modules/platforms/cpp/examples/continuous-query-example/src/continuous_query_example.cpp

/*
 * 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 <stdint.h>
#include <iostream>

#include <ignite/ignition.h>
#include <ignite/cache/query/continuous/continuous_query.h>

#include "ignite/examples/person.h"

using namespace ignite;
using namespace cache;
using namespace query;

using namespace examples;

/** Cache name. */
const char* CACHE_NAME = "cpp_cache_continuous_query";

/**
 * Listener class.
 */
template<typename K, typename V>
class Listener : public event::CacheEntryEventListener<K, V>
{
public:
    /**
     * Default constructor.
     */
    Listener()
    {
        // No-op.
    }

    /**
     * Event callback.
     *
     * @param evts Events.
     * @param num Events number.
     */
    virtual void OnEvent(const CacheEntryEvent<K, V>* evts, uint32_t num)
    {
        for (uint32_t i = 0; i < num; ++i)
        {
            std::cout << "Queried entry [key=" << (evts[i].HasValue() ? evts[i].GetKey() : K())
                      << ", val=" << (evts[i].HasValue() ? evts[i].GetValue() : V()) << ']'
                      << std::endl;
        }
    }
};

/**
 * Range Filter. Only lets through keys from the specified range.
 */
template<typename K, typename V>
struct RangeFilter : event::CacheEntryEventFilter<int32_t, std::string>
{
    /**
     * Default constructor.
     */
    RangeFilter() :
        rangeBegin(0),
        rangeEnd(0)
    {
        // No-op.
    }

    /**
     * Constructor.
     *
     * @param from Range beginning. Inclusive.
     * @param to Range end. Not inclusive.
     */
    RangeFilter(const K& from, const K& to) :
        rangeBegin(from),
        rangeEnd(to)
    {
        // No-op.
    }

    /**
     * Destructor.
     */
    virtual ~RangeFilter()
    {
        // No-op.
    }

    /**
     * Event callback.
     *
     * @param event Event.
     * @return True if the event passes filter.
     */
    virtual bool Process(const CacheEntryEvent<K, V>& event)
    {
        return event.GetKey() >= rangeBegin && event.GetKey() < rangeEnd;
    }

    /** Beginning of the range. */
    K rangeBegin;

    /** End of the range. */
    K rangeEnd;
};

namespace ignite
{
    namespace binary
    {
        template<>
        struct BinaryType< RangeFilter<int32_t, std::string> > :
            BinaryTypeDefaultAll< RangeFilter<int32_t, std::string> >
        {
            static void GetTypeName(std::string& dst)
            {
                dst = "RangeFilter<int32_t,std::string>";

            }

            static void Write(BinaryWriter& writer, const RangeFilter<int32_t, std::string>& obj)
            {
                writer.WriteInt32("rangeBegin", obj.rangeBegin);
                writer.WriteInt32("rangeEnd", obj.rangeEnd);
            }

            static void Read(BinaryReader& reader, RangeFilter<int32_t, std::string>& dst)
            {
                dst.rangeBegin = reader.ReadInt32("rangeBegin");
                dst.rangeEnd = reader.ReadInt32("rangeEnd");
            }
        };
    }
}


int main()
{
    IgniteConfiguration cfg;

    cfg.springCfgPath = "platforms/cpp/examples/continuous-query-example/config/continuous-query-example.xml";

    try
    {
        // Start a node.
        Ignite ignite = Ignition::Start(cfg);

        std::cout << std::endl;
        std::cout << ">>> Cache continuous query example started." << std::endl;
        std::cout << std::endl;

        // Get binding.
        IgniteBinding binding = ignite.GetBinding();

        // Registering remote filter.
        binding.RegisterCacheEntryEventFilter< RangeFilter<int32_t, std::string> >();

        // Get cache instance.
        Cache<int32_t, std::string> cache = ignite.GetOrCreateCache<int32_t, std::string>(CACHE_NAME);

        cache.Clear();

        const int32_t keyCnt = 20;

        for (int32_t i = 0; i < keyCnt; ++i)
        {
            std::stringstream builder;

            builder << i;

            cache.Put(i, builder.str());
        }

        // Declaring listener.
        Listener<int32_t, std::string> listener;

        // Declaring filter.
        RangeFilter<int32_t, std::string> filter(keyCnt, keyCnt + 5);

        // Declaring continuous query.
        continuous::ContinuousQuery<int32_t, std::string> qry(MakeReference(listener), MakeReference(filter));

        {
            // Continuous query scope. Query is closed when scope is left.
            continuous::ContinuousQueryHandle<int32_t, std::string> handle = cache.QueryContinuous(qry);

            // Add a few more keys and watch more query notifications.
            for (int32_t i = keyCnt; i < keyCnt + 10; ++i)
            {
                std::stringstream builder;

                builder << i;

                cache.Put(i, builder.str());
            }

            // Let user wait while callback is notified about remaining puts.
            std::cout << std::endl;
            std::cout << ">>> Press 'Enter' to continue..." << std::endl;
            std::cout << std::endl;

            std::cin.get();
        }

        // Stop node.
        Ignition::StopAll(false);
    }
    catch (IgniteError& err)
    {
        std::cout << "An error occurred: " << err.GetText() << std::endl;

        return err.GetCode();
    }

    std::cout << std::endl;
    std::cout << ">>> Example finished, press 'Enter' to exit ..." << std::endl;
    std::cout << std::endl;

    std::cin.get();

    return 0;
}