Module com.fasterxml.uuid

Package com.fasterxml.uuid.ext

Class LockedFile

java.lang.Object

com.fasterxml.uuid.ext.LockedFile

class LockedFile
extends Object

Utility class used by FileBasedTimestampSynchronizer to do actual file access and locking.

Class stores simple timestamp values based on system time accessed using System.currentTimeMillis(). A single timestamp is stored into a file using RandomAccessFile in fully synchronized mode. Value is written in ISO-Latin (ISO-8859-1) encoding (superset of Ascii, 1 byte per char) as 16-digit hexadecimal number, surrounded by brackets. As such, file produced should always have exact size of 18 bytes. For extra robustness, slight variations in number of digits are accepeted, as are white space chars before and after bracketed value.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	LockedFile.LoggerWrapper

Field Summary

Fields

Modifier and Type	Field	Description
(package private) static final int	DEFAULT_LENGTH	Expected file length comes from hex-timestamp (16 digits), preamble "[0x",(3 chars) and trailer "]\r\n" (2 chars, linefeed to help debugging -- in some environments, missing trailing linefeed causes problems: also, 2-char linefeed to be compatible with all standard linefeeds on MacOS, Unix and Windows).
(package private) static final String	HEX_DIGITS
(package private) static LockedFile.LoggerWrapper	logger
private static final org.slf4j.Logger	LOGGER
(package private) FileChannel	mChannel
(package private) final File	mFile
(package private) long	mLastTimestamp	Marker used to ensure that the timestamps stored are monotonously increasing.
(package private) FileLock	mLock
(package private) RandomAccessFile	mRAFile
(package private) boolean	mWeirdSize	Flag set if the original file (created before this instance was created) had size other than default size and needs to be truncated
(package private) ByteBuffer	mWriteBuffer
(package private) static final long	READ_ERROR

Constructor Summary

Constructors

Constructor	Description
LockedFile(File f)

Method Summary

Modifier and Type	Method	Description
void	deactivate()
protected static void	doDeactivate(File f, RandomAccessFile raf, FileLock lock)
(package private) static void	logging(boolean enabled)
long	readStamp()
void	writeStamp(long stamp)

Methods inherited from class java.lang.Object

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

Field Details

LOGGER

private static final org.slf4j.Logger LOGGER

logger

static LockedFile.LoggerWrapper logger

DEFAULT_LENGTH

static final int DEFAULT_LENGTH

Expected file length comes from hex-timestamp (16 digits), preamble "[0x",(3 chars) and trailer "]\r\n" (2 chars, linefeed to help debugging -- in some environments, missing trailing linefeed causes problems: also, 2-char linefeed to be compatible with all standard linefeeds on MacOS, Unix and Windows).

See Also:

• Constant Field Values

READ_ERROR

static final long READ_ERROR

See Also:

• Constant Field Values

mFile

final File mFile

mRAFile

RandomAccessFile mRAFile

mChannel

FileChannel mChannel

mLock

FileLock mLock

mWriteBuffer

ByteBuffer mWriteBuffer

mWeirdSize

boolean mWeirdSize

Flag set if the original file (created before this instance was created) had size other than default size and needs to be truncated

mLastTimestamp

long mLastTimestamp

Marker used to ensure that the timestamps stored are monotonously increasing. Shouldn't really be needed, since caller should take care of it, but let's be bit paranoid here.

HEX_DIGITS

static final String HEX_DIGITS

See Also:

• Constant Field Values

Constructor Details

LockedFile

LockedFile(File f)
    throws IOException

Throws:

IOException

Method Details

logging

static void logging(boolean enabled)

deactivate

public void deactivate()

readStamp

public long readStamp()

writeStamp

public void writeStamp(long stamp)
                throws IOException

Throws:

IOException

doDeactivate

protected static void doDeactivate(File f,
 RandomAccessFile raf,
 FileLock lock)