Java tutorial
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If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package javax.resource.spi.work; import java.lang.Object; import java.lang.Runnable; import java.lang.Exception; import java.lang.Throwable; /** * This interface models a <code>WorkManager</code> which provides a facility * to submit <code>Work</code> instances for execution. This frees the user * from having to create Java threads directly to do work. Further, this * allows efficient pooling of thread resources and more control over thread * usage. * * The various stages in <code>Work</code> processing are: * <ul> * <li> work submit: A <code>Work</code> instance is being submitted for * execution. The <code>Work</code> instance could either be accepted or * rejected with a <code>WorkRejectedException</code> set to an appropriate * error code. </li> * * <li> work accepted: The submitted <code>Work</code> instance has been * accepted. The accepted <code>Work</code> instance could either start * execution or could be rejected again with a * <code>WorkRejectedException</code> set to an appropriate error code. * There is no guarantee on when the execution would start unless a start * timeout duration is specified. When a start timeout is specified, the * <code>Work</code> execution must be started within the specified * duration (not a real-time guarantee), failing which a * <code>WorkRejectedException</code> set to an error code * (<code>WorkRejected.TIMED_OUT</code>) is thrown. </li> * * <li> work rejected: The <code>Work</code> instance has been rejected. * The <code>Work</code> instance could be rejected during <code>Work</code> * submittal or after the <code>Work</code> instance has been accepted * (but before Work instance starts execution). The rejection could be due * to internal factors or start timeout expiration. A * <code>WorkRejectedException</code> with an appropriate error code * (indicates the reason) is thrown in both cases. </li> * * <li> work started: The execution of the <code>Work</code> * instance has started. This means that a thread * has been allocated for its execution. But this * does not guarantee that the allocated thread has been scheduled to run * on a CPU resource. Once execution is started, the allocated thread * sets up an appropriate execution context (transaction , security, etc) * and calls Work.run(). Note, any exception thrown during execution context * setup or Work.run() leads to completion of processing. </li> * * <li> work completed: The execution of the <code>Work</code> has been * completed. The execution could complete with or without an exception. * The <code>WorkManager</code> catches any exception thrown during * <code>Work</code> processing (which includes execution context setup), * and wraps it with a <code>WorkCompletedException</code>. </li> * </ul> * * @version 1.0 * @author Ram Jeyaraman */ public interface WorkManager { /** * A constant to indicate timeout duration. A zero timeout value indicates * an action be performed immediately. The WorkManager implementation * must timeout the action as soon as possible. */ long IMMEDIATE = 0L; /** * A constant to indicate timeout duration. A maximum timeout value * indicates that an action be performed arbitrarily without any time * constraint. */ long INDEFINITE = Long.MAX_VALUE; /** * A constant to indicate an unknown start delay duration or other unknown * values. */ long UNKNOWN = -1; /** * Accepts a <code>Work</code> instance for processing. This call * blocks until the <code>Work</code> instance completes execution. * There is no guarantee on when the accepted <code>Work</code> * instance would start execution ie., there is no time constraint * to start execution. (that is, startTimeout=INDEFINITE) * * @param work The unit of work to be done. * Could be long or short-lived. * * @throws WorkRejectedException indicates that a * <code>Work</code> instance has been rejected from further processing. * This can occur due to internal factors. * * @throws WorkCompletedException indicates that a * <code>Work</code> instance has completed execution with an exception. */ void doWork(Work work) // startTimeout = INDEFINITE throws WorkException; /** * Accepts a <code>Work</code> instance for processing. This call * blocks until the <code>Work</code> instance completes execution. * * @param work The unit of work to be done. * Could be long or short-lived. * * @param startTimeout a time duration (in milliseconds) * within which the execution of the <code>Work</code> instance must * start. Otherwise, the <code>Work</code> instance is rejected with a * <code>WorkRejectedException</code> set to an appropriate error code * (<code>WorkRejectedException.TIMED_OUT</code>). Note, this * does not offer real-time guarantees. * * @param execContext an object containing the execution * context with which the submitted <code>Work</code> instance must * be executed. * * @param workListener an object which would be notified * when the various <code>Work</code> processing events (work accepted, * work rejected, work started, work completed) occur. * * @throws WorkRejectedException indicates that a * <code>Work</code> instance has been rejected from further processing. * This can occur due to internal factors or start timeout expiration. * * @throws WorkCompletedException indicates that a * <code>Work</code> instance has completed execution with an exception. */ void doWork(Work work, long startTimeout, ExecutionContext execContext, WorkListener workListener) throws WorkException; /** * Accepts a <code>Work</code> instance for processing. This call * blocks until the <code>Work</code> instance starts execution * but not until its completion. There is no guarantee on when * the accepted <code>Work</code> instance would start * execution ie., there is no time constraint to start execution. * (that is, startTimeout=INDEFINITE) * * @param work The unit of work to be done. * Could be long or short-lived. * * @return the time elapsed (in milliseconds) from <code>Work</code> * acceptance until start of execution. Note, this does not offer * real-time guarantees. It is valid to return -1, if the actual start * delay duration is unknown. * * @throws WorkRejectedException indicates that a * <code>Work</code> instance has been rejected from further processing. * This can occur due to internal factors. */ long startWork(Work work) // startTimeout = INDEFINITE throws WorkException; /** * Accepts a <code>Work</code> instance for processing. This call * blocks until the <code>Work</code> instance starts execution * but not until its completion. There is no guarantee on when * the accepted <code>Work</code> instance would start * execution ie., there is no time constraint to start execution. * * @param work The unit of work to be done. * Could be long or short-lived. * * @param startTimeout a time duration (in milliseconds) * within which the execution of the <code>Work</code> instance must * start. Otherwise, the <code>Work</code> instance is rejected with a * <code>WorkRejectedException</code> set to an appropriate error code * (<code>WorkRejectedException.TIMED_OUT</code>). Note, this * does not offer real-time guarantees. * * @param execContext an object containing the execution * context with which the submitted <code>Work</code> instance must * be executed. * * @param workListener an object which would be notified * when the various <code>Work</code> processing events (work accepted, * work rejected, work started, work completed) occur. * * @return the time elapsed (in milliseconds) from <code>Work</code> * acceptance until start of execution. Note, this does not offer * real-time guarantees. It is valid to return -1, if the actual start * delay duration is unknown. * * @throws WorkRejectedException indicates that a * <code>Work</code> instance has been rejected from further processing. * This can occur due to internal factors or start timeout expiration. */ long startWork(Work work, long startTimeout, ExecutionContext execContext, WorkListener workListener) throws WorkException; /** * Accepts a <code>Work</code> instance for processing. This call * does not block and returns immediately once a <code>Work</code> * instance has been accepted for processing. There is no guarantee * on when the submitted <code>Work</code> instance would start * execution ie., there is no time constraint to start execution. * (that is, startTimeout=INDEFINITE). * * @param work The unit of work to be done. * Could be long or short-lived. * * @throws WorkRejectedException indicates that a * <code>Work</code> instance has been rejected from further processing. * This can occur due to internal factors. */ void scheduleWork(Work work) // startTimeout = INDEFINITE throws WorkException; /** * Accepts a <code>Work</code> instance for processing. This call * does not block and returns immediately once a <code>Work</code> * instance has been accepted for processing. * * @param work The unit of work to be done. * Could be long or short-lived. * * @param startTimeout a time duration (in milliseconds) * within which the execution of the <code>Work</code> instance must * start. Otherwise, the <code>Work</code> instance is rejected with a * <code>WorkRejectedException</code> set to an appropriate error code * (<code>WorkRejectedException.TIMED_OUT</code>). Note, this * does not offer real-time guarantees. * * @param execContext an object containing the execution * context with which the submitted <code>Work</code> instance must * be executed. * * @param workListener an object which would be notified * when the various <code>Work</code> processing events (work accepted, * work rejected, work started, work completed) occur. * * @throws WorkRejectedException indicates that a * <code>Work</code> instance has been rejected from further processing. * This can occur due to internal factors. */ void scheduleWork(Work work, long startTimeout, ExecutionContext execContext, WorkListener workListener) throws WorkException; }