[WIP]fix invalid watcher iterator while found before removing it from map …

[ashione]

{
{
Lock lock( mWatchesLock);
wit = mWatches.find( pevent->wd);
}
wit->second;
}

iterator wit might be an invalid if this iterator has been removed from map collection after find method.

[ashione]

I found it fix invalid iterator issue but there is another deadlock condition:

• run & while function holds mWatcherLock, then handleAction wants minitLock
• removeWatcher function hodls mInitLock, but requires mWatcherLock

[SpartanJ]

Hi @ashione, thanks for collaborating!
I think this can generate a deadlock as you mentioned, let me check it a little bit.
Maybe we can get the iterator end inside the lock, something like:

bool foundIt = false;
{
	Lock lock( mWatchesLock );

	wit = mWatches.find( pevent->wd );
	foundIt = wit != mWatches.end();
}

if ( foundIt ) {

[ashione]

Hi @ashione, thanks for collaborating! I think this can generate a deadlock as you mentioned, let me check it a little bit. Maybe we can get the iterator end inside the lock, something like:

bool foundIt = false;
{
	Lock lock( mWatchesLock );

	wit = mWatches.find( pevent->wd );
	foundIt = wit != mWatches.end();
}

if ( foundIt ) {

Actually, we use this data in handleAction after iterator located but related inotify pointer had been deleted.
How to avoid accessing invalid iterator out of thie scope lock domain?