Package edu.caltech.nanodb.storage

Class DBFileWriter

java.lang.Object

edu.caltech.nanodb.storage.DBFileReader

edu.caltech.nanodb.storage.DBFileWriter

All Implemented Interfaces:

AutoCloseable

public class DBFileWriter
extends DBFileReader

A subclass of DBFileReader, this class provides the basic ability to read and write a DBFile as a single sequential file, obscuring the fact that it is actually broken into pages. As the file-pointer moves through the file, the Storage Manager is used to load individual pages into the buffer manager.

It is certainly possible that a value being read or written might span two adjacent data pages. In these cases, the access will be a little slower, as the operation must access partial data from the first page, and then access the remainder of the data from the next page.

Design Note:

This class always has the current DBPage pinned, and it will unpin the current page when it moves into the next page. This means that when the writer is closed, it may still have a page that is pinned. Therefore, the class implements AutoCloseable so that users can call DBFileReader.close() on a writer to unpin the last page, or they can use this type with the "try-with-resources" Java syntax.

Field Summary

Fields

Modifier and Type	Field	Description
private static org.apache.logging.log4j.Logger	logger	A logging object for reporting anything interesting that happens.

Fields inherited from class edu.caltech.nanodb.storage.DBFileReader

dbFile, dbPage, extendFile, pageSize, position, storageManager, tmpBuf

Constructor Summary

Constructors

Constructor	Description
DBFileWriter(DBFile dbFile, StorageManager storageManager)

Method Summary

Modifier and Type	Method	Description
void	write(byte[] b)
void	write(byte[] b, int off, int len)
void	writeBoolean(boolean v)
void	writeByte(int v)
void	writeChar(int v)
void	writeDouble(double v)
void	writeFloat(float v)
void	writeInt(int v)
void	writeLong(long v)
void	writeShort(int v)
void	writeVarString255(String value)
void	writeVarString65535(String value)

Methods inherited from class edu.caltech.nanodb.storage.DBFileReader

checkDBPage, close, getDBFile, getPosition, getPositionPageNo, getPositionPageOffset, movePosition, read, read, readBoolean, readByte, readChar, readDouble, readFloat, readInt, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readVarString255, readVarString65535, setPosition

Methods inherited from class java.lang.Object

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

Field Details

logger

private static org.apache.logging.log4j.Logger logger

A logging object for reporting anything interesting that happens.

Constructor Details

DBFileWriter

public DBFileWriter(DBFile dbFile,
 StorageManager storageManager)

Method Details

write

public void write(byte[] b,
 int off,
 int len)

write

public void write(byte[] b)

writeBoolean

public void writeBoolean(boolean v)

writeByte

public void writeByte(int v)

writeShort

public void writeShort(int v)

writeChar

public void writeChar(int v)

writeInt

public void writeInt(int v)

writeLong

public void writeLong(long v)

writeFloat

public void writeFloat(float v)

writeDouble

public void writeDouble(double v)

writeVarString255

public void writeVarString255(String value)

writeVarString65535

public void writeVarString65535(String value)