private void Pause(String description) throws Exception {
Utilities.Log.Debug(
"Pausing for "
+ Settings.PAUSE_SECONDS
+ " seconds: "
+ description
+ ". Other threads may be processing these tasks.");
Thread.currentThread().sleep(Settings.PAUSE_SECONDS * 1000);
Utilities.Log.Debug("Retrying after pause: " + description + ".");
}
// Execute all callable objects and pause if any of them has not completed
public void ExecuteWithRetries(String description) throws Exception {
ArrayList results = Lists.CreateBooleanList(false);
do {
try {
// Try to execute the tasks
results = Execute();
// If any of the tasks have not yet been executed, pause
if (Lists.AnyFalse(results)) Pause(description);
} catch (Exception ex) {
// Pause after an exception has occurred
Utilities.Log.Exception(ex);
Pause(description);
}
} while (Lists.AnyFalse(results));
}
/**
* Executes multiple callable objects in a multithreaded fashion
*
* @return Objects that are returned from each _callable object
* @throws Exception
*/
public ArrayList Execute() throws Exception {
if (_callables == null || _callables.size() == 0) return new ArrayList();
Utilities.Log.Debug("Attempting to share execution across " + _numThreads + " threads.");
ArrayList results = new ArrayList();
// If only one thread is desired, then there is no need to involve the more complicated thread
// pool logic
if (_numThreads == 1) {
for (Callable callable : _callables) {
Object result = callable.call();
if (result != null) results.add(result);
}
return results;
}
// The logic below enables multi-threaded execution
ExecutorService service = Executors.newFixedThreadPool(_numThreads);
ArrayList<Future<Object>> futures = new ArrayList<Future<Object>>();
for (Callable<Object> callable : _callables) futures.add(service.submit(callable));
for (Future<Object> future : futures) {
Object result = future.get(Settings.THREAD_TIMEOUT_MINUTES, TimeUnit.MINUTES);
if (result != null) results.add(result);
}
// Very important to shut down the service
service.shutdown();
return results;
}