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私の問題：JavaScriptがプラグインを呼び出し、NSOpenPanel（またはNSSavePanel）ダイアログを開くスレッドをフォークします。多くの場合、これは機能しますが、FirefoxとChromeの両方の「runModal」でクラッシュする場合があります。クラッシュはランダムに発生するようで、一部のマシン（おそらく10.7）では他のマシンよりも頻繁に発生します。クラッシュのスタックの場所はさまざまですが、通常はダイアログを開くスレッドで発生します。

クロスプラットフォームコードであるため、POSIXスレッドを使用しますが、NSThreadを生成してCocoaに通知します。

NSThread* t = [[NSThread alloc] init];
[t start];
[t release];

ダイアログを開くコード：

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // necessary?
NSOpenPanel* openPanel = [NSOpenPanel openPanel];
[openPanel setAllowsMultipleSelection:_allowMultipleFiles];
[openPanel setCanChooseFiles:YES];
[openPanel setCanChooseDirectories:YES];
NSInteger result = [openPanel runModal]; // crash
... handle result ...
[pool release];

スタックトレース：

Process:         plugin-container [25536]
Path:            /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container
Identifier:      org.mozilla.plugincontainer
Version:         ??? (1.0)
Code Type:       X86-64 (Native)
Parent Process:  firefox-bin [25531]

Date/Time:       2011-12-09 17:12:04.271 -0800
OS Version:      Mac OS X 10.6.8 (10K549)
Report Version:  6

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x000000000000000d
Crashed Thread:  14

Thread 14 Crashed:
0   XUL                             0x0000000100d84ff4 mac_plugin_interposing_child_OnSetCursor + 38068
1   XUL                             0x0000000100dd38bd mac_plugin_interposing_child_OnSetCursor + 359805
2   XUL                             0x0000000100d7b247 mac_plugin_interposing_child_OnHideCursor + 1175
3   com.apple.AppKit                0x00007fff801cbfdb _NSCreateWindowWithOpaqueShape2 + 610
4   com.apple.AppKit                0x00007fff80160691 -[NSWindow _commonAwake] + 1214
5   com.apple.AppKit                0x00007fff803c282f -[NSWindow _setModal:] + 138
6   com.apple.AppKit                0x00007fff803c2183 -[NSApplication _orderFrontModalWindow:relativeToWindow:] + 482
7   com.apple.AppKit                0x00007fff803c1ce7 -[NSApplication _commonBeginModalSessionForWindow:relativeToWindow:modalDelegate:didEndSelector:contextInfo:] + 714
8   com.apple.AppKit                0x00007fff803c1a18 -[NSApplication beginModalSessionForWindow:] + 36
9   com.apple.AppKit                0x00007fff803c193a -[NSApplication runModalForWindow:] + 106
10  XUL                             0x0000000100d7af01 mac_plugin_interposing_child_OnHideCursor + 337
11  com.apple.AppKit                0x00007fff80627112 -[NSSavePanel runModal] + 318
12  com.aspera.AsperaWeb            0x000000010509f9d4 Connect::Web::MacOpenFolderDialogImpl::doShow() + 596
13  com.aspera.AsperaWeb            0x00000001050a0fa3 Connect::Web::IDialogImpl::show() + 45
14  com.aspera.AsperaWeb            0x00000001050a1e07 Connect::Web::OpenFolderDialog::showHelper(bool) + 141
15  com.aspera.AsperaWeb            0x00000001050a1ef0 Connect::Web::OpenFolderDialog::run() + 42
16  com.aspera.AsperaWeb            0x000000010509eb91 Connect::Web::SingleJobWorker::run() + 63
17  com.aspera.AsperaWeb            0x0000000105098160 start_helper + 38
18  libSystem.B.dylib               0x00007fff8593afd6 _pthread_start + 331
19  libSystem.B.dylib               0x00007fff8593ae89 thread_start + 13

Thread 14 crashed with X86 Thread State (64-bit):
  rax: 0x0000000000000000  rbx: 0x0000000102063840  rcx: 0x0000000000000000  rdx: 0x0000000101e27ee0
  rdi: 0x0000000101e0bcc8  rsi: 0x0000000000000000  rbp: 0x0000000101e27ef0  rsp: 0x000000011d5805e0
   r8: 0x0000000101e0bcc8   r9: 0x00000001040fc0a4  r10: 0x00007fffffe001a0  r11: 0x0000000000000202
  r12: 0x0000000101e27ee0  r13: 0x0000000000000001  r14: 0x000000011d5805e0  r15: 0x000000011d580754
  rip: 0x0000000100d84ff4  rfl: 0x0000000000010246  cr2: 0x000000000000000d

二次スレッドでダイアログを開くのに問題があると思います。たぶん私はメインスレッドでそれを開く必要がありますか？ただし、JavaScript呼び出しを非同期に保ちたいと思います。NSNotificationQueueまたはperformSelectorOnMainThreadを見ています。

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3 に答える 3

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I have a dialog abstraction I use in FireBreath here: https://gist.github.com/1368648

It turns out that you can't use runModal on a secondary thread; it has to be on the main thread of the application. This is a challenge in a NPAPI plugin because you also can't block the main thread during a NPAPI call or the browser (at least chrome and firefox 4+) is likely to kill you.

The solution is to have it run on the main thread, but not as part of the NPAPI call; you can do this by using a performSelectorOnMainThread and not waiting for it to complete. If you provide some sort of callback (an NPObject javascript function works great) you can invoke that when your dialog is done.

FireBreath uses this method for its BrowserHost::ScheduleOnMainThread function, which is what I now use in that gist I referenced. Someone (you?) posted a comment on the gist asking if it works for me; the gist at the time of the comment did not, but I have updated it with the fix (which I just figured out yesterday). Since we updated it to use the performSelectorOnMainThread to run the call later I haven't been able to reproduce the crash.

Looking back, you're already familiar with calling back on the main thread this way: How to callback plugin thread on Safari 5.1 on OSX?

You use the same technique; you'd think blocking the thread there would also be dangerous, but since during a modal dialog the system event loop continues to run you're okay; your code doesn't return, but other events still get dispatched. The browser isn't waiting for a NPAPI call to return so it doesn't seem to have any issues.

于 2011-12-10T05:14:18.940 に答える
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All Appkit isn't thread safe and all Appkit methods should happen on the main thread. You can use the performselectoronmainthread... Methods to force the logic to be on the main thread.

于 2011-12-10T15:18:30.090 に答える
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Open panels should be asynchronous anyway, so there is no reason you can't show the open panel on the main thread. Simply don't use runModal. Ideally, show it as a sheet on the browser window.

When it gets back to you, you can return the result to the JavaScript side by whatever means you were already planning to use for that.

于 2011-12-10T02:18:33.220 に答える