Class AbstractMultiworkerIOReactor

java.lang.Object
org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor
All Implemented Interfaces:
IOReactor
Direct Known Subclasses:
DefaultConnectingIOReactor, DefaultListeningIOReactor

public abstract class AbstractMultiworkerIOReactor extends Object implements IOReactor
Generic implementation of IOReactor that can run multiple BaseIOReactor instances in separate worker threads and distribute newly created I/O sessions equally across those I/O reactors for more optimal resource utilization and better I/O performance. Usually it is recommended to have one worker I/O reactor per physical CPU core.

Important note about exception handling

Protocol specific exceptions as well as those I/O exceptions thrown in the course of interaction with the session's channel are to be expected are to be dealt with by specific protocol handlers. These exceptions may result in termination of an individual session but should not affect the I/O reactor and all other active sessions. There are situations, however, when the I/O reactor itself encounters an internal problem such as an I/O exception in the underlying NIO classes or an unhandled runtime exception. Those types of exceptions are usually fatal and will cause the I/O reactor to shut down automatically.

There is a possibility to override this behavior and prevent I/O reactors from shutting down automatically in case of a runtime exception or an I/O exception in internal classes. This can be accomplished by providing a custom implementation of the IOReactorExceptionHandler interface.

If an I/O reactor is unable to automatically recover from an I/O or a runtime exception it will enter the shutdown mode. First off, it cancel all pending new session requests. Then it will attempt to close all active I/O sessions gracefully giving them some time to flush pending output data and terminate cleanly. Lastly, it will forcibly shut down those I/O sessions that still remain active after the grace period. This is a fairly complex process, where many things can fail at the same time and many different exceptions can be thrown in the course of the shutdown process. The I/O reactor will record all exceptions thrown during the shutdown process, including the original one that actually caused the shutdown in the first place, in an audit log. One can obtain the audit log using getAuditLog(), examine exceptions thrown by the I/O reactor prior and in the course of the reactor shutdown and decide whether it is safe to restart the I/O reactor.

Since:
4.0
  • Field Details

  • Constructor Details

    • AbstractMultiworkerIOReactor

      public AbstractMultiworkerIOReactor(IOReactorConfig config, ThreadFactory threadFactory) throws IOReactorException
      Creates an instance of AbstractMultiworkerIOReactor with the given configuration.
      Parameters:
      config - I/O reactor configuration.
      threadFactory - the factory to create threads. Can be null.
      Throws:
      IOReactorException - in case if a non-recoverable I/O error.
      Since:
      4.2
    • AbstractMultiworkerIOReactor

      public AbstractMultiworkerIOReactor() throws IOReactorException
      Creates an instance of AbstractMultiworkerIOReactor with default configuration.
      Throws:
      IOReactorException - in case if a non-recoverable I/O error.
      Since:
      4.2
    • AbstractMultiworkerIOReactor

      @Deprecated public AbstractMultiworkerIOReactor(int workerCount, ThreadFactory threadFactory, HttpParams params) throws IOReactorException
      Creates an instance of AbstractMultiworkerIOReactor.
      Parameters:
      workerCount - number of worker I/O reactors.
      threadFactory - the factory to create threads. Can be null.
      params - HTTP parameters.
      Throws:
      IOReactorException - in case if a non-recoverable I/O error.
  • Method Details

    • convert

      @Deprecated static IOReactorConfig convert(int workerCount, HttpParams params)
      Deprecated.
      Do not use.
    • getStatus

      public IOReactorStatus getStatus()
      Description copied from interface: IOReactor
      Returns the current status of the reactor.
      Specified by:
      getStatus in interface IOReactor
      Returns:
      reactor status.
    • getAuditLog

      public List<ExceptionEvent> getAuditLog()
      Returns the audit log containing exceptions thrown by the I/O reactor prior and in the course of the reactor shutdown.
      Returns:
      audit log.
    • addExceptionEvent

      protected void addExceptionEvent(Throwable ex, Date timestamp)
      Adds the given Throwable object with the given time stamp to the audit log.
      Parameters:
      ex - the exception thrown by the I/O reactor.
      timestamp - the time stamp of the exception. Can be null in which case the current date / time will be used.
    • addExceptionEvent

      protected void addExceptionEvent(Throwable ex)
      Adds the given Throwable object to the audit log.
      Parameters:
      ex - the exception thrown by the I/O reactor.
    • setExceptionHandler

      public void setExceptionHandler(IOReactorExceptionHandler exceptionHandler)
      Sets exception handler for this I/O reactor.
      Parameters:
      exceptionHandler - the exception handler.
    • processEvents

      protected abstract void processEvents(int count) throws IOReactorException
      Triggered to process I/O events registered by the main Selector.

      Super-classes can implement this method to react to the event.

      Parameters:
      count - event count.
      Throws:
      IOReactorException - in case if a non-recoverable I/O error.
    • cancelRequests

      protected abstract void cancelRequests() throws IOReactorException
      Triggered to cancel pending session requests.

      Super-classes can implement this method to react to the event.

      Throws:
      IOReactorException - in case if a non-recoverable I/O error.
    • execute

      public void execute(IOEventDispatch eventDispatch) throws InterruptedIOException, IOReactorException
      Activates the main I/O reactor as well as all worker I/O reactors. The I/O main reactor will start reacting to I/O events and triggering notification methods. The worker I/O reactor in their turn will start reacting to I/O events and dispatch I/O event notifications to the given IOEventDispatch interface.

      This method will enter the infinite I/O select loop on the Selector instance associated with this I/O reactor and used to manage creation of new I/O channels. Once a new I/O channel has been created the processing of I/O events on that channel will be delegated to one of the worker I/O reactors.

      The method will remain blocked unto the I/O reactor is shut down or the execution thread is interrupted.

      Specified by:
      execute in interface IOReactor
      Parameters:
      eventDispatch - the I/O event dispatch.
      Throws:
      InterruptedIOException - if the dispatch thread is interrupted.
      IOReactorException - in case if a non-recoverable I/O error.
      See Also:
    • doShutdown

      protected void doShutdown() throws InterruptedIOException
      Activates the shutdown sequence for this reactor. This method will cancel all pending session requests, close out all active I/O channels, make an attempt to terminate all worker I/O reactors gracefully, and finally force-terminate those I/O reactors that failed to terminate after the specified grace period.
      Throws:
      InterruptedIOException - if the shutdown sequence has been interrupted.
    • addChannel

      protected void addChannel(ChannelEntry entry)
      Assigns the given channel entry to one of the worker I/O reactors.
      Parameters:
      entry - the channel entry.
    • registerChannel

      protected SelectionKey registerChannel(SelectableChannel channel, int ops) throws ClosedChannelException
      Registers the given channel with the main Selector.
      Parameters:
      channel - the channel.
      ops - interest ops.
      Returns:
      selection key.
      Throws:
      ClosedChannelException - if the channel has been already closed.
    • prepareSocket

      protected void prepareSocket(Socket socket) throws IOException
      Prepares the given Socket by resetting some of its properties.
      Parameters:
      socket - the socket
      Throws:
      IOException - in case of an I/O error.
    • awaitShutdown

      protected void awaitShutdown(long timeout) throws InterruptedException
      Blocks for the given period of time in milliseconds awaiting the completion of the reactor shutdown. If the value of timeout is set to 0 this method blocks indefinitely.
      Parameters:
      timeout - the maximum wait time.
      Throws:
      InterruptedException - if interrupted.
    • shutdown

      public void shutdown() throws IOException
      Description copied from interface: IOReactor
      Initiates shutdown of the reactor and blocks for a default period of time waiting for the reactor to terminate all active connections, to shut down itself and to release system resources it currently holds. It is up to individual implementations to decide for how long this method can remain blocked.
      Specified by:
      shutdown in interface IOReactor
      Throws:
      IOException - in case of an I/O error.
    • shutdown

      public void shutdown(long waitMs) throws IOException
      Description copied from interface: IOReactor
      Initiates shutdown of the reactor and blocks approximately for the given period of time in milliseconds waiting for the reactor to terminate all active connections, to shut down itself and to release system resources it currently holds.
      Specified by:
      shutdown in interface IOReactor
      Parameters:
      waitMs - wait time in milliseconds.
      Throws:
      IOException - in case of an I/O error.
    • closeChannel

      static void closeChannel(Channel channel)