop_back();
return t;
}
protected:
std::mutex &getMutex() { return m_mutex; }
std::deque<T> &getQueue() { return m_queue; }
std::deque<T> m_queue;
mutable std::mutex m_mutex;
Semaphore m_signal;
};
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template<typename K, typename V>
class LRUCache
{
public:
LRUCache(size_t limit, void (*cache_miss)(void *data, const K &key, V *dest),
void *data)
{
m_limit = limit;
m_cache_miss = cache_miss;
m_cache_miss_data = data;
}
void setLimit(size_t limit)
{
m_limit = limit;
invalidate();
}
void invalidate()
{
m_map.clear();
m_queue.clear();
}
const V *lookupCache(K key)
{
typename cache_type::iterator it = m_map.find(key);
V *ret;
if (it != m_map.end()) {
// found!
cache_entry_t &entry = it->second;
ret = &entry.second;
// update the usage information
m_queue.erase(entry.first);
m_queue.push_front(key);
entry.first = m_queue.begin();
} else {
// cache miss -- enter into cache
cache_entry_t &entry =
m_map[key];
ret = &entry.second;
m_cache_miss(m_cache_miss_data, key, &entry.second);
// delete old entries
if (m_queue.size() == m_limit) {
const K &id = m_queue.back();
m_map.erase(id);
m_queue.pop_back();
}
m_queue.push_front(key);
entry.first = m_queue.begin();
}
return ret;
}
private:
void (*m_cache_miss)(void *data, const K &key, V *dest);
void *m_cache_miss_data;
size_t m_limit;
typedef typename std::template pair<typename std::template list<K>::iterator, V> cache_entry_t;
typedef std::template map<K, cache_entry_t> cache_type;
cache_type m_map;
// we can't use std::deque here, because its iterators get invalidated
std::list<K> m_queue;
};