site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com Hi Mike, firstshell$ mdfind -live "kMDItemFSName=='hamishtest*'" [Type ctrl-C to exit] ........Then in another shell I type........ secondshell$ touch hamishtest1 ........I get an update in the first shell........ Query update: 1 matches ........Then if I type........ secondshell$ ln hamishtest1 hamishtest2 ^C firstshell$ mdfind -live "kMDItemFSName=='hamishtest*'" /Users/hamish/hamishtest1 /Users/hamish/hamishtest1 [Type ctrl-C to exit] firstshell$ mdfind -live "kMDItemFSName=='hamishtest*'" /Users/hamish/hamishtest1 [Type ctrl-C to exit] firstshell$ sudo fslogger-1.0-beta secondshell$ touch foo secondshell$ ln foo bar secondshell$ rm foo secondshell$ rm bar [firstshell stdout, edited for brevity:] # Event type = CREATE FILE VNODE 18 path = /Users/hamish/foo # Event type = CREATE FILE STRING 17 string = /Users/hamish/bar # Event type = DELETE STRING 18 string = /Users/hamish/foo # Event type = DELETE STRING 18 string = /Users/hamish/foo Thanks and best wishes, Hamish On 25 May 2005, at 07:41, Mike Smith wrote: Can anyone tell me how it works? Or could anyone recommend an efficient method for determining when a file in a given directory or any of its subdirectories changes, for a potentially large number of subdirectories? As a general rule, there isn't one. You're making a common mistake in associating "file" with "location". = Mike This email sent to hamish.allan@gold.ac.uk _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... Thank you for your detailed reply. You are right that I have a problem, but Spotlight has it too! For instance, if I initiate the following query........ ........I get nothing in the first shell, but if I restart the query I get........ ........If I then use the second shell to remove hamishtest1, no update, but if I run it again........ ........So now I have a file called hamishtest2, no file called hamishtest1, and a query which returns hamishtest1! You can see a related behaviour using Amit Singh's fslogger utility (thank you to Sam for pointing this out), which uses the new fsevents API: It looks like fsevents is performing caching, as rebooting between "rm foo" and "rm bar" causes the second DELETE to have the correct string = /Users/hamish/bar. It looks as though the first CREATE FILE might be setting this up, as it seems to create a relationship between VNODE and path (whereas the hard link event just has STRING / string). But I don't really understand why this is the case -- surely a DELETE refers not to a vnode, but to an index entry, in which case the correct string ought to be able to be reported? Presumably there is an inverted index (from vnode to path) for every vnode on the filesystem. This must be populated at startup time, as Spotlight returns hamishtest2 for my mdfind query after a reboot. But the behaviour would suggest that although it can be added to for a fresh vnode, the entry for an existing vnode cannot be updated. And the entry is only cleared when the link count reaches zero. I think that if the inverted index allowed multiple paths to be stored for a vnode, the correct behaviour could be achieved. Of course, some of my assumptions may not be correct. Any thoughts? This email is quite long already, but I'll give you a brief outline of my application. You may remember that I posted to this list recently about writing a Spotlight filesystem (http://lists.apple.com/ archives/darwin-dev/2005/May/msg00229.html). I thought it might be possible to get similar functionality without writing a VFS by having a daemon monitor the creation of new directories (either in a particular place, or with Spotlight- searchable attributes) and fill them with hard links to Spotlight search results. To preserve the pathname of the files found, I would create the full directory structure within the given folder; I therefore wanted a way to monitor whether that structure had changed, in order to halt any live updating of results and turn it into a 'normal' folder I should be fine with the existing fsevents API for this, because my daemon process would always create new directories rather than link to existing ones. File paths are indices used to locate files. There is no guarantee that there is exactly one index for a file, nor is there any way to efficiently enumerate all of the indices for a file. Once a file is open, there is a direct relationship between the descriptor and the vnode that does not require the existence of an index; this is how you can delete open files. This means that when a file is modified, there's no guarantee that you know "where" the file may be looked up; nor where it was looked up by whomever is modifying it; nor where the user "thinks" it is. These may be three different locations. Spotlight makes a number of specific assumptions about the notifications that it receives, and it is interested in a view of files that sounds very different from yours. Without knowing a lot more about you application, I can't help you much more; perhaps you could describe what you're trying to achieve? _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/hamish.allan% 40gold.ac.uk This email sent to site_archiver@lists.apple.com