No more handle exceptions with the Edge browser

[vogella]

Using the Edge browser on Windows still results in a the no more handlers exception even after the commit ed8f821 from @HeikoKlare

Before the commit, the error was in Edge.java:343, now it occurs in Edge.java:362.

https://github.com/eclipse-platform/eclipse.platform.swt/blob/master/bundles/org.eclipse.swt/Eclipse%20SWT%20Browser/win32/org/eclipse/swt/browser/Edge.java#L362C1-L363C1

It seems to happen if the user starts multiple time the same application in different workspaces. I will try to provide a test case to reproduce.

[vogella]

See #339

[HeikoKlare]

I am sorry that Edge instantiation does still not work properly. We did not have issues in productive usage recently, but we do not use it intensively either (usually only one instance). Some remarks on this:

• Even though a `no more handles" error is shown, that is probably not the reason. This error is thrown if anything unexpected happens during WebView2 instantiation.
• I once tried to parameterize the browser tests to also be executed for Edge (Execute browser tests for Edge #671 #672). But I have not been successful yet because of some interference between the test cases and their used Edge instances: it looked as if some OS events were not processed properly (see https://github.com/eclipse-platform/eclipse.platform.swt/pull/672/files#r1202546545).

I could image that the problem you describe, @vogella, is related to the one that can be seen in the tests.
What I tried to do in my previous fix attempt was to ensure that asynchronous OS events for browser instantiation are processed properly. Taking a fresh look at the code, I would first have a look at the involved Edge#callAndWait() implementations again:

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT Browser/win32/org/eclipse/swt/browser/Edge.java

Lines 212 to 247 in 2cdfd97

	static int callAndWait(long[] ppv, ToIntFunction<IUnknown> callable) {
	int[] phr = {COM.S_OK};
	IUnknown completion = newCallback((result, pv) -> {
	phr[0] = (int)result;
	if ((int)result == COM.S_OK) {
	ppv[0] = pv;
	new IUnknown(pv).AddRef();
	}
	return COM.S_OK;
	});
	ppv[0] = 0;
	phr[0] = callable.applyAsInt(completion);
	completion.Release();
	while (phr[0] == COM.S_OK && ppv[0] == 0) {
	processNextOSMessage();
	}
	return phr[0];
	}
	static int callAndWait(String[] pstr, ToIntFunction<IUnknown> callable) {
	int[] phr = new int[1];
	IUnknown completion = newCallback((result, pszJson) -> {
	phr[0] = (int)result;
	if ((int)result == COM.S_OK) {
	pstr[0] = wstrToString(pszJson, false);
	}
	return COM.S_OK;
	});
	pstr[0] = null;
	phr[0] = callable.applyAsInt(completion);
	completion.Release();
	while (phr[0] == COM.S_OK && pstr[0] == null) {
	processNextOSMessage();
	}
	return phr[0];
	}

From my understanding, the OS event processing is supposed to trigger the callback setting the results (ppv/phr). However, the callAndWait performs a release on the callback even before doing the event processing, so maybe the problem is something pretty simple like an interface pointer being released too early.

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT Browser/win32/org/eclipse/swt/browser/Edge.java

Lines 224 to 227 in 2cdfd97

	completion.Release();
	while (phr[0] == COM.S_OK && ppv[0] == 0) {
	processNextOSMessage();
	}

[HeikoKlare]

@vogella can you share which kind of error code is printed? I.e., there should be a message like
org.eclipse.swt.SWTError: No more handles [0x802a000c]
and the error code at the end of the message would be of particular interest. For error code 0x802a000c (wrong thred access), I have provided #1015 to better distinguish that kind of error.

[vogella]

We see two errors:
No more handles [0x8007139f]
No more handles [0x800700aa]

[0x8007139f] happens more frequently.

[HeikoKlare]

Thanks for sharing!

Some documentation I found (including the Microsoft documentation) states the following:

• 0x800700AA (ERROR_BUSY): May be used to indicate that the device is busy processing another operation. Applications should wait for that operation to complete before retrying.
• 0x8007139F: The group or resource is not in the correct state to perform the requested operation (also documented in a WebView2 issue)

The question is what kind of concurrent operation or incorrect state that is. One thing I could imagine is the access to a shared data directory: all Edge instances within (Eclipse) applications that have the same application name share the same data directory with the following path:

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Display.java

Line 2851 in 44432b2

appLocalDir = System.getenv("LOCALAPPDATA") + "\\" + Display.APP_NAME.replaceAll("[\\\\/:*?\"<>|]", "_");

This will be something like C:\Users\...\AppData\Local\Eclipse.

@vogella is it possible for you to set the system property org.eclipse.swt.browser.EdgeDataDir to something different for each application and test if the issue still occurs? This will result in a different data folder for each application and would allow to verify whether the shared data directory is related to the issue.

[vogella]

@HeikoKlare thanks for the information, we will try the org.eclipse.swt.browser.EdgeDataDir setting and I will report back if that solves the issue.