SynchronousLoadingBlockCache (Apache Accumulo Core 2.0.0 API)

java.lang.Object
- org.apache.accumulo.core.file.blockfile.cache.lru.SynchronousLoadingBlockCache

All Implemented Interfaces:

BlockCache

Direct Known Subclasses:

LruBlockCache
```
public abstract class SynchronousLoadingBlockCache
extends Object
implements BlockCache
```
This class implements loading in such a way that load operations for the same block will not run concurrently.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.apache.accumulo.core.spi.cache.BlockCache
  BlockCache.Loader, BlockCache.Stats

Constructor Summary

Constructors
Constructor Description

SynchronousLoadingBlockCache()

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`CacheEntry`	`getBlock(String blockName, BlockCache.Loader loader)`	This method allows a cache to prevent concurrent loads of the same block.
`protected abstract CacheEntry`	`getBlockNoStats(String blockName)`	Get a block from the cache without changing any stats the cache is keeping.
`protected abstract int`	`getMaxEntrySize()`	Get the maximum size of an individual cache entry.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.accumulo.core.spi.cache.BlockCache
cacheBlock, getBlock, getMaxHeapSize, getMaxSize, getStats

- Constructor Detail
  - SynchronousLoadingBlockCache
```
public SynchronousLoadingBlockCache()
```
- Method Detail
  - getMaxEntrySize
```
protected abstract int getMaxEntrySize()
```
    Get the maximum size of an individual cache entry.
  - getBlockNoStats
```
protected abstract CacheEntry getBlockNoStats(String blockName)
```
    Get a block from the cache without changing any stats the cache is keeping.
  - getBlock
```
public CacheEntry getBlock(String blockName,
                           BlockCache.Loader loader)
```
    Description copied from interface: BlockCache
    
    This method allows a cache to prevent concurrent loads of the same block. However a cache implementation is not required to prevent concurrent loads. SynchronousLoadingBlockCache is an abstract class that a cache can extent which does prevent concurrent loading of the same block.
    
    Specified by:
    
    getBlock in interface BlockCache
    
    Parameters:
    
    blockName - Block name to fetch
    
    loader - If the block is not present in the cache, the loader can be called to load it.
    
    Returns:
    
    Block or null if block is not in the cache or didn't load.