Package io.vertx.core.file

Interface AsyncFile

All Superinterfaces:

ReadStream<Buffer>, StreamBase, WriteStream<Buffer>

public interface AsyncFile
extends ReadStream<Buffer>, WriteStream<Buffer>

Represents a file on the file-system which can be read from, or written to asynchronously.

This class also implements ReadStream and WriteStream. This allows the data to be piped to and from other streams, e.g. an HttpClientRequest instance, using the Pipe class

Author:

Tim Fox

Method Summary

Modifier and Type	Method	Description
Future<Void>	close()	Close the file.
AsyncFile	drainHandler(Handler<Void> handler)	Set a drain handler on the stream.
AsyncFile	endHandler(Handler<Void> endHandler)	Set an end handler.
AsyncFile	exceptionHandler(Handler<Throwable> handler)	Set an exception handler on the read stream.
AsyncFile	fetch(long amount)	Fetch the specified amount of elements.
Future<Void>	flush()	Flush any writes made to this file to underlying persistent storage.
long	getReadLength()
long	getWritePos()
AsyncFile	handler(Handler<Buffer> handler)	Set a data handler.
default Future<AsyncFileLock>	lock()	Acquire a non-shared lock on the entire file.
Future<AsyncFileLock>	lock(long position, long size, boolean shared)	Acquire a lock on a portion of this file.
AsyncFile	pause()	Pause the ReadStream, it sets the buffer in fetch mode and clears the actual demand.
Future<Buffer>	read(Buffer buffer, int offset, long position, int length)	Reads length bytes of data from the file at position position in the file, asynchronously.
AsyncFile	resume()	Resume reading, and sets the buffer in flowing mode.
AsyncFile	setReadBufferSize(int readBufferSize)	Sets the buffer size that will be used to read the data from the file.
AsyncFile	setReadLength(long readLength)	Sets the number of bytes that will be read when using the file as a ReadStream.
AsyncFile	setReadPos(long readPos)	Sets the position from which data will be read from when using the file as a ReadStream.
AsyncFile	setWritePos(long writePos)	Sets the position from which data will be written when using the file as a WriteStream.
AsyncFile	setWriteQueueMaxSize(int maxSize)	Set the maximum size of the write queue to maxSize.
Future<Long>	size()
long	sizeBlocking()	Like size() but blocking.
default AsyncFileLock	tryLock()	Try to acquire a non-shared lock on the entire file.
AsyncFileLock	tryLock(long position, long size, boolean shared)	Try to acquire a lock on a portion of this file.
default <T> Future<T>	withLock(long position, long size, boolean shared, java.util.function.Supplier<Future<T>> block)	Acquire a lock on a portion of this file.
default <T> Future<T>	withLock(java.util.function.Supplier<Future<T>> block)	Acquire a non-shared lock on the entire file.
Future<Void>	write(Buffer buffer, long position)	Write a Buffer to the file at position position in the file, asynchronously.

Methods inherited from interface io.vertx.core.streams.ReadStream

collect, pipe, pipeTo

Methods inherited from interface io.vertx.core.streams.WriteStream

end, end, write, writeQueueFull

Method Detail

handler

AsyncFile handler(Handler<Buffer> handler)

Description copied from interface: ReadStream

Set a data handler. As data is read, the handler will be called with the data.

Specified by:

handler in interface ReadStream<Buffer>

Returns:

a reference to this, so the API can be used fluently

pause

AsyncFile pause()

Description copied from interface: ReadStream

Pause the ReadStream, it sets the buffer in fetch mode and clears the actual demand.

While it's paused, no data will be sent to the data handler.

Specified by:

pause in interface ReadStream<Buffer>

Returns:

a reference to this, so the API can be used fluently

resume

AsyncFile resume()

Description copied from interface: ReadStream

Resume reading, and sets the buffer in flowing mode.

If the ReadStream has been paused, reading will recommence on it.

Specified by:

resume in interface ReadStream<Buffer>

Returns:

a reference to this, so the API can be used fluently

endHandler

AsyncFile endHandler(Handler<Void> endHandler)

Description copied from interface: ReadStream

Set an end handler. Once the stream has ended, and there is no more data to be read, this handler will be called.

Specified by:

endHandler in interface ReadStream<Buffer>

Returns:

a reference to this, so the API can be used fluently

setWriteQueueMaxSize

AsyncFile setWriteQueueMaxSize(int maxSize)

Description copied from interface: WriteStream

Set the maximum size of the write queue to maxSize. You will still be able to write to the stream even if there is more than maxSize items in the write queue. This is used as an indicator by classes such as Pipe to provide flow control.

The value is defined by the implementation of the stream, e.g in bytes for a NetSocket, etc...

Specified by:

setWriteQueueMaxSize in interface WriteStream<Buffer>

Parameters:

maxSize - the max size of the write stream

Returns:

a reference to this, so the API can be used fluently

drainHandler

AsyncFile drainHandler(Handler<Void> handler)

Description copied from interface: WriteStream

Set a drain handler on the stream. If the write queue is full, then the handler will be called when the write queue is ready to accept buffers again. See Pipe for an example of this being used.

The stream implementation defines when the drain handler, for example it could be when the queue size has been reduced to maxSize / 2.

Specified by:

drainHandler in interface WriteStream<Buffer>

Parameters:

handler - the handler

Returns:

a reference to this, so the API can be used fluently

exceptionHandler

AsyncFile exceptionHandler(Handler<Throwable> handler)

Description copied from interface: ReadStream

Set an exception handler on the read stream.

Specified by:

exceptionHandler in interface ReadStream<Buffer>

Specified by:

exceptionHandler in interface StreamBase

Specified by:

exceptionHandler in interface WriteStream<Buffer>

Parameters:

handler - the exception handler

Returns:

a reference to this, so the API can be used fluently

fetch

AsyncFile fetch(long amount)

Description copied from interface: ReadStream

Fetch the specified amount of elements. If the ReadStream has been paused, reading will recommence with the specified amount of items, otherwise the specified amount will be added to the current stream demand.

Specified by:

fetch in interface ReadStream<Buffer>

Returns:

a reference to this, so the API can be used fluently

close

Future<Void> close()

Close the file. The actual close happens asynchronously.

Returns:

a future completed with the result

write

Future<Void> write(Buffer buffer,
                   long position)

Write a Buffer to the file at position position in the file, asynchronously.

If position lies outside of the current size of the file, the file will be enlarged to encompass it.

When multiple writes are invoked on the same file there are no guarantees as to order in which those writes actually occur

Parameters:

buffer - the buffer to write

position - the position in the file to write it at

Returns:

a future notified when the write is complete

read

Future<Buffer> read(Buffer buffer,
                    int offset,
                    long position,
                    int length)

Reads length bytes of data from the file at position position in the file, asynchronously.

The read data will be written into the specified Buffer buffer at position offset.

If data is read past the end of the file then zero bytes will be read.

When multiple reads are invoked on the same file there are no guarantees as to order in which those reads actually occur.

Parameters:

buffer - the buffer to read into

offset - the offset into the buffer where the data will be read

position - the position in the file where to start reading

length - the number of bytes to read

Returns:

a future notified when the write is complete

flush

Future<Void> flush()

Flush any writes made to this file to underlying persistent storage.

If the file was opened with flush set to true then calling this method will have no effect.

The actual flush will happen asynchronously.

Returns:

a future completed with the result

setReadPos

AsyncFile setReadPos(long readPos)

Sets the position from which data will be read from when using the file as a ReadStream.

Parameters:

readPos - the position in the file

Returns:

a reference to this, so the API can be used fluently

setReadLength

AsyncFile setReadLength(long readLength)

Sets the number of bytes that will be read when using the file as a ReadStream.

Parameters:

readLength - the bytes that will be read from the file

Returns:

a reference to this, so the API can be used fluently

getReadLength

long getReadLength()

Returns:

the number of bytes that will be read when using the file as a ReadStream

setWritePos

AsyncFile setWritePos(long writePos)

Sets the position from which data will be written when using the file as a WriteStream.

Parameters:

writePos - the position in the file

Returns:

a reference to this, so the API can be used fluently

getWritePos

long getWritePos()

Returns:

the current write position the file is at

setReadBufferSize

AsyncFile setReadBufferSize(int readBufferSize)

Sets the buffer size that will be used to read the data from the file. Changing this value will impact how much the data will be read at a time from the file system.

Parameters:

readBufferSize - the buffer size

Returns:

a reference to this, so the API can be used fluently

sizeBlocking

long sizeBlocking()

Like size() but blocking.

Throws:

FileSystemException - if an error occurs

size

Future<Long> size()

Returns:

the size of the file

tryLock

default AsyncFileLock tryLock()

Try to acquire a non-shared lock on the entire file.

Returns:

the lock if it can be acquired immediately, otherwise null

tryLock

AsyncFileLock tryLock(long position,
                      long size,
                      boolean shared)

Try to acquire a lock on a portion of this file.

Parameters:

position - where the region starts

size - the size of the region

shared - whether the lock should be shared

Returns:

the lock if it can be acquired immediately, otherwise null

lock

default Future<AsyncFileLock> lock()

Acquire a non-shared lock on the entire file.

Returns:

a future indicating the completion of this operation

lock

Future<AsyncFileLock> lock(long position,
                           long size,
                           boolean shared)

Acquire a lock on a portion of this file.

Parameters:

position - where the region starts

size - the size of the region

shared - whether the lock should be shared

Returns:

a future indicating the completion of this operation

withLock

default <T> Future<T> withLock(java.util.function.Supplier<Future<T>> block)

Acquire a non-shared lock on the entire file.

When the block is called, the lock is already acquired, it will be released when the Future<T> returned by the block completes.

When the block fails, the lock is released and the returned future is failed with the cause of the failure.

Parameters:

block - the code block called after lock acquisition

Returns:

the future returned by the block

withLock

default <T> Future<T> withLock(long position,
                               long size,
                               boolean shared,
                               java.util.function.Supplier<Future<T>> block)

Acquire a lock on a portion of this file.

When the block is called, the lock is already acquired , it will be released when the Future<T> returned by the block completes.

When the block fails, the lock is released and the returned future is failed with the cause of the failure.

Parameters:

position - where the region starts

size - the size of the region

shared - whether the lock should be shared

block - the code block called after lock acquisition

Returns:

the future returned by the block