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 Details

    • 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)
      Set an exception handler on the read stream and on the write stream.
      Specified by:
      exceptionHandler in interface ReadStream<Buffer>
      Specified by:
      exceptionHandler in interface StreamBase
      Specified by:
      exceptionHandler in interface WriteStream<Buffer>
      Parameters:
      handler - the 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(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, 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