Sync method

[nathany]

There is also a question of synchronization. Ideally you want to have a "Sync()" method that guarantees that when it returns, all events for modifications made before the call to Sync have now been delivered...

I know how to build a Sync from the fsevents API. I am less sure about the others; probably it is possible but it requires some thought. It also affects the API, because you need to know when the events triggered by the Sync have stopped. If the events are coming over a channel, you need some kind of sentinel event marking the sync position. This is all unclear to me. I think fsevents gives some clear guarantees about delivery that let you build Sync.

Windows FindFirstChangeNotification seems not to give any at all. For example, you find out about file changes in a directory by watching the mtime on the files, but the docs say: "The operating system detects a change to the last write-time only when the file is written to the disk. For operating systems that use extensive caching, detection occurs only when the cache is sufficiently flushed."

That's clearly useless for interactive go command build result caching. - @rsc, https://groups.google.com/d/msg/golang-dev/bShm2sqbrTY/IR8eI20Su8EJ