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#ifndef QPID_SYS_REFCOUNTEDMAP_H
#define QPID_SYS_REFCOUNTEDMAP_H
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
#include "qpid/sys/Mutex.h"
#include "qpid/RefCounted.h"
#include <boost/type_traits/remove_pointer.hpp>
#include <boost/bind.hpp>
#include <boost/tuple/tuple.hpp>
#include <boost/cast.hpp>
#include <boost/intrusive_ptr.hpp>
#include <vector>
#include <map>
#include <algorithm>
namespace qpid {
namespace sys {
template <class, class, class> class RefCountedMap;
template <class Key, class Data, class Base=RefCounted,
class Impl=std::map<Key, Data*> >
class RefCountedMapData : public Base {
public:
typedef RefCountedMap<Key, Data, Impl> Map;
bool attached() {
assert(map || self->second == this);
return map;
}
const Key& getKey() const { assert(attached()); return self->first; }
void released() const { if (map) map->lockedDetach(self); delete this; }
private:
friend class RefCountedMap<Key, Data, Impl>;
boost::intrusive_ptr<Map> map;
typename Impl::iterator self;
public:
};
/**
* A thread-safe, reference-counted, weak map of reference-counted values.
*
* The map does not hold a reference to its members, they must have
* external references to exist. When last external reference is
* released, the value is atomically erased from the map and deleted.
*
* The map itself is a member of a ref-counted holder class, the
* map ensures its holder is not deleted till the map is empty.
*/
template <class Key, class Data, class Impl=std::map<Key, Data*> >
class RefCountedMap : public RefCountedChild {
template <class, class, class, class> friend class RefCountedMapData;
typedef typename Impl::iterator iterator;
typedef typename Impl::value_type value_type;
mutable sys::Mutex lock;
Impl map;
// Acquire the lock and ensure map is not deleted before unlock.
class Lock {
boost::intrusive_ptr<const RefCountedMap> map;
sys::Mutex::ScopedLock lock;
public:
Lock(const RefCountedMap* m) : map(m), lock(m->lock) {}
};
// Called from Data::released.
void lockedDetach(iterator i) { Lock l(this); detach(i); }
void detach(iterator i) {
// Must be called with lock held.
assert(i->second->map == this);
map.erase(i);
i->second->map = 0; // May call this->release()
}
public:
RefCountedMap(RefCounted& container) : RefCountedChild(container) {}
~RefCountedMap() {}
/** Return 0 if not found */
boost::intrusive_ptr<Data> find(const Key& k) {
Lock l(this);
iterator i = map.find(k);
return (i == map.end()) ? 0 : i->second;
}
bool insert(const Key& k, boost::intrusive_ptr<Data> d) {
Lock l(this);
iterator i;
bool inserted;
boost::tuples::tie(i, inserted) =
map.insert(std::make_pair(k, d.get()));
if (inserted) {
assert(!d->map);
d->map=boost::polymorphic_downcast<RefCountedMap*>(this);
d->self=i;
}
return inserted;
}
size_t size() { Lock l(this); return map.size(); }
bool empty() { Lock l(this); return map.empty(); }
void erase(const Key& k) { Lock l(this); detach(map.find(k)); }
void clear() { Lock l(this); while (!map.empty()) detach(map.begin()); }
/** Clear the map, apply functor to each entry before erasing */
template <class F> void clear(F functor) {
Lock l(this);
while (!map.empty()) {
boost::intrusive_ptr<Data> ptr;
if (map.empty()) return;
ptr = map.begin()->second;
detach(map.begin());
sys::Mutex::ScopedUnlock u(lock);
functor(ptr);
}
}
/** Apply functor to each map entry. */
template <class F> void apply(F functor) {
std::vector<boost::intrusive_ptr<Data> > snapshot;
{
// Take a snapshot referencing all values in map.
Lock l(this);
snapshot.resize(map.size());
typedef value_type value_type;
std::transform(map.begin(), map.end(), snapshot.begin(),
boost::bind(&value_type::second, _1));
}
// Drop the lock to call functor.
std::for_each(snapshot.begin(), snapshot.end(), functor);
}
};
}} // namespace qpid::sys
#endif /*!QPID_SYS_REFCOUNTEDMAP_H*/
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