com.yahoo.io

Class Listener

java.lang.Object

java.lang.Thread

com.yahoo.io.Listener

All Implemented Interfaces:

Runnable

public class Listener
extends Thread

A basic Reactor implementation using NIO.

Author:

Bob Travis, Bjorn Borud

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field and Description
(package private) Map<Integer,Acceptor>	acceptors
(package private) Map<ServerSocketChannel,ConnectionFactory>	factories
private FatalErrorHandler	fatalErrorHandler
private static Logger	log
private LinkedList<UpdateInterest>	modifyInterestOpsQueue
private LinkedList<Connection>	newConnections
private List<SelectLoopHook>	selectLoopPostHooks
private List<SelectLoopHook>	selectLoopPreHooks
private Selector	selector

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
Listener(String name)

Method Summary

Modifier and Type	Method and Description
Connection	addNewConnection(Connection newConn) This method is used by the Acceptor to hand off newly accepted connections to the Listener.
void	addSelectLoopPostHook(SelectLoopHook hook) Add pre-select loop hook.
void	addSelectLoopPreHook(SelectLoopHook hook) Add pre-select loop hook.
void	listen(ConnectionFactory factory, int port) Add a listening port and create an Acceptor thread which accepts new connections on this port.
void	listenNoAcceptor(ConnectionFactory factory, int port) Add a listening port without creating a separate acceptor thread.
Listener	modifyInterestOps(Connection connection, int op, boolean set) This is the preferred way of modifying interest ops, giving a Connection rather than a SelectionKey as input.
Listener	modifyInterestOps(SelectionKey key, int op, boolean set) Enqueue change to interest set of SelectionKey.
Listener	modifyInterestOpsBatch(Connection connection, int op, boolean set) Batch version of modifyInterestOps().
Listener	modifyInterestOpsBatch(SelectionKey key, int op, boolean set) Does the same as modifyInterestOps(), but does not call wakeup on the selector.
Listener	modifyInterestOpsDone() Signal that a batch update of SelectionKey is done and the selector should be awoken.
private void	performAccept(SelectionKey key) Accept new connection.
private void	performConnect(SelectionKey key) Complete asynchronous connect operation.
private void	performRead(SelectionKey key) Perform read operation on channel which is now ready for reading
private void	performWrite(SelectionKey key) Perform write operation(s) on channel which is now ready for writing
private void	processModifyInterestOps() Process enqueued changes to SelectionKeys.
private void	processNewConnections() This method is called from the selectLoop() method in order to process new incoming connections.
void	registerConnection(Connection connection) Register a connection that was set up outside the listener.
void	run() Thread entry point
private void	runSelectLoopPostHooks() Run all the select loop post hooks
private void	runSelectLoopPreHooks() Run all the select loop pre hooks
private void	selectLoop() Check channels for readiness and deal with channels that have pending operations.
void	setFatalErrorHandler(FatalErrorHandler f) Register a handler for fatal errors.
void	shutdown() Perform clean shutdown of Listener.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

log

private static Logger log

selector

private Selector selector

acceptors

Map<Integer,Acceptor> acceptors

factories

Map<ServerSocketChannel,ConnectionFactory> factories

fatalErrorHandler

private FatalErrorHandler fatalErrorHandler

selectLoopPreHooks

private List<SelectLoopHook> selectLoopPreHooks

selectLoopPostHooks

private List<SelectLoopHook> selectLoopPostHooks

newConnections

private final LinkedList<Connection> newConnections

modifyInterestOpsQueue

private final LinkedList<UpdateInterest> modifyInterestOpsQueue

Constructor Detail

Listener

public Listener(String name)

Method Detail

setFatalErrorHandler

public void setFatalErrorHandler(FatalErrorHandler f)

Register a handler for fatal errors.

Parameters:

f - The FatalErrorHandler instance to be registered

addSelectLoopPreHook

public void addSelectLoopPreHook(SelectLoopHook hook)

Add pre-select loop hook. Not threadsafe so please do this during initial setup before you start the listener.

addSelectLoopPostHook

public void addSelectLoopPostHook(SelectLoopHook hook)

Add pre-select loop hook. Not threadsafe so please do this during initial setup before you start the listener.

runSelectLoopPreHooks

private void runSelectLoopPreHooks()

Run all the select loop pre hooks

runSelectLoopPostHooks

private void runSelectLoopPostHooks()

Run all the select loop post hooks

listen

public void listen(ConnectionFactory factory,
                   int port)
            throws IOException

Add a listening port and create an Acceptor thread which accepts new connections on this port.

Parameters:

factory - The connection factory for new connections on this port

port - The port we are going to listen to.

Throws:

IOException

listenNoAcceptor

public void listenNoAcceptor(ConnectionFactory factory,
                             int port)
                      throws IOException

Add a listening port without creating a separate acceptor thread.

Parameters:

factory - The connection factory for new connections on this port

port - The port we are going to listen to.

Throws:

IOException

modifyInterestOps

public Listener modifyInterestOps(Connection connection,
                                  int op,
                                  boolean set)

This is the preferred way of modifying interest ops, giving a Connection rather than a SelectionKey as input. This way the we can look it up and ensure the correct SelectionKey is always used.

Returns:

Returns a this reference for chaining

modifyInterestOpsBatch

public Listener modifyInterestOpsBatch(Connection connection,
                                       int op,
                                       boolean set)

Batch version of modifyInterestOps().

Returns:

Returns a this reference for chaining

modifyInterestOps

public Listener modifyInterestOps(SelectionKey key,
                                  int op,
                                  boolean set)

Enqueue change to interest set of SelectionKey. This is a workaround for an NIO design error that makes it impossible to update interest sets for a SelectionKey while a select is in progress -- and sometimes you actually want to do this from other threads, which will then block. Hence, we make it possible to enqueue requests for SelectionKey modification in the thread where select runs.

Returns:

Returns a this reference for chaining

modifyInterestOpsBatch

public Listener modifyInterestOpsBatch(SelectionKey key,
                                       int op,
                                       boolean set)

Does the same as modifyInterestOps(), but does not call wakeup on the selector. Allows adding more modifications before we wake up the selector.

Returns:

Returns a this reference for chaining

modifyInterestOpsDone

public Listener modifyInterestOpsDone()

Signal that a batch update of SelectionKey is done and the selector should be awoken. Also see modifyInterestOps().

Returns:

Returns a this reference for chaining

processModifyInterestOps

private void processModifyInterestOps()

Process enqueued changes to SelectionKeys. Also see modifyInterestOps().

run

public void run()

Thread entry point

Specified by:

run in interface Runnable

Overrides:

run in class Thread

selectLoop

private void selectLoop()

Check channels for readiness and deal with channels that have pending operations.

addNewConnection

public Connection addNewConnection(Connection newConn)

This method is used by the Acceptor to hand off newly accepted connections to the Listener. Note that this is run in the context of the Acceptor thread, so doing things here versus doing them in the acceptNewConnections(), which runs in the context of the Listener thread, is a tradeoff that may need to be re-evaluated

processNewConnections

private void processNewConnections()

This method is called from the selectLoop() method in order to process new incoming connections.

performAccept

private void performAccept(SelectionKey key)

Accept new connection. This will loop over accept() until there are no more new connections to accept. If any error occurs after a successful accept, the socket in question will be discarded, but we will continue to try to accept new connections if available.

performConnect

private void performConnect(SelectionKey key)

Complete asynchronous connect operation. Note that asynchronous connect does not work properly in 1.4, so you should not use this if you run anything older than 1.5/5.0.

performRead

private void performRead(SelectionKey key)

Perform read operation on channel which is now ready for reading

performWrite

private void performWrite(SelectionKey key)

Perform write operation(s) on channel which is now ready for writing

registerConnection

public void registerConnection(Connection connection)

Register a connection that was set up outside the listener. Typically what we do when we actively reach out and connect somewhere.

shutdown

public void shutdown()

Perform clean shutdown of Listener. TODO: implement