I need to show elements on a table depending on the element (Person) clicked on another table. The problem is that, using a Service, if the user clicks on two elements of the first table very quickly, the data of the two elements is showed in the table, and I only want to show the data from the last one clicked. Hope you can help me.
Here is my code:
personTable.getSelectionModel().selectedItemProperty().addListener(
(observable, oldValue, newValue) -> {
try {
contactoTable.setPlaceholder(new Label("Cargando..."));
showPersonDetails(newValue);
} catch (SQLException ex) {
Logger.getLogger(PersonOverviewController.class.getName()).log(Level.SEVERE, null, ex);
}
});
And showPersonDatails:
contactoTable.setVisible(true);
contactoTable.getItems().clear();
firstNameLabel.setText(person.getFirstName());
lastNameLabel.setText(person.getLastName());
mailLabel.setText(person.getMail());
phoneLabel.setText(person.getPhone());
descriptionLabel.setText(person.getDescription());
service = new Service<Void>() {
#Override
protected Task<Void> createTask() {
return new Task<Void>() {
#Override
protected Void call() throws Exception {
//Background work
DBManager db = new DBManager();
String query = "SELECT * FROM eventos";
ResultSet r = db.executeSelect(query);
contactoTable.getItems().clear();
contactoData.clear();
while (r.next()) {
String q = "SELECT * FROM " + r.getString("Nombre").replace(" ", "_") + " WHERE Nombre = '" + person.getFirstName() + "' AND Apellidos = '" + person.getLastName() + "' AND Correo = '" + person.getMail() + "'";
ResultSet result = db.executeSelect(q);
while (result.next()) {
contactoData.add(new Row(r.getString("Nombre"), result.getString("Asistencia")));
}
}
final CountDownLatch latch = new CountDownLatch(1);
Platform.runLater(() -> {
try {
//FX Stuff done here
contactoTable.setPlaceholder(new Label("No invitado a ningún evento"));
contactoTable.setItems(contactoData);
} finally {
latch.countDown();
}
});
latch.await();
//Keep with the background work
return null;
}
};
}
};
service.start();
You are referencing the same data list (contactoData) from multiple threads, with apparently no synchronization on the list. If the user selects two different items in rapid succession, you launch a service for each one, each service running its task in a different thread. Consequently you have no control over the order the two different threads perform their (multiple) manipulations on contactoData. For example, it is possible (even probable) that the order for two services executing asynchronously is:
First service clears the list
Second service clears the list
First service adds elements to the list
Second service adds elements to the list
and in this case the list contains elements generated by both services, not just one of them.
So you should have your tasks operate on, and return, a new list they create. Then process that list on the FX Application Thread.
It's also not clear why you need a service here, as you only seem to ever use each service once. You may as well just use a task directly.
You also probably want to ensure that the last selection is the one displayed. Since the tasks are running asynchronously, it's possible that if two tasks were started in quick succession, the second would complete before the first. This would result in the second selection being displayed, and then the first selection replacing it. You can avoid this by doing the UI update in an onSucceeded handler, and canceling any current task when you start a new one (thus preventing the currently-executing task from invoking its onSucceeded handler).
Finally, it's really not clear to me why you are making the task wait until the UI is updated.
Here is an updated version of your code:
private Task<List<Row>> updateContactTableTask ;
// ...
private void showPersonDetails(Person person) {
contactoTable.getItems().clear();
firstNameLabel.setText(person.getFirstName());
lastNameLabel.setText(person.getLastName());
mailLabel.setText(person.getMail());
phoneLabel.setText(person.getPhone());
descriptionLabel.setText(person.getDescription());
if (updateContactTableTask != null && updateContactTableTask.isRunning()) {
updateContactTableTask.cancel();
}
updateContactTableTask = new Task<List<Row>>() {
#Override
protected List<Row> call() throws Exception {
List<Row> resultList = new ArrayList<>() ;
//Background work
DBManager db = new DBManager();
String query = "SELECT * FROM eventos";
ResultSet r = db.executeSelect(query);
// quit if we got canceled here...
if (isCancelled()) {
return resultList;
}
while (r.next() && ! isCancelled()) {
// Note: building a query like this is inherently unsafe
// You should use a PreparedStatement in your DBManager class instead
String q = "SELECT * FROM " + r.getString("Nombre").replace(" ", "_") + " WHERE Nombre = '" + person.getFirstName() + "' AND Apellidos = '" + person.getLastName() + "' AND Correo = '" + person.getMail() + "'";
ResultSet result = db.executeSelect(q);
while (result.next()) {
resultList.add(new Row(r.getString("Nombre"), result.getString("Asistencia")));
}
}
return resultList ;
}
};
updateContactTableTask.setOnSucceeded(e -> {
// not really clear you still need contactoData, but if you do:
contactoData.setAll(updateContactTableTask.getValue());
contactoTable.setPlaceholder(new Label("No invitado a ningún evento"));
contactoTable.setItems(contactoData);
});
updateContactTableTask.setOnFailed(e -> {
// handle database errors here...
});
new Thread(updateContactTableTask).start();
}
As an aside, it's not clear to me if, and if so, how, you are closing your database resources. E.g. the result sets never seem to get closed. This could cause resource leaks. However this is incidental to the question (and relies on knowing how your DBManager class is implemented), so I won't address it here.
Related
I have changed all my multi-thread actions in my application to Akka a few weeks ago.
However, since it seems that I am starting to run out of Heap space (after a week or so).
By basically looking at all actors with
ActorSelection selection = getContext().actorSelection("/*");
the number of actors seems to increase all the time. After an hour of running I have more then 2200. They are called like:
akka://application/user/$Aic
akka://application/user/$Alb
akka://application/user/$Alc
akka://application/user/$Am
akka://application/user/$Amb
I also noticed that when opening websockets (and closing them) there are these:
akka://application/system/Materializers/StreamSupervisor-2/flow-21-0-unnamed
akka://application/system/Materializers/StreamSupervisor-2/flow-2-0-unnamed
akka://application/system/Materializers/StreamSupervisor-2/flow-27-0-unnamed
akka://application/system/Materializers/StreamSupervisor-2/flow-23-0-unnamed
Is there something specific that I need to do to close them and let them be cleaned?
I am not sure the memory issue is related, but the fact that there seem so many after an hour on the production server it could be.
[EDIT: added the code to analyse/count the actors]
public class RetrieveActors extends AbstractActor {
private String identifyId;
private List<String> list;
public RetrieveActors(String identifyId) {
Logger.debug("Actor retriever identity: " + identifyId);
this.identifyId = identifyId;
}
#Override
public Receive createReceive() {
Logger.info("RetrieveActors");
return receiveBuilder()
.match(String.class, request -> {
//Logger.info("Message: " + request + " " + new Date());
if(request.equalsIgnoreCase("run")) {
list = new ArrayList<>();
ActorSelection selection = getContext().actorSelection("/*");
selection.tell(new Identify(identifyId), getSelf());
//ask(selection, new Identify(identifyId), 1000).thenApply(response -> (Object) response).toCompletableFuture().get();
} else if(request.equalsIgnoreCase("result")) {
//Logger.debug("Run list: " + list + " " + new Date());
sender().tell(list, self());
} else {
sender().tell("Wrong command: " + request, self());
}
}).match(ActorIdentity.class, identity -> {
if (identity.correlationId().equals(identifyId)) {
ActorRef ref = identity.getActorRef().orElse(null);
if (ref != null) { // to avoid NullPointerExceptions
// Log or store the identity of the actor who replied
//Logger.info("The actor " + ref.path().toString() + " exists and has replied!");
list.add(ref.path().toString());
// We want to discover all children of the received actor (recursive traversal)
ActorSelection selection = getContext().actorSelection(ref.path().toString() + "/*");
selection.tell(new Identify(identifyId), getSelf());
}
}
sender().tell(list.toString(), self());
}).build();
}
}
I'm getting spurious errors when trying to doInBackground of an AsyncTask which I initiate in MainActivity when the user clicks btnSearch.
Here's the part of doInBackground where I might get no error, might get error after 1 transaction, might get error at record 23001 after 23 transactions. I got returnCode < 0 after trying to insertWord.
private class LoadDatabase extends AsyncTask<Object, Integer, Void
{
protected Void doInBackground(Object[] params)
{
...
my_openDb("DatabaseConnector.LoadDatabase.doInBackground");
while(scDict.hasNext())
{
int kTransactions = 0;
try
{
mDatabase.beginTransaction();
while(kTransactions < MAX_TRANSACTIONS && scDict.hasNext())
{
s = scDict.next();
count++;
long returnCode = insertWord(s); // error here **********
if(returnCode < 0)
{
if(debug) Log.w("`````Abort--can't add <",s + "> at " + count + " with RC = " + returnCode + " and KT = " + kTransactions );
my_closeDb("DatabaseConnector.LoadDatabase.doInBackground DISASTER");//$$
System.exit(0);
}
++ kTransactions;
}
mDatabase.setTransactionSuccessful();
}
catch(Exception e){ Log.w("`````", "Exception " + e.toString()); }
finally
{
mDatabase.endTransaction();
publishProgress((Integer) (int) s.charAt(0));
}
}
my_closeDb("doInBackground outer while ended");
Method insertWord:
long insertWord(String _word)
{
long r = -1;
ContentValues newWord = new ContentValues();
newWord.put(WORD_COLUMN_NAME, _word);
try {
// r = mDatabase.insert (TABLE_NAME,null,newWord);
r = mDatabase.insertWithOnConflict(TABLE_NAME,null,newWord,SQLiteDatabase.CONFLICT_REPLACE);
return r;
} catch (Exception e) {
if(debug)Log.w("DBC", "insert failed for <" + _word + ">");
if(debug)Log.w("DBC", "exception " + e.toString());
my_closeDb(DatabaseConnector.insertWord");
}
return -1 ; // -1 if can't insert
}
The commented out line always worked in the past, until major overhaul to simplify code. (GREAT idea.)(NOT!) I got the idea of insertWithOnConflict from https://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html where they say insertWithOnConflict is the General method for inserting a row into the database.
Of course I got insert from a text book. AS says it's a convenience method for inserting a row into the database. But it does lack the algorithm for resolving conflicts. There shouldn't be any conflicts. I made the change to insertWithOnConflict when I got errors with insert.
That was probably my first warning that I was on thin ice.
I call DatabaseConnector from MainActivity, which calls inner classes: DatabaseHelper, which calls LoadDatabase and then doInBackground.
I'm not sure I should have an AsyncTask so directly connected to MainActivity because of Answers and comments suggesting concurrence issues might be a problem.
Another suggestion was to put the AsyncTask inside MainActivity. That would mean I'd have to move classes DatabaseConnector and its inner classes there, too. If it all seems overly-complicated, I just followed the big example in a textbook. But you must connect the database to the activity, and you do need help, and if the task MUST run in the background, so it must be AsyncTask, as I understand it.
Call from MainActivity:
dbc = new DatabaseConnector(MainActivity.this, getAssets(), databaseFileExists());
In DatabaseConnector:
public DatabaseConnector(Context _context, AssetManager _assets, boolean dbExists)
{
mContext = _context;
mDbOpenHelper = new DbOpenHelper(_context, DATABASE_NAME, null, 1);
SQLiteDatabase db = mDbOpenHelper.getWritableDatabase();
if( ! dbExists)
createAndOrFillDb(db);
}
createAndOrFillDb:
void createAndOrFillDb(SQLiteDatabase db)
{
...
db.execSQL("CREATE TABLE " + TABLE_NAME + "(" + WORD_COLUMN_NAME + " TEXT primary key );")
//...
cursor = db.query(TABLE_NAME, mColumns, null, null, null, null, WORD_COLUMN_NAME);
//...
LoadDatabase
__loadDb;
__loadDb = new LoadDatabase();
__loadDb.execute((Object[]) null);
}
So my questions are
(1) Do you think I'm getting spurious results during transactions in doInBackground because of it being in a class separate from MainActivity and if so, what can I do about it?
(2) Do you think I should just stick 1200 lines of code into MainActivity, resulting in a 2200-line monster so I won't have to worry about concurrency?
(3) Maybe initiate doInBackground from a thread separate from UI? (No clue how to control that, but I'm willing to try.)
(4) What else might you suggest?
I'm using Java to download HTML contents of websites whose URLs are stored in a database. I'd like to put their HTML into database, too.
I'm using Jsoup for this purpose:
public String downloadHTML(String byLink) {
String htmlInPage = "";
try {
Document doc = Jsoup.connect(byLink).get();
htmlInPage = doc.html();
} catch (org.jsoup.UnsupportedMimeTypeException e) {
// process this and some other exceptions
}
return htmlInPage;
}
I'd like to download websites concurrently and use this function:
public void downloadURL(int websiteId, String url,
String categoryName, ExecutorService executorService) {
executorService.submit((Runnable) () -> {
String htmlInPage = downloadHTML(url);
System.out.println("Category: " + categoryName + " " + websiteId + " " + url);
String insertQuery =
"INSERT INTO html_data (website_id, html_contents) VALUES (?,?)";
dbUtils.query(insertQuery, websiteId, htmlInPage);
});
}
dbUtils is my class based on Apache Commons DbUtils. Details are here: http://pastebin.com/iAKXchbQ
And I'm using everything mentioned above in a such way: (List<Object[]> details are explained on pastebin, too)
public static void main(String[] args) {
DbUtils dbUtils = new DbUtils("host", "db", "driver", "user", "pass");
List<String> categoriesList =
Arrays.asList("weapons", "planes", "cooking", "manga");
String sql = "SELECT lw.id, lw.website_url, category_name " +
"FROM list_of_websites AS lw JOIN list_of_categories AS lc " +
"ON lw.category_id = lc.id " +
"where category_name = ? ";
ExecutorService executorService = Executors.newFixedThreadPool(10);
for (String category : categoriesList) {
List<Object[]> sitesInCategory = dbUtils.select(sql, category );
for (Object[] entry : sitesInCategory) {
int websiteId = (int) entry[0];
String url = (String) entry[1];
String categoryName = (String) entry[2];
downloadURL(websiteId, url, categoryName, executorService);
}
}
executorService.shutdown();
}
I'm not sure if this solution is correct but it works. Now I want to modify code to save HTML not from all websites in my database, but only their fixed ammount in each category.
For example, download and save HTML of 50 websites from the "weapons" category, 50 from "planes", etc. I don't think it's necessary to use sql for this purpose: if we select 50 sites per category, it doesn't mean we save them all, because of possibly incorrect syntax and connection problems.
I've tryed to create separate class implementing Runnable with fields: counter and maxWebsitesPerCategory, but these variables aren't updated. Another idea was to create field Map<String,Integer> sitesInCategory instead of counter, put each category as a key there and increment its value until it reaches maxWebsitesPerCategory, but it didn't work, too. Please, help me!
P.S: I'll also be grateful for any recommendations connected with my realization of concurrent downloading (I haven't worked with concurrency in Java before and this is my first attempt)
How about this?
for (String category : categoriesList) {
dbUtils.select(sql, category).stream()
.limit(50)
.forEach(entry -> {
int websiteId = (int) entry[0];
String url = (String) entry[1];
String categoryName = (String) entry[2];
downloadURL(websiteId, url, categoryName, executorService);
});
}
sitesInCategory has been replaced with a stream of at most 50 elements, then your code is run on each entry.
EDIT
In regard to comments. I've gone ahead and restructured a bit, you can modify/implement the content of the methods I've suggested.
public void werk(Queue<Object[]> q, ExecutorService executorService) {
executorService.submit(() -> {
try {
Object[] o = q.remove();
try {
String html = downloadHTML(o); // this takes one of your object arrays and returns the text of an html page
insertIntoDB(html); // this is the code in the latter half of your downloadURL method
}catch (/*narrow exception type indicating download failure*/Exception e) {
werk(q, executorService);
}
}catch (NoSuchElementException e) {}
});
}
^^^ This method does most of the work.
for (String category : categoriesList) {
Queue<Object[]> q = new ConcurrentLinkedQueue<>(dbUtils.select(sql, category));
IntStream.range(0, 50).forEach(i -> werk(q, executorService));
}
^^^ this is the for loop in your main
Now each category tries to download 50 pages, upon failure of downloading a page it moves on and tries to download another page. In this way, you will either download 50 pages or have attempted to download all pages in the category.
I am getting too many deadlocks on OrientDb while I am using Java API to query the vertices. After the deadlock happens, the entire database becomes unresponsive and I have to kill the daemon and start again. As example, the error that I get from deadlocks is :
com.orientechnologies.common.concur.OTimeoutException: Can not lock record for 2000 ms. seems record is deadlocked by other record
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.acquireReadLock(OAbstractPaginatedStorage.java:1300)
at com.orientechnologies.orient.core.tx.OTransactionAbstract.lockRecord(OTransactionAbstract.java:120)
at com.orientechnologies.orient.core.id.ORecordId.lock(ORecordId.java:282)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.lockRecord(OAbstractPaginatedStorage.java:1776)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.readRecord(OAbstractPaginatedStorage.java:1416)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.readRecord(OAbstractPaginatedStorage.java:694)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.executeReadRecord(ODatabaseDocumentTx.java:1569)
at com.orientechnologies.orient.core.tx.OTransactionNoTx.loadRecord(OTransactionNoTx.java:80)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.load(ODatabaseDocumentTx.java:1434)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.readRecord(ONetworkProtocolBinary.java:1456)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.executeRequest(ONetworkProtocolBinary.java:346)
at com.orientechnologies.orient.server.network.protocol.binary.OBinaryNetworkProtocolAbstract.execute(OBinaryNetworkProtocolAbstract.java:216)
at com.orientechnologies.common.thread.OSoftThread.run(OSoftThread.java:65)
Following is the block that I use to query edges and create associations between vertices
public User generateFriend(String mobile, String userRID) {
StringBuilder errorMsg = new StringBuilder();
Iterable<OrientVertex> vertexes;
//Retrieve friends of the user
List<User> friendsList = new ArrayList<User>();
vertexes = db.queryVertices("select expand( unionAll(inE('E_Friend').out,outE('E_Friend').in) ) from " + userRID,errorMsg);
if (!errorMsg.toString().equals("")) {
throw new DbException("Db exception occured, " + errorMsg);
}
for (OrientVertex v : vertexes){
friendsList.add(vertexToUser(v));
}
//Create edges if between the user and other users with mobile number in the list and if the edge is not yet created
User u = findUserByMobileNo(friendsList,mobile);
if ( u == null){
u = findByMobileNo(mobile);
if (u != null) {
//create edge
db.executeQuery("select createEdge('E_Friend','" + userRID + "','" + u.getRid() + "') from " + userRID, new HashMap<String, Object>(), errorMsg);
if (!errorMsg.toString().equals("")) {
throw new DbException("Db exception occured, " + errorMsg);
}
}
}
return u;
}
public Iterable<OrientVertex> queryVertices(String query, StringBuilder errMsg){
logger.error("before getGraph, " + errMsg.toString());
graph = getGraph(errMsg);
if (!errMsg.toString().equals("")){
return null;
}
logger.error("after getGraph, " + errMsg.toString());
Iterable<OrientVertex> vertices = null;
try {
OSQLSynchQuery<OrientVertex> qr = new OSQLSynchQuery<OrientVertex>(query);
vertices = graph.command(qr).execute();
logger.error("after graph command execute, " + errMsg.toString());
}
catch (Exception ex){
errMsg.append(ex.getMessage());
logger.error("graph command exception, " + errMsg.toString());
}
logger.error("before return vertices, " + errMsg.toString());
return vertices;
}
public List<ODocument> executeQuery(String sql, HashMap<String,Object> params,StringBuilder errMsg) {
List<ODocument> result = new ArrayList<ODocument>();
try {
db = getDatabase(errMsg);
if (!errMsg.toString().equals("")){
return null;
}
OSQLSynchQuery<ODocument> query = new OSQLSynchQuery<ODocument>(sql);
if (params.isEmpty()) {
result = db.command(query).execute();
} else {
result = db.command(query).execute(params);
}
} catch (Exception e) {
errMsg.append(e.getMessage());
//TODO: Add threaded error log saving mechanism
}
return result;
}
Due to index missing on table deadlock come, so check your all table which are involved in this operation and find out that indexes are present or not on column.
Refer link in which I have a same problem of deadlock.
I'm following this tutorial to write a workflow for 3 HTML forms (without using CQ5 form component and CQ5 workflow submit button). I use this code to write Process step handling for my workflow:
public class MyProcess implements WorkflowProcess {
public void execute(WorkItem item, WorkflowSession session,
MetaDataMap map) throws WorkflowException {
boolean advanced = false;
Boolean goBack = map.get("goBack", Boolean.class);
List<Route> routes = null;
if (goBack == null || goBack == false) {
routes = session.getRoutes(item);
} else {
routes = session.getBackRoutes(item);
}
for (Route route : routes) {
LOG.info("===============================");
LOG.info("Rout name: " + route.getName());
LOG.info("Destinations: ");
for (WorkflowTransition dest: route.getDestinations()) {
LOG.info("dest: " + dest.getTo().getTitle());
}
LOG.info("===============================");
if (route.hasDefault()) {
String fromTitle = item.getNode().getTitle();
String toTitle = route.getDestinations().get(0).getTo()
.getTitle();
session.complete(item, route);
LOG.info("===============================");
LOG.info(item.getId() + " advanced from " + fromTitle
+ " to " + toTitle);
LOG.info("===============================");
advanced = true;
}
}
// fallback if no route was marked as default
if (!advanced) {
session.complete(item, routes.get(0));
String fromTitle = item.getNode().getTitle();
String toTitle = routes.get(0).getDestinations().get(0).getTo()
.getTitle();
LOG.info("===============================");
LOG.info(item.getId() + " advanced from " + fromTitle + " to "
+ toTitle);
LOG.info("===============================");
}
}
}
My question is: after i use session.complete to advance to next step, how can i refresh the workflow session to reach the current step information.
I think #yashahuja is correct. I was poking around and on the aem 'working with workflow' page I found some information about persisting data throw workflow steps using MetaDataMap.
From this page: http://dev.day.com/docs/en/cq/current/workflows/wf-extending.html
"Use workflow metadata to persist information that is required during the lifetime of the workflow. A common requirement of workflow steps is to persist data for future use in the workflow, or to retrieve the persisted data.
Workflow metadata is stored in a MetaDataMap object. The Java API provides the Workflow.getMetaDataMap method that returns the MetaDataMap object. Also, the WorkItem.getWorkflowData method returns a WorkflowData object that provides the same getMetaDataMap object.
Therefore, the workflow MetaDataMap object is available to the OSGi service or ECMA script of a step component."
example:
public void execute(WorkItem item, WorkflowSession session, MetaDataMap args) throws WorkflowException {
MetaDataMap wfd = item.getWorkflow().getMetaDataMap();
wfd.put("mykey", "My Step Value");
Set<String> keyset = wfd.keySet();
Iterator<String> i = keyset.iterator();
while (i.hasNext()){
Object key = i.next();
log.info("The workflow medata includes key {} and value {}",key.toString(),wfd.get(key).toString());
}