com.bigdata.nio

Class TestPageServer

java.lang.Object

junit.framework.Assert

junit.framework.TestCase

com.bigdata.nio.TestPageServer

All Implemented Interfaces:

junit.framework.Test

public class TestPageServer
extends junit.framework.TestCase

Test class uses non-blocking I/O to communicate between collection of clients and a single page server backed by test data. This test is designed to exercise features of the nio package and to stress test a non-blocking design for a custom client-server protocol. FIXME Verify that we can use non-blocking IO for the segments (disk) and figure out how to coordinate moving data to/from disk and to/from the network. There appear to be four relevant methods (they do not update the file pointer) for this purpose: FileChannel.read(ByteBuffer, long), FileChannel.write(ByteBuffer, long), FileChannel.transferFrom(java.nio.channels.ReadableByteChannel, long, long), and FileChannel.transferTo(long, long, java.nio.channels.WritableByteChannel). The DBCache API will have to be changed to expose similar methods that correctly read from the cache or DB as appropriate and correctly write on the safe, log or DB as appropriate.
Note: A FileChannel is NOT a SelectableChannel! It is derived from AbstractInterruptibleChannel rather than from AbstractSelectableChannel. This means that we can not use selection keys with the files and that may limit the opporunities for non-blocking IO to disk.

  There is no direct support for asynchronous File IO.
  
  The way the SEDA team worked around this issue is by using a 
  RandomAccessFile, and by having a dedicated queue that would process 
  messages placed into the queue.  The stage processing the messages would 
  then perform the actions within its thread, and then send along any 
  messages as a result from the actions.
 

Version:

$Id$

Author:

Bryan Thompson

See Also:

http://www.onjava.com/pub/a/onjava/2004/09/01/nio.html, http://coconut.codehaus.org/, http://sourceforge.net/projects/pyrasun/, http://gleamynode.net/dev/tl-netty2-example-sumup/docs/, http://directory.apache.org/subprojects/mina/index.html, -XX:MaxDirectMemorySize option (controls direct memory allocation). Problems with File#transferTo under Linux (Java 1.5, not resolved?), http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5103988, NIO Network File Transfer Seriously Underperforming, Note that GC page faults may causing blocking in any case!

Constructor Summary

Constructors

Constructor and Description
TestPageServer()

Method Summary

Methods inherited from class junit.framework.TestCase

assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertEquals, assertFalse, assertFalse, assertNotNull, assertNotNull, assertNotSame, assertNotSame, assertNull, assertNull, assertSame, assertSame, assertTrue, assertTrue, countTestCases, createResult, fail, fail, failNotEquals, failNotSame, failSame, format, getName, run, run, runBare, runTest, setName, setUp, tearDown, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

TestPageServer

public TestPageServer()