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#ifndef QPID_CLUSTER_EXP_UNIQUEIDS_H
#define QPID_CLUSTER_EXP_UNIQUEIDS_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 <set>
namespace qpid {
namespace cluster {
/**
* Assign ID numbers, ensuring that all the assigned IDs are unique
* T is the numeric type - actually any type with >, == and ++ will do.
*/
template <class T> class UniqueIds
{
public:
/** Get an ID that is different from all other active IDs.
*@return the ID, which is now considered active.
*/
T get() {
sys::Mutex::ScopedLock l(lock);
T old = mark;
while (active.find(++mark) != active.end() && mark != old)
;
assert(mark != old); // check wrap-around
active.insert(mark);
return mark;
}
/** Release an ID, so it is inactive and available for re-use */
void release(T id) {
sys::Mutex::ScopedLock l(lock);
active.erase(id);
}
/** Allocate an ID, release automatically at end of scope */
struct Scope {
UniqueIds& ids;
T id;
Scope(UniqueIds& ids_) : ids(ids_), id(ids.get()) {}
~Scope() { ids.release(id); }
};
private:
sys::Mutex lock;
std::set<T> active;
T mark;
};
}} // namespace qpid::cluster
#endif /*!QPID_CLUSTER_EXP_UNIQUEIDS_H*/
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