nh-rep/code/pre_processing/ParametricSample/Mathematics/ThreadSafeMap.h

// David Eberly, Geometric Tools, Redmond WA 98052
// Copyright (c) 1998-2021
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
// https://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// Version: 4.0.2019.08.13

#pragma once

#include <map>
#include <mutex>
#include <vector>

namespace gte
{
    template <typename Key, typename Value>
    class ThreadSafeMap
    {
    public:
        // Construction and destruction.
        ThreadSafeMap() = default;
        virtual ~ThreadSafeMap() = default;

        // All the operations are thread-safe.
        bool HasElements() const
        {
            bool hasElements;
            mMutex.lock();
            {
                hasElements = (mMap.size() > 0);
            }
            mMutex.unlock();
            return hasElements;
        }

        bool Exists(Key key) const
        {
            bool exists;
            mMutex.lock();
            {
                exists = (mMap.find(key) != mMap.end());
            }
            mMutex.unlock();
            return exists;
        }

        void Insert(Key key, Value value)
        {
            mMutex.lock();
            {
                mMap[key] = value;
            }
            mMutex.unlock();
        }

        bool Remove(Key key, Value& value)
        {
            bool exists;
            mMutex.lock();
            {
                auto iter = mMap.find(key);
                if (iter != mMap.end())
                {
                    value = iter->second;
                    mMap.erase(iter);
                    exists = true;
                }
                else
                {
                    exists = false;
                }
            }
            mMutex.unlock();
            return exists;
        }

        void RemoveAll()
        {
            mMutex.lock();
            {
                mMap.clear();
            }
            mMutex.unlock();
        }

        bool Get(Key key, Value& value) const
        {
            bool exists;
            mMutex.lock();
            {
                auto iter = mMap.find(key);
                if (iter != mMap.end())
                {
                    value = iter->second;
                    exists = true;
                }
                else
                {
                    exists = false;
                }
            }
            mMutex.unlock();
            return exists;
        }

        void GatherAll(std::vector<Value>& values) const
        {
            mMutex.lock();
            {
                if (mMap.size() > 0)
                {
                    values.resize(mMap.size());
                    auto viter = values.begin();
                    for (auto const& m : mMap)
                    {
                        *viter++ = m.second;
                    }
                }
                else
                {
                    values.clear();
                }
            }
            mMutex.unlock();
        }

    protected:
        std::map<Key, Value> mMap;
        mutable std::mutex mMutex;
    };
}