com.firefly.utils.concurrent

类 IteratingCallback

java.lang.Object

com.firefly.utils.concurrent.IteratingCallback

所有已实现的接口:

Callback

直接已知子类:

IteratingNestedCallback

public abstract class IteratingCallback
extends Object
implements Callback

This specialized callback implements a pattern that allows a large job to be broken into smaller tasks using iteration rather than recursion.

A typical example is the write of a large content to a socket, divided in chunks. Chunk C1 is written by thread T1, which also invokes the callback, which writes chunk C2, which invokes the callback again, which writes chunk C3, and so forth.

The problem with the example is that if the callback thread is the same that performs the I/O operation, then the process is recursive and may result in a stack overflow. To avoid the stack overflow, a thread dispatch must be performed, causing context switching and cache misses, affecting performance.

To avoid this issue, this callback uses an AtomicReference to record whether success callback has been called during the processing of a sub task, and if so then the processing iterates rather than recurring.

Subclasses must implement method process() where the sub task is executed and a suitable IteratingCallback.Action is returned to this callback to indicate the overall progress of the job. This callback is passed to the asynchronous execution of each sub task and a call the succeeded() on this callback represents the completion of the sub task.

嵌套类概要

嵌套类

限定符和类型	类和说明
protected static class	IteratingCallback.Action The indication of the overall progress of the overall job that implementations of process() must return.

从接口继承的嵌套类/接口 com.firefly.utils.concurrent.Callback

Callback.Completable, Callback.Nested, Callback.NonBlocking

字段概要

从接口继承的字段 com.firefly.utils.concurrent.Callback

NOOP

构造器概要

构造器

限定符	构造器和说明
protected	IteratingCallback()
protected	IteratingCallback(boolean needReset)

方法概要

限定符和类型	方法和说明
void	close()
void	failed(Throwable x) Invoked when the sub task fails.
boolean	isClosed()
boolean	isFailed()
boolean	isSucceeded()
void	iterate() This method must be invoked by applications to start the processing of sub tasks.
protected void	onCompleteFailure(Throwable cause) Invoked when the overall task has completed with a failure.
protected void	onCompleteSuccess() Invoked when the overall task has completed successfully.
protected abstract IteratingCallback.Action	process() Method called by iterate() to process the sub task.
boolean	reset() Resets this callback.
void	succeeded() Invoked when the sub task succeeds.
String	toString()

从类继承的方法 java.lang.Object

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

从接口继承的方法 com.firefly.utils.concurrent.Callback

from, from, isNonBlocking

构造器详细资料

IteratingCallback

protected IteratingCallback()

IteratingCallback

protected IteratingCallback(boolean needReset)

方法详细资料

process

protected abstract IteratingCallback.Action process()
                                             throws Exception

Method called by iterate() to process the sub task.

Implementations must start the asynchronous execution of the sub task (if any) and return an appropriate action:

• IteratingCallback.Action.IDLE when no sub tasks are available for execution but the overall job is not completed yet
• IteratingCallback.Action.SCHEDULED when the sub task asynchronous execution has been started
• IteratingCallback.Action.SUCCEEDED when the overall job is completed

返回:

the appropriate Action

抛出:

Exception - if the sub task processing throws

onCompleteSuccess

protected void onCompleteSuccess()

Invoked when the overall task has completed successfully.

另请参阅:

onCompleteFailure(Throwable)

onCompleteFailure

protected void onCompleteFailure(Throwable cause)

Invoked when the overall task has completed with a failure.

参数:

cause - the throwable to indicate cause of failure

另请参阅:

onCompleteSuccess()

iterate

public void iterate()

This method must be invoked by applications to start the processing of sub tasks. It can be called at any time by any thread, and it's contract is that when called, then the process() method will be called during or soon after, either by the calling thread or by another thread.

succeeded

public void succeeded()

Invoked when the sub task succeeds. Subclasses that override this method must always remember to call super.succeeded().

指定者:

succeeded 在接口中 Callback

另请参阅:

Callback.failed(Throwable)

failed

public void failed(Throwable x)

Invoked when the sub task fails. Subclasses that override this method must always remember to call super.failed(Throwable).

指定者:

failed 在接口中 Callback

参数:

x - the reason for the operation failure

close

public void close()

isClosed

public boolean isClosed()

isFailed

public boolean isFailed()

返回:

whether this callback has failed

isSucceeded

public boolean isSucceeded()

返回:

whether this callback has succeeded

reset

public boolean reset()

Resets this callback.

A callback can only be reset to IDLE from the SUCCEEDED or FAILED states or if it is already IDLE.

返回:

true if the reset was successful

toString

public String toString()

覆盖:

toString 在类中 Object