hi I'm using DiskArbitration.framework to get list of disks
+(NSArray*)arrayOfDisks {
DASessionRef session = DASessionCreate(kCFAllocatorDefault);
if (session) {
DARegisterDiskAppearedCallback(session, NULL, driveGo, NULL);
DASessionScheduleWithRunLoop(session,
CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
CFRelease(session);
}
return nil;
}
void driveGo(DADiskRef disk, void *context) {
NSLog(#"%s", DADiskGetBSDName(disk));
}
it logs up just fine, but how can I return array back?
it just loop so I even dont know how to check is it done or not.
You could change your method and store the array in a private variable:
(void*) driveGo(DADiskRef disk, void *context) {
NSLog(#"%s", DADiskGetBSDName(disk));
self->_myArray = DADiskGetBSDName(disk);
}
it just loop so I even dont know how to check is it done or not.
There is no “done”. Your callback will be called for every “disk” that is currently known to DiskArb and every “disk” that appears from then on. There is no separation between the two.
Most applications should work with that, rather than against it. Let DiskArb tell you the moment new “disks” appear, change (DescriptionChanged), are mounted or unmounted (also DescriptionChanged), or disappear. Keep your information up to date as those changes come in, and always have the current state.
Most applications do not need to get a complete and fixed snapshot of the current set of mounted volumes. But if, for some reason, you do, you might try the getmntinfo function instead.
Related
Sooo...
I have written a plugin, and the whole plugin works fine.
ONLY PROBLEM:
My TS3 Client crashes.
To give a context:
(Warning: That code is just poorly pasted. On GitHub, it crashes at line 270 and 285)
// Helper Function
String^ getChannelName(uint64 serverConnectionHandlerID, uint64 channelID) {
char* tmp;
if (ts3Functions.getChannelVariableAsString(serverConnectionHandlerID, channelID, CHANNEL_NAME, &tmp) == ERROR_ok) {
return marshal_as<String^>(tmp);
}
else
{
return "ERROR_GETTING_CHANNELNAME";
}
}
void assemble_a() {
List<String^>^ clients;
List<String^>^ channel;
// Some middlepart here, but I made sure it works as it should
// And the actual part where it is crashing
if (resChL == ERROR_ok) {
for (int i = 0; channelListPtr[i]; ++i) {
String^ a = getChannelName(schid, channelListPtr[i]);
const char* b = (const char*)(Marshal::StringToHGlobalAnsi(a)).ToPointer();
ts3Functions.logMessage(b, LogLevel_DEBUG, "DEBUG_VC", schid);
if (String::IsNullOrEmpty(a) == false) {
channel->Add(a); // It crashes RIGHT at this point
}
}
}
}
So I am asking on the TS3 forum for a long time, got a lot of answers, and noone could tell me why it actually crashes, and I didn't manage to figure it out on my own either.
It does actually print the channel name [*spacer0]t but as soon as it should append it to the String List, it crashes.
It throws the message The thread has tried to write or read from a virtual address that it does not have the accesspermissions for.
I seriously have no idea what to do, trying to fix it now for over 2 weeks.
For full context: GitHub Sourcecode
Sorry if this question MIGHT be a little out of topic here (Is it? I don't know...) but I don't really know what to do with that problem anymore...
EDIT:
Errormessage from try/catch is:
System.NullReferebceException: The Objectreference was not set to the Objectinstance, occured in tsapi.assembleGrammar()
List<String^>^ channel;
...
channel->Add(a);
channel is null. You need to initialize it with something, probably gcnew List<String^>(). I'm not sure why you're getting an access denied message instead of NullReferenceException.
Other issues
Make sure you're handling all the unmanaged strings properly. For example, does getChannelVariableAsString require a call to explicitly free the buffer? Be absolutely sure to call FreeHGlobal to free the memory that StringToHGlobalAnsi allocated for you.
I have a pretty standard MVC3 application. I'm trying to store some data that's application-wide (not user wide) in a the cache (in this case, a Theme object/name). When debugging (on the development server that integrates with Visual Studio), if I call SwitchTheme, I see the new theme right away. On IIS7, whatever theme was cached, stays cached; it doesn't update to the new theme.
Edit: Some code:
public static Theme CurrentTheme { get {
Theme currentTheme = HttpContext.Current.Cache[CURRENT_THEME] as Theme;
if (currentTheme == null)
{
string themeName = DEFAULT_THEME;
try
{
WebsiteSetting ws = WebsiteSetting.First(w => w.Key == WebsiteSetting.CURRENT_THEME);
if (ws != null && !string.IsNullOrEmpty(ws.Value))
{
themeName = ws.Value;
}
}
catch (Exception e)
{
// DB not inited, or we're installing, or something broke.
// Don't panic, just use the default.
}
// Sets HttpContext.Current.Cache[CURRENT_THEME] = new themeName)
Theme.SwitchTo(themeName);
currentTheme = HttpContext.Current.Cache[CURRENT_THEME] as Theme;
}
return currentTheme;
} }
public static void SwitchTo(string name)
{
HttpContext.Current.Cache.Insert(CURRENT_THEME, new Theme(name), null, System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(30));
// Persist change to the DB.
// But don't do this if we didn't install the application yet.
try
{
WebsiteSetting themeSetting = WebsiteSetting.First(w => w.Key == WebsiteSetting.CURRENT_THEME);
if (themeSetting != null)
{
themeSetting.Value = name;
themeSetting.Save();
}
// No "else"; if it's not there, we're installing, or Health Check will take care of it.
}
catch (Exception e)
{
// DB not inited or install not complete. No worries, mate.
}
}
I'm not sure where the problem is. I am calling the same method and updating the cache; but IIS7 just shows me the old version.
I can disable output caching in IIS, but that's not what I want to do. That seems like a hacky work-around at best.
Without a code sample it's difficult to know what your problem is. In an attempt to provide some assistance, here is how I frequently set the cache in my applications:
public static void SetCache(string key, object value) {
if (value != null) {
HttpRuntime.Cache.Insert(key, value, null, System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(30));
}
}
The HTTP cache is reset only if you do so manually or the app domain (or app pool) resets for whatever reason. Are you sure that's not happening in this case? And generally speaking, any global static variables would also be maintained in memory under the same circumstances.
There are many reasons why an app pool might be reset at any given point, such as a change to a web.config file, etc. I suggest checking that's not happening in your case.
By the way, output caching is a different thing, although it is maintained in memory largely the same way.
Given that this only happens on IIS7 when Output Caching is not disabled, this seems very likely to be an IIS7 bug. Seriously.
Whether it is or not, is irrelevant to the solution. What you need to do is find some manual process of invalidating the cache, such as touching the web.config file.
But beware: doing this will wipe out the cache (as you expect), but also all static variables (as a side-effect). Whether this is another bug or not, I don't know; but in my case, this was sufficient to solve the problem.
Update: I have dropped the cache system in favor of a database solution - pitty.
I have a backend MVC controller where i need data caching. I use MemoryCache.Default to store key/value pairs, nothing big. Nevermind policies and expire times, i'f got that. The thing that mystifys me is why my cache gets cleaned out after I'f accessed a key (retrived the value) the first time. If i don't access the cached item, eventually the item will expire and my remove handler is called - it's all good. But when i retrive the item the first time, my remove handler is called after a short while. The ChacheEntryRemovedReason is set to:
CacheSpecificEviction // A cache entry was evicted for as reason that is defined by a particular cache implementation.
I can't find any explanation to what this means.
The mystifying thing here is that when i inspect the cache object when debugging in the handler (and on succeeding controller calls), the cache enum is empty. If I "set" (add) a new CacheItem to the cache, I can yet again access the key once, and history repeats.
The behavior is like a one-off caching mechanism which i totally don't need.
Any help or comments would be much appreciated!
Some simplified code just for the fun of it:
private static ObjectCache cache = MemoryCache.Default;
internal void insertInCache(string key, int value) {
CacheItemPolicy policy= new CacheItemPolicy() {
AbsoluteExpiration = ObjectCache.InfiniteAbsoluteExpiration,
Priority = CacheItemPriority.NotRemovable,
SlidingExpiration = TimeSpan.FromMinutes(ITEM_EXPIRE_TIME),
RemovedCallback = new CacheEntryRemovedCallback(RemovedHandler)
};
cache.Set(key, value, policy);
}
static void RemovedHandler(CacheEntryRemovedArguments args) {
if(args.RemovedReason == CacheEntryRemovedReason.Expired) {
//do something - or i actually want it to disappear when expired
} else {
cache.Set(args.CacheItem, somepolicy);//reinsert to keep in cache
}
}
//Apparently this triggers some cache mong mode
internal void getSome(string key){
int thisIsWhatIWanted = (int)cache.GetCacheItem(key).Value;
}
This is just example code so please don't nag me about my skillz.
My own best guess is that it may have to do with the cache not being setup properly, MVC witchery or the fact I'm running my application on a debug IIS (visual studido)
I'm using the code from the official site, and I am consistently seeing the same behavior on multiple test devices - instead of getting the current location of the device, it gets the previous location (up to 30 miles away, where I was an hour ago).
private void setupMaps()
{
watcher = new GeoCoordinateWatcher(GeoPositionAccuracy.High);
watcher.MovementThreshold = 10.0f;
watcher.StatusChanged += new EventHandler<GeoPositionStatusChangedEventArgs>(watcher_statusChanged);
watcher.PositionChanged += new EventHandler<GeoPositionChangedEventArgs<GeoCoordinate>>(watcher_PositionChanged);
new Thread(startLocServInBackground).Start();
}
void startLocServInBackground()
{
watcher.TryStart(true, TimeSpan.FromSeconds(60));
}
void watcher_statusChanged(object sender, GeoPositionStatusChangedEventArgs e)
{
switch (e.Status)
{
case GeoPositionStatus.Disabled:
// The Location Service is disabled or unsupported.
// Check to see if the user has disabled the location service.
if (watcher.Permission == GeoPositionPermission.Denied)
{
// the user has disabled LocServ on their device.
showMessage("Location is required but it is disabled. Turn it on in Settings");
}
else
{
showMessage("Location is not functioning on this phone. Sorry, Crux cannot run");
}
break;
case GeoPositionStatus.Initializing:
// The location service is initializing.
LoadingInfo.Text = "finding location";
break;
case GeoPositionStatus.NoData:
// The Location Service is working, but it cannot get location data
// due to poor signal fidelity (most likely)
// this fired intermittently when data was coming back :/
//MessageBox.Show("Location data is not available.");
break;
case GeoPositionStatus.Ready:
// The location service is working and is receiving location data.
//statusTextBlock.Text = "Location data is available.";
LoadingInfo.Text = "Location found";
// THIS FIRES AFTER POSITION CHANGED HAS STOPPED FIRING
break;
}
}
private void initPostPanel()
{
PostPanel.Visibility = Visibility.Visible;
}
void watcher_PositionChanged(object sender, GeoPositionChangedEventArgs<GeoCoordinate> e)
{
// update the textblock readouts.
latitude = e.Position.Location.Latitude.ToString("0.0000000000");
longitude = e.Position.Location.Longitude.ToString("0.0000000000");
// THIS FIRES TWICE, BEFORE STATUS IS FIRED AS READY. THEN THIS DOESN'T CALL AGAIN
}
What I would expect to have happen is to get a continuous series of calls to PositionChanged after StatusChanged is called with a Status of Ready. If the calls continued after Ready, I expect I would eventually get the correct coordinates - but it never calls after that point.
This does not occur with the emulator, only on the actual device (making this extremely difficult to test - since it actually involves driving between each test!)
I am running the source code from the tutorial as well, and it does roughly the same.
Can anyone tell me more about the expected behavior here and how I get what I need - which is simply a set of coordinates for the device at the current location when the app is being used.
I had the same problem myself - there are 2 parts to this.
Turns out the GeoCoordinateWatcher returns the last known good position - which is almost always out of date. What I do is something like this:
Check that the status is GeoPositionStatus.Ready and then ensure the datetime of the position is recent (within the last 5 mins). You can then go further and check that e.Position.Location.HorizontalAccuracy <= 350 (so under 350m) - but doing this with the datetime check as well can cause the phone to take a long time to get a position the lower you set the accuracy, so it may be best to get an initial position with the date check, and then continue to try get a better position with the Accuracy check. I also start the watcher as soon as the app starts to get faster results.
The other issue is MovementThreshold. If you do as I said above, it might still take a while before you get an accurate position, and you will likely experience the intermittent problem you mentioned where it does not fire the 2nd time (it does eventually, depending how long you wait - this can be minutes). The best thing I have found is to start the GeoCoordinateWatcher with the threshold set to 0. Once you have got an accurate position, stop the watcher, set the threshold to the actual one you want (eg 10), and then start it again. If you set this without stopping first, it will not use the new value.
<!-- language: c# -->
GeoPositionStatus = CurrentGeoDeviceStatus;
static void geoCoordWatcher_StatusChanged(object sender, GeoPositionStatusChangedEventArgs e)
{
CurrentGeoDeviceStatus = e.Status;
}
void watcher_PositionChanged(object sender, GeoPositionChangedEventArgs<GeoCoordinate> e)
{
if (gpsReady && e.Position.Timestamp.DateTime.AddMinutes(5) > DateTime.Now)
{
latitude = e.Position.Location.Latitude.ToString("0.0000000000");
longitude = e.Position.Location.Longitude.ToString("0.0000000000");
locReady = true;
}
}
It looks like the fix was to block it from using the first value and getting it from the second event instead:
bool gpsReady = false;
void watcher_PositionChanged(object sender, GeoPositionChangedEventArgs<GeoCoordinate> e)
{
if (gpsReady)
{
latitude = e.Position.Location.Latitude.ToString("0.0000000000");
longitude = e.Position.Location.Longitude.ToString("0.0000000000");
locReady = true;
}
gpsReady = true;
}
I'm still baffled about why I don't get more events or why it fires an incorrect value first, but the above code seems to be working.
One note, for anyone else trying this, is that you might think getting the value in the StatusChanged event would work, like so:
case GeoPositionStatus.Ready:
latitude = watcher.Position.Location.Latitude.ToString("0.0000000000");
longitude = watcher.Position.Location.Longitude.ToString("0.0000000000");
break;
I don't know why, but the above code seemed to work perfectly when I was running attached to the debugger and then frequently hung (that is, the event never fired and my UI seemed to hang) in practical use. I never managed to reproduced the issue while attached to the debugger.
UPDATE: It looks like this isn't working all of the time. In some cases it doesn't fire the second time and so my code never completes running. If anyone can provide more information around this that gets me closer to simply having the actual current location of the device without fail, I will definitely mark your answer as the answer. Thanks!
I've read Apple's Pasteboard Programming Guide, but it doesn't answer a particular question I have.
I'm trying to write a Cocoa application (for OS X, not iOS) that will keep track of everything that is written to the general pasteboard (so, whenever any application copies and pastes, but not, say, drags-and-drops, which also makes use of NSPasteboard). I could (almost) accomplish this by basically polling the general pasteboard on a background thread constantly, and checking changeCount. Of course, doing this would make me feel very dirty on the inside.
My question is, is there a way to ask the Pasteboard server to notify me through some sort of callback any time a change is made to the general pasteboard? I couldn't find anything in the NSPasteboard class reference, but I'm hoping it lurks somewhere else.
Another way I could imagine accomplishing this is if there was a way to swap out the general pasteboard implementation with a subclass of NSPasteboard that I could define myself to issue a callback. Maybe something like this is possible?
I would greatly prefer if this were possible with public, App Store-legal APIs, but if using a private API is necessary, I'll take that too.
Thanks!
Unfortunately the only available method is by polling (booo!). There are no notifications and there's nothing to observe for changed pasteboard contents. Check out Apple's ClipboardViewer sample code to see how they deal with inspecting the clipboard. Add a (hopefully not overzealous) timer to keep checking for differences and you've got a basic (if clunky) solution that should be App-Store-Friendly.
File an enhancement request at bugreporter.apple.com to request notifications or some other callback. Unfortunately it wouldn't help you until the next major OS release at the earliest but for now it's polling until we all ask them to give us something better.
There was once a post on a mailing list where the decision against a notification api was described. I can't find it right now though. The bottom line was that probably too many applications would register for that api even though they really wouldn't need to. If you then copy something the whole system goes through the new clipboard content like crazy, creating lots of work for the computer. So i don't think they'll change that behavior anytime soon. The whole NSPasteboard API is internally built around using the changeCount, too. So even your custom subclass of NSPasteboard would still have to keep polling.
If you really want to check if the pasteboard changed, just keep observing the changeCount very half second. Comparing integers is really fast so there's really no performance issue here.
Based on answer provided by Joshua I came up with similar implementation but in swift, here is the link to its gist: PasteboardWatcher.swift
Code snippet from same:
class PasteboardWatcher : NSObject {
// assigning a pasteboard object
private let pasteboard = NSPasteboard.generalPasteboard()
// to keep track of count of objects currently copied
// also helps in determining if a new object is copied
private var changeCount : Int
// used to perform polling to identify if url with desired kind is copied
private var timer: NSTimer?
// the delegate which will be notified when desired link is copied
weak var delegate: PasteboardWatcherDelegate?
// the kinds of files for which if url is copied the delegate is notified
private let fileKinds : [String]
/// initializer which should be used to initialize object of this class
/// - Parameter fileKinds: an array containing the desired file kinds
init(fileKinds: [String]) {
// assigning current pasteboard changeCount so that it can be compared later to identify changes
changeCount = pasteboard.changeCount
// assigning passed desired file kinds to respective instance variable
self.fileKinds = fileKinds
super.init()
}
/// starts polling to identify if url with desired kind is copied
/// - Note: uses an NSTimer for polling
func startPolling () {
// setup and start of timer
timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: Selector("checkForChangesInPasteboard"), userInfo: nil, repeats: true)
}
/// method invoked continuously by timer
/// - Note: To keep this method as private I referred this answer at stackoverflow - [Swift - NSTimer does not invoke a private func as selector](http://stackoverflow.com/a/30947182/217586)
#objc private func checkForChangesInPasteboard() {
// check if there is any new item copied
// also check if kind of copied item is string
if let copiedString = pasteboard.stringForType(NSPasteboardTypeString) where pasteboard.changeCount != changeCount {
// obtain url from copied link if its path extension is one of the desired extensions
if let fileUrl = NSURL(string: copiedString) where self.fileKinds.contains(fileUrl.pathExtension!){
// invoke appropriate method on delegate
self.delegate?.newlyCopiedUrlObtained(copiedUrl: fileUrl)
}
// assign new change count to instance variable for later comparison
changeCount = pasteboard.changeCount
}
}
}
Note: in the shared code I am trying to identify if user has copied a
file url or not, the provided code can easily be modified for other general
purposes.
For those who need simplified version of code snippet that gets the job done in Swift 5.7,
it just works (base on #Devarshi code):
func watch(using closure: #escaping (_ copiedString: String) -> Void) {
let pasteboard = NSPasteboard.general
var changeCount = NSPasteboard.general.changeCount
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
guard let copiedString = pasteboard.string(forType: .string),
pasteboard.changeCount != changeCount else { return }
defer {
changeCount = pasteboard.changeCount
}
closure(copiedString)
}
}
how to use is as below:
watch {
print("detected : \($0)")
}
then if you attempt copy any text in your pasteboard, it will watch and print out to the console like below..
detected : your copied message in pasteboard
detected : your copied message in pasteboard
in case, full code sample for how to use it for example in SwiftUI:
import SwiftUI
#main
struct TestApp: App {
var body: some Scene {
WindowGroup {
ContentView()
.onAppear {
watch {
print("detect : \($0)")
}
}
}
}
func watch(using closure: #escaping (_ copiedString: String) -> Void) {
let pasteboard = NSPasteboard.general
var changeCount = NSPasteboard.general.changeCount
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
guard let copiedString = pasteboard.string(forType: .string),
pasteboard.changeCount != changeCount else { return }
defer {
changeCount = pasteboard.changeCount
}
closure(copiedString)
}
}
}
It's not necessary to poll. Pasteboard would generally only be changed by the current view is inactive or does not have focus. Pasteboard has a counter that is incremented when contents change. When window regains focus (windowDidBecomeKey), check if changeCount has changed then process accordingly.
This does not capture every change, but lets your application respond if the Pasteboard is different when it becomes active.
In Swift...
var pasteboardChangeCount = NSPasteboard.general().changeCount
func windowDidBecomeKey(_ notification: Notification)
{ Swift.print("windowDidBecomeKey")
if pasteboardChangeCount != NSPasteboard.general().changeCount
{ viewController.checkPasteboard()
pasteboardChangeCount = NSPasteboard.general().changeCount
}
}
I have a solution for more strict case: detecting when your content in NSPasteboard was replaced by something else.
If you create a class that conforms to NSPasteboardWriting and pass it to -writeObjects: along with the actual content, NSPasteboard will retain this object until its content is replaced. If there are no other strong references to this object, it get deallocated.
Deallocation of this object is the moment when new NSPasteboard got new content.