Colocating Computations with Data

IgniteCache<Integer, String> cache = ignite.cache("myCache");

IgniteCompute compute = ignite.compute();

int key = 1;

// This closure will execute on the remote node where
// data for the given 'key' is located.
compute.affinityRun("myCache", key, () -> {
    // Peek is a local memory lookup.
    System.out.println("Co-located [key= " + key + ", value= " + cache.localPeek(key) + ']');
});

class MyComputeAction : IComputeAction
{
    [InstanceResource] private readonly IIgnite _ignite;

    public int Key { get; set; }

    public void Invoke()
    {
        var cache = _ignite.GetCache<int, string>("myCache");
        // Peek is a local memory lookup
        Console.WriteLine("Co-located [key= " + Key + ", value= " + cache.LocalPeek(Key) + ']');
    }
}

public static void AffinityRunDemo()
{
    var cfg = new IgniteConfiguration();
    var ignite = Ignition.Start(cfg);

    var cache = ignite.GetOrCreateCache<int, string>("myCache");
    cache.Put(0, "foo");
    cache.Put(1, "bar");
    cache.Put(2, "baz");
    var keyCnt = 3;

    var compute = ignite.GetCompute();

    for (var key = 0; key < keyCnt; key++)
    {
        // This closure will execute on the remote node where
        // data for the given 'key' is located.
        compute.AffinityRun("myCache", key, new MyComputeAction {Key = key});
    }
}

/*
 * Function class.
 */
struct FuncAffinityRun : compute::ComputeFunc<void>
{
    /*
    * Default constructor.
    */
    FuncAffinityRun()
    {
        // No-op.
    }

    /*
    * Parameterized constructor.
    */
    FuncAffinityRun(std::string cacheName, int32_t key) :
        cacheName(cacheName), key(key)
    {
        // No-op.
    }

    /**
     * Callback.
     */
    virtual void Call()
    {
        Ignite& node = GetIgnite();

        Cache<int32_t, std::string> cache = node.GetCache<int32_t, std::string>(cacheName.c_str());

        // Peek is a local memory lookup.
        std::cout << "Co-located [key= " << key << ", value= " << cache.LocalPeek(key, CachePeekMode::ALL) << "]" << std::endl;
    }

    std::string cacheName;
    int32_t key;
};

/**
 * Binary type structure. Defines a set of functions required for type to be serialized and deserialized.
 */
namespace ignite
{
    namespace binary
    {
        template<>
        struct BinaryType<FuncAffinityRun>
        {
            static int32_t GetTypeId()
            {
                return GetBinaryStringHashCode("FuncAffinityRun");
            }

            static void GetTypeName(std::string& dst)
            {
                dst = "FuncAffinityRun";
            }

            static int32_t GetFieldId(const char* name)
            {
                return GetBinaryStringHashCode(name);
            }

            static int32_t GetHashCode(const FuncAffinityRun& obj)
            {
                return 0;
            }

            static bool IsNull(const FuncAffinityRun& obj)
            {
                return false;
            }

            static void GetNull(FuncAffinityRun& dst)
            {
                dst = FuncAffinityRun();
            }

            static void Write(BinaryWriter& writer, const FuncAffinityRun& obj)
            {
                writer.WriteString("cacheName", obj.cacheName);
                writer.WriteInt32("key", obj.key);
            }

            static void Read(BinaryReader& reader, FuncAffinityRun& dst)
            {
                dst.cacheName = reader.ReadString("cacheName");
                dst.key = reader.ReadInt32("key");
            }
        };
    }
}


int main()
{
    IgniteConfiguration cfg;
    cfg.springCfgPath = "/path/to/configuration.xml";

    Ignite ignite = Ignition::Start(cfg);

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

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

    // Registering our class as a compute function.
    binding.RegisterComputeFunc<FuncAffinityRun>();

    // Get compute instance.
    compute::Compute compute = ignite.GetCompute();

    int key = 1;

    // This closure will execute on the remote node where
    // data for the given 'key' is located.
    compute.AffinityRun(cache.GetName(), key, FuncAffinityRun(cache.GetName(), key));
}

// this task sums up the values of the salary field for the given set of keys
private static class SumTask implements IgniteCallable<BigDecimal> {
    private Set<Long> keys;

    public SumTask(Set<Long> keys) {
        this.keys = keys;
    }

    @IgniteInstanceResource
    private Ignite ignite;

    @Override
    public BigDecimal call() throws Exception {

        IgniteCache<Long, BinaryObject> cache = ignite.cache("person").withKeepBinary();

        BigDecimal sum = new BigDecimal(0);

        for (long k : keys) {
            BinaryObject person = cache.localPeek(k, CachePeekMode.PRIMARY);
            if (person != null)
                sum = sum.add(new BigDecimal((float) person.field("salary")));
        }

        return sum;
    }
}

public static void calculateAverage(Ignite ignite, Set<Long> keys) {

    // get the affinity function configured for the cache
    Affinity<Long> affinityFunc = ignite.affinity("person");

    // this map stores collections of keys for each partition
    HashMap<Integer, Set<Long>> partMap = new HashMap<>();
    keys.forEach(k -> {
        int partId = affinityFunc.partition(k);

        Set<Long> keysByPartition = partMap.computeIfAbsent(partId, key -> new HashSet<Long>());
        keysByPartition.add(k);
    });

    BigDecimal total = new BigDecimal(0);

    IgniteCompute compute = ignite.compute();

    List<String> caches = Arrays.asList("person");

    // iterate over all partitions
    for (Map.Entry<Integer, Set<Long>> pair : partMap.entrySet()) {
        // send a task that gets specific keys for the partition
        BigDecimal sum = compute.affinityCall(caches, pair.getKey().intValue(), new SumTask(pair.getValue()));
        total = total.add(sum);
    }

    System.out.println("the average salary is " + total.floatValue() / keys.size());
}

This API is not presently available for C#/.NET.

This API is not presently available for C++.

// this task sums up the value of the 'salary' field for all objects stored in
// the given partition
public static class SumByPartitionTask implements IgniteCallable<BigDecimal> {
    private int partId;

    public SumByPartitionTask(int partId) {
        this.partId = partId;
    }

    @IgniteInstanceResource
    private Ignite ignite;

    @Override
    public BigDecimal call() throws Exception {
        // use binary objects to avoid deserialization
        IgniteCache<Long, BinaryObject> cache = ignite.cache("person").withKeepBinary();

        BigDecimal total = new BigDecimal(0);
        try (QueryCursor<Cache.Entry<Long, BinaryObject>> cursor = cache
                .query(new ScanQuery<Long, BinaryObject>(partId).setLocal(true))) {
            for (Cache.Entry<Long, BinaryObject> entry : cursor) {
                total = total.add(new BigDecimal((float) entry.getValue().field("salary")));
            }
        }

        return total;
    }
}

This API is not presently available for C#/.NET.

This API is not presently available for C++.

IgniteCache<String, Integer> cache = ignite.cache("mycache");

// Increment the value for a specific key by 1.
// The operation will be performed on the node where the key is stored.
// Note that if the cache does not contain an entry for the given key, it will
// be created.
cache.invoke("mykey", (entry, args) -> {
    Integer val = entry.getValue();

    entry.setValue(val == null ? 1 : val + 1);

    return null;
});

void CacheInvoke()
{
    var ignite = Ignition.Start();

    var cache = ignite.GetOrCreateCache<int, int>("myCache");

    var proc = new Processor();

    // Increment cache value 10 times
    for (int i = 0; i < 10; i++)
        cache.Invoke(1, proc, 5);
}

class Processor : ICacheEntryProcessor<int, int, int, int>
{
    public int Process(IMutableCacheEntry<int, int> entry, int arg)
    {
        entry.Value = entry.Exists ? arg : entry.Value + arg;

        return entry.Value;
    }
}

/**
 * Processor for invoke method.
 */
class IncrementProcessor : public cache::CacheEntryProcessor<std::string, int32_t, int32_t, int32_t>
{
public:
    /**
     * Constructor.
     */
    IncrementProcessor()
    {
        // No-op.
    }

    /**
     * Copy constructor.
     *
     * @param other Other instance.
     */
    IncrementProcessor(const IncrementProcessor& other)
    {
        // No-op.
    }

    /**
     * Assignment operator.
     *
     * @param other Other instance.
     * @return This instance.
     */
    IncrementProcessor& operator=(const IncrementProcessor& other)
    {
        return *this;
    }

    /**
     * Call instance.
     */
    virtual int32_t Process(MutableCacheEntry<std::string, int32_t>& entry, const int& arg)
    {
        // Increment the value for a specific key by 1.
        // The operation will be performed on the node where the key is stored.
        // Note that if the cache does not contain an entry for the given key, it will
        // be created.
        if (!entry.IsExists())
            entry.SetValue(1);
        else
            entry.SetValue(entry.GetValue() + 1);

        return entry.GetValue();
    }
};

/**
 * Binary type structure. Defines a set of functions required for type to be serialized and deserialized.
 */
namespace ignite
{
    namespace binary
    {
        template<>
        struct BinaryType<IncrementProcessor>
        {
            static int32_t GetTypeId()
            {
                return GetBinaryStringHashCode("IncrementProcessor");
            }

            static void GetTypeName(std::string& dst)
            {
                dst = "IncrementProcessor";
            }

            static int32_t GetFieldId(const char* name)
            {
                return GetBinaryStringHashCode(name);
            }

            static int32_t GetHashCode(const IncrementProcessor& obj)
            {
                return 0;
            }

            static bool IsNull(const IncrementProcessor& obj)
            {
                return false;
            }

            static void GetNull(IncrementProcessor& dst)
            {
                dst = IncrementProcessor();
            }

            static void Write(BinaryWriter& writer, const IncrementProcessor& obj)
            {
                // No-op.
            }

            static void Read(BinaryReader& reader, IncrementProcessor& dst)
            {
                // No-op.
            }
        };
    }
}

int main()
{
    IgniteConfiguration cfg;
    cfg.springCfgPath = "platforms/cpp/examples/put-get-example/config/example-cache.xml";

    Ignite ignite = Ignition::Start(cfg);

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

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

    // Registering our class as a cache entry processor.
    binding.RegisterCacheEntryProcessor<IncrementProcessor>();

    std::string key("mykey");
    IncrementProcessor inc;

    cache.Invoke<int32_t>(key, inc, NULL);
}