org.duraspace.fcrepo.cloudsync.service.backend
Class TaskManager

java.lang.Object
  java.lang.Thread
      org.duraspace.fcrepo.cloudsync.service.backend.TaskManager

All Implemented Interfaces:

Runnable, TaskCompletionListener

public class TaskManager
extends Thread
implements TaskCompletionListener

This Thread is responsible for managing the execution of tasks.

Signals and State Transitions

• For tasks in the "starting" state, spin up an appropriate TaskRunner and move to the "running" state in the database.
• For tasks in the "pausing" state, set a flag with the appropriate TaskRunner, requesting that it pause itself. Give the task some way to signal that it is actually paused, during which, among other things, the state in the database is set to "paused".
• For tasks in the "resuming" state, notify() the appropriate TaskRunner and move the state to "running" in the database.
• For tasks in the "canceling" state, set a flag with the appropriate TaskRunner, requesting that it cancel itself. Give the task some way to signal its completion, during which, among other things, the state in the database is set to idle.

Note: The requestPause() and requestCancel() methods of a TaskRunner may be called multiple times in a row. Implementations should ensure these are not expensive calls to make. In addition, requestCancel() may be called immediately after requestPause(), before pausing actually occurs. TaskRunners should be smart enough to assume the request to Pause has been overridden by the request to cancel.

TaskManager Lifecycle

The requestShutdown() method of this class is expected to be called from the Servlet Context Listener. The method will loop until all tasks are in the idle state, then signal to the TaskManager thread to complete. If any tasks are not in the idle state, they will be set to "canceling".

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

TaskManager(TaskDao taskDao, TaskLogDao taskLogDao, ObjectSetDao objectSetDao, ObjectStoreDao objectStoreDao, HttpClientConfig httpClientConfig)

Method Summary

void	run()
void	shutdown()
Date	taskCanceled(Task task)
Date	taskFailed(Task task, Throwable cause)
Date	taskSucceeded(Task task)

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskManager

public TaskManager(TaskDao taskDao,
                   TaskLogDao taskLogDao,
                   ObjectSetDao objectSetDao,
                   ObjectStoreDao objectStoreDao,
                   HttpClientConfig httpClientConfig)

Method Detail

run

public void run()

Specified by:

run in interface Runnable

Overrides:

run in class Thread

shutdown

public void shutdown()

taskSucceeded

public Date taskSucceeded(Task task)

Specified by:

taskSucceeded in interface TaskCompletionListener

taskFailed

public Date taskFailed(Task task,
                       Throwable cause)

Specified by:

taskFailed in interface TaskCompletionListener

taskCanceled

public Date taskCanceled(Task task)

Specified by:

taskCanceled in interface TaskCompletionListener