Class StreamDrainer

java.lang.Object

ubic.gemma.core.util.StreamDrainer

public class StreamDrainer
extends Object

Reads a stream to its end on a daemon thread, keeping the last maxChars characters.

Use it for a child process's standard error when the parent waits for the process, or reads its standard output, before reading standard error. A child blocks once it has written a pipe buffer's worth (64 KiB on Linux) that nobody reads, so without this such a child and the parent wait on each other forever.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DEFAULT_MAX_CHARS	Enough for an error message and its context; the start of a long output is dropped.

Method Summary

Modifier and Type	Method	Description
String	await(long timeout, TimeUnit unit)	Wait up to the given time for the end of the stream, then return what was kept.
String	getText()
static StreamDrainer	start(InputStream stream, String name)	Start reading the stream on a new daemon thread, keeping the last DEFAULT_MAX_CHARS characters.
static StreamDrainer	start(InputStream stream, String name, int maxChars)

Methods inherited from class Object

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

Field Details

DEFAULT_MAX_CHARS

public static final int DEFAULT_MAX_CHARS

Enough for an error message and its context; the start of a long output is dropped.

See Also:

• Constant Field Values

Method Details

start

public static StreamDrainer start(InputStream stream,
 String name)

Start reading the stream on a new daemon thread, keeping the last DEFAULT_MAX_CHARS characters.

Parameters:

name - for the thread, e.g. "RepeatMasker stderr"

start

public static StreamDrainer start(InputStream stream,
 String name,
 int maxChars)

await

public String await(long timeout,
 TimeUnit unit)
             throws InterruptedException

Wait up to the given time for the end of the stream, then return what was kept.

The end of a process's stream normally follows its exit closely, but a descendant that inherited the stream can hold it open, hence the timeout.

Throws:

InterruptedException

getText

public String getText()

Returns:

what has been kept so far