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/**
* Copyright (C) 2015 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <type_traits>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/static_assert.h"
#include "mongo/stdx/functional.h"
#include "mongo/util/decoration_container.h"
namespace mongo {
/**
* Registry of decorations.
*
* A decoration registry corresponds to the "type" of a DecorationContainer. For example, if
* you have two registries, r1 and r2, a DecorationContainer constructed from r1 has instances
* the decorations declared on r1, and a DecorationContainer constructed from r2 has instances
* of the decorations declared on r2.
*/
class DecorationRegistry {
MONGO_DISALLOW_COPYING(DecorationRegistry);
public:
DecorationRegistry() = default;
/**
* Declares a decoration of type T, constructed with T's default constructor, and
* returns a descriptor for accessing that decoration.
*
* NOTE: T's destructor must not throw exceptions.
*/
template <typename T>
DecorationContainer::DecorationDescriptorWithType<T> declareDecoration() {
MONGO_STATIC_ASSERT_MSG(std::is_nothrow_destructible<T>::value,
"Decorations must be nothrow destructible");
return DecorationContainer::DecorationDescriptorWithType<T>(std::move(declareDecoration(
sizeof(T), std::alignment_of<T>::value, &constructAt<T>, &destructAt<T>)));
}
size_t getDecorationBufferSizeBytes() const {
return _totalSizeBytes;
}
/**
* Constructs the decorations declared in this registry on the given instance of
* "decorable".
*
* Called by the DecorationContainer constructor. Do not call directly.
*/
void construct(DecorationContainer* decorable) const;
/**
* Destroys the decorations declared in this registry on the given instance of "decorable".
*
* Called by the DecorationContainer destructor. Do not call directly.
*/
void destruct(DecorationContainer* decorable) const;
private:
/**
* Function that constructs (initializes) a single instance of a decoration.
*/
using DecorationConstructorFn = stdx::function<void(void*)>;
/**
* Function that destructs (deinitializes) a single instance of a decoration.
*/
using DecorationDestructorFn = stdx::function<void(void*)>;
struct DecorationInfo {
DecorationInfo() {}
DecorationInfo(DecorationContainer::DecorationDescriptor descriptor,
DecorationConstructorFn constructor,
DecorationDestructorFn destructor);
DecorationContainer::DecorationDescriptor descriptor;
DecorationConstructorFn constructor;
DecorationDestructorFn destructor;
};
using DecorationInfoVector = std::vector<DecorationInfo>;
template <typename T>
static void constructAt(void* location) {
new (location) T();
}
template <typename T>
static void destructAt(void* location) {
static_cast<T*>(location)->~T();
}
/**
* Declares a decoration with given "constructor" and "destructor" functions,
* of "sizeBytes" bytes.
*
* NOTE: "destructor" must not throw exceptions.
*/
DecorationContainer::DecorationDescriptor declareDecoration(size_t sizeBytes,
size_t alignBytes,
DecorationConstructorFn constructor,
DecorationDestructorFn destructor);
DecorationInfoVector _decorationInfo;
size_t _totalSizeBytes{0};
};
} // namespace mongo
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