X-Git-Url: https://gerrit.onap.org/r/gitweb?a=blobdiff_plain;f=datarouter-node%2Fsrc%2Fmain%2Fjava%2Forg%2Fonap%2Fdmaap%2Fdatarouter%2Fnode%2FTaskList.java;h=1eb73c69161d6438a95506d78b22cd9f923f9115;hb=0a440fd3ae3b413cd7de57677aec690f14ec7d53;hp=c8d58e6ed5f50e49809ce0e456f24c37087988da;hpb=e4b20cc6f7c31f48ddd0de5bcd054b09a35cd510;p=dmaap%2Fdatarouter.git diff --git a/datarouter-node/src/main/java/org/onap/dmaap/datarouter/node/TaskList.java b/datarouter-node/src/main/java/org/onap/dmaap/datarouter/node/TaskList.java index c8d58e6e..1eb73c69 100644 --- a/datarouter-node/src/main/java/org/onap/dmaap/datarouter/node/TaskList.java +++ b/datarouter-node/src/main/java/org/onap/dmaap/datarouter/node/TaskList.java @@ -1,113 +1,120 @@ -/******************************************************************************* - * ============LICENSE_START================================================== - * * org.onap.dmaap - * * =========================================================================== - * * Copyright © 2017 AT&T Intellectual Property. All rights reserved. - * * =========================================================================== - * * Licensed under the Apache License, Version 2.0 (the "License"); - * * you may not use this file except in compliance with the License. - * * You may obtain a copy of the License at - * * - * * http://www.apache.org/licenses/LICENSE-2.0 - * * - * * Unless required by applicable law or agreed to in writing, software - * * distributed under the License is distributed on an "AS IS" BASIS, - * * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - * * See the License for the specific language governing permissions and - * * limitations under the License. - * * ============LICENSE_END==================================================== - * * - * * ECOMP is a trademark and service mark of AT&T Intellectual Property. - * * - ******************************************************************************/ - - -package org.onap.dmaap.datarouter.node; - -import java.util.*; - -/** - * Manage a list of tasks to be executed when an event occurs. - * This makes the following guarantees: - * - */ -public class TaskList { - private Iterator runlist; - private HashSet tasks = new HashSet(); - private HashSet togo; - private HashSet sofar; - private HashSet added; - private HashSet removed; - /** - * Construct a new TaskList - */ - public TaskList() { - } - /** - * Start executing the sequence of tasks. - */ - public synchronized void startRun() { - sofar = new HashSet(); - added = new HashSet(); - removed = new HashSet(); - togo = new HashSet(tasks); - runlist = togo.iterator(); - } - /** - * Get the next task to execute - */ - public synchronized Runnable next() { - while (runlist != null) { - if (runlist.hasNext()) { - Runnable task = runlist.next(); - if (removed.contains(task)) { - continue; - } - if (sofar.contains(task)) { - continue; - } - sofar.add(task); - return(task); - } - if (added.size() != 0) { - togo = added; - added = new HashSet(); - removed.clear(); - runlist = togo.iterator(); - continue; - } - togo = null; - added = null; - removed = null; - sofar = null; - runlist = null; - } - return(null); - } - /** - * Add a task to the list of tasks to run whenever the event occurs. - */ - public synchronized void addTask(Runnable task) { - if (runlist != null) { - added.add(task); - removed.remove(task); - } - tasks.add(task); - } - /** - * Remove a task from the list of tasks to run whenever the event occurs. - */ - public synchronized void removeTask(Runnable task) { - if (runlist != null) { - removed.add(task); - added.remove(task); - } - tasks.remove(task); - } -} +/******************************************************************************* + * ============LICENSE_START================================================== + * * org.onap.dmaap + * * =========================================================================== + * * Copyright © 2017 AT&T Intellectual Property. All rights reserved. + * * =========================================================================== + * * Licensed under the Apache License, Version 2.0 (the "License"); + * * you may not use this file except in compliance with the License. + * * You may obtain a copy of the License at + * * + * * http://www.apache.org/licenses/LICENSE-2.0 + * * + * * Unless required by applicable law or agreed to in writing, software + * * distributed under the License is distributed on an "AS IS" BASIS, + * * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * * See the License for the specific language governing permissions and + * * limitations under the License. + * * ============LICENSE_END==================================================== + * * + * * ECOMP is a trademark and service mark of AT&T Intellectual Property. + * * + ******************************************************************************/ + + +package org.onap.dmaap.datarouter.node; + +import java.util.HashSet; +import java.util.Iterator; + +/** + * Manage a list of tasks to be executed when an event occurs. This makes the following guarantees: + *
    + *
  • Tasks can be safely added and removed in the middle of a run.
    • + *
  • No task will be returned more than once during a run.
    • + *
  • No task will be returned when it is not, at that moment, in the list of tasks.
    • + *
  • At the moment when next() returns null, all tasks on the list have been returned during the run.
    • + *
  • Initially and once next() returns null during a run, next() will continue to return null until startRun() is + * called. + *
+ */ +public class TaskList { + + private Iterator runlist; + private HashSet tasks = new HashSet<>(); + private HashSet togo; + private HashSet sofar; + private HashSet added; + private HashSet removed; + + /** + * Start executing the sequence of tasks. + */ + public synchronized void startRun() { + sofar = new HashSet<>(); + added = new HashSet<>(); + removed = new HashSet<>(); + togo = new HashSet<>(tasks); + runlist = togo.iterator(); + } + + /** + * Get the next task to execute + */ + public synchronized Runnable next() { + while (runlist != null) { + if (runlist.hasNext()) { + Runnable task = runlist.next(); + if (addTaskToSoFar(task)) { + return task; + } + } + if (!added.isEmpty()) { + togo = added; + added = new HashSet<>(); + removed.clear(); + runlist = togo.iterator(); + continue; + } + togo = null; + added = null; + removed = null; + sofar = null; + runlist = null; + } + return (null); + } + + /** + * Add a task to the list of tasks to run whenever the event occurs. + */ + public synchronized void addTask(Runnable task) { + if (runlist != null) { + added.add(task); + removed.remove(task); + } + tasks.add(task); + } + + /** + * Remove a task from the list of tasks to run whenever the event occurs. + */ + public synchronized void removeTask(Runnable task) { + if (runlist != null) { + removed.add(task); + added.remove(task); + } + tasks.remove(task); + } + + private boolean addTaskToSoFar(Runnable task) { + if (removed.contains(task)) { + return false; + } + if (sofar.contains(task)) { + return false; + } + sofar.add(task); + return true; + } +}