Package org.apache.catalina.ha.deploy
Class FileMessageFactory
- java.lang.Object
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- org.apache.catalina.ha.deploy.FileMessageFactory
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public class FileMessageFactory extends Object
This factory is used to read files and write files by splitting them up into smaller messages. So that entire files don't have to be read into memory.
The factory can be used as a reader or writer but not both at the same time. When done reading or writing the factory will close the input or output streams and mark the factory as closed. It is not possible to use it after that.
To force a cleanup, call cleanup() from the calling object.
This class is not thread safe.- Version:
- 1.0
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Field Summary
Fields Modifier and Type Field Description protected booleanclosedOnce the factory is used, it cannot be reused.protected longcreationTimeThe time this instance was created.protected byte[]dataThe bytes that we hold the data in, not thread safe.protected FilefileThe file that we are reading/writingprotected FileInputStreaminWhen openForWrite=false, the input stream is held by this variableprotected booleanisWritingFlag that indicates if a thread is writing messages to disk.protected AtomicLonglastMessageProcessedThe number of the last message processed.protected intmaxValidTimeThe maximum valid time(in seconds) from creationTime.protected Map<Long,FileMessage>msgBufferMessages received out of order are held in the buffer until required.protected intnrOfMessagesProcessedThe number of messages we have writtenprotected booleanopenForWriteTrue means that we are writing with this factory.protected FileOutputStreamoutWhen openForWrite=true, the output stream is held by this variablestatic intREAD_SIZEThe number of bytes that we read from fileprotected longsizeThe total size of the fileprotected longtotalNrOfMessagesThe total number of packets that we split this file into
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description protected voidcheckState(boolean openForWrite)Check to make sure the factory is able to perform the function it is asked to do.voidcleanup()Closes the factory, its streams and sets all its references to nullFilegetFile()static FileMessageFactorygetInstance(File f, boolean openForWrite)Creates a factory to read or write from a file.intgetMaxValidTime()booleanisValid()FileMessagereadMessage(FileMessage f)Reads file data into the file message and sets the size, totalLength, totalNrOfMsgs and the message number
If EOF is reached, the factory returns null, and closes itself, otherwise the same message is returned as was passed in.voidsetMaxValidTime(int maxValidTime)booleanwriteMessage(FileMessage msg)Writes a message to file.
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Field Detail
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READ_SIZE
public static final int READ_SIZE
The number of bytes that we read from file- See Also:
- Constant Field Values
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file
protected final File file
The file that we are reading/writing
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openForWrite
protected final boolean openForWrite
True means that we are writing with this factory. False means that we are reading with this factory
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closed
protected boolean closed
Once the factory is used, it cannot be reused.
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in
protected FileInputStream in
When openForWrite=false, the input stream is held by this variable
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out
protected FileOutputStream out
When openForWrite=true, the output stream is held by this variable
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nrOfMessagesProcessed
protected int nrOfMessagesProcessed
The number of messages we have written
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size
protected long size
The total size of the file
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totalNrOfMessages
protected long totalNrOfMessages
The total number of packets that we split this file into
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lastMessageProcessed
protected AtomicLong lastMessageProcessed
The number of the last message processed. Message IDs are 1 based.
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msgBuffer
protected final Map<Long,FileMessage> msgBuffer
Messages received out of order are held in the buffer until required. If everything is worked as expected, messages will spend very little time in the buffer.
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data
protected byte[] data
The bytes that we hold the data in, not thread safe.
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isWriting
protected boolean isWriting
Flag that indicates if a thread is writing messages to disk. Access to this flag must be synchronised.
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creationTime
protected long creationTime
The time this instance was created. (in milliseconds)
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maxValidTime
protected int maxValidTime
The maximum valid time(in seconds) from creationTime.
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Method Detail
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getInstance
public static FileMessageFactory getInstance(File f, boolean openForWrite) throws FileNotFoundException, IOException
Creates a factory to read or write from a file. When opening for read, the readMessage can be invoked, and when opening for write the writeMessage can be invoked.- Parameters:
f- File - the file to be read or writtenopenForWrite- boolean - true, means we are writing to the file, false means we are reading from it- Returns:
- FileMessageFactory
- Throws:
FileNotFoundException- - if the file to be read doesn't existIOException- - if it fails to create the file that is to be written
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readMessage
public FileMessage readMessage(FileMessage f) throws IllegalArgumentException, IOException
Reads file data into the file message and sets the size, totalLength, totalNrOfMsgs and the message number
If EOF is reached, the factory returns null, and closes itself, otherwise the same message is returned as was passed in. This makes sure that not more memory is ever used. To remember, neither the file message or the factory are thread safe. Don't hand off the message to one thread and read the same with another.- Parameters:
f- FileMessage - the message to be populated with file data- Returns:
- FileMessage - returns the same message passed in as a parameter, or null if EOF
- Throws:
IllegalArgumentException- - if the factory is for writing or is closedIOException- - if a file read exception occurs
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writeMessage
public boolean writeMessage(FileMessage msg) throws IllegalArgumentException, IOException
Writes a message to file. If (msg.getMessageNumber() == msg.getTotalNrOfMsgs()) the output stream will be closed after writing.- Parameters:
msg- FileMessage - message containing data to be written- Returns:
- returns true if the file is complete and outputstream is closed, false otherwise.
- Throws:
IllegalArgumentException- - if the factory is opened for read or closedIOException- - if a file write error occurs
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cleanup
public void cleanup()
Closes the factory, its streams and sets all its references to null
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checkState
protected void checkState(boolean openForWrite) throws IllegalArgumentExceptionCheck to make sure the factory is able to perform the function it is asked to do. Invoked by readMessage/writeMessage before those methods proceed.- Parameters:
openForWrite- The value to check- Throws:
IllegalArgumentException- if the state is not the expected one
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getFile
public File getFile()
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isValid
public boolean isValid()
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getMaxValidTime
public int getMaxValidTime()
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setMaxValidTime
public void setMaxValidTime(int maxValidTime)
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