org.apache.ignite

## Interface IgniteDataStreamer<K,V>

- All Superinterfaces:
    AutoCloseable

      public interface IgniteDataStreamer<K,V>
      extends AutoCloseable

  Data streamer is responsible for streaming external data into cache. It achieves it by properly buffering updates and properly mapping keys to nodes responsible for the data to make sure that there is the least amount of data movement possible and optimal network and memory utilization.

  Note that data streamer data manipulation methods do not support transactions. When updating data with `allowOverwrite()` set to `false` new entry is created on primary and backups if it has not existed. If `allowOverwrite()` is `true` then batches are applied with regular `cache.put(..)` methods starting implicit transactions if streamer is targeted to a transactional cache.

  However, explicit transactional updates inside are possible with custom `StreamReceiver`. This way batches can be applied within transaction(s) on target node. See `receiver(StreamReceiver)` for details.

  Data streamer doesn’t guarantee:

  - Data order. Data records may be loaded into a cache in a different order compared to putting into the streamer;
  - Immediate data loading. Data can be kept for a while before loading;
  - By default, data consistency until successfully finished;
  - By default, working with external storages.

  If `allowOverwrite()` setting is `false` (default), consider:

  - You should not have the same keys repeating in the data being streamed;
  - Streamer cancelation or streamer node failure can cause data inconsistency;
  - If loading into a persistent cache, concurrently created snapshot may contain inconsistent data and might not be restored entirely.
  Most important behaviour of data streamer is defined by `StreamReceiver` and `allowOverwrite()` property.

  Also note that `IgniteDataStreamer` is not the only way to add data into cache. Alternatively you can use `IgniteCache.loadCache(IgniteBiPredicate, Object...)` method to add data from underlying data store. You can also use standard cache `put(...)` and `putAll(...)` operations as well, but they most likely will not perform as well as this class for adding data. And finally, data can be added from underlying data store on demand, whenever it is accessed - for this no explicit data adding step is needed.

  `IgniteDataStreamer` supports the following configuration properties:

  - `perNodeBufferSize(int)` - when entries are added to data streamer via `addData(Object, Object)` method, they are not sent to in-memory data grid right away and are buffered internally for better performance and network utilization. This setting controls the size of internal per-node buffer before buffered data is sent to remote node. Default is defined by `DFLT_PER_NODE_BUFFER_SIZE` value.
  - `perNodeParallelOperations(int)` - sometimes data may be added to the data streamer via `addData(Object, Object)` method faster than it can be put in cache. In this case, new buffered stream messages are sent to remote nodes before responses from previous ones are received. This could cause unlimited heap memory utilization growth on local and remote nodes. To control memory utilization, this setting limits maximum allowed number of parallel buffered stream messages that are being processed on remote nodes. If this number is exceeded, then `addData(Object, Object)` method will block to control memory utilization. Default is equal to CPU count on remote node multiply by `DFLT_PARALLEL_OPS_MULTIPLIER`.
  - `autoFlushFrequency(long)` - automatic flush frequency in milliseconds. Essentially, this is the time after which the streamer will make an attempt to submit all data added so far to remote nodes. Note that there is no guarantee that data will be delivered after this concrete attempt (e.g., it can fail when topology is changing), but it won't be lost anyway. Disabled by default (default value is `0`).
  - `allowOverwrite(boolean)` - Sets flag enabling overwriting existing values in cache. Data streamer will perform better if this flag is disabled, which is the default setting.
  - `receiver(StreamReceiver)` - defines how cache will be updated with added entries. It allows to provide user-defined custom logic to update the cache in the most effective and flexible way.
  - `deployClass(Class)` - optional deploy class for peer deployment. All classes streamed by a data streamer must be class-loadable from the same class-loader. Ignite will make the best effort to detect the most suitable class-loader for data loading. However, in complex cases, where compound or deeply nested class-loaders are used, it is best to specify a deploy class which can be any class loaded by the class-loader for given data.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `DFLT_MAX_PARALLEL_OPS` Deprecated. Is not used anymore.
    `static int` | `DFLT_PARALLEL_OPS_MULTIPLIER` Default multiplier for data streamer pool size to get concurrent batches count for each remote node.
    `static int` | `DFLT_PER_NODE_BUFFER_SIZE` Default operations batch size to sent to remote node for loading.
    `static int` | `DFLT_PER_THREAD_BUFFER_SIZE` Default batch size per thread to send to buffer on node.
    `static long` | `DFLT_UNLIMIT_TIMEOUT` Default timeout for streamer's operations.

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `IgniteFuture<?>` | `addData(Collection<? extends Map.Entry<K,V>> entries)` Adds data for streaming on remote node.
    `IgniteFuture<?>` | `addData(K key, V val)` Adds data for streaming on remote node.
    `IgniteFuture<?>` | `addData(Map.Entry<K,V> entry)` Adds data for streaming on remote node.
    `IgniteFuture<?>` | `addData(Map<K,V> entries)` Adds data for streaming on remote node.
    `boolean` | `allowOverwrite()` Gets flag enabling overwriting existing values in cache.
    `void` | `allowOverwrite(boolean allowOverwrite)` Sets flag enabling overwriting existing values in cache.
    `long` | `autoFlushFrequency()` Gets automatic flush frequency.
    `void` | `autoFlushFrequency(long autoFlushFreq)` Sets automatic flush frequency.
    `String` | `cacheName()` Name of cache to stream data to.
    `void` | `close()` Closes data streamer.
    `void` | `close(boolean cancel)` Streams any remaining data and closes this streamer.
    `void` | `deployClass(Class<?> depCls)` Optional deploy class for peer deployment.
    `void` | `flush()` Streams any remaining data, but doesn't close the streamer.
    `IgniteFuture<?>` | `future()` Gets future for this streaming process.
    `boolean` | `keepBinary()` Gets flag indicating that objects should be kept in binary format when passed to the stream receiver.
    `void` | `keepBinary(boolean keepBinary)` Sets flag indicating that objects should be kept in binary format when passes to the steam receiver.
    `int` | `perNodeBufferSize()` Gets size of per node key-value pairs buffer.
    `void` | `perNodeBufferSize(int bufSize)` Sets size of per node key-value pairs buffer.
    `int` | `perNodeParallelOperations()` Gets maximum number of parallel stream operations for a single node.
    `void` | `perNodeParallelOperations(int parallelOps)` Sets maximum number of parallel stream operations for a single node.
    `int` | `perThreadBufferSize()` Gets buffer size set by `perThreadBufferSize(int)`.
    `void` | `perThreadBufferSize(int size)` Allows to set buffer size for thread in case of stream by `addData(Object, Object)` call.
    `void` | `receiver(StreamReceiver<K,V> rcvr)` Sets custom stream receiver to this data streamer.
    `IgniteFuture<?>` | `removeData(K key)` Adds key for removal on remote node.
    `boolean` | `skipStore()` Gets flag indicating that write-through behavior should be disabled for data streaming.
    `void` | `skipStore(boolean skipStore)` Sets flag indicating that write-through behavior should be disabled for data streaming.
    `long` | `timeout()` Gets timeout set by `timeout(long)`.
    `void` | `timeout(long timeout)` Sets the timeout that is used in the following cases: any data addition method can be blocked when all per node parallel operations are exhausted.
    `void` | `tryFlush()` Makes an attempt to stream remaining data.

- - ### Field Detail

    - #### DFLT_MAX_PARALLEL_OPS

          @Deprecated
          static final int DFLT_MAX_PARALLEL_OPS

      Deprecated. Is not used anymore.
      Default max concurrent put operations count.
      See Also:
        Constant Field Values

    - #### DFLT_PARALLEL_OPS_MULTIPLIER

          static final int DFLT_PARALLEL_OPS_MULTIPLIER

      Default multiplier for data streamer pool size to get concurrent batches count for each remote node.
      See Also:
        `IgniteConfiguration.getDataStreamerThreadPoolSize()`, `perNodeParallelOperations()`, Constant Field Values

    - #### DFLT_PER_NODE_BUFFER_SIZE

          static final int DFLT_PER_NODE_BUFFER_SIZE

      Default operations batch size to sent to remote node for loading.
      See Also:
        Constant Field Values

    - #### DFLT_PER_THREAD_BUFFER_SIZE

          static final int DFLT_PER_THREAD_BUFFER_SIZE

      Default batch size per thread to send to buffer on node.
      See Also:
        Constant Field Values

    - #### DFLT_UNLIMIT_TIMEOUT

          static final long DFLT_UNLIMIT_TIMEOUT

      Default timeout for streamer's operations.
      See Also:
        Constant Field Values

  - ### Method Detail

    - #### cacheName

          String cacheName()

      Name of cache to stream data to.
      Returns:
        Cache name or `null` for default cache.

    - #### allowOverwrite

          boolean allowOverwrite()

      Gets flag enabling overwriting existing values in cache. Data streamer will perform better if this flag is disabled.

      This flag is disabled by default (default is `false`).

      Returns:
        `True` if overwriting is allowed or if receiver is changed by `receiver(StreamReceiver)`. `False` otherwise.

    - #### allowOverwrite

          void allowOverwrite(boolean allowOverwrite)
                       throws javax.cache.CacheException

      Sets flag enabling overwriting existing values in cache. Data streamer will perform better if this flag is disabled. Note that when this flag is `false`, updates will not be propagated to the cache store (i.e. `skipStore()` flag will be set to `true` implicitly).

      This flag is disabled by default (default is `false`).

      The flag has no effect when custom cache receiver set using `receiver(StreamReceiver)` method.

      Parameters:
        `allowOverwrite` - Flag value.
      Throws:
        `javax.cache.CacheException` - If failed.

    - #### skipStore

          boolean skipStore()

      Gets flag indicating that write-through behavior should be disabled for data streaming. Default is `false`.
      Returns:
        Skip store flag.

    - #### skipStore

          void skipStore(boolean skipStore)

      Sets flag indicating that write-through behavior should be disabled for data streaming. Default is `false`.
      Parameters:
        `skipStore` - Skip store flag.

    - #### keepBinary

          boolean keepBinary()

      Gets flag indicating that objects should be kept in binary format when passed to the stream receiver. Default is `false`.
      Returns:
        Skip store flag.

    - #### keepBinary

          void keepBinary(boolean keepBinary)

      Sets flag indicating that objects should be kept in binary format when passes to the steam receiver. Default is `false`.
      Parameters:
        `keepBinary` - Keep binary flag.

    - #### perNodeBufferSize

          int perNodeBufferSize()

      Gets size of per node key-value pairs buffer.
      Returns:
        Per node buffer size.

    - #### perNodeBufferSize

          void perNodeBufferSize(int bufSize)

      Sets size of per node key-value pairs buffer.

      This method should be called prior to `addData(Object, Object)` call.

      If not provided, default value is `DFLT_PER_NODE_BUFFER_SIZE`.

      Parameters:
        `bufSize` - Per node buffer size.

    - #### perNodeParallelOperations

          int perNodeParallelOperations()

      Gets maximum number of parallel stream operations for a single node.
      Returns:
        Maximum number of parallel stream operations for a single node.

    - #### perNodeParallelOperations

          void perNodeParallelOperations(int parallelOps)

      Sets maximum number of parallel stream operations for a single node.

      This method should be called prior to `addData(Object, Object)` call.

      If not provided, default value is calculated as follows `DFLT_PARALLEL_OPS_MULTIPLIER` * `DATA_STREAMER_POOL_SIZE_ON_REMOTE_NODE`.

      Parameters:
        `parallelOps` - Maximum number of parallel stream operations for a single node.
      See Also:
        `IgniteConfiguration.getDataStreamerThreadPoolSize()`

    - #### perThreadBufferSize

          void perThreadBufferSize(int size)

      Allows to set buffer size for thread in case of stream by `addData(Object, Object)` call.
      Parameters:
        `size` - Size of buffer.

    - #### perThreadBufferSize

          int perThreadBufferSize()

      Gets buffer size set by `perThreadBufferSize(int)`.
      Returns:
        Buffer size.

    - #### timeout

          void timeout(long timeout)

      Sets the timeout that is used in the following cases:
      - any data addition method can be blocked when all per node parallel operations are exhausted. The timeout defines the max time you will be blocked waiting for a permit to add a chunk of data into the streamer;
      - Total timeout time for `flush()` operation;
      - Total timeout time for `close()` operation.
      By default the timeout is disabled.
      Parameters:
        `timeout` - Timeout in milliseconds.
      Throws:
        `IllegalArgumentException` - If timeout is zero or less than `-1`.

    - #### timeout

          long timeout()

      Gets timeout set by `timeout(long)`.
      Returns:
        Timeout in milliseconds.

    - #### autoFlushFrequency

          long autoFlushFrequency()

      Gets automatic flush frequency. Essentially, this is the time after which the streamer will make an attempt to submit all data added so far to remote nodes. Note that there is no guarantee that data will be delivered after this concrete attempt (e.g., it can fail when topology is changing), but it won't be lost anyway.

      If set to `0`, automatic flush is disabled.

      Automatic flush is disabled by default (default value is `0`).

      Returns:
        Flush frequency or `0` if automatic flush is disabled.
      See Also:
        `flush()`

    - #### autoFlushFrequency

          void autoFlushFrequency(long autoFlushFreq)

      Sets automatic flush frequency. Essentially, this is the time after which the streamer will make an attempt to submit all data added so far to remote nodes. Note that there is no guarantee that data will be delivered after this concrete attempt (e.g., it can fail when topology is changing), but it won't be lost anyway.

      If set to `0`, automatic flush is disabled.

      Automatic flush is disabled by default (default value is `0`).

      Parameters:
        `autoFlushFreq` - Flush frequency or `0` to disable automatic flush.
      See Also:
        `flush()`

    - #### future

          IgniteFuture<?> future()

      Gets future for this streaming process. This future completes whenever method `close(boolean)` completes. By attaching listeners to this future it is possible to get asynchronous notifications for completion of this streaming process.
      Returns:
        Future for this streaming process.

    - #### deployClass

          void deployClass(Class<?> depCls)

      Optional deploy class for peer deployment. All classes added by a data streamer must be class-loadable from the same class-loader. Ignite will make the best effort to detect the most suitable class-loader for data loading. However, in complex cases, where compound or deeply nested class-loaders are used, it is best to specify a deploy class which can be any class loaded by the class-loader for given data.
      Parameters:
        `depCls` - Any class loaded by the class-loader for given data.

    - #### receiver

          void receiver(StreamReceiver<K,V> rcvr)

      Sets custom stream receiver to this data streamer.

      Disables `allowOverwrite(boolean)` and sets `allowOverwrite()` returning `true`.

      Parameters:
        `rcvr` - Stream receiver.

    - #### removeData

          IgniteFuture<?> removeData(K key)
                              throws javax.cache.CacheException,
                                     IgniteInterruptedException,
                                     IllegalStateException

      Adds key for removal on remote node. Equivalent to `addData(key, null)`.
      Parameters:
        `key` - Key.
      Returns:
        Future for this operation. Note: It may never complete unless `flush()` or `close()` are explicitly called.
      Throws:
        `javax.cache.CacheException` - If failed to map key to node.
        `IgniteInterruptedException` - If thread has been interrupted.
        `IllegalStateException` - If grid has been concurrently stopped or `close(boolean)` has already been called on streamer.

    - #### addData

          IgniteFuture<?> addData(K key,
                                  @Nullable
                                  V val)
                           throws javax.cache.CacheException,
                                  IgniteInterruptedException,
                                  IllegalStateException,
                                  IgniteDataStreamerTimeoutException

      Adds data for streaming on remote node. This method can be called from multiple threads in parallel to speed up streaming if needed.

      Note that streamer will stream data concurrently by multiple internal threads, so the data may get to remote nodes in different order from which it was added to the streamer. The data may not be sent until `flush()` or `close()` are called.

      Note: if `allowOverwrite()` set to `false` (by default) then data streamer will not overwrite existing cache entries for better performance (to change, set `allowOverwrite(boolean)` to `true`)

      Parameters:
        `key` - Key.
        `val` - Value or `null` if respective entry must be removed from cache.
      Returns:
        Future for this operation. Note: It may never complete unless `flush()` or `close()` are explicitly called.
      Throws:
        `javax.cache.CacheException` - If failed to map key to node.
        `IgniteInterruptedException` - If thread has been interrupted.
        `IllegalStateException` - If grid has been concurrently stopped or `close(boolean)` has already been called on streamer.
        `IgniteDataStreamerTimeoutException` - If `timeout` is exceeded.
      See Also:
        `allowOverwrite()`

    - #### addData

          IgniteFuture<?> addData(Map.Entry<K,V> entry)
                           throws javax.cache.CacheException,
                                  IgniteInterruptedException,
                                  IllegalStateException,
                                  IgniteDataStreamerTimeoutException

      Adds data for streaming on remote node. This method can be called from multiple threads in parallel to speed up streaming if needed.

      Note that streamer will stream data concurrently by multiple internal threads, so the data may get to remote nodes in different order from which it was added to the streamer. The data may not be sent until `flush()` or `close()` are called.

      Note: if `allowOverwrite()` set to `false` (by default) then data streamer will not overwrite existing cache entries for better performance (to change, set `allowOverwrite(boolean)` to `true`)

      Parameters:
        `entry` - Entry.
      Returns:
        Future for this operation. Note: It may never complete unless `flush()` or `close()` are explicitly called.
      Throws:
        `javax.cache.CacheException` - If failed to map key to node.
        `IgniteInterruptedException` - If thread has been interrupted.
        `IllegalStateException` - If grid has been concurrently stopped or `close(boolean)` has already been called on streamer.
        `IgniteDataStreamerTimeoutException` - If `timeout` is exceeded.
      See Also:
        `allowOverwrite()`

    - #### addData

          IgniteFuture<?> addData(Collection<? extends Map.Entry<K,V>> entries)
                           throws IllegalStateException,
                                  IgniteDataStreamerTimeoutException

      Adds data for streaming on remote node. This method can be called from multiple threads in parallel to speed up streaming if needed.

      Note that streamer will stream data concurrently by multiple internal threads, so the data may get to remote nodes in different order from which it was added to the streamer. The data may not be sent until `flush()` or `close()` are called.

      Note: if `allowOverwrite()` set to `false` (by default) then data streamer will not overwrite existing cache entries for better performance (to change, set `allowOverwrite(boolean)` to `true`)

      Parameters:
        `entries` - Collection of entries to be streamed.
      Returns:
        Future for this stream operation. Note: It may never complete unless `flush()` or `close()` are explicitly called.
      Throws:
        `IllegalStateException` - If grid has been concurrently stopped or `close(boolean)` has already been called on streamer.
        `IgniteDataStreamerTimeoutException` - If `timeout` is exceeded.
      See Also:
        `allowOverwrite()`

    - #### addData

          IgniteFuture<?> addData(Map<K,V> entries)
                           throws IllegalStateException,
                                  IgniteDataStreamerTimeoutException

      Adds data for streaming on remote node. This method can be called from multiple threads in parallel to speed up streaming if needed.

      Note that streamer will stream data concurrently by multiple internal threads, so the data may get to remote nodes in different order from which it was added to the streamer. The data may not be sent until `flush()` or `close()` are called.

      Note: if `allowOverwrite()` set to `false` (by default) then data streamer will not overwrite existing cache entries for better performance (to change, set `allowOverwrite(boolean)` to `true`)

      Parameters:
        `entries` - Map to be streamed.
      Returns:
        Future for this stream operation. Note: It may never complete unless `flush()` or `close()` are explicitly called.
      Throws:
        `IllegalStateException` - If grid has been concurrently stopped or `close(boolean)` has already been called on streamer.
        `IgniteDataStreamerTimeoutException` - If `timeout` is exceeded.
      See Also:
        `allowOverwrite()`

    - #### flush

          void flush()
              throws javax.cache.CacheException,
                     IgniteInterruptedException,
                     IllegalStateException,
                     IgniteDataStreamerTimeoutException

      Streams any remaining data, but doesn't close the streamer. Data can be still added after flush is finished. This method blocks and doesn't allow to add any data until all data is streamed.

      If another thread is already performing flush, this method will block, wait for another thread to complete flush and exit. If you don't want to wait in this case, use `tryFlush()` method.

      Note that #flush() guarantees completion of all futures returned by `addData(Object, Object)`, listeners should be tracked separately.

      Throws:
        `javax.cache.CacheException` - If failed to load data from buffer.
        `IgniteInterruptedException` - If thread has been interrupted.
        `IllegalStateException` - If grid has been concurrently stopped or `close(boolean)` has already been called on streamer.
        `IgniteDataStreamerTimeoutException` - If `timeout` is exceeded.
      See Also:
        `tryFlush()`

    - #### tryFlush

          void tryFlush()
                 throws javax.cache.CacheException,
                        IgniteInterruptedException,
                        IllegalStateException

      Makes an attempt to stream remaining data. This method is mostly similar to `flush()`, with the difference that it won't wait and will exit immediately.
      Throws:
        `javax.cache.CacheException` - If failed to load data from buffer.
        `IgniteInterruptedException` - If thread has been interrupted.
        `IllegalStateException` - If grid has been concurrently stopped or `close(boolean)` has already been called on streamer.
      See Also:
        `flush()`

    - #### close

          void close(boolean cancel)
              throws javax.cache.CacheException,
                     IgniteInterruptedException,
                     IgniteDataStreamerTimeoutException

      Streams any remaining data and closes this streamer.
      Parameters:
        `cancel` - `True` to cancel ongoing streaming operations.
      Throws:
        `javax.cache.CacheException` - If failed to close data streamer.
        `IgniteInterruptedException` - If thread has been interrupted.
        `IgniteDataStreamerTimeoutException` - If `timeout` is exceeded, only if cancel is `false`.

    - #### close

          void close()
              throws javax.cache.CacheException,
                     IgniteInterruptedException,
                     IgniteDataStreamerTimeoutException

      Closes data streamer. This method is identical to calling `close(false)` method.

      The method is invoked automatically on objects managed by the `try-with-resources` statement.

      Specified by:
        `close` in interface `AutoCloseable`
      Throws:
        `javax.cache.CacheException` - If failed to close data streamer.
        `IgniteInterruptedException` - If thread has been interrupted.
        `IgniteDataStreamerTimeoutException` - If `timeout` is exceeded.

${current.year} Copyright © Apache Software Foundation
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Ignite Database and Caching Platform | : ver. 2.16.0
Release Date | : December 15 2023