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lightning-sunbird  0.9+nobinonly
Public Member Functions | Public Attributes
nsIAsyncOutputStream Interface Reference

If an output stream is non-blocking, it may return NS_BASE_STREAM_WOULD_BLOCK when written to. More...

import "nsIAsyncOutputStream.idl";

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List of all members.

Public Member Functions

void closeWithStatus (in nsresult reason)
 This method closes the stream and sets its internal status.
void asyncWait (in nsIOutputStreamCallback aCallback, in unsigned long aFlags, in unsigned long aRequestedCount, in nsIEventTarget aEventTarget)
 Asynchronously wait for the stream to be writable or closed.
void close ()
 Close the stream.
void flush ()
 Flush the stream.
unsigned long write (in string aBuf, in unsigned long aCount)
 Write data into the stream.
unsigned long writeFrom (in nsIInputStream aFromStream, in unsigned long aCount)
 Writes data into the stream from an input stream.
unsigned long writeSegments (in nsReadSegmentFun aReader, in voidPtr aClosure, in unsigned long aCount)
 Low-level write method that has access to the stream's underlying buffer.
boolean isNonBlocking ()

Public Attributes

const unsigned long WAIT_CLOSURE_ONLY = (1<<0)
 If passed to asyncWait, this flag overrides the default behavior, causing the OnOutputStreamReady notification to be suppressed until the stream becomes closed (either as a result of closeWithStatus/close being called on the stream or possibly due to some error in the underlying stream).

Detailed Description

If an output stream is non-blocking, it may return NS_BASE_STREAM_WOULD_BLOCK when written to.

The caller must then wait for the stream to become writable. If the stream implements nsIAsyncOutputStream, then the caller can use this interface to request an asynchronous notification when the stream becomes writable or closed (via the AsyncWait method).

While this interface is almost exclusively used with non-blocking streams, it is not necessary that nsIOutputStream::isNonBlocking return true. Nor is it necessary that a non-blocking nsIOutputStream implementation also implement nsIAsyncOutputStream.

Definition at line 56 of file nsIAsyncOutputStream.idl.


Member Function Documentation

void nsIAsyncOutputStream::asyncWait ( in nsIOutputStreamCallback  aCallback,
in unsigned long  aFlags,
in unsigned long  aRequestedCount,
in nsIEventTarget  aEventTarget 
)

Asynchronously wait for the stream to be writable or closed.

The notification is one-shot, meaning that each asyncWait call will result in exactly one notification callback. After the OnOutputStreamReady event is dispatched, the stream releases its reference to the nsIOutputStreamCallback object. It is safe to call asyncWait again from the notification handler.

This method may be called at any time (even if write has not been called). In other words, this method may be called when the stream already has room for more data. It may also be called when the stream is closed. If the stream is already writable or closed when AsyncWait is called, then the OnOutputStreamReady event will be dispatched immediately. Otherwise, the event will be dispatched when the stream becomes writable or closed.

Parameters:
aCallbackThis object is notified when the stream becomes ready.
aFlagsThis parameter specifies optional flags passed in to configure the behavior of this method. Pass zero to specify no flags.
aRequestedCountWait until at least this many bytes can be written. This is only a suggestion to the underlying stream; it may be ignored. The caller may pass zero to indicate no preference.
aEventTargetSpecify NULL to receive notification on ANY thread (possibly even recursively on the calling thread -- i.e., synchronously), or specify that the notification be delivered to a specific event target.
void nsIOutputStream::close ( ) [inherited]

Close the stream.

Forces the output stream to flush any buffered data.

Exceptions:
NS_BASE_STREAM_WOULD_BLOCKif unable to flush without blocking the calling thread (non-blocking mode only)

This method closes the stream and sets its internal status.

If the stream is already closed, then this method is ignored. Once the stream is closed, the stream's status cannot be changed. Any successful status code passed to this method is treated as NS_BASE_STREAM_CLOSED, which is equivalent to nsIInputStream::close.

NOTE: this method exists in part to support pipes, which have both an input end and an output end. If the output end of a pipe is closed, then reads from the input end of the pipe will fail. The error code returned when an attempt is made to read from a "closed" pipe corresponds to the status code passed in when the output end of the pipe is closed, which greatly simplifies working with pipes in some cases.

Parameters:
aStatusThe error that will be reported if this stream is accessed after it has been closed.
void nsIOutputStream::flush ( ) [inherited]

Flush the stream.

Exceptions:
NS_BASE_STREAM_WOULD_BLOCKif unable to flush without blocking the calling thread (non-blocking mode only)
Returns:
true if stream is non-blocking

NOTE: writing to a blocking output stream will block the calling thread until all given data can be consumed by the stream.

unsigned long nsIOutputStream::write ( in string  aBuf,
in unsigned long  aCount 
) [inherited]

Write data into the stream.

Parameters:
aBufthe buffer containing the data to be written
aCountthe maximum number of bytes to be written
Returns:
number of bytes written (may be less than aCount)
Exceptions:
NS_BASE_STREAM_WOULD_BLOCKif writing to the output stream would block the calling thread (non-blocking mode only)
<other-error>on failure
unsigned long nsIOutputStream::writeFrom ( in nsIInputStream  aFromStream,
in unsigned long  aCount 
) [inherited]

Writes data into the stream from an input stream.

Parameters:
aFromStreamthe stream containing the data to be written
aCountthe maximum number of bytes to be written
Returns:
number of bytes written (may be less than aCount)
Exceptions:
NS_BASE_STREAM_WOULD_BLOCKif writing to the output stream would block the calling thread (non-blocking mode only)
<other-error>on failure

NOTE: This method is defined by this interface in order to allow the output stream to efficiently copy the data from the input stream into its internal buffer (if any). If this method was provided as an external facility, a separate char* buffer would need to be used in order to call the output stream's other Write method.

unsigned long nsIOutputStream::writeSegments ( in nsReadSegmentFun  aReader,
in voidPtr  aClosure,
in unsigned long  aCount 
) [inherited]

Low-level write method that has access to the stream's underlying buffer.

The reader function may be called multiple times for segmented buffers. WriteSegments is expected to keep calling the reader until either there is nothing left to write or the reader returns an error. WriteSegments should not call the reader with zero bytes to provide.

Parameters:
aReaderthe "provider" of the data to be written
aClosureopaque parameter passed to reader
aCountthe maximum number of bytes to be written
Returns:
number of bytes written (may be less than aCount)
Exceptions:
NS_BASE_STREAM_WOULD_BLOCKif writing to the output stream would block the calling thread (non-blocking mode only)
<other-error>on failure

NOTE: this function may be unimplemented if a stream has no underlying buffer (e.g., socket output stream).


Member Data Documentation

If passed to asyncWait, this flag overrides the default behavior, causing the OnOutputStreamReady notification to be suppressed until the stream becomes closed (either as a result of closeWithStatus/close being called on the stream or possibly due to some error in the underlying stream).

Definition at line 120 of file nsIAsyncOutputStream.idl.


The documentation for this interface was generated from the following file: