Module org.eclipse.jetty.io

Package org.eclipse.jetty.io.content

Class AsyncContent

java.lang.Object

org.eclipse.jetty.io.content.AsyncContent

All Implemented Interfaces:

Closeable, AutoCloseable, Content.Sink, Content.Source

public class AsyncContent
extends Object
implements Content.Sink, Content.Source, Closeable

A Content.Source that is also a Content.Sink. Content written to the Content.Sink is converted to a Content.Chunk and made available to calls to the read() method. If necessary, any Runnable passed to the demand(Runnable) method is invoked once content is written to the Content.Sink.

Constructor Summary

Constructors

Constructor	Description
AsyncContent()

Method Summary

Modifier and Type	Method	Description
void	close()
int	count()
void	demand(Runnable demandCallback)	Demands to invoke the given demand callback parameter when a chunk of content is available.
void	fail(Throwable failure)	Fails this content source with a last failure chunk, failing and discarding accumulated content chunks that were not yet read.
void	fail(Throwable failure, boolean last)	Fails this content source with a failure chunk that may or not may be last.
void	flush()
long	getLength()
boolean	isClosed()
Content.Chunk	read()	Reads a chunk of content.
void	write(boolean last, ByteBuffer byteBuffer, org.eclipse.jetty.util.Callback callback)	Writes the given ByteBuffer, notifying the Callback when the write is complete.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.jetty.io.Content.Source

rewind

Constructor Details

AsyncContent

public AsyncContent()

Method Details

write

public void write(boolean last,
 ByteBuffer byteBuffer,
 org.eclipse.jetty.util.Callback callback)

Writes the given ByteBuffer, notifying the Callback when the write is complete.

Implementations guarantee that calls to this method are safely reentrant so that stack overflows are avoided in the case of mutual recursion between the execution of the Callback and a call to this method.

The write completes:

• immediately with a failure when this instance is closed or already has a failure
• successfully when a non empty Content.Chunk returned by read() is released
• successfully just before the Content.Chunk is returned by read(), for any empty chunk Content.Chunk.

Specified by:

write in interface Content.Sink

Parameters:

last - whether the ByteBuffer is the last to write

byteBuffer - the ByteBuffer to write

callback - the callback to notify when the write operation is complete

flush

public void flush()
           throws IOException

Throws:

IOException

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

isClosed

public boolean isClosed()

getLength

public long getLength()

Specified by:

getLength in interface Content.Source

Returns:

the content length, if known, or -1 if the content length is unknown

read

public Content.Chunk read()

Description copied from interface: Content.Source

Reads a chunk of content.

See how to use this method idiomatically.

The returned chunk could be:

• null, to signal that there isn't a chunk of content available
• an Content.Chunk instance with non null Content.Chunk.getFailure(), to signal that there was a failure trying to produce a chunk of content, or that the content production has been failed externally
• a Content.Chunk instance, containing the chunk of content.

Once a read returns an Content.Chunk instance with non-null Content.Chunk.getFailure() then if the failure is last further reads will continue to return the same failure chunk instance, otherwise further read() operations may return different non-failure chunks.

Once a read returns a last chunk, further reads will continue to return a last chunk (although the instance may be different).

The content reader code must ultimately arrange for a call to Retainable.release() on the returned Content.Chunk.

Additionally, prior to the ultimate call to Retainable.release(), the reader code may make additional calls to Retainable.retain(), that must ultimately be matched by a correspondent number of calls to Retainable.release().

Concurrent reads from different threads are not recommended, as they are inherently in a race condition.

Reads performed outside the invocation context of a demand callback are allowed. However, reads performed with a pending demand are inherently in a race condition (the thread that reads with the thread that invokes the demand callback).

Specified by:

read in interface Content.Source

Returns:

a chunk of content, possibly a failure instance, or null

See Also:

• Content.Source.demand(Runnable)
• Retainable

demand

public void demand(Runnable demandCallback)

Description copied from interface: Content.Source

Demands to invoke the given demand callback parameter when a chunk of content is available.

See how to use this method idiomatically.

Implementations guarantee that calls to this method are safely reentrant so that stack overflows are avoided in the case of mutual recursion between the execution of the Runnable callback and a call to this method. Invocations of the passed Runnable are serialized and a callback for demand call is not invoked until any previous demand callback has returned. Thus the Runnable should not block waiting for a callback of a future demand call.

The demand callback may be invoked spuriously: a subsequent call to Content.Source.read() may return null.

Calling this method establishes a pending demand, which is fulfilled when the demand callback is invoked.

Calling this method when there is already a pending demand results in an IllegalStateException to be thrown.

If the invocation of the demand callback throws an exception, then Content.Source.fail(Throwable) is called.

Specified by:

demand in interface Content.Source

Parameters:

demandCallback - the demand callback to invoke where there is a content chunk available

See Also:

• Content.Source.read()

fail

public void fail(Throwable failure)

Description copied from interface: Content.Source

Fails this content source with a last failure chunk, failing and discarding accumulated content chunks that were not yet read.

The failure may be notified to the content reader at a later time, when the content reader reads a content chunk, via a Content.Chunk instance with a non null Content.Chunk.getFailure().

If Content.Source.read() has returned a last chunk, this is a no operation.

Typical failure: the content being aborted by user code, or idle timeouts.

If this method has already been called, then it is a no operation.

Specified by:

fail in interface Content.Source

Parameters:

failure - the cause of the failure

See Also:

• Content.Chunk.getFailure()

fail

public void fail(Throwable failure,
 boolean last)

Description copied from interface: Content.Source

Fails this content source with a failure chunk that may or not may be last. If last is true, then the failure is persistent and a call to this method acts as Content.Source.fail(Throwable). Otherwise the failure is transient and a failure chunk will be read in order with content chunks, and subsequent calls to read may produce other content.

A Content.Source or its reader may treat a transient failure as persistent.

Specified by:

fail in interface Content.Source

Parameters:

failure - A failure.

last - true if the failure is persistent, false if the failure is transient.

See Also:

• Content.Chunk.getFailure()

count

public int count()