HistogramWriter (Yamcs :: Core 5.3.0 API)

java.lang.Object
- org.yamcs.yarch.rocksdb.HistogramWriter

Direct Known Subclasses:

SingleColumnHistogramWriter
```
public abstract class HistogramWriter
extends Object
```
Writes histograms for one table.
There is one of these objects for each table used by the table writers.
The HistogramRebuilder will use another writer during build
It does allow concurrent access

Field Summary

Fields
Modifier and Type	Field	Description
`protected List<org.yamcs.yarch.rocksdb.HistogramWriter.ColumnHistogramWriter>`	`columnWriters`
`protected RdbTable`	`table`
`protected TableDefinition`	`tableDefinition`
`protected Tablespace`	`tablespace`

Constructor Summary

Constructors
Constructor Description

HistogramWriter(RdbTable table)

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract void`	`addHistogram(Row sertuple)`
`static HistogramWriter`	`newWriter(RdbTable table)`
`abstract CompletableFuture<org.rocksdb.Snapshot>`	`startQueueing(String dir)`	called from the histogram rebuilder to start queueing all new data while the builder rebuilds a (part) of the.
`abstract void`	`stopQueueing(String partitionDir)`	called from the histogram rebuilder to stop queuing and start again updating histograms starting with the ones queued

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

Field Detail

tablespace
```
protected final Tablespace tablespace
```

tableDefinition

protected final TableDefinition tableDefinition

table
```
protected final RdbTable table
```

columnWriters

protected final List<org.yamcs.yarch.rocksdb.HistogramWriter.ColumnHistogramWriter> columnWriters

Constructor Detail

HistogramWriter

public HistogramWriter(RdbTable table)

Method Detail
- addHistogram
```
public abstract void addHistogram(Row sertuple)
                           throws IOException,
                                  org.rocksdb.RocksDBException
```
  Throws:
  
  IOException
  
  org.rocksdb.RocksDBException
- startQueueing
```
public abstract CompletableFuture<org.rocksdb.Snapshot> startQueueing(String dir)
                                                               throws IOException
```
  called from the histogram rebuilder to start queueing all new data while the builder rebuilds a (part) of the.
  Returns a snapshot of the database for the given partition at the time of the call.
  The caller is responsible for releasing the snapshot histograms
  
  Parameters:
  
  dir -
  
  Throws:
  
  IOException
- stopQueueing
```
public abstract void stopQueueing(String partitionDir)
```
  called from the histogram rebuilder to stop queuing and start again updating histograms starting with the ones queued
  
  Parameters:
  
  partitionDir -
- newWriter
```
public static HistogramWriter newWriter(RdbTable table)
```