org.apache.ignite.cache.store

## Class CacheLoadOnlyStoreAdapter<K,V,I>

- java.lang.Object
- - org.apache.ignite.cache.store.CacheLoadOnlyStoreAdapter<K,V,I>

- Type Parameters:
    `K` - Key type.
    `V` - Value type.
    `I` - Input type.
  All Implemented Interfaces:
    javax.cache.integration.CacheLoader<K,V>, javax.cache.integration.CacheWriter<K,V>, CacheStore<K,V>

      public abstract class CacheLoadOnlyStoreAdapter<K,V,I>
      extends Object
      implements CacheStore<K,V>

  This adapter designed to support stores with bulk loading from stream-like source.

  This class processes input data in the following way:

  - Iterator of input record obtained from user-defined `inputIterator(Object...)`.
  - Iterator continuously queried for input records and they are grouped into batches of `batchSize`.
  - Batch is placed into processing queue and puled by one of `threadsCnt` working threads.
  - Each record in batch is passed to user-defined `parse(Object, Object...)` method and result is stored into cache.

  Two methods should be implemented by inheritants:

  - `inputIterator(Object...)`. It should open underlying data source and iterate all record available in it. Individual records could be in very raw form, like text lines for CSV files.
  - `parse(Object, Object...)`. This method should process input records and transform them into key-value pairs for cache.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `DFLT_BATCH_QUEUE_SIZE` Default batch queue size (max batches count to limit memory usage).
    `static int` | `DFLT_BATCH_SIZE` Default batch size (number of records read with `inputIterator(Object...)`
    `static int` | `DFLT_THREADS_COUNT` Default number of working threads (equal to the number of available processors).

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `CacheLoadOnlyStoreAdapter()`

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `delete(Object key)`
    `void` | `deleteAll(Collection<?> keys)`
    `int` | `getBatchQueueSize()` Returns batch queue size.
    `int` | `getBatchSize()` Returns batch size.
    `int` | `getThreadsCount()` Returns number of worker threads.
    `protected abstract Iterator<I>` | `inputIterator(Object... args)` Returns iterator of input records.
    `V` | `load(K key)`
    `Map<K,V>` | `loadAll(Iterable<? extends K> keys)`
    `void` | `loadCache(IgniteBiInClosure<K,V> c, Object... args)` Loads all values from underlying persistent storage.
    `protected abstract @Nullable IgniteBiTuple<K,V>` | `parse(I rec, Object... args)` This method should transform raw data records into valid key-value pairs to be stored into cache.
    `void` | `sessionEnd(boolean commit)` Tells store to commit or rollback a transaction depending on the value of the `'commit'` parameter.
    `void` | `setBatchQueueSize(int batchQueueSize)` Sets batch queue size.
    `void` | `setBatchSize(int batchSize)` Sets batch size.
    `void` | `setThreadsCount(int threadsCnt)` Sets number of worker threads.
    `void` | `write(javax.cache.Cache.Entry<? extends K,? extends V> entry)`
    `void` | `writeAll(Collection<javax.cache.Cache.Entry<? extends K,? extends V>> entries)`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### DFLT_BATCH_SIZE

          public static final int DFLT_BATCH_SIZE

      Default batch size (number of records read with `inputIterator(Object...)` and then submitted to internal pool at a time).
      See Also:
        Constant Field Values

    - #### DFLT_BATCH_QUEUE_SIZE

          public static final int DFLT_BATCH_QUEUE_SIZE

      Default batch queue size (max batches count to limit memory usage).
      See Also:
        Constant Field Values

    - #### DFLT_THREADS_COUNT

          public static final int DFLT_THREADS_COUNT

      Default number of working threads (equal to the number of available processors).

  - ### Constructor Detail

    - #### CacheLoadOnlyStoreAdapter

          public CacheLoadOnlyStoreAdapter()

  - ### Method Detail

    - #### inputIterator

          protected abstract Iterator<I> inputIterator(@Nullable
                                                       Object... args)
                                                throws javax.cache.integration.CacheLoaderException

      Returns iterator of input records.

      Note that returned iterator doesn't have to be thread-safe. Thus it could operate on raw streams, DB connections, etc. without additional synchronization.

      Parameters:
        `args` - Arguments passes into `IgniteCache.loadCache(IgniteBiPredicate, Object...)` method.
      Returns:
        Iterator over input records.
      Throws:
        `javax.cache.integration.CacheLoaderException` - If iterator can't be created with the given arguments.

    - #### parse

          @Nullable
          protected abstract @Nullable IgniteBiTuple<K,V> parse(I rec,
                                                                          @Nullable
                                                                          Object... args)

      This method should transform raw data records into valid key-value pairs to be stored into cache.

      If `null` is returned then this record will be just skipped.

      Parameters:
        `rec` - A raw data record.
        `args` - Arguments passed into `IgniteCache.loadCache(IgniteBiPredicate, Object...)` method.
      Returns:
        Cache entry to be saved in cache or `null` if no entry could be produced from this record.

    - #### loadCache

          public void loadCache(IgniteBiInClosure<K,V> c,
                                @Nullable
                                Object... args)

      Loads all values from underlying persistent storage. Note that keys are not passed, so it is up to implementation to figure out what to load. This method is called whenever `IgniteCache.loadCache(IgniteBiPredicate, Object...)` method is invoked which is usually to preload the cache from persistent storage.

      This method is optional, and cache implementation does not depend on this method to do anything. Default implementation of this method in `CacheStoreAdapter` does nothing.

      For every loaded value method `IgniteBiInClosure.apply(Object, Object)` should be called on the passed in closure. The closure will then make sure that the loaded value is stored in cache.

      Specified by:
        `loadCache` in interface `CacheStore<K,V>`
      Parameters:
        `c` - Closure for loaded values.
        `args` - Arguments passes into `IgniteCache.loadCache(IgniteBiPredicate, Object...)` method.

    - #### getBatchSize

          public int getBatchSize()

      Returns batch size.
      Returns:
        Batch size.

    - #### setBatchSize

          public void setBatchSize(int batchSize)

      Sets batch size.
      Parameters:
        `batchSize` - Batch size.

    - #### getBatchQueueSize

          public int getBatchQueueSize()

      Returns batch queue size.
      Returns:
        Batch queue size.

    - #### setBatchQueueSize

          public void setBatchQueueSize(int batchQueueSize)

      Sets batch queue size.
      Parameters:
        `batchQueueSize` - Batch queue size.

    - #### getThreadsCount

          public int getThreadsCount()

      Returns number of worker threads.
      Returns:
        Number of worker threads.

    - #### setThreadsCount

          public void setThreadsCount(int threadsCnt)

      Sets number of worker threads.
      Parameters:
        `threadsCnt` - Number of worker threads.

    - #### load

          public V load(K key)

      Specified by:
        `load` in interface `javax.cache.integration.CacheLoader<K,V>`

    - #### loadAll

          public Map<K,V> loadAll(Iterable<? extends K> keys)

      Specified by:
        `loadAll` in interface `javax.cache.integration.CacheLoader<K,V>`

    - #### write

          public void write(javax.cache.Cache.Entry<? extends K,? extends V> entry)

      Specified by:
        `write` in interface `javax.cache.integration.CacheWriter<K,V>`

    - #### writeAll

          public void writeAll(Collection<javax.cache.Cache.Entry<? extends K,? extends V>> entries)

      Specified by:
        `writeAll` in interface `javax.cache.integration.CacheWriter<K,V>`

    - #### delete

          public void delete(Object key)

      Specified by:
        `delete` in interface `javax.cache.integration.CacheWriter<K,V>`

    - #### deleteAll

          public void deleteAll(Collection<?> keys)

      Specified by:
        `deleteAll` in interface `javax.cache.integration.CacheWriter<K,V>`

    - #### sessionEnd

          public void sessionEnd(boolean commit)

      Tells store to commit or rollback a transaction depending on the value of the `'commit'` parameter.
      Specified by:
        `sessionEnd` in interface `CacheStore<K,V>`
      Parameters:
        `commit` - `True` if transaction should commit, `false` for rollback.

2021 Copyright © Apache Software Foundation
| Follow @ApacheIgnite
Ignite Database and Caching Platform | : ver. 2.10.0
Release Date | : March 10 2021