/root/doris/be/src/common/object_pool.h

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// 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.

#pragma once

#include <mutex>
#include <vector>

#include "util/spinlock.h"

namespace doris {

// An ObjectPool maintains a list of C++ objects which are deallocated
// by destroying the pool.
// Thread-safe.
class ObjectPool {
public:
    ObjectPool() = default;

    ~ObjectPool() { clear(); }

    template <class T>
    T* add(T* t) {
        // TODO: Consider using a lock-free structure.
        std::lock_guard<SpinLock> l(_lock);
        _objects.emplace_back(Element {t, [](void* obj) { delete reinterpret_cast<T*>(obj); }});
        return t;
    }

    template <class T>
    T* add_array(T* t) {
        std::lock_guard<SpinLock> l(_lock);
        _objects.emplace_back(Element {t, [](void* obj) { delete[] reinterpret_cast<T*>(obj); }});
        return t;
    }

    void clear() {
        std::lock_guard<SpinLock> l(_lock);
        // reverse delete object to make sure the obj can
        // safe access the member object construt early by
        // object pool
        for (auto obj = _objects.rbegin(); obj != _objects.rend(); obj++) {
            obj->delete_fn(obj->obj);
        }
        _objects.clear();
    }

    void acquire_data(ObjectPool* src) {
        _objects.insert(_objects.end(), src->_objects.begin(), src->_objects.end());
        src->_objects.clear();
    }

    uint64_t size() {
        std::lock_guard<SpinLock> l(_lock);
        return _objects.size();
    }

private:
    ObjectPool(const ObjectPool&) = delete;
    void operator=(const ObjectPool&) = delete;

    /// A generic deletion function pointer. Deletes its first argument.
    using DeleteFn = void (*)(void*);

    /// For each object, a pointer to the object and a function that deletes it.
    struct Element {
        void* obj = nullptr;
        DeleteFn delete_fn;
    };

    std::vector<Element> _objects;
    SpinLock _lock;
};

} // namespace doris

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Created: 2024-11-20 15:52