Package com.sun.xml.ws.api.pipe

Class Fiber

java.lang.Object
com.sun.xml.ws.api.pipe.Fiber
All Implemented Interfaces:
Cancelable, Component, ComponentRegistry, Runnable
public final class Fiber extends Object implements Runnable, Cancelable, ComponentRegistry
User-level thread. Represents the execution of one request/response processing.

JAX-WS RI is capable of running a large number of request/response concurrently by using a relatively small number of threads. This is made possible by utilizing a Fiber — a user-level thread that gets created for each request/response processing.

A fiber remembers where in the pipeline the processing is at, what needs to be executed on the way out (when processing response), and other additional information specific to the execution of a particular request/response.

Suspend/Resume


Fiber can be suspended by a Tube. When a fiber is suspended, it will be kept on the side until it is resumed. This allows threads to go execute other runnable fibers, allowing efficient utilization of smaller number of threads.

Context-switch Interception


FiberContextSwitchInterceptor allows Tubes and Adapters to perform additional processing every time a thread starts running a fiber and stops running it.

Context ClassLoader


Just like thread, a fiber has a context class loader (CCL.) A fiber's CCL becomes the thread's CCL when it's executing the fiber. The original CCL of the thread will be restored when the thread leaves the fiber execution.

Debugging Aid


Because Fiber doesn't keep much in the call stack, and instead use conts to store the continuation, debugging fiber related activities could be harder.

Setting the LOGGER for FINE would give you basic start/stop/resume/suspend level logging. Using FINER would cause more detailed logging, which includes what tubes are executed in what order and how they behaved.

When you debug the server side, consider setting serializeExecution to true, so that execution of fibers are serialized. Debugging a server with more than one running threads is very tricky, and this switch will prevent that. This can be also enabled by setting the system property on. See the source code.
Author:
Kohsuke Kawaguchi, Jitendra Kotamraju

  • Field Details

    • owner

      public final Engine owner

    • serializeExecution

      public static volatile boolean serializeExecution
      Set this boolean to true to execute fibers sequentially one by one. See class javadoc.

  • Method Details

    • addListener

      public void addListener(Fiber.Listener listener)
      Deprecated.
      Adds suspend/resume callback listener
      Parameters:
      listener - Listener
      Since:
      2.2.6

    • removeListener

      public void removeListener(Fiber.Listener listener)
      Deprecated.
      Removes suspend/resume callback listener
      Parameters:
      listener - Listener
      Since:
      2.2.6

    • setDeliverThrowableInPacket

      public void setDeliverThrowableInPacket(boolean isDeliverThrowableInPacket)

    • start

      public void start(@NotNull Tube tubeline, @NotNull Packet request, @Nullable Fiber.CompletionCallback completionCallback)
      Starts the execution of this fiber asynchronously.

      This method works like Thread.start().
      Parameters:
      tubeline - The first tube of the tubeline that will act on the packet.
      request - The request packet to be passed to startPoint.processRequest().
      completionCallback - The callback to be invoked when the processing is finished and the final response packet is available.
      See Also:

    • start

      public void start(@NotNull Tube tubeline, @NotNull Packet request, @Nullable Fiber.CompletionCallback completionCallback, boolean forceSync)
      Starts the execution of this fiber. If forceSync is true, then the fiber is started for an ostensibly async invocation, but allows for some portion of the tubeline to run sync with the calling client instance (Port/Dispatch instance). This allows tubes that enforce ordering to see requests in the order they were sent at the point the client invoked them.

      The forceSync parameter will be true only when the caller (e.g. AsyncInvoker or SEIStub) knows one or more tubes need to enforce ordering and thus need to run sync with the client. Such tubes can return NextAction.INVOKE_ASYNC to indicate that the next tube in the tubeline should be invoked async to the current thread.

      This method works like Thread.start().

      Parameters:
      tubeline - The first tube of the tubeline that will act on the packet.
      request - The request packet to be passed to startPoint.processRequest().
      completionCallback - The callback to be invoked when the processing is finished and the final response packet is available.
      Since:
      2.2.6
      See Also:

    • resume

      public void resume(@NotNull Packet resumePacket)
      Wakes up a suspended fiber.

      If a fiber was suspended without specifying the next Tube, then the execution will be resumed in the response processing direction, by calling the Tube.processResponse(Packet) method on the next/first Tube in the Fiber's processing stack with the specified resume packet as the parameter.

      If a fiber was suspended with specifying the next Tube, then the execution will be resumed in the request processing direction, by calling the next tube's Tube.processRequest(Packet) method with the specified resume packet as the parameter.

      This method is implemented in a race-free way. Another thread can invoke this method even before this fiber goes into the suspension mode. So the caller need not worry about synchronizing NextAction.suspend() and this method.
      Parameters:
      resumePacket - packet used in the resumed processing

    • resume

      public void resume(@NotNull Packet resumePacket, boolean forceSync)
      Similar to resume(Packet) but allowing the Fiber to be resumed synchronously (in the current Thread). If you want to know when the fiber completes (not when this method returns) then add/wrap a CompletionCallback on this Fiber. For example, an asynchronous response endpoint that supports WS-ReliableMessaging including in-order message delivery may need to resume the Fiber synchronously until message order is confirmed prior to returning to asynchronous processing.
      Since:
      2.2.6

    • resume

      public void resume(@NotNull Packet resumePacket, boolean forceSync, Fiber.CompletionCallback callback)
      Similar to resume(Packet, boolean) but allowing the Fiber to be resumed and at the same time atomically assign a new CompletionCallback to it.
      Since:
      2.2.6

    • resumeAndReturn

      public void resumeAndReturn(@NotNull Packet resumePacket, boolean forceSync)
      Wakes up a suspended fiber and begins response processing.
      Since:
      2.2.6

    • resume

      public void resume(@NotNull Throwable throwable)
      Wakes up a suspended fiber with an exception.

      The execution of the suspended fiber will be resumed in the response processing direction, by calling the Tube.processException(Throwable) method on the next/first Tube in the Fiber's processing stack with the specified exception as the parameter.

      This method is implemented in a race-free way. Another thread can invoke this method even before this fiber goes into the suspension mode. So the caller need not worry about synchronizing NextAction.suspend() and this method.
      Parameters:
      throwable - exception that is used in the resumed processing

    • resume

      public void resume(@NotNull Throwable throwable, @NotNull Packet packet)
      Wakes up a suspended fiber with an exception.

      The execution of the suspended fiber will be resumed in the response processing direction, by calling the Tube.processException(Throwable) method on the next/first Tube in the Fiber's processing stack with the specified exception as the parameter.

      This method is implemented in a race-free way. Another thread can invoke this method even before this fiber goes into the suspension mode. So the caller need not worry about synchronizing NextAction.suspend() and this method.
      Parameters:
      throwable - exception that is used in the resumed processing
      packet - Packet that will be visible on the Fiber after the resume
      Since:
      2.2.8

    • resume

      public void resume(@NotNull Throwable error, boolean forceSync)
      Wakes up a suspend fiber with an exception. If forceSync is true, then the suspended fiber will resume with synchronous processing on the current thread. This will continue until some Tube indicates that it is safe to switch to asynchronous processing.
      Parameters:
      error - exception that is used in the resumed processing
      forceSync - if processing begins synchronously
      Since:
      2.2.6

    • resume

      public void resume(@NotNull Throwable error, @NotNull Packet packet, boolean forceSync)
      Wakes up a suspend fiber with an exception. If forceSync is true, then the suspended fiber will resume with synchronous processing on the current thread. This will continue until some Tube indicates that it is safe to switch to asynchronous processing.
      Parameters:
      error - exception that is used in the resumed processing
      packet - Packet that will be visible on the Fiber after the resume
      forceSync - if processing begins synchronously
      Since:
      2.2.8

    • cancel

      public void cancel(boolean mayInterrupt)
      Marks this Fiber as cancelled. A cancelled Fiber will never invoke its completion callback
      Specified by:
      cancel in interface Cancelable
      Parameters:
      mayInterrupt - if cancel should use Thread.interrupt()
      Since:
      2.2.6
      See Also:

    • addInterceptor

      public void addInterceptor(@NotNull FiberContextSwitchInterceptor interceptor)
      Adds a new FiberContextSwitchInterceptor to this fiber.

      The newly installed fiber will take effect immediately after the current tube returns from its Tube.processRequest(Packet) or Tube.processResponse(Packet), before the next tube begins processing.

      So when the tubeline consists of X and Y, and when X installs an interceptor, the order of execution will be as follows:
      1. X.processRequest()
      2. interceptor gets installed
      3. interceptor.execute() is invoked
      4. Y.processRequest()

    • removeInterceptor

      public boolean removeInterceptor(@NotNull FiberContextSwitchInterceptor interceptor)
      Removes a FiberContextSwitchInterceptor from this fiber.

      The removal of the interceptor takes effect immediately after the current tube returns from its Tube.processRequest(Packet) or Tube.processResponse(Packet), before the next tube begins processing.


      So when the tubeline consists of X and Y, and when Y uninstalls an interceptor on the way out, then the order of execution will be as follows:
      1. Y.processResponse() (notice that this happens with interceptor.execute() in the callstack)
      2. interceptor gets uninstalled
      3. interceptor.execute() returns
      4. X.processResponse()
      Returns:
      true if the specified interceptor was removed. False if the specified interceptor was not registered with this fiber to begin with.

    • getContextClassLoader

      @Nullable public ClassLoader getContextClassLoader()
      Gets the context ClassLoader of this fiber.

    • setContextClassLoader

      public ClassLoader setContextClassLoader(@Nullable ClassLoader contextClassLoader)
      Sets the context ClassLoader of this fiber.

    • run

      @Deprecated public void run()
      Deprecated.
      DO NOT CALL THIS METHOD. This is an implementation detail of Fiber.
      Specified by:
      run in interface Runnable

    • runSync

      @NotNull public Packet runSync(@NotNull Tube tubeline, @NotNull Packet request)
      Runs a given Tube (and everything thereafter) synchronously.

      This method blocks and returns only when all the successive Tubes complete their request/response processing. This method can be used if a Tube needs to fallback to synchronous processing.

      Example: 

       class FooTube extends AbstractFilterTubeImpl {
   NextAction processRequest(Packet request) {
     // run everything synchronously and return with the response packet
     return doReturnWith(Fiber.current().runSync(next,request));
   }
   NextAction processResponse(Packet response) {
     // never be invoked
   }
 }
      Parameters:
      tubeline - The first tube of the tubeline that will act on the packet.
      request - The request packet to be passed to startPoint.processRequest().
      Returns:
      The response packet to the request.
      See Also:

    • resetCont

      public void resetCont(Tube[] conts, int contsSize)
      Only to be used by Tubes that manipulate the Fiber to create alternate flows
      Since:
      2.2.6

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getPacket

      @Nullable public Packet getPacket()
      Gets the current Packet associated with this fiber.

      This method returns null if no packet has been associated with the fiber yet.

    • getCompletionCallback

      public Fiber.CompletionCallback getCompletionCallback()
      Returns completion callback associated with this Fiber
      Returns:
      Completion callback
      Since:
      2.2.6

    • setCompletionCallback

      public void setCompletionCallback(Fiber.CompletionCallback completionCallback)
      Updates completion callback associated with this Fiber
      Parameters:
      completionCallback - Completion callback
      Since:
      2.2.6

    • isSynchronous

      public static boolean isSynchronous()
      (ADVANCED) Returns true if the current fiber is being executed synchronously.

      Fiber may run synchronously for various reasons. Perhaps this is on client side and application has invoked a synchronous method call. Perhaps this is on server side and we have deployed on a synchronous transport (like servlet.)

      When a fiber is run synchronously (IOW by runSync(Tube, Packet)), further invocations to runSync(Tube, Packet) can be done without degrading the performance.

      So this value can be used as a further optimization hint for advanced Tubes to choose the best strategy to invoke the next Tube. For example, a tube may want to install a FiberContextSwitchInterceptor if running async, yet it might find it faster to do runSync(Tube, Packet) if it's already running synchronously.

    • isStartedSync

      public boolean isStartedSync()
      Returns true if the current Fiber on the current thread was started synchronously. Note, this is not strictly the same as being synchronous because the assumption is that the Fiber will ultimately be dispatched asynchronously, possibly have a completion callback associated with it, etc. Note, the 'startedSync' flag is cleared once the current Fiber is converted to running asynchronously.
      Since:
      2.2.6

    • current

      @NotNull public static Fiber current()
      Gets the current fiber that's running.

      This works like Thread.currentThread(). This method only works when invoked from Tube.

    • getCurrentIfSet

      public static Fiber getCurrentIfSet()
      Gets the current fiber that's running, if set.

    • getSPI

      public <S> S getSPI(Class<S> spiType)
      Description copied from interface: Component
      Gets the specified SPI.

      This method works as a kind of directory service for SPIs, allowing various components to define private contract and talk to each other.

      Specified by:
      getSPI in interface Component
      Returns:
      null if such an SPI is not provided by this object.

    • getComponents

      public Set<Component> getComponents()
      Description copied from interface: ComponentRegistry
      Returns the set of Components registered with this object
      Specified by:
      getComponents in interface ComponentRegistry
      Returns:
      set of registered components