## org.apache.http.impl.nio.reactor
Class AbstractMultiworkerIOReactor

    java.lang.Object
      org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor

All Implemented Interfaces:
  IOReactor

Direct Known Subclasses:
  DefaultConnectingIOReactor, DefaultListeningIOReactor

    @ThreadSafe
    public abstract class AbstractMultiworkerIOReactor

extends Object
implements IOReactor

Generic implementation of `IOReactor` that can run multiple `BaseIOReactor` instance in separate worker threads and distribute newly created I/O session equally across those I/O reactors for a more optimal resource utilization and a 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.

The following parameters can be used to customize the behavior of this class:

- `CoreConnectionPNames.TCP_NODELAY`
- `CoreConnectionPNames.SO_TIMEOUT`
- `CoreConnectionPNames.SO_LINGER`
- `NIOReactorPNames.SELECT_INTERVAL`
- `NIOReactorPNames.GRACE_PERIOD`
- `NIOReactorPNames.INTEREST_OPS_QUEUEING`

Since:
  4.0

Field Summary
`protected List<ExceptionEvent>` `auditLog`
`protected IOReactorConfig` `config`
`protected IOReactorExceptionHandler` `exceptionHandler`
`protected boolean` `interestOpsQueueing`
`protected HttpParams` `params` Deprecated. (4.2)
`protected Selector` `selector`
`protected long` `selectTimeout`
`protected IOReactorStatus` `status`

Constructor Summary
`AbstractMultiworkerIOReactor()` Creates an instance of AbstractMultiworkerIOReactor with default configuration.
`AbstractMultiworkerIOReactor(int workerCount, ThreadFactory threadFactory, HttpParams params)` Deprecated. (4.2) use `AbstractMultiworkerIOReactor(IOReactorConfig, ThreadFactory)`
`AbstractMultiworkerIOReactor(IOReactorConfig config, ThreadFactory threadFactory)` Creates an instance of AbstractMultiworkerIOReactor with the given configuration.

Method Summary
`protected void` `addChannel(ChannelEntry entry)` Assigns the given channel entry to one of the worker I/O reactors.
`protected void` `addExceptionEvent(Throwable ex)` Adds the given `Throwable` object to the audit log.
`protected void` `addExceptionEvent(Throwable ex, Date timestamp)` Adds the given `Throwable` object with the given time stamp to the audit log.
`protected void` `awaitShutdown(long timeout)` Blocks for the given period of time in milliseconds awaiting the completion of the reactor shutdown.
`protected abstract void` `cancelRequests()` Triggered to cancel pending session requests.
`protected void` `doShutdown()` Activates the shutdown sequence for this reactor.
`void` `execute(IOEventDispatch eventDispatch)` Activates the main I/O reactor as well as all worker I/O reactors.
`List<ExceptionEvent>` `getAuditLog()` Returns the audit log containing exceptions thrown by the I/O reactor prior and in the course of the reactor shutdown.
`IOReactorStatus` `getStatus()` Returns the current status of the reactor.
`protected void` `prepareSocket(Socket socket)` Prepares the given `Socket` by resetting some of its properties.
`protected abstract void` `processEvents(int count)` Triggered to process I/O events registered by the main `Selector`.
`protected SelectionKey` `registerChannel(SelectableChannel channel, int ops)` Registers the given channel with the main `Selector`.
`void` `setExceptionHandler(IOReactorExceptionHandler exceptionHandler)` Sets exception handler for this I/O reactor.
`void` `shutdown()` 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.
`void` `shutdown(long waitMs)` 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.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### status

    protected volatile IOReactorStatus status

### params

    @Deprecated
    protected final HttpParams params

  Deprecated. (4.2)

### config

    protected final IOReactorConfig config

### selector

    protected final Selector selector

### selectTimeout

    protected final long selectTimeout

### interestOpsQueueing

    protected final boolean interestOpsQueueing

### exceptionHandler

    protected IOReactorExceptionHandler exceptionHandler

### auditLog

    protected List<ExceptionEvent> auditLog

Constructor Detail

### 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

  Deprecated. (4.2) use `AbstractMultiworkerIOReactor(IOReactorConfig, ThreadFactory)`

  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 Detail

### 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:
    `processEvents(int)`, `cancelRequests()`

### 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.

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