FetchResultPersister (thomasjungblut-common 2.0.0 API)

java.lang.Object
- de.jungblut.crawl.FetchResultPersister<T>

All Implemented Interfaces:

java.lang.Runnable
```
public final class FetchResultPersister<T extends FetchResult>
extends java.lang.Object
implements java.lang.Runnable
```
Asynchronous persister thread, taking a resultwriter and handles the logic behind asynchronous writing to disk or an arbitrary sink implemented by the ResultWriter. The lifecycle is the following, you can submit an instance of this class as a thread and if you want to stop it you can call the stop() method. Then it will make the backed queue read-only and flush all items in it to the result writer.

Author:

thomas.jungblut

Constructor Summary

Constructors
Constructor	Description
`FetchResultPersister(ResultWriter<T> resWriter)`
`FetchResultPersister(ResultWriter<T> resWriter, org.apache.hadoop.conf.Configuration conf)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`add(T result)`	Add a crawled result to the back queue.
`void`	`run()`	Run logic of this `Runnable`.
`void`	`stop()`	Stop this persister and make the queue read-only.

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

- Constructor Detail
  - FetchResultPersister
```
public FetchResultPersister(ResultWriter<T> resWriter)
                     throws java.io.IOException
```
    Throws:
    
    java.io.IOException
  - FetchResultPersister
```
public FetchResultPersister(ResultWriter<T> resWriter,
                            org.apache.hadoop.conf.Configuration conf)
                     throws java.io.IOException
```
    Throws:
    
    java.io.IOException
- Method Detail
  - add
```
public final void add(T result)
```
    Add a crawled result to the back queue. Notice that after stop() has been called, this queue will not accept any items anymore.
  - stop
```
public void stop()
```
    Stop this persister and make the queue read-only.
  - run
```
public final void run()
```
    Run logic of this Runnable. Basically if we haven't stopped, we will poll the queue, if there is no item anymore we will wait for 10 seconds. If we have received a stop() command, the queue will be freezed and all exisiting items will be flushed to disk. ResultWriter close is guaranteed to run in case of failure (guarded by finally).
    
    Specified by:
    
    run in interface java.lang.Runnable