Class: AsyncFile

vertx/file_system. AsyncFile

new AsyncFile(asyncFile)

An AsyncFile represents a file on the file-system which can be read from, or written to asynchronously. Methods also exist to get a ReadStream or a WriteStream on the file. This allows the data to be pumped to and from other streams. Instances of this class are not thread-safe

These should not be created directly. Rather they are created internally by vert.x and provided to callback handlers and as return values from synchronous functions.

Parameters:
Name Type Description
asyncFile org.vertx.java.core.file.AsyncFile the underlying java representation of this AsyncFile
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Extends

Methods

close(handler)

Close the file asynchronously
Parameters:
Name Type Description
handler ResultHandler the handler to be called when the operation completes
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dataHandler(handler)

Set a data handler. As data is read, the handler will be called with a Buffer containing the data read.
Parameters:
Name Type Description
handler BodyHandler the handler to call
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drainHandler(handler)

Set a drain handler on the stream. If the write queue is full, then the handler will be called when the write queue has been reduced to maxSize/2. See module:vertx/pump~Pump for an example of this being used.
Parameters:
Name Type Description
handler Handler the handler to call when the stream has been drained
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endHandler(handler)

Set an end handler. Once the stream has ended, and there is no more data to be read, the handler will be called.
Parameters:
Name Type Description
handler Handler the handler to call
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exceptionHandler(handler)

Set an exception handler.
Parameters:
Name Type Description
handler Handler the handler to call
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exceptionHandler(handler)

Set an exception handler on the stream
Parameters:
Name Type Description
handler Handler the handler to call when an exception occurs
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flush(handler)

Flush any writes made to this file to persistent storage.
Parameters:
Name Type Description
handler ResultHandler The handler to be called when the flush has completed
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pause()

Pause the ReadStream. While the stream is paused, no data will be sent to the data Handler
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read(buffer, offset, position, length, handler)

Read from the file asynchronously
Parameters:
Name Type Description
buffer Buffer The buffer to fill with the contents of the file
offset number The offset point in the Buffer from which to start writing
position number The position in the file from which to begin reading
length number the number of bytes to read
handler ResultHandler the handler to call when close() has been completed and will be provided the filled Buffer as a parameter
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resume()

Resume reading. If the ReadStream has been paused, reading will recommence on it.
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write(buffer, position, handler) → {module:vertx/file_system}

Write to the file asynchronously
Parameters:
Name Type Description
buffer Buffer | string the data to write
position number the byte position from which to start writing
handler ResultHandler the handler to call when the write has completed
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Returns:
Type
module:vertx/file_system

writeQueueFull()

This will return true if there are more bytes in the write queue than the value set using writeQueueMaxSize
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writeQueueMaxSize(size)

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 bytes in the write queue. This is used as an indicator by classes such as Pump to provide flow control.
Parameters:
Name Type Description
size number the size of the write queue
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