alma.acs.util.stringqueue

Class QueueFile

java.lang.Object

alma.acs.util.stringqueue.QueueFile

public class QueueFile
extends java.lang.Object

Each file used by the cache.

The cache is composed by

• a File to know the length of the file on disc.
• a RandomAccessFile for reading and writing

There are two booleans signaling if the file is used for reading and writing. In this way we know when the reads and writes are terminated and the file can be safely closed.

Author:

acaproni

Field Summary

Fields

Modifier and Type	Field and Description
java.lang.String	fileName The name of the file
java.lang.Integer	key The key identifying this file.

Constructor Summary

Constructors

Constructor and Description
QueueFile(java.lang.String fName, java.lang.Integer key, java.io.RandomAccessFile rf, java.io.File f, java.lang.String tstampStrTag) Constructor

Method Summary

Modifier and Type	Method and Description
void	close() Release all the resources (for instance it releases the random file).
java.io.File	getFile() An helper methods that returns the File.
long	getFileLength() Return the size of the file
long	getNumOfStringsInFile()
java.lang.String	maxDate()
java.lang.String	minDate()
java.lang.String	readFromFile(QueueEntry entry) Read a string from the file
void	setReadingMode(boolean reading) Set the reading mode of the file.
void	setWritingMode(boolean writing) Set the writing mode of the file.
QueueEntry	writeOnFile(java.lang.String str, java.lang.Integer key) Write the passed string in the file.

Methods inherited from class java.lang.Object

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

Field Detail

fileName

public final java.lang.String fileName

The name of the file

key

public final java.lang.Integer key

The key identifying this file.

The key is stored only to perform run-time tests of correctness.

Constructor Detail

QueueFile

public QueueFile(java.lang.String fName,
                 java.lang.Integer key,
                 java.io.RandomAccessFile rf,
                 java.io.File f,
                 java.lang.String tstampStrTag)
          throws java.io.IOException

Constructor

Parameters:

fName - The name of the file

key - The key of this entry

rf - The RandomAccessFile used for I/O

f - The File used to get the length

tstampStrTag - The string to find the timestamp in each pushed string

Throws:

java.io.IOException - In case of error writing in the file

See Also:

QueueFile(String fName, Integer key)}

Method Detail

getFile

public java.io.File getFile()
                     throws java.io.FileNotFoundException

An helper methods that returns the File.

As soon as raFile is not null, file is not null too. A new File is built if file is null otherwise the method returns a reference to file.

Returns:

The file

Throws:

java.io.FileNotFoundException - If the file does not exist

close

public void close()

Release all the resources (for instance it releases the random file).

getFileLength

public long getFileLength()

Return the size of the file

Returns:

the size of the file

writeOnFile

public QueueEntry writeOnFile(java.lang.String str,
                              java.lang.Integer key)
                       throws java.io.IOException,
                              StringQueueException

Write the passed string in the file.

Parameters:

str - The string to write in the file

Returns:

The ending position of the string in the file

Throws:

java.io.IOException - In case of error while performing I/O

StringQueueException - In case of error reading the date of the log from str

readFromFile

public java.lang.String readFromFile(QueueEntry entry)
                              throws java.io.IOException

Read a string from the file

Parameters:

entry - The cache entry to saying how to read the entry

Returns:

The string read from the file

Throws:

java.io.IOException

setReadingMode

public void setReadingMode(boolean reading)

Set the reading mode of the file.

Parameters:

reading - true if the file is used for reading

setWritingMode

public void setWritingMode(boolean writing)

Set the writing mode of the file.

Parameters:

writing - true if the file is used for writing

minDate

public java.lang.String minDate()

Returns:

the date of the youngest log in this file in ISO format

getNumOfStringsInFile

public long getNumOfStringsInFile()

Returns:

The number of strings in this file

maxDate

public java.lang.String maxDate()

Returns:

the date of the oldest log in this file in ISO format