com.levigo.jadice.document.io

Class FileCacheInputStream

java.lang.Object

java.io.InputStream

com.levigo.jadice.document.io.SeekableInputStream

com.levigo.jadice.document.io.FileCacheInputStream

All Implemented Interfaces:

Closeable, DataInput, AutoCloseable, ImageInputStream

public class FileCacheInputStream
extends SeekableInputStream

An concrete SeekableInputStream which works by caching the data in a temporary file. Configurable: jadice.io.fileCacheInputStream.read-ahead integer 2048 Read ahead specifies the number of bytes that are read, in excess of the number of bytes that would need to be read during fill operations. Read ahead significantly reduces the IO overhead.s

Field Summary

Fields inherited from class com.levigo.jadice.document.io.SeekableInputStream

bitOffset, byteOrder, flushedPos

Constructor Summary

Constructors

Constructor and Description
FileCacheInputStream(InputStream is) Create a new FileCacheInputStream which caches the given stream's data in a temporary file which is created in the default system temp directory.
FileCacheInputStream(InputStream is, File tmpFile, boolean removeOnExitOrClose) Create a new FileCacheInputStream which caches the given stream's data in the given temporary file.
FileCacheInputStream(InputStream is, File tmpFile, boolean removeOnExitOrClose, int readAhead) Create a new FileCacheInputStream which caches the given stream's data in the given temporary file.

Method Summary

Modifier and Type	Method and Description
void	close() Closes this seekable input stream.
static int	getCacheFileTimeToLiveSeconds() Get the time in seconds after which stale cache files are expunged.
static String	getDefaultCachePath() Return the default cache path to use, of no explicit path is given.
static int	getDefaultReadAhead() Return the default read-ahead
long	getSizeEstimate() A rough estimated size for this stream instance, which is used for internal cache management.
long	getStreamPosition()
boolean	isCached() Returns true since this ImageInputStream caches data in order to allow seeking backwards.
boolean	isCachedFile() Returns true since this ImageInputStream maintains a file cache.
boolean	isCachedMemory() Returns false since this ImageInputStream does not maintain a main memory cache.
static boolean	isDeleteStaleCacheFiles() Return whether stale cache files are automatically expunged.
long	length() Returns the length of this stream contents, if available.
int	read() Reads a single byte from the stream and returns it as an int between 0 and 255.
int	read(byte[] b) A convenience method that calls read(b, 0, b.length).
int	read(byte[] b, int off, int len) Reads up to len bytes from the stream, and stores them into b starting at index off.
void	seek(long pos) Sets the current stream position, measured from the beginning of this data stream, at which the next read occurs.
static void	setCacheFileTimeToLiveSeconds(int cacheFileTimeToLiveSeconds) Set the time in seconds after which stale cache files are expunged.
static void	setDefaultCachePath(String defaultCachePath) Set the default cache path to use, of no explicit path is given.
static void	setDefaultReadAhead(int defaultReadAhead) Set the default read-ahead in bytes.
static void	setDeleteStaleCacheFiles(boolean deleteStaleCacheFiles) Set whether to automatically delete stale cache files left over by earlier instances of this class.

Methods inherited from class com.levigo.jadice.document.io.SeekableInputStream

checkClosed, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, mark, mark, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedInt, readUnsignedShort, readUTF, reset, resetToInitialState, setBitOffset, setByteOrder, skip, skipBytes, skipBytes

Methods inherited from class java.io.InputStream

available, markSupported

Methods inherited from class java.lang.Object

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

Constructor Detail

FileCacheInputStream

public FileCacheInputStream(InputStream is)
                     throws IOException

Create a new FileCacheInputStream which caches the given stream's data in a temporary file which is created in the default system temp directory. The file is removed if the application exits or the stream is closed.

Parameters:

is - the input stream to cache.

Throws:

IOException

FileCacheInputStream

public FileCacheInputStream(InputStream is,
                            File tmpFile,
                            boolean removeOnExitOrClose)
                     throws IOException

Create a new FileCacheInputStream which caches the given stream's data in the given temporary file. If the file points to a directory, a temporary file is created inside the directory. If the file is null, a temporary file is created in the default system temp directory. The read-ahead is configured using a system property.

Parameters:

is - the input stream to cache.

tmpFile - the file/directory to in which to hold the data.

removeOnExitOrClose - whether the file sould be removed on the application's exit or stream close.

Throws:

IOException

FileCacheInputStream

public FileCacheInputStream(InputStream is,
                            File tmpFile,
                            boolean removeOnExitOrClose,
                            int readAhead)
                     throws IOException

Create a new FileCacheInputStream which caches the given stream's data in the given temporary file. If the file points to a directory, a temporary file is created inside the directory. If the file is null, a temporary file is created in the default system temp directory.

Parameters:

is - the input stream to cache.

tmpFile - the file/directory in which to hold the data. If this is null, a temp file is automatically generated.

removeOnExitOrClose - whether the file sould be removed on the application's exit or stream close.

readAhead - The read-ahead to use (in bytes)

Throws:

IllegalArgumentException - if is is null

IOException

Method Detail

getStreamPosition

public long getStreamPosition()
                       throws IOException

Throws:

IOException

See Also:

ImageInputStream.getStreamPosition()

length

public long length()
            throws IOException

Description copied from class: SeekableInputStream

Returns the length of this stream contents, if available. Otherwise -1L will be returned.

Specified by:

length in interface ImageInputStream

Specified by:

length in class SeekableInputStream

Returns:

the length, measured in bytes or -1L if unknown.

Throws:

IOException - if an I/O error occurs.

See Also:

ImageInputStream.length()

read

public int read()
         throws IOException

Description copied from class: SeekableInputStream

Reads a single byte from the stream and returns it as an int between 0 and 255. If EOF is reached, -1 is returned.

Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.

The bit offset within the stream must be reset to zero before the read occurs.

Specified by:

read in interface ImageInputStream

Specified by:

read in class SeekableInputStream

Returns:

the value of the next byte in the stream, or -1 if EOF is reached.

Throws:

IOException - if the stream has been closed.

See Also:

InputStream.read()

seek

public void seek(long pos)
          throws IOException

Description copied from class: SeekableInputStream

Sets the current stream position, measured from the beginning of this data stream, at which the next read occurs. The offset may be set beyond the end of this data stream. Setting the offset beyond the end does not change the data length, an EOFException will be thrown only if a read is performed. The bit offset is set to 0.

An IndexOutOfBoundsException will be thrown if pos is smaller than the flushed position (as returned by getflushedPosition).

It is legal to seek past the end of the file; an EOFException will be thrown only if a read is performed.

Specified by:

seek in interface ImageInputStream

Specified by:

seek in class SeekableInputStream

Parameters:

pos - a long containing the desired file pointer position.

Throws:

IOException - if any other I/O error occurs.

See Also:

SeekableInputStream.seek(long)

close

public void close()
           throws IOException

Description copied from class: SeekableInputStream

Closes this seekable input stream. Further attempts to read from it will throw IOExceptions. Additional attempts to SeekableInputStream.close(), however, have no effect.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface ImageInputStream

Overrides:

close in class SeekableInputStream

Throws:

IOException

See Also:

InputStream.close()

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

Description copied from class: SeekableInputStream

Reads up to len bytes from the stream, and stores them into b starting at index off. If no bytes can be read because the end of the stream has been reached, -1 is returned.

The bit offset within the stream must be reset to zero before the read occurs.

Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.

Specified by:

read in interface ImageInputStream

Specified by:

read in class SeekableInputStream

Parameters:

b - an array of bytes to be written to.

off - the starting position within b to write to.

len - the maximum number of bytes to read.

Returns:

the number of bytes actually read, or -1 to indicate EOF.

Throws:

IOException - if an I/O error occurs.

See Also:

InputStream.read(byte[], int, int)

read

public int read(byte[] b)
         throws IOException

Description copied from class: SeekableInputStream

A convenience method that calls read(b, 0, b.length).

The bit offset within the stream is reset to zero before the read occurs.

Specified by:

read in interface ImageInputStream

Overrides:

read in class SeekableInputStream

Parameters:

b - the byte buffer to fill up

Returns:

the number of bytes actually read, or -1 to indicate EOF.

Throws:

IOException - if an I/O error occurs.

See Also:

InputStream.read(byte[])

isCached

public boolean isCached()

Returns true since this ImageInputStream caches data in order to allow seeking backwards.

Specified by:

isCached in interface ImageInputStream

Overrides:

isCached in class SeekableInputStream

Returns:

true.

See Also:

isCachedMemory(), isCachedFile()

isCachedFile

public boolean isCachedFile()

Returns true since this ImageInputStream maintains a file cache.

Specified by:

isCachedFile in interface ImageInputStream

Overrides:

isCachedFile in class SeekableInputStream

Returns:

true.

See Also:

isCached(), isCachedMemory()

isCachedMemory

public boolean isCachedMemory()

Returns false since this ImageInputStream does not maintain a main memory cache.

Specified by:

isCachedMemory in interface ImageInputStream

Overrides:

isCachedMemory in class SeekableInputStream

Returns:

false.

See Also:

isCached(), isCachedFile()

getSizeEstimate

public long getSizeEstimate()

Description copied from class: SeekableInputStream

A rough estimated size for this stream instance, which is used for internal cache management.

Specified by:

getSizeEstimate in class SeekableInputStream

Returns:

an estimated size

setDeleteStaleCacheFiles

public static void setDeleteStaleCacheFiles(boolean deleteStaleCacheFiles)

Set whether to automatically delete stale cache files left over by earlier instances of this class. If true, stale files are expunged if they are unmodified since getCacheFileTimeToLiveSeconds() seconds.

isDeleteStaleCacheFiles

public static boolean isDeleteStaleCacheFiles()

Return whether stale cache files are automatically expunged.

Returns:

true if the automatic expunge is active

setCacheFileTimeToLiveSeconds

public static void setCacheFileTimeToLiveSeconds(int cacheFileTimeToLiveSeconds)

Set the time in seconds after which stale cache files are expunged.

getCacheFileTimeToLiveSeconds

public static int getCacheFileTimeToLiveSeconds()

Get the time in seconds after which stale cache files are expunged.

Returns:

the time to live in seconds

setDefaultReadAhead

public static void setDefaultReadAhead(int defaultReadAhead)

Set the default read-ahead in bytes.

getDefaultReadAhead

public static int getDefaultReadAhead()

Return the default read-ahead

Returns:

the number of bytes to read-ahead

setDefaultCachePath

public static void setDefaultCachePath(String defaultCachePath)

Set the default cache path to use, of no explicit path is given.

Parameters:

defaultCachePath - the path name, or null if the default temporary path should be used.

getDefaultCachePath

public static String getDefaultCachePath()

Return the default cache path to use, of no explicit path is given.

Returns:

the path name, or null if the default temporary path should be used.