How does synchronize in the File Path component work?

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Permalink Reply by David Rutten on January 6, 2014 at 9:06am

It watches for file system events regarding the files in question. They're a bit cumbersome to deal with because the file system may raise multiple events for a single file change. For example when writing a large file you may get several events during the entire write process. There's also issues with path length and such, it's all terribly 1980's and I don't quite understand why there still isn't something better available.

Also it seems that watching for filesystem events on network drives is exceptionally slow, so only use them for local drives.

The basis of events in .NET are reasonably simple:

• An event is a special type of field that is part of a class/structure. It can be both static and instance bound.
• A handler is a method with a specific signature (one that matches the event signature). This method can be private, protected, internal, public, static, non-static, doesn't matter.
• You register/unregister a handler with an event using the AddHandler and RemoveHandler keywords in VB and the += and -= operators in C#.
• An event can have any number of handler associated with it and a single handler can 'watch' any number of events, provided it fits the signature for all of them.
• When the event is 'raised', it basically calls all the handler methods in order.
• When a handler is associated with an event, the event keeps the handler alive. In other words, Garbage Collector will not collect the object which contains the handler, unless the object containing the event is also collectable. This is one of the more intricate ways in which memory is 'leaked' in .NET applications, it's often difficult to remember to properly unregister handlers and it's hard to find out exactly how many and which handlers are listening to a specific event.

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David Rutten

david@mcneel.com